SUMMARY - Health and Safety Executive · A Agronomic impact of Directive 91/414/EEC D rew ssociates CONTENTS Pages Executive Summary (C Knott) i Summaries of crops (C Knott, M Ogilvy)

Drew Associates Limited The Old Rectory Littleton Drew Wiltshire SN14 7NA

Pesticides Safety Directorate Defra

Mallard House, Kings Pool 3 Peasholme Green

York YO1 7PX

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Agronomic impact of Directive 91/414/EEC A D rew ssociates

CONTENTS Pages Executive Summary (C Knott) i Summaries of crops (C Knott, M Ogilvy) 1 1. Winter wheat (M Ogilvy) 29 2, Oilseed rape (C Knott) 63 3. Sugar beet (M Ogilvy) 90

4. Forage Maize (C Knott) 106

5. Potatoes (M Ogilvy) 129 6. Field Peas and Field Beans (C Knott) 156 7. Vining Peas (C Knott) 194 8. Brassicas (Leaf) (C Knott) 217 9. Carrots (C Knott) 252


EXECUTIVE SUMMARY The study shows the status of pesticides the 91/414 EEC Review in June 2006 and the impact on pesticide availability for the crops so far – the situation is changing rapidly and further losses are anticipated. The crops studied were selected by the Pesticide Safety Directorate (PSD) and included five major arable, four horticultural crops, and a forage crop. Specific pesticides/pesticide groups it would be desirable to maintain to avoid major difficulties for crop production are given and prospects for alternatives to fill foreseen gaps are indicated. It is not yet possible to quantify impacts of losses on National yields or quality because some important ‘Essential Uses’ remain until the end of 2007.

Table 1. Area (hectares) of arable crops and forage maize in the United Kingdom 2005 harvest; horticultural crops in the United Kingdom 2004 harvest, potatoes 2005; Gross margins (average) forecasts 2006, maize used on-farm. (Sources: Defra National and Basic Horticultural Statistics, 2006; Nix, 2005)

Wheat

Oilseed rape

Maize forage

Sugar beet

Field Beans

Field Peas

Potatoes

Vining Peas (2004)

Carrots (2004)

Brassicas** Leaf (2004)

1,869,000 593,000 124,000 148,000 187,000 43,000# 137,000 31,455 9,833 31,048

£285/ha w £235/ha w - £1100/ha £240/ha w £160/ha £1300/ha* £750/ha £1800/ha* £1175/ha Key: w winter crop; # mainly peas for stockfeed, (includes peas for human consumption 12,685 ha in 2004); * *cabbage, Brussels sprouts, calabrese, GM for cauliflower; * maincrop ware potatoes, maincrop carrots

Crop specialists, Research Organisations, Crop Levy bodies, Crop Protection Companies and the European Crop Protection Association (ECPA) were consulted for their views on the impact of 91/414EEC, important pesticides and gaps in the armoury to control pests/weeds/diseases. Their help is gratefully acknowledged. Pesticide Usage Surveys by the Central Science Laboratories provided valuable information on the popularity and importance of the pesticides used in the survey year; a list of current authorisations is given for each crop together with the aims of some Companies to re-register in the UK or in another EU Member State in the same climatic zone (Tables given in the main report). Impact of the 91/414/EEC Review Of the 967 active substances in the 91/414/EEC Review process, to date (June, 2006) 45% were not supported across the EU. Crop Protection Company decisions to support an existing active substance depends on several factors: size of the EU market and return on the investment; probability of gaining Annex I inclusion; cost of generating data required (e.g. ecotoxicological studies for old active substances) and availability of new actives for replacement. Some ‘existing’ active substances have failed Annex 1 inclusion. We do not yet know whether those remaining will achieve Annex 1 inclusion but there are likely to be further important losses. The greatest impact of loss of unsupported pesticides in the 91/414/EEC review has been on minor uses, mainly in the horticulture sector. At product re-registration stage, dose rates and number of applications may be reduced and this could have an impact on efficacy. Some active substances on Annex 1 have water issues (toxicity

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to aquatic organisms, drinking water quality). Several review reports advise Member States to mitigate for these and other factors when assessing re-registration. There are approximately 2750 plant protection products (ppps) available in the UK (December 2005) and it was anticipated by the European Crop Protection Assosciation (ECPA), and PSD that company rationalisation would take place at product re-registration stage and not at the time of Annex I inclusion. It is too early to assess the impact of product re-registration after Annex 1 inclusion, but contrary to expectations of UK losses, information from most Companies is that there is the intention of re-registering all UK on-label uses for the crops studied here. Actions to support Minor Uses In recognition of the impact on minor uses (crops or situations that are relatively small in area or sporadic) the Horticulture Development Council (HDC), the UK Minor Uses Network (PSD) and the European Commission Technical Group on Minor Uses are supporting minor use initiatives relating to the control of pests, weeds and diseases. HDC Project FV 287 (2006), by CSL, surveyed Approvals in other EU countries across all horticultural crops. Off–label Approvals http://www.pesticides.gov.uk/applicant_guide.asp?id=1226 based on recognition of on-label approvals in another Member State in the same climatic zone are possible for UK minor crops of areas less than 50,000 ha. The use of the pesticide on the crop must have an on-label approval in the Member State in which the use is approved. There must be an extant on-label approval for the use of the same product on another edible crop in the UK. This route is useful in the event of other MS finding an answer to the problem. However, the UK regulatory system does not permit recognition of off-label approvals in other MS although this would be helpful for minor crops. In the US the IR-4 Program co-operates with the crop protection industry to provide new pest control solutions for US growers of speciality crops. The data protection arrangements offer incentive for development and this approach is being investigated. Funding for the IR-4 Program comes from a variety of sources. Two major USDA agencies, CSREES and ARS, provide the bulk of the funding as appropriated annually by the US Congress and amounted to $13,409,100 in 2004 (Holm et al., 2005). Impact of the MRL Regulation (EC) 396/2005 It is too early to assess the impact of the new regulation 396/2005 on the availability of pesticides for the crop sectors, but there is likely to be a considerable impact on horticulture - where no data are available, or where data were generated using old analytical techniques for some SOLAs. The PSD archive study so far, for actives in List 1 of the review, estimates that 10 – 15% of residues data requires updating. This could be greater for actives on List 3. MRL setting may also preclude some important uses and it might not be possible to grow some UK crops. The cost implications for growers through HDC are considerable.

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http://www.pesticides.gov.uk/applicant_guide.asp?id=1226


Potential impact of the new proposed draft regulation and revision of 91/414/EEC on UK crops

• Mutual Recognition will be helpful where products containing Annex 1 active substances (excluding candidates for substitution) are registered for the crop/use combination in EU Member States in the proposed Central (same climatic zone) but not in the UK.

• National Provisional Authorizations have been helpful in the UK (Crop Protection

Companies), but their loss may have a negative impact on availability of pesticides by delaying decisions for new actives pending a decision on Annex I listing (ECPA).

• Member States shall not authorise a plant protection product containing a ‘candidate for

substitution’ if Comparative Assessment shows that for uses specified in the application there already is an authorised product (or non-chemical control method) which present significantly less risks to health or to the environment. This will take into consideration: that it does not present significant economic or practical disadvantages; that the chemical diversity of the active substance is adequate to minimise occurrence of resistance in the target organism. There could be an impact where older pesticides are used. This is likely to affect horticultural/minor-use crops, where fewer products (several of them old) are approved than for wheat.

• ECPA report that there may be a reduction in pesticide development in the future as a result

of cost/patent arrangements in the draft regulation 91/414/EEC and this is likely to affect all UK crops except wheat and maize.

• The new regulation will form part of the wider “Thematic Strategy for the sustainable use of

pesticides” which includes the Water Framework Directive. There are concerns regarding water issues with some widely used herbicides (e.g. isoproturon and trifluralin for cereals).

• Member States may grant an extension of authorisation for ppps already authorised to a

minor use on a crop that is not widely grown in that Member State or on a widely grown crop to meet an exceptional need (Article 49). This will continue to be very useful to the UK minor crop sector and help other Member States that have not had the benefit of a similar system to UK Specific Off-Label Approvals (SOLAs). The MS List of Minor Uses could also help to identify sources of residues data for minor crops and possible potential for data sharing.

The likely impacts of the 91/414/EEC review process on pesticide availability for UK crops studied

Gross margins for horticultural crops are considerably higher than for winter wheat but there is a risk of crop rejection if quality is unacceptable. As a consequence a high standard of weed, pest and disease control is the aim in horticultural crops and there is a greater need (and incentive to pay) for pesticides but fewer tools as a result of the 91/414/EEC Review. Mechanical weed control is possible in some crops (e.g. maize, leaf brassicas, field beans) but it is expensive and there are also negative environmental impacts.

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Impact so far: 1. There has been no impact yet from the 91/414/EEC Review on winter wheat production. Active substances approved for cereals for example simazine and cyanazine, were lost in the 91/414 Review but there is a wide range of herbicides available for these crops, so no ‘Essential Uses’ were needed and there was no impact. 2. The greatest impacts of the 91/414/EEC Review on the UK crops in this study are from herbicide losses. Few insecticides and fungicides have been lost so far. ‘Essential Uses’ have allowed time to find alternatives but expire 31 December 2007. These will not be extended and no more derogations will be permitted for actives that fail Annex 1 listing in future. It is too early to assess the effect on product efficacy of reduced rates and timings required at re-registration stage, but impacts could be severe where there are no alternatives.

3. Herbicide losses will affect maize, carrots, vining peas, field peas and field beans. Alternative solutions for weed control may eventually become available but the slow process of the review and decisions on Annex 1 inclusion will result in delays.

• UK vining peas will be uneconomic to grow and process, there will be factory closures and frozen and canned peas will be imported from mainland Europe, where different herbicides (active substances supported in the Review) are still available. The UK crop has been dependent on triazines (terbutryn, cyanazine) and fomesafen not supported in the Review. If there is a risk of contamination of produce with toxic weed parts the whole crop is rejected - financial loss £1000/ha After 2007 there will be no broad-spectrum pre-emergence herbicide for vining peas unless those containing actives aclonifen or imazamox currently approved in France are available in the UK for 2008.

• The impact of poor weed control in field peas resulting from the loss of terbutryn,

cyanazine and fomesafen, will be on yield, and quality – there are price deductions for peas contaminated with weed seeds and if crops grown for seed are weedy, they are rejected. There will be more desiccant use to avoid harvesting difficulties and production costs will increase in a crop where gross margins are low £160/ha.

• Weeds in forage maize reduce yield and feed quality. Atrazine, which failed Annex 1

inclusion, was the main herbicide used. In 2005 the cost of weed control in maize with atrazine, was c. £15/ha (including application). In 2006 the cost was £51 to £80/ha assuming both grass and broad-leaved species were present. The next generation of herbicides will be even more expensive. Maize can be mechanically weeded but the cost is higher than for weed control with herbicides. Tractor hoeing costs £69 for two passes or £104/ha for three (Nix, 2005). The UK dairy sector is less reliant on forage maize than some other major milk producing countries, however it is an essential part of winter rations for many producers. Milk at 18 p/L is being produced at cost – the significant increase in herbicide costs or reduction in yield of maize if weeds are not controlled will compound the severe financial pressure being experienced by the majority of dairy farmers and will give further encouragement to cease milk production which in turn may impact on the sustainability of the dairy supply chain.

• If weeds are not controlled in field beans the main impact will be from weed seed return

and infestation of the following crop, and on harvesting difficulties. A desiccant will be needed £28/ha where some weeds remain green. Simazine is used on most of the field bean crop, and. and the cost of weed control, excluding application, will increase from £4/ha for simazine to £67/ha for a tank-mix. Winter field beans will be even less

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profitable. Few alternatives remain because other actives (cyanazine etc.) will also be lost and the future of trifluralin is doubtful.

• For carrots there is no alternative to metoxuron, used to suppress volunteer potato foliage

and the reservoir for potato blight infection will have an impact on neighbouring potato crops. The other losses (pentanochlor, prometryne), and linuron dose restrictions will limit weed control options and quality and yield will be affected. Alternatives have been identified - aclonifen, approved for carrots in Denmark and submitted for registration in France, is urgently needed.

• The loss of cyanazine, and tighter rotations for oilseed rape may result in an increase in

infestations of charlock – a contaminant that downgrades quality of produce. 4. The loss of the nematicide aldicarb:

• This will probably have little impact on the potato crop for potato cyst nematode control because oxamyl and fosthiazate (both are now on Annex 1) are replacements. There may be an impact for the processing crop in particular if oxamyl and fosthiazate prove less effective for spraing suppression.

• In sugar beet (and carrots), oxamyl gives a shorter period of early aphid control. Costs

will be increased for some sugar beet growers who previously used aldicarb and did not use the more expensive imidacloprid seed treatment to control aphid. The loss of aldicarb has compromised resistance strategy options for the control of MACE as well as low-level esterase (R1) resistant M. persicae.

5. The revocation of chlorfenvinphos after the UK Review of anticholinesterase compounds was followed by withdrawal of this active in the UK and it was not supported in the EC Review. Retailers also imposed restrictions on the use of organophosphates.

• This has had an impact on leaf brassicas (but is more serious for swedes and turnips not studied here) where cabbage root fly is now more difficult to control. In leaf brassicas plant loss from cabbage root fly affects uniformity of size and yield, and sometimes quality in calabrese and Brussels sprouts. Alternatives are chlorpyrifos and spinosad (both on Annex 1). Whether these control measures are adequate, remains to be seen.

• In carrots, larvae of carrot fly tunnel into roots, spoiling quality and crops are rejected.

Carrot fly was manageable with insecticide seed treatment followed by repeat applications of lambda-cyhalothrin. However, although the 150ml dose remains the same (new SOLA, August 2006) the number of applications permitted has been reduced to four, and total dose reduced to 450ml. It remains to be seen whether carrot fly can be controlled adequately in future. Reliance on pyrethroids is not a good resistance strategy.

6. Triazamate (withdrawn from the EC review), was very effective for cabbage aphid control. There is concern that it will now be difficult to maintain quality in leaf brassicas. 7. After 2007 the loss of fumigant 2-aminobutane used on skin spot-susceptible varieties and for gangrene control in stored Scottish seed potatoes will mean reduced control of these diseases that are favoured by cool, wet climates. Widespread use of the alternative imazalil in successive generations of multiplication could result in resistance developing in the UK.

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8. Finally, the cost to growers through their levy bodies, in particular the Horticulture Development Council (HDC), of trials to find alternatives will be considerable.

• A significant proportion of growers levy through the HDC has been already been spent on projects to identify alternatives. Since 2002, the overall cost of these projects for horticultural crops is £4.714 million and of this £2.7 million is for vegetables (C Harvey, Chairman, HDC, pers. comm.). Where/if alternative herbicides are identified, and no residues data are available, further HDC funds will be needed for residues studies and SOLAs. HDC estimate that, since it began, the Specific Off-Label Approval programme has cost growers £3.5 million for approximately 960 SOLAs.

• In the case of maize, funding is very limited indeed and insufficient to fund work. • In future HGCA funding may be required to develop herbicide ppps for oilseed rape – only

maize and wheat are considered to be a major EU crops by Crop Protection Companies.

• Substantial funds will also be needed for residues studies for alternatives, or to update old data for SOLAs. There was also a cost for conversion of approvals under the extensions of use (LTAEU) to on-label approvals as SOLAs as required by the EC Directive.

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A summary of the impact of 91/414/EEC so far (as of June 2006) on the crops studied is shown in the Table below. Crop Losses, not

supported (June 06) Losses, failed Annex 1 (June 06)

Re-registration dose-rate restrictions

Impact on production cost, quality, yield etc.

Herbicides & desiccants Winter wheat Reduced dose

isoproturon Too low for black-grass control. Increase resistance selection pressure on options remaining

Oilseed rape cyanazine - Quality, alternative bifenox? Maize cyanazine atrazine simazine Yield, feed value. Cost weed control increased by

£36-£65/ha, cannot be absorbed by dairy farmer Sugar beet - - Reduced dose

metamitron and ethofumesate. Ethofumesate applied once in 3 years

Efficacy Revert to intra-row band spraying/tillage? 3 year may affect horticultural crops onions

Field beans cyanazine fomesafen terbutryn

simazine New alternatives higher cost, desiccant needed

Field peas cyanazine* fomesafen terbutryn

- Yield, cost desiccant needed

Potatoes - - Reduced doses linuron, metribuzin

Scottish seed crops weed control difficult Cost weed control higher

Vining peas cyanazine* fomesafen terbutryn

- Quality; rejection loss to grower £1000/ha; processing costs increase if weed control poor, factory closures

Brassicas, (leaf) cyanazine, sodium monochloroacetate

- Quality, size-grade, maturity, harvestability

Carrots prometryne pentanochlor metoxuron

- Reduced dose linuron

Yield, quality (size grade), weed contaminant bunching carrots, potato crop – source blight infection

Insecticides, Molluscicides, Nematicides Sugar beet

triazamate

aldicarb Aphid control cost increase seed treatment used Resistance strategy compromised for resistant M. persicae Other aphicides

Field peas triazamate None, alternative aphicides Potatoes

nicotine (data lacking)

aldicarb Perhaps on processing crop, otherwise alternative oxamyl and fosthiazate None, alternative aphicides

Vining peas triazamate None, alternatives Brassicas (leaf) triazamate

(chlorfenvinphos)#

Aphid: Quality, increased use of other insecticides. (Cabbage root fly: Quality – size grade, yield plant loss)

Carrots (chlorfenvinphos)# aldicarb

(Aug.2006 SOLA) lambda-cyhalothrin total dose & number applications reduced

Carrot fly: Quality, crop rejection May be insufficient. Quality (fanging), crop rejection but oxamyl alternative; early aphicide needed

Fungicides Field beans carbendazim MRL None (resistance a problem) Potatoes 2-aminobutane

peroxyacetic acid

Quality loss skin spot. Capital investment in equipment and stores needed Scottish seed potato exports c. £14 million pa. Reliance on imazalil alternative risks resistance development. Resistance management needed

Brassicas, Leaf quintozene None. tolclofos-methyl alternative greatest impact bold type; # UK anticholinesterase review; * bentazone/MCPB will not be manufactured when cyanazine goes

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Impact of potential losses: 1. If trifluralin fails Annex 1 listing, or, if included but not re-registered in the UK, there will be a considerable impact on production of several crops:

• On grass weed resistance management in winter wheat, especially for black-grass control where there are increasing problems of herbicide resistance and few alternative chemical controls. Loss of trifluralin would increase selection pressure on the remaining herbicides and may lead to inadequate chemical control, reduced yields, require more expensive cultural control methods and have a serious adverse effect on the economics of wheat production.

• Herbicide resistant grass-weeds are increasing in oilseed rape and field beans grown on

heavy land and management in these crops with propyzamide is more expensive. Trifluralin is cheap £5/ha, used in tank-mixes is also of value for general weed control in oilseed rape and field beans. Production costs will increase.

• Trifluralin is used in 60% of leaf brassicas for control of polygonums and fat-hen and for

early plantings where tractor hoeing is unsuccessful in wet conditions. The cost of broad-leaved weed control will increase.

2. In June 2006 decisions had not been made on the remaining eight active substances on List 1 including carbendazim, flusilazole or vinclozolin. Commission proposals are that they should be included on Annex 1 for use in some major crops, but some uses will be lost. Decisions will not be made until September 2006. The most important of these is flusilazole a systemic, protective and curative triazole for Light leaf spot control in oilseed rape and it is used in formulation with carbendazim. There are other triazole alternatives. In the crops studied here the loss of carbendazim and vinclozolin would not cause difficulties. 3. There are concerns about the future of the desiccant sulphuric acid, although it is supported in the EC review so far (commodity List 4H). If it is not included in Annex 1 there would be an impact on Scottish seed potato production. 4. Metaldehyde (List 2) for slug control is important in many crops. It had general approval for ‘all edible and non-edible crops’ but it may not be re-registered for some minor crops if more data is required, because of the cost.

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Specific pesticide or pesticide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties There was concern in all crop sectors about increasing development of resistance in pests, diseases and grass weeds and a diminishing range of pesticides. Consequently it is desirable to maintain all pesticide groups currently approved, and those with new modes of action were also sought. Key actives have already been lost for minor crops as a result of the 91/414 review, and it is important to retain those remaining. Reliance on only a few actives for vegetables may risk exceedance of MRLs, in other situations in a few cases, exceedance of the 1µg/L limit in drinking water. Full lists for individual crops are given in the following crop summaries. A wide range of herbicides is needed to cover the whole weed spectrum, particularly for horticultural crops, where produce quality is important. Without them conventional crop production would not be possible - not all key herbicides are mentioned here. Pesticides needed in several crops, or for particularly important uses in a single crop, are: Herbicides – glyphosate, bipyridyls used before cropping; trifluralin, isoproturon, propyzamide, graminicides (‘fops’ and ‘dims’), nicosulfuron, pinoxaden, tri-allate; flupyrsulfuron-methyl, fluroxypyr/flufenacet, iodosulfuron/mesosulfuron, pendimethalin, clomazone, bentazone, rimsulfuron, bromoxynil, bromoxynil/prosulfuron, metazachlor, isoxaben/terbuthylazine, mesotrione/terbuthylazine, ethofumesate, metamitron, phenmedipham/desmedipham, phenmedipham and mixtures, metribuzin, propachlor, linuron, clopyralid, MCPB/MCPA, mecoprop-P, metsulfuron-methyl, diflufenican, flufenacet and several others. Desiccants/harvest aids – diquat, glyphosate, carfentrazone-ethyl, sulphuric acid. Nematicides – oxamyl, fosthiazate, ethoprophos and carbosulfan. Insecticides – chlorpyrifos; dimethoate; neonicotinoids (imidacloprid, clothianidin, thiacloprid); pyrethroids (tefluthrin, beta-cyfluthrin, lambda-cyhalothrin and others); carbamate (pirimicarb alone and in formulation with lambda-cyhalothrin); spinosad; pymetrozine; flonicamid. Molluscicides – metaldehyde, methiocarb. Fungicides – seed or tuber treatments hymexazol, cymoxanil/fludioxonil/metalaxyl-M, thiram, imazalil, thiabendazole, bitertanol/fuberidazole, carboxin, fludioxynil, the guanidines, prothiaconazole, silthiofam. Foliar sprays metalaxyl-M, triazoles (prothioconazole, epoxiconazole, tebuconazole, flusilazole etc.), chlorothalonil, boscalid, strobilurins (azoxystrobin, pyraclostrobin), morpholines (iprodione and fenpropimorph), proquinazid, quinoxyfen, mancozeb mixtures, fluazinam, cymoxanil, cyazofamid, propamocarb hydrochloride and zoxamide formulations. Plant Growth Regulators – chlormequat, 2-chloroethylphosphonic acid, mepiquat and formulations, trinexapac-ethyl, chloropropham and ethylene.

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Prospects for alternatives for any foreseen major gaps in pesticide availability There were 69 ‘new’ (i.e. registered after 1993) substances on Annex 1 (1 June 2006) – including 28 herbicides, 21 fungicides, 11 insecticides, 1 nematicide and 1 molluscicide. Some are isomers of old actives. There were more with dossiers prepared. Globally, pesticide development has slowed down compared with the period 1990-1999. A report by Phillips McDougall, given at the ECPA conference in November 2005 showed that for fruit and vegetables, no new herbicide active substances had been introduced over the period 2000-2004, and none were in R & D. There are a few for wheat but broad-leaved herbicides for wheat are usually damaging to broad-leaved crops. A few fungicides are still being developed for cereals but no insecticides. There are several fungicides and insecticides for fruit and vegetables – probably those developed earlier for the larger cereal markets. Crop Protection Companies are finding it more difficult to gain approvals for broad-spectrum insecticides. In the US ‘reduced risk/OP alternatives’ are given preference. In addition, registration of residual herbicides that are very persistent in the soil may be difficult. Thus, instead of one broad-spectrum herbicide that lasts for the duration of a crop, a programme of several herbicides will be needed to remove weeds and maintain quality standards. In future:

• Inadequate data protection under 91/414 is an issue for Crop Protection Companies and may restrict development. The USA IR 4 project has a useful solution for minor uses.

• We can expect few new pesticides for the EU, particularly herbicides for broad-leaved

weeds, which, for reasons of safety, are more crop-specific. • There is more optimism for new fungicides, insecticides and graminicides because they can

be used on a wide range of crop species. There are opportunities for development of new molluscicides and of plant growth regulators for the large cereal market.

• Crop Protection Companies now consider all EU crops except wheat and maize are of minor

importance, thus pesticide development in the EU will focus on these.

• Crop Protection Companies are investing in new biotechnology traits in crops. It is likely that some of this investment is being re-directed away from traditional agrochemical development. This may mean fewer pesticides are developed in future.

Non-chemical methods In most crops the cost of alternative non-chemical methods are often more expensive than chemical control and can themselves have negative environmental impacts. They may not be an option in some systems of vegetable production, for example baby carrots grown on at high population on close rows. The increasing occurrence of grass weed resistance and limited availability of active substances may mean ploughing and delayed drilling, (or increased area of ‘set-aside’) will be used more, as part of an integrated herbicide resistance management strategy for winter wheat.

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Alternative herbicides Alternative herbicides will be available for most crops, some of them through Mutual Recognition, for maize, field beans, brassicas, peas and carrots but they will be more costly. There may also be a delay because of the slow process of the EC Review. There is no replacement yet for: metoxuron for volunteer potato suppression in carrots or for cyanazine + MCPB/MCPA to prevent formation of toxic volunteer potato berries. Alternative insecticides and nematicides A complete solution to cabbage root and carrot fly control is still required, and in addition a different class of chemistry is needed for pest resistance strategy. There may be an answer, but not for at least 5 years. Novel insecticides for wheat with different modes of action are needed especially for wheat bulb fly and aphid control. Alternative fungicides It is unlikely that there will be any new products with novel chemistry for the major cereal foliar diseases available for commercial use within the next five years. Septoria tritici control in wheat is a challenge. Many crops are reliant on triazoles and fungicides with new modes of action are needed.

Geoffrey Hollis, Team Leader Cathy Knott, Malcolm Ogilvy

for Drew Associates Limited June 2006

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WINTER WHEAT Summary The total area of winter and spring sown wheat grown in the UK for the 2005 harvest year was 1,869,000 ha, 42% of the total cropped area. The area of spring-sown wheat is normally only 1% or 2% of the total. Recommendations for the wheat crop are based mostly on information from research funded by farmers through the Home Grown Cereals Authority (HGCA) statutory levy and/or work commissioned by Defra. To date, none of the projects result from any impact of 91/414/EEC. The HGCA R & D budget is £2.4 million/annum.

1. The likely impact of the 91/414/EEC review process on pesticide availability

Herbicides There have been no significant agronomic impacts as a result of the review process so far. Some minor outclassed herbicides have been lost, but nearly all the currently approved active substances have received Annex I listing. Decisions are still to be made on trifluralin (List 2); fenoxaprop-P-ethyl and diflufenican (both on List 3A). Trifluralin is the herbicide considered to be the most threatened by the on-going review process. It is particularly valued in wheat production because of its low cost (c. £5/ha), in the context of low profitability margins for wheat production, and as a tool in the management of herbicide resistant grass weeds where its loss would increase resistance selection pressure on other herbicides. This could be particularly serious in the case of black-grass where there are increasing problems of herbicide resistance to key selective herbicides and very few alternatives. Inadequate chemical control would reduce yields, require more expensive cultural alternatives and could have a profound effect on the economics of winter wheat production. Reductions in the maximum rate of isoproturon will reduce weed control efficacy especially for black-grass and may exacerbate the problem. There is widespread grass weed resistance to fenoxaprop-P-ethyl, indicating a minimal impact of potential loss. Diflufenican is a key component of broad-leaved weed control programmes in wheat, and it will be supported for re-registration. Insecticides and molluscicides There have been no losses of any agronomic significance for insecticides and molluscicides in the review process to date and the majority, including the critically important chlorpyrifos and major pyrethroids are now on Annex 1. The uncertainty on future availability of dimethoate would be of particular concern for the control of established wheat bulb fly infestations, although the cost effectiveness of dimethoate sprays is inconsistent. Fungicides The review process has had no significant impact on fungicide availability for wheat so far. However in June 2006, none of the conazole fungicides had been Annex I listed. These are critically important, for a range of wheat diseases, especially epoxiconazole and prothioconazole for Septoria tritici control. There is likely to be some rationalisation at the re-registration stage, but this should have little impact, providing key substances (see below) are retained.

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Plant growth regulators There have been no losses of PGR active substances in the review process, although to date only trinexapac-ethyl and prohexadione-calcium are included on Annex I. 2. Specific pesticides or pesticide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

It would be desirable to maintain the pesticides/plant protection products listed as follows. Those substances considered especially important are given in bold type. Herbicides Annex I listed: glyphosate, bipyridyls, clodinofop-propargyl, iodosulfuron/mesosulfuron, isoproturon, chlorotoluron, fluroxypyr/flufenacet, pendimethalin, flupyrsulfuron-methyl, mecoprop-P, metsulfuron-methyl, tri-allate and ioxynil/bromoxynil. Annex I pending: trifluralin, diflufenican, flufenacet, amidosulfuron, pinoxaden, tri-allate and prosulfocarb. Insecticides and molluscicides It would be highly undesirable to lose any of the very limited range of insecticide and molluscicide active substances approved for winter wheat. Annex I: pirimicarb, chlorpyrifos, clothianidin seed treatment and the pyrethroids, especially lambda-cyhalothrin, cypermethrin and esfenvalerate. Annex I pending: the molluscicides, metaldehyde and methiocarb; dimethoate, tau-fluvalinate, zeta-cypermethrin, plus tefluthrin and imidacloprid seed treatments. Fungicides Seed treatments: Only thiram has achieved Annex I status to date. Annex I pending: bitertanol/fuberidazole, carboxin, fludioxynil, the guanidines, prothiaconazole, fluquinconazole and silthiofam. Foliar diseases: Annex I: The strobilurins, chlorothalonil, dithiocarbamates, proquinazid and quinoxyfen. Annex I pending: The conazoles, particularly epoxiconazole and prothioconazole for their high efficacy in controlling Septoria tritici; and tebuconazole for rusts and ear diseases, prochloraz, boscalid and the morpholines (particularly fenpropimorph). Plant growth regulators Annex 1: trinexapac-ethyl. Annex 1 pending: chlormequat, chlormequat/imazaquin, 2-chloroethylphosphonic acid (alone and in mixture with mepiquat chloride). 3. Prospects for alternatives for any foreseen major gaps in pesticide availability

Herbicides and desiccants No foreseen major gaps have been identified as a result of the review process so far. There is a need for new active substances with novel modes of action to counter increasing herbicides resistance, particularly for grass weeds, but it appears unlikely any will be available in the medium term. Potential loss of trifluralin would leave a gap for a substitute herbicide with a comparable low price

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and lack of any known weed resistance, especially for black-grass control. Cultural control alternatives for grass weed control are available but can be unreliable and relatively expensive. Insecticides and molluscicides There are no foreseen major gaps in insecticide or molluscicides as a result of the review process so far and none expected. There is a need for new insecticides with novel modes of action as alternatives to the current restricted range. Improvement in integrated and cultural control techniques and options are developing rapidly for some pests, particularly Orange Wheat Blossom midge. Fungicides No predictable major gaps likely to develop from the ongoing review process were identified. New cereal fungicides offering novel modes of action are unlikely to be become available in the near future. Levels of genetic resistance with recommended wheat cultivars to major diseases such as Septoria leaf blotch are generally inadequate without the use of fungicides. Lack of alternatives is of considerable concern with the increasing problems of disease resistance to current fungicides. Plant growth regulators There are no foreseen major gaps so far and no new cereal PGRs known to be in late stage development trials. There is a wide range of cultural methods and integrated control techniques thatcan be employed to supplement, or minimise, the need for PGRs. Lodging-resistant varieties are particularly valuable.

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OILSEED RAPE Summary

The oilseed rape area (including non set-aside and set-aside) reached a 5-year high of 593,000 ha in 2005. Most recommendations for the crop are based on information from research funded by farmers through the Home Grown Cereals Authority HGCA statutory levy and/or commissioned by Defra. The HGCA annual R & D budget is £2.4 million (excluding variety trials) and so far no work has been undertaken as a result of any impact of 91/414/EEC. It seems likely that active substances will be supported with acceptable data packages and be re-registered for oilseed rape in N Europe and the UK, and that new pesticides will be developed because oilseed rape is becoming an important EU crop for biofuel as well as for feed.


Herbicides Cyanazine was not supported in the 91/414 EEC review but there was a derogation for use in winter oilseed rape until 31 December 2007. It is not approved for spring rape. Cyanazine applied post-emergence, controls charlock, which is not controlled by other rape herbicides.

• There is a risk of processors/crushers rejecting or reducing the price of crops infested with seeds of rape volunteers, cruciferous species (charlock and wild radish) because the quality for oil production or crushing is affected. If the crop is rejected the financial loss for average yields would be £470/ha (winter rape) or £290/ha (spring rape). The area of winter rape currently affected by charlock is c. 20,000 ha, this equates to £9,400,000 per annum. Close rotations of oilseed rape crops are becoming common. If charlock is not controlled, it sets seed to infest the next crop – it is likely to become a widespread problem, affecting quality.

Bifenox (List 3A) controls charlock and has a SOLA for use, at grower’s risk, in winter and spring rape but it can be damaging. A new product ‘Springbok’ (dimethenamid-p/metazachlor) covers a broad-spectrum and improves control of charlock, but may still be inadequate. Trifluralin (List 2) inclusion on Annex 1 is doubtful and there is a potential impact if it is lost. If it is included on Annex 1, regulatory authorities in some Northern EU Member States may not permit re-registration because of water issues. Trifluralin products are cheap c. £5/ha, and are used on more than 30% of oilseed rape crops, often in combination with lower than recommended dose-rates of metazachlor to extend the weed spectrum, including black-grass and to improve control of poppy (cost c. £38/ha). There is little herbicide choice for spring rape – trifluralin is approved for both winter and spring crops. In spring rape trifluralin is often all that is required, or a sequence of trifluralin pre-sowing followed by metazachlor pre-emergence is used.

• Loss of trifluralin at £5/ha, would lead to increased costs and reliance on metazachlor (broad

spectrum) ½ dose + clomazone, cost £64, or £55/ha full dose of metazachlor alone. • If trifluralin were not available, there would be no control of spring-emerging resistant

black-grass, knotgrass, black bindweed, fat-hen, fumitory in spring rape, or pansy, fumitory in poorly established winter rape.

• There is no evidence of grass weed resistance to trifluralin. The loss of trifluralin would exacerbate the current resistance management problems of grass weeds and production costs would increase by £37/ha - an alternative, propyzamide is more expensive.

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The decision on Annex 1 inclusion for most of the important herbicide active substances for oilseed rape has still to be made. New UK statutory restrictions on ACCase inhibitors for management of herbicide resistance in grass weeds mean that a range of different ‘fops’ or ‘dims’ will be needed. So far only tepraloxydim is on Annex 1, the rest are on List 3. Propyzamide is on Annex 1 and re-registration in the UK will be sought for oilseed rape (winter). Insecticides and nematicides All insecticides were supported in the 91/414/EEC review, and most are included on Annex 1. Insecticidal seed treatment beta-cyfluthrin/imidacloprid is important and very widely used but the decision on imidacloprid (List 3A) has not been made. Thiodicarb failed Annex 1 inclusion but other molluscicides were more important for rape. At re-registration stage data may be required for each crop use of metaldehyde (List 3A) and this will be generated for oilseed rape - an important market. Fungicides Commission proposals are that carbendazim, flusilazole or vinclozolin remaining on List 1 should be included on Annex 1 for use in oilseed rape but decisions will not be made until September 2006. The most important of these for oilseed rape is flusilazole a systemic, protective and curative triazole used alone or in formulation with carbendazim (or famoxadone) There is no decision yet on Annex 1 inclusion for some triazoles: prothioconazole (‘new’ active), tebuconazole (List 3B) and cyproconazole (List 3B) Triazole fungicides offer the main defence against Light leaf spot and Phoma. If not controlled, average yield loss is 1–1.5t/ha from Light leaf spot, 0.5–0.7t/ha can result from Phoma infections. Light leaf spot severity differs between seasons and it is more prevalent in Scotland, where strains less sensitive to triazoles make control more difficult. In high-risk areas, robust rates of flusilazole/carbendazim are currently advised. The new prothioconazole/tebuconazole may be the best alternative if flusilazole is lost.

2.Specific pesticides it would be desirable to maintain from the agronomic perspective to avoid major difficulties (unless specified, active substances are on Annex 1)

Herbicides Graminicides ‘fops’ and ‘dims’ (all on List 3B except tepraloxydim Annex 1) important for volunteer cereal control but there will be restrictions; propyzamide for winter rape – for resistant grass weeds. Trifluralin (List 2) it is cheap and is used with metazachlor to extend the weed spectrum, and for resistant black-grass; metazachlor (List 3A) for broad-leaved weed control, and quinmerac (List 3B), which gives additional cleavers control; dimethenamid-p used in formulation with metazachlor increases the spectrum; clomazone (List 3A) for control of cleavers pre-emergence and a few other species; bifenox (List 3A) may be a suitable alternative to cyanazine for control of charlock; clopyralid for mayweeds and thistle control. Glyphosate is the most widely used cheap herbicide to clean up stubbles and for desiccation; diquat has already been re-registered for desiccant use in oilseed rape.

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Insecticides and molluscicides Metaldehyde (List 3 A) and methiocarb (List 2) molluscicides. Neonicotinoid seed treatment, beta-cyfluthrin/imidacloprid (Annex 1/List 3A), is extremely important for Cabbage stem flea-beetle control and it currently controls all resistant forms of peach potato aphid for several weeks following emergence. Pirimicarb for brassica aphid; pyrethroids are essential for control of other pests (cabbage-stem flea beetle, pollen beetle, cabbage seed weevil and pod midge). Thiacloprid for pollen beetle control, to avoid resistance to pyrethroids. Fungicides Seed treatments: thiram, iprodione. The status of fungicide resistance in the UK is under review but the use of anti-resistance strategies are very important in prolonging the useful life of fungicides, even once resistance in the pathogen has started to develop. It is important to reduce the risk of it developing by using fungicide mixtures and fungicides with different modes of action. Foliar sprays: It is important to keep triazoles, particularly prothioconazole (‘new’ pending Annex 1)/tebuconazole (List 3B) for Light leaf spot control and flusilazole (List 1). Sclerotinia protectants strobilurins and boscalid; prothioconazole, also offers control and is a significant addition to fungicides for Sclerotinia. Iprodione/thiophanate-methyl is less important but could be needed if resistance develops. (Tebuconazole is also used as a plant growth regulator).

3.Prospects for alternatives for any foreseen major gaps in pesticide availability

Herbicides There is little herbicide development for oilseed rape because it is competitive and has a lower requirement for broad-leaved weed control. The introduction of Genetically Modified Herbicide-Tolerant rape would simplify weed control, but seems unlikely in the near future in the UK because of concerns about seed longevity and consumer opposition. Ethametsulfuron, registered for use in oilseed rape in Canada, but not the EU, controls charlock. Dimethachlor (List 3B) is approved for broad-leaved weed control for oilseed rape in Germany. Resistant black-grass: no other class of compound has so far been developed. Insecticides and molluscicides Insecticides approved are adequate for control of the main pests but new ones with different modes of action would be useful for resistance strategies. No seed treatment is yet approved for slugs but seed treatments incur cost ahead of knowing whether there is a problem. However, forecasting could be used to determine instances in which treated seed is justified. Future possibilities could perhaps include beta-cyfluthrin/clothianidin seed treatment. Fungicides Fungicides for the main diseases of oilseed rape are adequate but strains of Light leaf spot less sensitive to triazoles are developing. It is important that growers adopt strategies to avoid resistance and that new fungicides with a different mode of action are sought. A new fungicide, cyprodinil/fludioxonil, will be approved for control of Sclerotinia in some higher value crops, but there are no plans for introduction into oilseed rape.

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SUGAR BEET Summary

The area of sugar beet has declined to approximately 148,000 ha in 2005. British Beet Research Organisation (BBRO) is owned jointly by the processors, British Sugar plc and the National Farmers Union and funded by a contractual levy paid 50/50 by the growers and British Sugar. Broom's Barn Research Station is the centre of expertise. Approximately £1.2 - £1.3 million p.a. of levy is spent on sugar beet research. Some funding has been spent on mitigation of the loss of aldicarb in the 91/414/EEC Review. 1. The likely impact of the 91/414/EEC review process on pesticide availability

Herbicides There have been no losses so far and the majority of the most important herbicides are now on Annex I. It appears unlikely there will be any future losses giving a major impact on weed control in this crop although probable future restrictions on the dose rates of ethofumesate and metamitron could compromise herbicide efficacy to some extent. Insecticides, nematicides and molluscicides The nematicide aldicarb failed Annex 1 inclusion and the specific aphicide, triazamate are the two pesticides, which have already been lost (aldicarb) or will not be available after 2006 (triazamate). The immediate impact of aldicarb loss has been very minor due to the availability of alternative products and the same will apply to triazamate. However the future impact could be greater in the case of aldicarb because its loss has compromised resistance strategies for the control of insecticide resistant Myzus persicae. Sugar beet is highly vulnerable to the likely future development of aphid resistance to neonicotinoid seed treatments. There is a potential risk of heavy yield losses from an inability to control aphid borne virus diseases. Fungicides There have been no fungicide losses of any significance and none are expected, although the important conazole foliar fungicides and the essential hymexazol seed treatments have yet to obtain Annex I listing (June 2006). 2. Specific pesticides or groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

It would be desirable to retain the pesticides listed as follows. Those substances considered especially important are given in bold type. Herbicides Annex I listed: bipyridyls, glyphosate, tepraloxydim, clopyralid, ethofumesate, phenmedipham and desmedipham. Annex I pending: cycloxydim, fluazifop-p-butyl, propaquizafop, chloridazon, lenacil, metamitron, trifluralin and triflusulfuron-methyl. Insecticides, nematicides and molluscicides. Annex I listed: chlorpyrifos, cypermethrin, lambda-cyhalothrin, pirimicarb, oxamyl, clothianidin and beta-cyfluthrin.

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Annex I pending: dimethoate, imidacloprid, tefluthrin, benfuracarb, carbosulfan and methiocarb. Fungicides Annex I listed: thiram, propiconazole, quinoxyfen and pyraclostrobin. Annex I pending: hymexazol, cyproconazole, flusilazole, carbendazim, sulphur, epoxiconazole and fenpropidin. 3. Prospects for alternatives for any foreseen major gaps in pesticide availability

Herbicides There are no foreseen gaps at present. Insecticides, nematicides and molluscicides There is a high incidence of aphid populations resistant to carbamate, organophosphate and pyrethroid insecticides. The industry is dangerously reliant on neonicotinoid seed treatments to combat a virus disease complex transmitted by aphids. Current prospects for alternatives are poor. Fungicides There were no foreseen major gaps identified in the study. The epidemiology of foliar diseases in sugar beet indicates minimal risk of resistance development. There is, however, considerable concern that no alternatives to hymexazol seed treatment for blackleg control are available or in development.

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FORAGE MAIZE Summary

Forage maize, grown for animal feed, occupied 124,000 ha in 2005. Maize research is funded by farmers’ annual subscription (a non-statutory levy) to the Maize Growers Association (MGA). The R & D budget for the maize crop is £10,000 p.a., considerably lower than that of levy bodies. The cost to the growers of generating residues data for a Specific Off-Label Approvals (SOLAs) is likely to be prohibitive for this sector. UK off-label approvals based on recognition of approvals in other EU (current Northern zone) member states are not possible where a crop area exceeds 50,000 ha and unfortunately are not possible for forage maize. Only 16 crop protection active substances are now (July 2006) approved for UK forage maize and they include 11 herbicides.

1.The likely impacts of the 91/414/EEC review process on pesticide availability

Herbicides In 2004 atrazine failed to achieve Annex 1 inclusion in the 91/414 EEC Review. UK growers could no longer use atrazine after 10 September 2005. There were no derogations for ‘Essential Use’ of atrazine in maize, thus little time to find alternatives. Ireland, Spain and Portugal have derogations for ‘Essential Use’ in maize until 31 December 2007. Other losses were cyanazine (not supported) and simazine, which failed Annex 1, but these were less important in maize.

• Weeds in maize reduce yields and feed value. Atrazine (residual and contact-acting) was the main herbicide used in nearly all of the maize area. It covered a broad-spectrum of grasses and broad-leaved weeds and provided season-long weed control of most species encountered. Alternatives may cover an adequate broad-leaved weed spectrum but so far none have been as effective as atrazine on grasses and broad-leaved weeds. Several sprays may be needed post-emergence and there are restrictions on: late timings, the number of sulfonylurea applications and following cropping.

• The greatest impact from the loss of atrazine will be on increased costs of weed control. In

2005 weed control cost for Atrazine alone + application cost was £15.50/ha. (Where black nightshade was a problem a programme of atrazine followed by bromoxynil + cost of two applications £46/ha.). In 2006 weed control including application costs will be £51.50 to £80 /ha or more, assuming both grass and broad-leaved species were present. The next generation of herbicides will be even more expensive. Maize is grown on wide rows and can be mechanically weeded but the costs are higher than for weed control with herbicides. Two or three passes with a tractor hoe would be needed – cost £69.50 or £104.25 (Nix, 2005).

The UK dairy sector is less reliant on forage maize than some other major milk producing countries, however, it is an essential part of winter rations for many producers. Milk at 18 p/L is being produced at cost – the significant increase in herbicide costs or reduction in yield of maize if weeds are not controlled will compound the severe financial pressure being experienced by the majority of dairy farmers. It likely that this will give further encouragement to dairy farmers to cease milk production which in turn may impact on the sustainability of the dairy supply chain.

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Insecticides and molluscicides There is very little use of insecticides in forage maize. So far no active substances have been lost through failure to achieve Annex 1 listing. Fungicides No fungicide is approved in the UK except thiram seed treatment, thus no impact. 2. Specific pesticides it would be desirable to maintain from the agronomic perspective to avoid major difficulties (unless specified active substances are on Annex 1)

Herbicides Glyphosate for use pre-cropping; bromoxynil and bromoxynil/prosulfuron for black nightshade control; mesotrione/terbuthylazine (List 3B) for control of black nightshade and orache, the two major weeds in maize; nicosulfuron (List 3A) will be essential for grass weed control; clopyralid needs to be maintained for mayweed control. Insecticides and molluscicides Imported seed treatments containing clothianadin or thiometoxam essential to control frit fly, leatherjackets and wireworm, and a molluscicide methiocarb (List 2). Continued availability is dependent on re-registration in other countries. Molluscicide bait metaldehyde (List 3A). Chlorpyrifos soil-applied for control of common pests of maize. The only insecticide currently approved in the UK that could give some control of Diabrotica. Fungicide Seed treatment thiram UK approval (for addition to an insecticide seed treatment available in future. 3. Prospects for alternatives for any foreseen major gaps in pesticide availability

Maize is an important crop worldwide and new pesticides are being developed elsewhere. Mutual Recognition could be very helpful in gaining access to new products for forage maize if the crop/use is on-label in another EU Member State in the same climatic zone. If GM Herbicide-Tolerant maize is widely grown elsewhere in the future there will be little conventional herbicide development. There are promising herbicides (for annual grass and broad-leaved weeds, including mayweeds) in the pipeline for UK maize: pre-emergence flufenacet/isoxaflutole (not a sulfonylurea); post-emergence sulfonylurea-based foramsulfuron/isoxadifen/iodosulfuron both will be effective but expensive compared with atrazine. Effective means of control for Diabrotica are urgently needed. Clothianidin seed treatment is being submitted for UK registration at two dose rates: standard for wireworm and a higher premium dose rate for Diabrotica. Maize eyespot is occasionally found in mild, wet conditions in the UK. Fungicide development and registration in the main EU maize growing areas is therefore unlikely. Fungicides approved for cereals may be appropriate and a SOLA may be possible for this minor use but residues data would be required. No work has yet been done and funding would be needed.

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POTATOES Summary

In 2005 the potato area was 137,000 ha. Potatoes are grown as ware for human consumption (fresh or processed) and the smaller, high value seed crop, some of which is exported. R & D is financed by statutory levy collected from growers and trade purchasers through the British Potato Council (BPC). The R & D budget for 2006/2007 is approximately £1.5m. Levy has funded R & D for mitigation against losses or potential losses of pesticides. Minimising the impact of pests and diseases is considered to be of crucial commercial significance by BPC. 1. The likely impact of the 91/414/EEC review process on pesticides availability

Herbicides and desiccants Four minor herbicides were lost in the initial review process and there has been no significant impact on potato production so far. However, any future threat to the retention of linuron (on Annex 1) would exacerbate the earlier withdrawal of monolinuron. Anticipated rate restrictions on linuron and metribuzin will increase treatment costs in some circumstances and create difficulties for seed crop production where there are few alternative approved herbicides. There have been no losses of desiccants to date. The predominant products are diquat and sulphuric acid. Diquat has Annex I listing and is reasonably assured of re-registration. There is uncertainty for the retention of sulphuric acid, where Annex I listing is still pending. The potential loss of this desiccant would have a major economic impact on the Scottish seed potato industry. Alternative chemicals for this sector are technically less suitable and withdrawal of sulphuric acid would increase the risk of poorer quality with more diseased tubers and less control over critical size requirements. The impact would be much less for the ware crop, where a range of alternative haulm destruction methods is available and retailers already restrict the use of sulphuric acid. Insecticides, molluscicides and nematicides Aldicarb failed Annex I inclusion and the ‘Essential Use’ derogation expires in December 2007. The main uses are for the control of two major pests; potato cyst nematode (PCN) and the free-living nematodes (FLN) which are vectors of Tobacco Rattle Virus (TRV), which causes tuber symptoms known as spraing. TRV is particularly damaging to the potato cultivars favoured by the processing industry. The likely impacts of withdrawal are contentious as it is uncertain if alternative nematicides will be as effective as aldicarb, especially for the suppression of spraing in the processing sector. Failure to achieve adequate nematode control would result in major yield reductions and in the case of FLN/ spraing suppression, a very serious impact on the all important tuber quality. Overall, it now appears that substitute nematicides have a reasonable prospect of acceptable performance, especially for PCN control and the demise of aldicarb may have much less impact on crop production and costs than was previously thought. The loss of chlorpyrifos from September 2006 for cutworm control is unlikely to have much impact. The future retention of nicotine is uncertain and ‘Essential Use’ derogation will be sought. There are only two insecticides approved for wireworm control, ethoprophos (List 2) and fosthiazate (new Annex 1) but they have much larger markets for PCN control and there are reasonable prospects for continued availability. Molluscicides are widely used in potatoes. Thiodicarb failed Annex 1 inclusion, and there is no decision yet on the alternative molluscicides metaldehyde (List 3A) and methiocarb (List 2).

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Fungicides The two major uses of fungicides are as foliar sprays for the control of late blight and as tuber treatment for control of a range of seed and soil borne diseases. For late blight only the fentin (tin) products have been lost as a result of the review process so far. The impact has been minimal because of the availability of a range of alternatives, including new products, affording a comparable standard of foliar and tuber blight control. A number of the important blight fungicides do not yet have Annex I listing. Dose rates and numbers of applications may be reduced at the re-registration stage when/if Annex I listing is achieved and this may impact on efficiency. However with a very wide range of substances approved for blight control and the regular introduction of new fungicides it appears unlikely the review process will cause any significant problems. In the specialist seed/soil borne disease control sector, 2-aminobutane (2AB) for the control of skin spot in seed potatoes cannot be used after 2007, when the ‘Essential Use’ derogation expires. Use is confined to only 2% of the crop treated with fungicides. There are strongly divided views on the impact of 2AB loss, ranging from a negligible effect, to a risk of increasing disease incidence in the ware crop, the need for major capital investment to facilitate integrated control methods and a higher risk of disease resistance to alternative fungicides. Peroxyacetic acid, used on seed potato tubers pre-planting, has not been supported. It is valued for resistance management and ‘Essential Use’ derogation will be requested. Plant growth regulators It appears unlikely the review process will adversely affect the availability of the three approved PGRs for use in UK potato production. Both chloropropham and maleic hydrazide have achieved Annex I listing and manufacturers have confirmed intentions to support re-registration of all three chemicals. 2. Specific pesticide or pesticide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

It would be particularly desirable to maintain the pesticides/PGRs listed as follows. Those substances considered especially important are given in bold type. Herbicides and desiccants Annex I listed herbicides: bipyridyls, glufosinate-ammonium, glyphosate; bentazone, linuron and pendimethalin. Annex I pending herbicides: cycloxydim, propaquizafop, quizalofop-p-tefuryl, clomazone, metribuzin, metribuzin/flufenacet (flufenacet in Annex I), prosulfocarb and rimsulfuron. Annex I listed desiccants: diquat, carfentrazone-ethyl and pyraflufen-ethyl. Annex I pending desiccant: sulphuric acid. Insecticides, molluscicides and nematicides Annex I listed: nematicides oxamyl, fosthiazate; insecticides pirimicarb, pymetrozine, thiacloprid, and the pyrethroids, especially cypermethrin and lambda-cyhalothrin. Annex I pending: nematicides 1,3-dichlorpropene, ethoprophos; insecticides flonicamid, nicotine; molluscicides metaldehyde and methiocarb.

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Fungicides For late blight control Annex I listed: chlorothalonil, cyazofamid, famoxadone (in cymoxanil/famoxadone), diothiocarbamates (especially mancozeb as a component of mixed formulations), fenamidone (in mixtures), metalaxyl-M (in mixtures) and zoxamide (in mixtures). Annex I pending: copper products, benthiavalicarb-isopropyl, cymoxanil (alone and in mixtures), dimethomorph, propamocarb hydrochloride (in mixtures), and fluazinam. For seed and soil borne diseases Annex I listed: azoxystrobin, imazalil, thiabendazole and iprodione. Annex I pending: flutolanil, pencycuron and toclofos-methyl. Plant growth regulators Annex I listed: chloropropham (CIPC) and maleic hydrazide. Annex I pending: ethylene. 3. Prospects for alternatives for any foreseen major gaps in pesticides availability

Herbicides and desiccants There are no major foreseen gaps for ware potato herbicides. The anticipated rate restriction of linuron may present difficulties in the seed crop where there are few alternative approved herbicides and no indications of new chemistry to supplement linuron activity. The possible loss of sulphuric acid is mainly of concern for the Scottish seed crop industry because existing alternatives are regarded as technically inferior and less flexible in use. No new desiccants in late development have been identified. Insecticides, molluscicides and nematicides There will be major gaps if the alternative nematicides that are now approved for PCN and FLN/spraing suppression fail to perform as well as aldicarb. There are no indications of any new nematicides for the potato crop, but one new biological control system is now available and a number of alternative technologies are in development. Fungicides For late blight control No gaps were identified for this sector where there is a very wide range of active substances and new fungicides continue to be introduced. For seed and soil borne diseases The only foreseen major gap is for skin spot control in seed potatoes, where alternative fungicides are generally less effective. An integrated control approach involving a range of cultural and improved chemical application techniques offers good prospects. Early screening trials have given promising results with a boscalid/pyraclostrobin treatment. Plant growth regulators No foreseen major gaps were identified in this study.

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Arable Crops FIELD PEAS and FIELD BEANS Summary

In 2005 the UK area of field peas harvested dry including those for human consumption was 43,000 ha, and field beans 187,000 ha. The area of field beans is increasing, but peas are decreasing. R & D is funded by non-statutory levy from growers, through the Processors and Growers Research Organisation (PGRO). The levy is of the order of £300,000 per annum. UK Off–label Approvals based on recognition of on-label approval in another member state and where there is a product on-label approval for the same crop use should be possible for field peas, where the area is now less than 50,000 ha. Mutual Recognition of pesticides for peas could be helpful because they are widely grown in other EU countries in the same climatic zone but there may be fewer opportunities for field beans (particularly winter-sown) because the area in other EU Member States is small.

1. The likely impact of the 91/414/EEC review process on pesticide availability for field peas

Herbicides Unless effective herbicides are available for combining peas the crop will be difficult to grow successfully in the UK, but there will be no impact from herbicide loss in mainland Europe. UK peas have been dependent on triazine herbicides but in other EU Member States, different actives that were supported in the Review are approved. After 2007 there will be no broad-spectrum pre-emergence herbicide unless those used in France become available. Cyanazine, terbutryn and fomesafen were not supported in the 91/414/EEC Review. There is an ‘Essential Use’ derogation for combining peas, which expires 31 December 2007. In addition a decision has been made that bentazone/MCPB (Pulsar) will not be manufactured after 2007 because without cyanazine as a tank-mix partner, weed control would be poor. Pendimethalin/cyanazine, terbutryn/terbuthylazine and fomesafen/terbutryn are widely used for pre-emergence control of some grasses and broad-leaved weeds, including black-bindweed, which causes lodging. Fomesafen and pendimethalin also control volunteer oilseed rape, which has become a widespread and persistent problem. The loss of cyanazine for post-emergence use will also have a considerable impact. It is used in tank-mixes, mainly with bentazone/MCPB, on c. 60% of the crop, where soil is too dry for residual activity; for species that escape control with residual pre-emergence herbicides and on certain soil types.

• Weed competition causes yield loss in field peas (up to 29%). • There are losses due to harvesting difficulties unless a desiccant is applied and this increases

production costs. • There are price deductions for peas contaminated with weed seeds and if crops grown for

seed are weedy, they are rejected. A few pre-emergence herbicides may be available after 2007 but they are less effective. Trifluralin/linuron is approved but trifluralin may fail Annex 1 inclusion. Pendimethalin (Annex 1) will be the basis for weed control but it needs a partner and could be tank-mixed with clomazone, which controls cleavers and a few other broad-leaved weeds. Effective early post-emergence herbicides for broad-leaved weeds will be available, but those approved for later applications have important weaknesses.

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Insecticides There were no insecticide losses in the 91/414/EEC review process, except for withdrawal of triazamate but it was seldom used in peas and there was no impact. The revocation of broad-spectrum organophosphate insecticides after the UK anticholinesterase review, has increased reliance on pyrethroids in peas and beans and increased the risk of developing pest resistance. Fenitrothion (organophosphate) was used to control field thrips in the past. It later failed Annex 1 inclusion. Fungicides All fungicides for peas were supported in 91/414/EEC review process and so far there are no significant losses of active substances through failure to achieve Annex 1 listing. The Commission proposal is that vinclozolin should be included on Annex 1 for use in some other crops but not for peas. Usage is greater in field peas than on vining peas but other alternatives are available.

2. Specific pesticides it would be desirable to maintain from the agronomic perspective to avoid major difficulties (unless specified, active substances are on Annex 1)

Herbicides Glyphosate, non-selective herbicide used pre-cropping. It is vital to retain the few remaining herbicides: pendimethalin, pendimethalin + bentazone, bentazone, MCPB, MCPB/MCPA; clomazone, isoxaben/terbuthylazine all on List 3. Graminicides, all List 3 except tepraloxydim. Resistant grass weeds are not yet a problem in pea crops but it would be useful to maintain tri-allate (but some evidence of a low level of resistance). Diquat will be essential – it was used to desiccate 37% of the pea area in 2004 and is likely to become more widely used where weed control is poor after 2007. Insecticides and molluscicides A range is limited and the following are essential: pyrethroids, particularly lambda-cyhalothrin; pirimicarb for aphid control, alone or in formulation with lambda-cyhalothrin; molluscicide bait metaldehyde (List 3A). Fungicides All the seed treatments: cymoxanil (List 3B)/fludioxonil (List 3A)/metalaxyl-M is widely used. Cymoxanil is particularly important for control of downy mildew because some strains are already resistant to metalaxyl and the disease cannot be controlled with available foliar applied fungicides; fosetyl–aluminium, an alternative for downy mildew control; thiram/thiabendazole for Ascochyta control in some seasons; thiram (cheap), for varieties with good field resistance to downy mildew. Foliar sprays: chlorothalonil and mixtures are the most important; triazoles (cyproconazole on List 3B, metconazole); azoxystrobin for Botrytis, leaf & pod spot; iprodione SOLA, the only fungicide approved for Sclerotinia control. 3. Prospects for alternatives for any foreseen major gaps in pesticide availability Herbicides There is urgent need for new broad-spectrum pre-emergence herbicides, such as those registered in France: aclonifen (List 3B) used in tank-mix with pendimethalin; formulated product imazamox/pendimethalin both on Annex 1.

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Insecticides Active substances with different modes of action are needed for resistance strategy. Insecticide resistance in pea aphid has not been found yet, but there are few control options at present. Field thrips: possibilities thiametoxam seed treatment, and lambda-cyhalothrin foliar sprays. Fungicides Gaps identified for were not a result of fungicides lost in the EC Review. A very limited range is available for field peas and new fungicides, particularly with curative and different modes of action are needed. There are prospects for filling gaps for example, several fungicides have an on-label approval for Botrytis, but only offer a reduction in disease. Cyprodonil (new Annex 1) used in France, could offer an improvement for Sclerotinia and Botrytis control. Foliar spray cyprodinil/fludioxynil is approved in France.

1.The likely impact of the 91/414/EEC review process on pesticide availability for field beans

Herbicides Simazine failed Annex 1 listing in the 91/414/EEC Review. There is a derogation for ‘Essential Use’ in field beans until 31 December 2007. Simazine controls a wide spectrum of grass and broad-leaved weeds and is the most widely used herbicide on c. 75% of the field bean crop. Terbutryn, fomesafen and cyanazine were not supported in the EC Review, but also have derogations for ‘Essential Uses’ until 31 December 2007. Products containing pendimethalin/cyanazine or terbutryn/terbuthylazine are used pre-emergence in spring beans for grasses and broad-leaved weeds, including black-bindweed, which causes lodging. After 2007 a few pre-emergence alternatives may remain but they are less effective. Pendimethalin on Annex 1, will remain but needs a partner and could be tank-mixed with these, or clomazone, which controls cleavers and a few broad-leaved weeds. The only post-emergence option for beans is bentazone (on Annex 1), which is seldom used because it is expensive and only controls a narrow weed spectrum.

• The main impact will be on the cost of weed control - excluding application, simazine at £4/ha compared with a tank-mix £67/ha. In addition a desiccant (£28/ha + application cost) may be needed.

• Winter and spring beans are harvested after most weeds have set seeds, which return to infest the following crop. Field beans are regarded as a cleaning break crop in the rotation with winter wheat but this will not be the case after 2007.

• Limited data suggest that winter beans will not suffer yield loss, spring beans up to 17% loss depending on weed population and species.

• Weeds cause lodging and harvesting difficulties. A desiccant may be needed where weeds remain green thus adding to production costs.

• Field beans can be weeded mechanically and the crop is more tolerant of damage than peas. However, it is a more costly method of weed removal – two or three passes are needed.

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Trifluralin (List 2) may not be included on Annex 1. Use in beans has increased because it is cheap c. £5/ha and it is effective on some broad-leaved weeds including fat-hen and polygonums. It is also of value for the management of herbicide resistant grass-weeds and it is an important product for use in field beans grown on heavy land, where black-grass resistance is increasing. If trifluralin is lost there will be more use of propyzamide (Annex 1), increasing production costs by c. £37/ha. Insecticides and molluscicides So far, the 91/414/EEC review has had no impact on insecticide availability for UK field beans. The most important insecticides achieved Annex 1 inclusion. Slugs are a problem in wet years in beans and peas but metaldehyde is not widely used, therefore a company decision to re-register may depend on whether data is required for each crop/use combination. Fungicides So far, the review has had no impact on fungicide availability for UK field beans. The Commission proposal is that vinclozolin should be included on Annex 1 for use in some crops but not for beans (at the time of writing, no decision has been reached). Vinclozolin is seldom used and other alternatives are available. There is no decision yet on Annex 1 inclusion for the triazoles, tebuconazole (List 3B) and cyproconazole (List 3B) or for cymoxanil (List 3B) seed treatment. 2. Specific pesticides it would be desirable to maintain from the agronomic perspective to avoid major difficulties (unless specified, active substances are on Annex 1)

Herbicides and desiccants Glyphosate, non-selective herbicide pre-cropping. It is important to maintain the few remaining options: pendimethalin is essential; clomazone (List 3A) for cleavers control; isoxaben/terbuthylazine (both List 3B) (spring beans only); trifluralin(List 2)/linuron; bentazone the only post-emergence herbicide for broad-leaved weeds, needed for charlock control. Trifluralin (List 2) (spring and winter), propyzamide (winter) for resistant black-grass control in beans and as part of the management strategy for the arable rotation as a whole; tri-allate (spring and winter). Graminicides (tepraloxydim, others on List 3) to control grasses and volunteer cereals. Harvest aids diquat and glyphosate are likely to be needed if weeds become a problem after 2007. Insecticides and molluscicides Pyrethroids, particularly lambda-cyhalothrin; pirimicarb alone or with lambda-cyhalothrin Molluscicide bait metaldehyde (List 3A) in wet years on heavier soil types slugs are a problem. Fungicides It is essential to maintain the seed treatment cymoxanil/fludioxonil/metalaxyl-M, cymoxanil (List 3B) is particularly important for downy mildew control because some strains are already resistant to metalaxyl. To avoid disease resistance: Chlorothalonil alone and in formulation; azoxystrobin for control of rust, SOLA for Ascochyta; metalaxyl-M (in formulation with chlorothalonil) the only foliar spray for control of downy mildew; boscalid (pending) /pyraclostrobin; triazoles tebuconazole (list 3B), cyproconazole (List 3B), metconazole for rust and chocolate spot; iprodione, a morpholine, alone or in formulation with thiophanate-methyl for chocolate spot.

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3. Prospects for alternatives for any foreseen major gaps in pesticide availability

Herbicides The 91/414/EEC review has resulted in a serious gap and there is urgent need for new broad-spectrum pre-emergence herbicides. The potential alternatives for peas would also be suitable for UK field beans. Insecticides and molluscicides A limited range of insecticides is available for field beans. A more persistent insecticide for Bruchid beetle control is required. Bean aphid resistance to pyrethroids or pirimicarb has not been found yet, but active substances with different modes of action are needed for resistance strategy. Slugs and snails: both peas and beans are reliant on metaldehyde bait pellet as the only means of control. An alternative solution is needed but there are no prospects yet. Fungicides The gap identified highlights a requirement for new chemistry to avoid disease resistance and was not a result of fungicides lost in the Review. Metalaxyl-M is the only foliar spray approved for downy mildew control but some strains of the disease are now resistant. Fungicides for potatoes and vines may have potential. There is also a need for alternative seed treatments.

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VINING PEAS Summary The area of vining peas, harvested green for freezing and canning has declined and estimates for 2005 suggest only 31,025 ha were grown. Growers levy through PGRO/HDC, has funded projects to find alternative pesticides. The main impact of loss of pesticides in vining peas will be on quality, in contrast to field peas grown for animal feed. Off–label Approvals based on recognition of on-label approvals in other EU Member States in the same climatic zone are possible for UK minor crops of areas less than 50,000 ha. There must be an extant on-label approval for the use of the same product on another edible crop in the UK. There is a wider pesticide choice in France for peas and this route could be used increasingly. Mutual Recognition will also be useful.


Herbicides Unless alternative effective herbicides are available for UK vining peas the crop will be uneconomic to grow and process, there will be factory closures and frozen and canned peas will be imported from mainland Europe, where different herbicides (active substances supported in the Review) are still available. The UK crop has been dependent on triazines. After 2007 there will be no broad-spectrum pre-emergence herbicide for vining peas unless those used in France, which include actives aclonifen (used in tank-mix with pendimethalin) or imazamox (pendimethalin /imazamox) become available. Fomesafen, terbutryn and cyanazine were not supported in the 91/414/EEC Review. There are ‘Essential Use’ derogations for vining peas, which expire 31 December 2007. These active substances form the basis for weed control. In addition a decision has been made that bentazone/MCPB (Pulsar) will not be manufactured after 2007 because without cyanazine as a tank-mix partner, weed control would be poor. In vining peas weed control is based on early removal with pre-emergence herbicides terbutryn/terbuthylazine and fomesafen/terbutryn, which control a wide spectrum of broad-leaved weeds, annual meadow-grass and fomesafen also controls volunteer oilseed rape. Post-emergence cyanazine tank-mixes are needed for species that escape control with residual pre-emergence herbicides if soil conditions are dry and for certain soil types. A tank-mix of cyanazine + MCPB/MCPA is the only means of preventing formation of toxic berries on volunteer potatoes.

• Quality is the most important factor for vining peas and there is ‘nil tolerance’ for contaminants. Weed contaminants adversely affect consumer confidence. Where separation is difficult or impossible, and if there is a possibility of contamination of produce with toxic weed parts (berries of black nightshade, briony spp. and volunteer potatoes) that pose a risk to the consumer, the whole crop is rejected - financial loss £1000/ha.

• There are price deductions for crops contaminated with weed parts. Produce for processing will require extra cleaning in the factory at £50/tonne and there are crop losses of c. 3% associated with the cleaning process. If the level of contamination is too high, cleaning is uneconomic and the peas are rejected.

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• Weeds can also cause yield loss due to competition of up to 30%. • A continuous flow of crop to the factory is needed and any delays caused by slow, difficult

harvesting in weedy crops cannot be tolerated – the field is bypassed. Very few herbicides will remain after 2007: those for use pre-emergence are not as broad-spectrum as those that will be lost; the post-emergence herbicides for broad-leaved weeds also have important weaknesses. Insecticides and molluscicides There were no insecticide losses in the 91/414/EEC review process. Triazamate was withdrawn, but it was seldom used in peas. Retailers did not permit the use of organophosphate insecticides in UK vining peas for processing and by 2002 they were no longer used. The most important insecticides are included on Annex 1, but dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. . Fungicides No fungicides for vining peas have been lost in the 91/414/EEC review process so far. The Commission proposed that vinclozolin (List 1) should be not be included on Annex 1 for peas but alternatives are available. 2. Specific pesticides it would be desirable to maintain from the agronomic perspective to avoid major difficulties (unless specified, active substances are on Annex 1)

Herbicides Glyphosate, non-selective herbicide pre-cropping. It is vital to retain the few remaining: pendimethalin SOLA, isoxaben/terbuthylazine (both List 3B), clomazone (List 3A), bentazone, MCPB, MCPB/MCPA. Graminicides tepraloxydim; and cycloxydim (List 3A). Resistant grass weeds are not yet a problem but tri-allate (List 3B) could be useful, although there is some evidence of a low level of resistance. Insecticides and molluscicides A limited range is available for vining peas: pyrethroids particularly lambda-cyhalothrin; pirimicarb and pirimicarb/lambda-cyhalothrin; metaldehyde (List 3A) - the only means of control of slugs Fungicides All the seed treatments: cymoxanil (List 3B)/fludioxonil (List 3A)/metalaxyl-M is widely used, cymoxanil is particularly important for control of downy mildew because some strains are already resistant to metalaxyl and downy mildew cannot be controlled with available foliar-applied fungicides; fosetyl-aluminium (List 2) as an alternative. Thiram/thiabendazole is useful for Ascochyta control in some seasons. Thiram for damping-off disease - the only fungicide approved for application in the UK. Foliar sprays: azoxystrobin protectant for Botrytis, leaf & pod spot and Sclerotinia; metconazole (List 2) Botrytis, leaf & pod spot, but it is less effective than azoxystrobin; iprodione SOLA for Botrytis and Sclerotinia.

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Herbicides There is urgent need for a new broad-spectrum pre-emergence herbicides, such as those registered in France: aclonifen (List 3B) used in tank-mix with pendimethalin; imazamox/pendimethalin (both Annex 1). Aclonifen and imazamox are not registered for any UK crop. There is no herbicide alternative to prevent toxic volunteer potato berry formation, and hand pulling will be costly. Insecticides and molluscicides Gaps identified were not a result of insecticides lost in the EC Review. There are no control measures at all for bean seed fly or field thrips although thiametoxam seed treatment (new on Annex1) appears promising. Pea aphid resistance to pyrethroids or pirimicarb has not been found yet, but active substances with different modes of action are needed. No neonicotinoid is approved (as of July 2006). Metaldehyde molluscicide bait pellet is the only means of control of slugs and snails – if found in harvested produce, crops may be rejected by the processor, but there is also a risk of crop contamination with the pellets if they are applied late. An alternative solution is needed. Fungicides Gaps identified for were not a result of fungicides lost in the EC Review. A very limited range is available and new fungicides, particularly with curative and different modes of action are needed. Foliar spray cyprodinil/fludioxynil is approved in France, UK registration for vining peas is imminent. Cyprodonil could offer an improvement for Sclerotinia and Botrytis control.

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BRASSICAS Summary (Brussels sprouts, cabbage, calabrese/broccoli and cauliflower)

The total area of leaf, head and flower-head brassicas declined to 31,471 ha in 2005. R & D is financed by statutory levy collected from growers through the Horticultural Development Council (HDC) and some from Defra. A significant proportion of HDC levy has been spent on trials to identify alternatives to brassica pesticides lost in the 91/414/EEC Review and the UK anticholinesterase Review. High standards of pest, disease and weed control are required to maintain quality in vegetable crops.


Herbicides The following herbicides were not supported in the 91/414/EEC review: tebutam, sodium monochloroacetate, cyanazine. The ‘Essential Uses’ for brassicas expire 31 December 2007. They are not widely used but are applied post-emergence to remove weeds escaping control with pre-emergence herbicides. Cyanazine (SOLA) is particularly useful in controlling brassica-related weed species such as charlock. The weed seeds can contaminate heads of cauliflower and calabrese and reduce quality. After 2007 the control of charlock will be difficult because it is not controlled by other herbicides approved for brassicas. The future of trifluralin (List 2) is under consideration for non-inclusion in Annex 1. Trifluralin, soil-incorporated pre-planting, is the most widely used herbicide on 60% of the leaf brassica area. It is useful for early plantings in wet conditions where efficacy of tractor-hoeing is poor because weeds re-root. It is effective on herbicide-resistant black-grass, although not a current problem in horticultural brassicas it could be in future.

• Weed competition in leaf brassicas affects quality (size-grade uniformity) and maturity. Tall species, such as fat-hen, interfere with mechanical harvesting; nettles are unpleasant for hand pickers.

• Trifluralin is cheap (£5/ha) and is the basic starting point for control of problem weeds – polygonums, fat-hen and annual meadow-grass. The impact would be on increased cost of weed control c. £17/ha and control of weeds within the row would also be reduced.

If trifluralin is lost, leaf brassicas will still be grown but weed control will be expensive, and there could be an impact on quality and harvestability. The decisions on Annex 1 inclusion for other important actives metazachlor (List 3A), propachlor (List 3B) have not been made. Insecticides and molluscicides Chlorfenvinphos was revoked in 2002 as a result of the UK review of anticholinesterase compounds. The usage of organophosphates had already declined in some crops because of restrictions imposed by retailers, but it remained important for control of cabbage root fly, the most serious pest of UK brassica crops. Chlorfenvinphos was not supported in the 91/414/EEC review. ‘Essential Uses’ were permitted in other EU member states, but not in the UK.

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• Cabbage root fly larvae cause plant death in leaf brassicas, affecting uniformity of size of produce and maturity. In dry soil conditions larvae tunnel into the aerial parts of calabrese and Brussels sprouts, reducing quality and crops are rejected.

• Without control, it is estimated that about 24% of the plants in leaf brassica crops would be lost or rendered unmarketable by the cabbage root fly – financial loss £44 million.

Control measures have now been found. Chlorpyrifos and spinosad control cabbage root fly in most seasons: chlorpyrifos as a seed/module treatment; spinosad has new SOLA (February 2006) for cabbage root fly control in Brussels sprouts, cabbage and cauliflower (SOLA submitted for calabrese) as a module drench pre-transplanting or as a foliar spray 3 days after transplanting. Spinosad can be applied before the 1 April (unlike chlorpyrifos). Sometimes a subsequent treatment with chlorpyrifos granules is necessary. Control of the third generation is difficult and occurs more frequently in warm autumns. Control of aerial attacks is also difficult. Whether these control measures are adequate, remains to be seen. The problem has not been solved and new insecticides are needed particularly for root brassicas (not studied here). Triazamate was withdrawn by the approval holder and is not supported in the 91/414/EEC review. Triazamate was considered the best systemic insecticide for control of mealy grey aphid and the number of insecticide applications could be reduced. Other aphicides are not as effective as triazamate on mealy grey aphid.

• Now, early identification and treatment with other aphicides is essential - once colonies become established control is much more difficult and spoilage is inevitable.

• The aphid checks the growth of young plants, causing some plant death. Quality is spoilt where leaves curl up, and where produce is contaminated with aphid colonies.

Thiodicarb failed Annex 1 inclusion but there is no decision yet on other molluscicides. Fungicides Quintozene, a protectant, soil-applied fungicide was widely used by Plant Propagators. It was on List 1 of the 91/414 Review of existing actives but not supported and was revoked in 2002. No ‘Essential Use’ requests were granted. Toclofos-methyl (Annex 1) approved for damping off and wirestem in brassicas remains. Flusilazole (List 1) is approved for oilseed rape, and an application has been made for a UK SOLA for brassicas for control of Light leaf spot. However, the Commission proposed that flusilazole should be included on Annex 1 for use in some crops including oilseed rape, but not for others and a decision has not been made. There are also decisions to be made on Annex 1 inclusion of important triazoles approved for brassicas (on List 3B). It is very important for resistance management that as many active substances with alternative modes of action as possible are retained.


Herbicides Glyphosate non-selective herbicide pre-cropping. Trifluralin (List 2), applied pre-planting and incorporated;propachlor, metazachlor, clomazone (all on List 3) are also important for residual weed control; pendimethalin not widely used because soil disturbance at planting reduces efficacy within the row, but it is effective on Polygonums and will

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be very important if trifluralin is lost; clopyralid post-emergence important for thistle and mayweed control There is little use of graminicides in leaf brassicas, but options of tepraloxydim and cycloxydim will be needed for control of grass weeds or volunteer cereals; carbetamide (List 3A) (cabbage only) only needed if trifluralin goes and grass weed resistance increases; Insecticides and molluscicides Insecticides with alternative modes of action are important for resistance strategies It is vital that active substances for cabbage root fly control in brassicas remain: chlorpyrifos and the new spinosad; chlorpyrifos on imported seed. MACE Resistance in UK peach potato aphids (Myzus persicae) populations is an important issue for brassica growers. So far no current resistance mechanisms exist with regard to nicotine, neonicotinoids or pymetrozine. To avoid resistance, the use of neonicotinoids will be limited to 2 applications/crop this includes imidacloprid seed treatments. All the current options are needed for aphid control: imidacloprid seed treatment; pyrethroids (lambda-cyhalothrin, deltamethrin etc.); pirimicarb alone or in formulation with a pyrethroid; pymetrozine; new thiacloprid, and nicotine. So are dimethoate (List 2) (cabbage only) and chlorpyrifos. Rotenone is not widely used but may be useful as another tool for aphid resistance management. Pyrethroids are used for cheap caterpillar control; spinosad controls diamond back moth caterpillars - a serious problem in 2006. Molluscicides: Metaldehyde (List 3A) should be maintained, and possibly methiocarb (List 2) for slugs. Fungicides Seed treatment: thiram for damping-off diseases Propagation: toclofos-methyl for wirestem control; fosetyl-aluminium is important for downy mildew; propamocarb hydrochloride (List 2) is occasionally used for control of Pythium spp.; azoxystrobin for black rot; copper oxychloride (List 3A) field and propagation for reduction of spear rot and Xanthomonas. Field: Strobilurins and formulation (azoxystrobin, boscalid (pending)/pyraclostrobin); triazoles (e.g. tebuconazole, difenconazole both List 3B); chlorothalonil are all important for a range of foliar diseases and needed for an resistance strategy: Metalaxyl-M formulations essential for downy mildew, white blister. Post-harvest: cabbage metalaxyl-M for Phytopthora and iprodione for Botrytis control are the only approved fungicides.


The area of oilseed rape has increased dramatically in recent years and there is a risk of pests and diseases spreading from neighbouring rape crops. However, brassicas may benefit from pesticides developed for rape in future. Herbicides Herbicides developed for oilseed rape are likely to be suitable for brassicas and some could replace cyanazine. None are soil-incorporated and would not replace trifluralin in some respects. Active substances that appear promising in HDC trials: oxadiargyl (on Annex 1), prosulfocarb (List 3A), oxyfluorfen (List 3B) used in Spain, dimethachlor (List 3B); dimethenamid-p (new Annex 1)

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formulation; post-weed-emergence bifenox (List 3A). In most cases residues data would need to be generated. Insecticides and molluscicides More insecticides are in global development for fruit and vegetables than for other crop sectors. New ones with different modes of action are needed for resistance strategies. Aphid: Flonicamid could be useful. Insecticides for control of mealy grey cabbage aphid, MACE resistant peach potato aphid and cabbage root fly are evaluated at Warwick HRI, Wellesbourne in HDC projects. Caterpillars: Indoxacarb (new Annex 1) approval for control in brassicas is sought for the UK through Mutual Recognition. It is benign to beneficials but kills all caterpillars including those of diamond back moth (not controlled by pyrethroids) and silver Y moth. For the future, rynoxapyr another new active (new chemistry anthranilimide), classed in the US as ‘Reduced Risk/OP Alternative’. Cabbage root fly, aphid and other pests: New broad spectrum active (new chemistry) is in development but not available for a few years. Slugs: New more effective measures are needed. Fungicides New fungicides with different modes of action for resistance management and with curative activity are needed. Global fungicide development for the vegetable sector has increased. There are several brassica diseases where there are no means of control (club-root) or potential gaps where control measures are inadequate or limited. There are HDC projects to find alternatives. The following may offer potential solutions for some diseases: cyazofamid, flusulfamide (USA), fluazinam, cyprodinil/fludioxynil, cyazofamid, mancozeb/zoxamide, fluoxystrobin/tebuconazole to be registered for brassicas for Dark leaf spot; flutolanil and pencycuron, triflumizole, fluopicolide and a new generation of spinosad.

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CARROTS Summary

The area of carrots grown in the UK in 2005 was 9,500 ha. Most recommendations for the crop are based on information from research funded by growers through the Horticultural Development Council (HDC) statutory Levy and Defra/LINK. A significant proportion of growers levy through HDC has been spent on trials to identify alternatives to carrot pesticides lost in the 91/414/EEC Review and the UK anticholinesterase Review. Carrots are high value compared with wheat and high standards of pest, disease and weed control are needed to maintain quality.


Herbicides Three key herbicides for carrots metoxuron, prometryn and pentanochlor were not supported in the 91/414/EEC Review. The derogations for the ‘Essential Use’ of expire December 2007. No single herbicide controls the whole weed spectrum encountered and programmes with low doses of different herbicides are used. Metoxuron applied post-emergence provides good suppression of volunteer potatoes. It controls a wide range of weeds including mayweeds and is used in most post-emergence programmes. Prometryn has both contact and residual action and is the only herbicide effective on fumitory and useful for small nettle. Pentanochlor provides the only post-emergence option for control of knotgrass. It is particularly effective against cleavers and redshank. Linuron applied pre- and post-emergence forms the basis for weed control in carrots. It is on the Annex 1 positive list, but when it is re-registered in the UK the maximum dose-rate per annum will be limited to 950 g a.i. /ha. This could occur before alternative aclonifen is available in the UK. Fast access to alternative herbicide aclonifen used for carrots in Denmark is needed. Growers will have to revise their weed control strategy.

• Weeds affect quality in terms of size grade and uniformity of crop (a standard specified by the retailer or processor). Failure to meet specifications results in crop rejection or no sales.

• Yield loss of up to 100% can occur but depends on the numbers and species of weeds. • Weeds reduce harvest work rate, cause harvest losses and increase costs. • So far there is no potential replacement for metoxuron for volunteer potato suppression.

Volunteer potatoes uncontrolled in carrots can be a reservoir of potato blight infection - this causes concern to potato growers. If no herbicidal control was available (needed for 8% of the crop in the 2003 survey), then if the crop was not harvestable, losses could amount to more than £10 million per annum. Far more costly methods for control of volunteer potatoes will be used: hand-pulling or selective application of glyphosate.

• Although mechanical weed control with hoe, tine and brush weeders is possible in carrots grown in wide rows, weeds within the row are not controlled, and it is not an option for baby carrots grown at high densities on a close-row bed system. All methods are considerably more expensive than with herbicides - the cost of weeding once with a brush weeder is £63 /ha and three are usually needed.

Decisions on Annex 1 inclusion for other important herbicides metribuzin (List 2) or clomazone (List 3A) have yet to be made. At product re-registration stage there will be dose-rate restrictions for metribuzin, but this will have no impact on carrots, where only low doses are safe to the crop.

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Insecticides and nematicides The nematicide aldicarb failed to achieve Annex 1 listing in the 91/414/EEC Review - the derogation for ‘Essential Use’ in carrots expires 31 December 2007. Fanging is caused by nematodes (and other factors) and quality is reduced. Fanging affects c. 7.5% of the UK carrot crop, and the loss is estimated at £4.7 million p.a. In 2005 an alternative nematicide oxamyl, achieved Annex 1 listing, and there is now a SOLA for use in carrots. Oxamyl is not as persistent and incidental control of aphid is reduced. As a result of the UK review of anticholinesterase compounds chlorfenvinphos was revoked in 2002. It was used for carrot fly, a serious pest - if not controlled, larvae tunnel into the carrot root and crops are rejected (maincrop value is £6,600/ha). Later, chlorfenvinphos was not supported in the 91/414/EEC review. No ‘Essential Uses’ could be requested in the UK. Control was adequate with tefluthrin seed treatment followed by several applications of lambda-cyhalothrin (the most effective pyrethroid). The lambda-cyhalothrin SOLA for carrot fly control permitted 6 applications at 150 ml/ha dose rate. Some growers require 10 weeks cover. Following re-registration in November 2005 after Annex 1 inclusion of lambda-cyhalothrin, the label dose was for 100 ml/ha (harmonisation across EU) and a new SOLA restricted applications to 4 and individual doses 100 ml/ha – and this would have reduced control. A new SOLA (August, 2006) allows 4 applications, 150 ml maximum dose, total dose 450 ml. It remains to be seen whether carrot fly can be controlled adequately in future. Fungicides Carrot fungicides were supported in the 91/414/EEC review because there were uses in several other crops. So far none have been lost through failure to achieve Annex 1 listing.


Herbicides Glyphosate non-selective herbicide used pre-cropping. The few herbicides that remain for carrots must be maintained: linuron; pendimethalin; clomazone (List 3A); isoxaben (List 3B) used where mayweeds are a severe problem; metribuzin (List 2) at low doses will be very important for post-emergence weed control. Tepraloxydim; propaquizafop, cycloxydim, fluazifop-p-butyl (all three on List 3A) ‘fop’ and ‘dim’ graminicides important, for both grass weed and barley cover crop removal. Insecticides and nematicides Soil applied: oxamyl SOLA nematicide. Seed treatment: tefluthrin (List 3B) (SOLA) and foliar sprays of lambda-cyhalothrin (SOLA) at 150 ml/ha for carrot fly control. Foliar sprays: pyrethroids (all effective) are essential for cutworm control (chlorpyrifos cannot be used now); carbosulfan (List 2) little used but could be important for early carrot fly control if pyrethroid resistance develops or if seed treatment product lost; pirimicarb (Annex 1), registration for carrots essential for aphid control to prevent the spread of virus; nicotine is also useful; rotenone is not currently used, but could be important if resistance develops.

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Fungicides Coniothyrium minitans, a biofungicide applied before cropping, is needed although it will take several seasons to determine long-term efficacy relative to fungicide application. Seed treatment: cymoxanil (List 3B) /fludioxonil (List 3A) /metalaxyl-M Soil-applied: metalaxyl-M, only means of control for cavity spot, needed until a more effective alternative is found. Foliar sprays: A mixture of products from different mode of action groups is important for anti-resistance strategies: triazoles, strobilurins & morpholines. Strobilurins for Sclerotinia; tebuconazole (List 3B); fenpropimorph (List 3A); azoxystrobin/ difenoconazole (List 3B) important for powdery mildew and Alternaria, and thiophanate-methyl/ iprodione.

3.Prospects for alternatives for any foreseen major gaps in pesticide availability

Herbicides Alternatives have been found for carrots. Because of the slow process of the 91/414 review aclonifen (List 3B), approved for carrots in Denmark, will not be available to UK growers before the ‘Essential Uses’ expire (or before the dose for linuron is limited). In an HDC project aclonifen in tank-mix with pendimethalin pre-emergence looked very promising. Effective post-emergence treatments were tank-mixes of diflufenican + linuron (residues and metabolism data needed for diflufenican), pendimethalin + linuron, aclonifen + linuron or aclonifen alone. So far there is no potential replacement for metoxuron for volunteer potato suppression. Insecticides and nematicides A trial, funded by HDC, to screen new insecticide alternatives for carrot fly control began in 2006. There is also a need for new nematicides or alternative methods of control. Fungicides Currently there are no approvals for control of several carrot diseases, including new ones. Growers are reliant on a single active substance, metalaxyl-M, for control of Cavity spot and alternatives needed. New fungicides with curative activity and different modes of action are also needed. Fungicides for potato blight control and for use in vines are potential sources for carrots. A new foliar spray, cyprodinil/fludioxynil approved for Sclerotinia in France, is to be registered in the UK; fluazinam is another possibility.

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WINTER WHEAT Recommendations for the wheat crop are based mostly on information from research funded by farmers through the Home Grown Cereals Authority (HGCA) statutory levy and/or work commissioned by Defra. The cost of on-going projects is currently £2.7million from HGCA plus £7.9 million from co-sponsors. Most of the current R and D projects are for cereals and disease management and resistance. To date, none of these projects result from any impact of 91/414/EEC. The HGCA R and D budget is £2.4 million/annum and knowledge transfer is £400K. Other organisations carry out additional research.

Background Crop area and use The total area of winter and spring sown wheat grown in the UK for the 2005 harvest year was 1,869,000 ha (Defra, 2006) 42% of the total cropped area and is expected to be about 1,771,000 ha in 2006. The area of spring-sown wheat is normally only 1% or 2% of the UK wheat area. For the purposes of this study, winter and spring wheat are not differentiated for treatment usage figures, but pesticide approvals listed relate only to winter wheat. Wheat is by far the most important arable crop in Great Britain and in 2004 comprised 42% of the area of all crops. Average yields of winter wheat are 8 t/ha, but there are important differences in yields between milling varieties (grown for bread-making and baking) and feed varieties, and whether the crop is a first, second or third wheat after a break crop in the rotation. Milling wheat varieties are generally lower yielding (average 9% or less) but normally attract a price premium over feed wheats. There is also a substantial variation in yields between growers ranging from a low of 6.75 t/ha to 9.75 t/ha for feed wheat, with the best farmers achieving 11 t/ha. In the three years 2002/3 to 2004/5, between 25 - 40% of UK wheat was used for milling, 50 - 60% mainly for feed and between 5 - 25% was exported (Nix, 2005). Although the UK is a net exporter of wheat, between 0.8 - 1.5 million tonnes of high quality milling wheat is imported each year for domestic bread-making (M Mendelsohn, pers. comm.). Rotations There is a range of different cropping patterns and rotations for winter wheat that vary according to a number of factors, including soil type and region. Commonly wheat would be grown in rotation with other combinable crops especially winter or spring-sown beans and winter or spring oilseed rape on the heavier soils. A rotation in the Eastern region on heavier soils was a sequence of two winter wheat crops followed by oilseed rape (spring or winter), before wheat again and then beans (WW - WW - OSR - WW - S/W beans) but in future the vast majority of rotations will include only first wheat crops because of a marked drop in yield of the second wheat. On lighter soils in East Anglia a higher proportion of spring-sown crops are grown in the rotation, with more emphasis on first wheat crops. On lighter soils in southern England a shorter rotation would be more typical with a sequence of winter wheat, winter oilseed rape, winter wheat and spring beans (WW - W.OSR - WW- S/W beans). Oats might be substituted for spring beans in this sequence where black-grass is not a problem. Wheat would not normally be grown more than twice consecutively, but growing continuous wheat is still practised on some heavy soils. In Scotland spring barley would figure more prominently in cereal rotations. Oilseed rape may be grown more frequently in the rotation in future (WW – OSR).

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Economics/profitability The profitability of winter wheat has fallen dramatically since the 1990s when wheat was over £100/t. The average price of wheat in 2004/5 was just £62/t and at this level, The Arable Group (TAG) crop consultancy (J Orson, pers. comm.) calculated that farmers need to achieve yields of at least 7.5 - 8 t/ha to make growing the crop worthwhile. Whilst a small price recovery to £72/t is now being quoted for the 2006 harvest, average-yielding farms will still be under severe economic pressure. Only those farms achieving above average yields of 9 - 11 t/ha and/or receiving high premiums for the best quality bread-making wheat are likely to be making significant margins above their production costs.

Weed Control in Winter Wheat Although there is a very wide range of weed species that occur in winter wheat, there are relatively few which have major impacts on yield and only these will be considered briefly in this overview. Information has been drawn from discussions with weed specialists, the Chapter by Peter Lutman in the biodiversity review for Defra PN0940 (Marshall et al., 2001) and a range of other published literature especially Topic sheets and Guides produced by the HGCA and available on their website www.hgca.com. This included the recent review of HGCA funded weed research 1994 - 2005 by Edwards (2006). Studies of the variable impact of different weed species has enabled lists to be drawn up which reliably rank individual species according to the degree their presence can be tolerated by the crop (Clarke, 2006). The rankings given in Table 1 are based on the numbers of weed plants, which can be tolerated by the crop to give less than a 5% yield loss in winter wheat. Such a threshold provides a guide to when control is economically justified and illustrates the relative importance of different weed species, although in practice farmers are likely to control oilseed rape. Table 1. Number of weeds tolerated by a vigorous w. wheat crop [based on Blair, Cussans and Lutman, cited by Clarke (2006)]

Tolerance Index Species

None 0 Barren brome, Black-grass, Cleavers, Couch, Italian ryegrass, Meadow brome, Wild-oats Up to 20 plants/m2 1 Charlock, Mayweed, Oilseed rape*, Poppy, Thistle 20 - 49 plants/m2 2 Campion, Chickweed, Fat-hen, Forget-me-not, Redshank 50 - 99 plants/m2 3 Annual meadow-grass, Crane's bill, Fool's parsley, Fumitory, Groundsel, Knotgrass, Red

dead-nettle, Scarlet pimpernel, Sow-thistle, Speedwell, Wild onion Over 100 plants/ m2 4 Black-bindweed, Field pansy, Parsley piert, Venus's-looking glass

Impacts of weeds are:

• on yield, due to competition which is likely to be most severe when weeds emerge at the same time as the wheat crop. At this time of emergence several of the grass weeds can be particularly damaging.

• effect on ease of harvesting and on grain quality. • on value of the grain when contaminated with weed seeds. • in acting as hosts to cereal pests and diseases. Black-grass, for example, can increase the risk

of ergot infection in wheat.

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Black-grass (Alopecurus myosuroides): Black-grass occurs widely but is particularly common on heavy soils in central southern and eastern England. It has been encouraged by intensive growing systems (continuous autumn sown crops) and the widespread use of reduced cultivations. Black-grass is in the top category of competitive weeds in wheat. The value of threshold levels is contentious, but they give an indication of the relative impact of different species. Studies at Rothamsted show that 12.5 black-grass plants/m2 can reduce yields by 5%; moreover black-grass frequently occurs at densities of over 500 plants/m2 causing severe yield losses. In 1997 it infested c. 700,000 ha of winter-sown cereals (Orson & Harris, 1997) and this figure is probably higher now. There is a serious problem with herbicide resistance in black-grass (see section on control). Wild-oats (Avena spp.): There are two problem species, winter and common wild-oat. These annual weeds germinate in winter and/or spring and they are also in the top rank of competitive weeds. Wild-oats can be more competitive than black-grass, although they tend to occur at lower populations densities than black-grass. Five wild-oat plants/m2 can reduce yields by 5%. Herbicide-resistant wild-oats are widespread, but incidence is less common than with black-grass. Italian rye-grass (Lolium multiflorum): This species is often a legacy of grassland production but it is now widespread in arable areas. It is a vigorous and prolific plant and the critical threshold for reducing yields by 5% is only 5 plants/m2. Herbicide-resistant ryegrass biotypes are known to be increasing, particularly for ACCase inhibitors ('fops' and 'dims'). The brome grasses: There are three main species of brome; barren brome (Anisantha sterilis), meadow brome (Bromus commutatus) and soft brome (B. hordeaceus). These are all weed species associated with continuous autumn sown crops, particularly where non-plough tillage and early drilling are practised. Barren brome is the most common species but distribution tends to be confined largely to crop headlands. Problems are greatest in winter wheat grown after a dry late summer/early autumn when seed remains dormant. Barren brome and meadow brome both have a wheat crop tolerance of zero (Table 1). Resistance to herbicides has not been identified so far. Cleavers (Galium aparine): This is commonly recognized as the most aggressive weed of winter wheat and is the only broad-leaved weed to have a zero index in the weed tolerance listings (Table 1). Individual cleaver plants are more competitive than black-grass and wild-oats and 20 - 30 plants/m2 can halve wheat yields. Apart from direct effects on yield, cleaver seeds are difficult to separate from grain and can be a serious contaminant. Couch grasses (Elytrigia repens and Agrostis stolonifera): The two most common couch grasses are common couch (E. repens) and black bent (A. stolonifera). They are both rhizomatous perennial grasses, but shoot growth from over-wintered rhizomes is slow and competition from the crop restricts this aerial growth until late in the season when the crop starts to senesce. Meadow grasses: Although individually less competitive than other important grass weeds (Table1), meadow grasses are prolific seed producers. Unchecked they can occur in large populations. The most common and important of these species is annual meadow-grass (Poa annua), which is identified as a significant target in weed management programmes for winter wheat. There are some indications of increasing difficulty of control with the soil acting urea herbicides (S Cook, pers. comm.) and a degree of enhanced metabolism resistance is suspected, although not yet confirmed (S Moss, Rothamsted Research, pers. comm.).

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Control of grass weeds In intensive winter wheat production, weed control has been very much focussed on the use of herbicides. The mainstay for control of black-grass in particular has been the pre-emergence/early post-emergence broad-spectrum soil acting herbicides isoproturon and trifluralin. Pendimethalin is also very useful, although more expensive, and there is a range of post-emergence ACCase inhibitors 'fops' and 'dims' and ALS inhibitor sulfonylurea herbicides. One of the more recent introductions is the formulated mixture of mesosulfuron/iodosulfuron (product Atlantis), which is very effective on both black-grass and rye-grass. Isoproturon, chlorotoluron and pendimethalin also give a useful control of wild-oats at early stages of growth. In addition, tri-allate is important for this weed, as are a number of post-emergence sprays such as fenoxaprop, clodinafop-propargyl and the newly approved pinoxaden a new class of ACCase inhibitor (a ‘den’). Italian rye-grass is well controlled by the newer products mesosulfuron/iodosulfuron and pinoxaden. Useful degrees of control are also afforded by chlorotoluron, flufenacet/pendimethalin and iodosulfuron. In the past brome grasses were difficult to control with selective herbicides, but more reliable results are now being achieved with sulfosulfuron. Control of couch grass tends to rely heavily on the use of glyphosate as a pre-harvest spray (but cannot be used on seed crops) or for pre-planting autumn stubble application. Annual meadow-grass is normally controlled by the soil acting residuals herbicides isoproturon, chlorotoluron, flufenacet and pendimethalin provided there is adequate soil moisture. Iodosulfuron post emergence is highly effective, as is the formulation with mesosulfuron (Atlantis), but these are expensive options. Control of annual broad-leaved weeds Broad-leaved weed control in winter cereals is usually linked to grass weed control with autumn treatments, making use of broad-spectrum herbicides such as isoproturon, pendimethalin and trifluralin. In recent years mixing of diflufenican with isoproturon has become common because it gives a single treatment control of almost all the main cereal weeds except cleavers. Spring treatments are targeted at broad-leaved weeds that survive the earlier autumn herbicide applications. Cleavers is often the main target where use of mecoprop, fluroxypyr and amidosulfuron are important. Often a low dose of the sulfonylurea metsulfuron will be admixed to this treatment where there is survival of other broad-leaved weeds such as mayweeds. Herbicide resistance The brief overview of chemical control in winter wheat must all be qualified by herbicide-resistance management strategies, particularly in the case of grass weed control. This is probably the single most important agronomic issue facing winter wheat production in the UK and it has been described as a real threat to the sustainability of arable farming in the UK. This subject has been comprehensively addressed in many recent publications and knowledge transfer media including the Weed Resistance Action Group (WRAC) website hosted by PSD, (www.pesticides.gov.uk). HGCA has supported publications of guidelines by the WRAG, the most recent being the 2003 edition, which is a standard reference on managing and preventing herbicide resistance.

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PSD has recently reviewed grass weed resistance in the UK in some considerable depth as a background to the proposed introduction of more stringent label restrictions to re-inforce resistance management and prevention strategies. Internal papers on the subject have included an update of the likely financial impact of herbicide-resistance originally detailed in a paper by Orson and Harris (1997). This study therefore only gives a brief summary of the most salient aspects to place in context how the ongoing 91/414/EEC review process and expected revisions might impact on this critical issue.

• In the UK the main herbicide-resistance problems in wheat are with the grass weeds: black-grass, Italian rye-grass and wild oats.

• Resistance is widespread with all of these grass weeds, but it is most serious with black-

grass. Resistant black-grass is now considered to be present on virtually all farms that use grass weed herbicides on a regular basis (Moss, 2006) although, in the absence of detailed surveys, the actual number of hectares with herbicide resistant biotypes is unknown.

• Results of resistance testing services and surveys have shown the herbicide resistance

problems are becoming more prevalent.

• Currently the two main groups of wheat herbicides affected are the 'fop' and 'dim' selective graminicides (ACCase inhibitors) and the ureas, isoproturon and chlorotoluron. Resistance to pendimethalin can occur but is at a low level and resistance has never been detected in the UK to the other dinitroaniline, trifluralin.

• The enhanced metabolism mechanism of herbicide resistance has typically occurred in

situations where herbicides have been regularly used for the control of black-grass or Italian rye-grass in winter wheat. Similarly, the target site mechanism resistance to the ACCase mode of action of the ‘fops’ and ‘dims’ has also occurred where herbicides with this mode of action has been regularly adopted for the control of these two weeds. There is increasing concern that target site resistance to the ALS mode of action of the sulfonylureas is occurring in black-grass after the use of mesosulfuron/iodosulfuron (Atlantis) in previous wheat crops. In 2006 so far, 24 cases of mesosulfuron/iodosulfuron grass weed resistance have been confirmed (S Moss, Rothamsted, pers. comm.). Target site resistance to sulfonylureas does not appear to be as robust as that to the ACCase mode of action and hence the full implications of its occurrence have yet to be identified.

• Clear guidelines for managing and preventing herbicide resistance have been widely

promulgated. Farmers have generally ignored guidelines for preventing the development of resistance to the sulfonylureas because of economic necessity at a time of low or negative financial margins for wheat and also because the lack of alternative effective chemical solutions.

• A key part of the strategy formulated by WRAG for managing and preventing herbicide

resistance is to rotate herbicides with different modes of action. This clearly requires the retention of as wide a range of herbicide types as possible. The perceived legislative threat to the continued availability of the urea herbicides isoproturon and chlorotoluron and the dinitroaniline, trifluralin is the major concern to the industry in this context.

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Cultural control Traditionally ploughing was the universal preparation for a cereal crop but there has been a strong move away from this to reduced cultivation systems, primarily for cost reasons. Recent escalations in fuel and labour costs, coupled with low cereal prices, have made ploughing even less attractive. However, perennial grass weed populations often increase with reduced tillage. The increasing problems with grass weeds associated with intensive winter cropping, reduced cultivations and the development of herbicide resistance is favouring a move away from heavy reliance on herbicides towards a more integrated approach in which cultural control methods play a larger part. Cultural control techniques include ploughing, mechanical weed control, adoption of a diverse a rotation as possible, stale seedbed methods and delayed drilling of winter cereals. These are all methods advocated for consideration in the resistant management strategy guidelines. However, as indicated, many growers under economic pressures prefer to stay heavily reliant on chemical weed control, especially with the perceived panacea of mesosulfuron/ iodosulfuron, which gave effective black-grass control in the 2004/2005 season. The relatively high costs of integrating cultural alternatives are illustrated by a recently completed LINK project (2002-2005). In this project a computer guided mechanical hoeing system for inter-row weed control combined with intra-row band spraying of herbicides was evaluated. The technique was effective, but the cost of equipment was too expensive to be commercially attractive at the present time. Herbicides for winter wheat The most recent Pesticides Usage Survey for 2004 gives data on the herbicides used in 2003/2004 in winter wheat crop. A summary of those most widely used (i.e. on more than 10% of the crop area) in 2004 is given in Table 2. The relative importance of the different active substances is clearly illustrated, especially the dominant position of isoproturon alone and in mixtures. This active alone was used on over 40% of the wheat census area. Fluroxypyr, for control of cleavers, was used on 36% of the area. Mecoprop-P and pendimethalin were the next most widely used broad-leaved weed herbicides with just over 20% in each case. Glyphosate was also in the top five of the most used herbicides being sprayed mainly before sowing on 23% of the area. The iodosulfuron/mesosulfuron combination ('Atlantis') is now the established means for control of grass weeds in difficult situations, especially black-grass and the area treated will certainly have increased considerably in 2005 and 2006. Tri-allate was used on 80,101 ha in 2004 – supplies have been difficult to obtain in some years. On average wheat was treated in 2003/2004 with three herbicide applications. Separate treatments were applied to control grass and broad-leaved weeds and there were applications in both autumn and spring. Some of the principal herbicides were used at or at less than half the full label rate. There are 48 active substances currently approved (June 2006) for winter wheat in the UK and these are given in Appendix 1. There are 313 products approved (June 2006), Many are formulated mixtures of two or more active substances, for example there are 6 different bromoxynil mixtures, 6 diflufenican mixtures and 13 mixtures of dicamba/mecoprop-P. Unlike many other crops grown in the UK, there is a very wide selection of herbicide active substances and formulations for wheat growers to choose from.

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Table 2. Main herbicides used on winter wheat in 2004 (main = on at least 10% of the crop area 1,981,661 ha grown in GB 2004); Review status; Aim re-registration for UK wheat; Activity; Approx. area treated; area treated in 2004 as approx. % of area sown (Source CSL Pesticide Usage Survey data, 2004) Target weed groups/ Herbicides approved 2006 (full List Appendix 1)

Review Status Aim re-register wheat UK

Activity Approx. area treated2004 (ha x1000)

Area treated as % area

sown Total weeds Glyphosate Annex 1 √ phosphonic acid 513 26 Grasses Clodinafop-propargyl Annex 1 √ aryloxyphenoxy-propionate 381 19 Clodinafop-propargyl/trifluralin Annex 1/List 2 √ aryloxyphenoxy-propionate /dinitroaniline 235 12 Fenoxaprop-P-ethyl List 3A √ phenoxypropionic acid 217 11 Iodosulfuron/mesosulfuron Annex 1/Annex 1 √ sulfonylureas 227 11 Broad-leaved weeds/Grasses Diflufenican/isoproturon List 3A/Annex 1 √ anilide/urea 421 21 Florasulam/fluroxypyr Annex 1/Annex 1 - triazolopyrimidine/aryloxyalkanoic acid 206 10 Flufenacet/pendimethalin Annex 1/Annex 1 - oxyacetamide/dinitroaniline 284 14 Flupyrsulfuron-methyl Annex 1 √ sulfonylurea 369 19 Fluroxypyr Annex 1 ⎯ aryloxyalkanoic acid 706 36 Isoproturon Annex 1 √ urea 908 46 Mecoprop-P Annex 1 √ aryloxypropionic acid 486 25 Metsulfuron-methyl Annex 1 √ sulfonylurea 331 17 Pendimethalin Annex 1 ⎯ dinitroaniline 426 21 Trifluralin List 2 ⎯ dinitroaniline 381 19 - Company request confidentiality; √ yes

1. The likely impacts of the 91/414/EEC review process on herbicide availability for UK wheat Losses/Impact A small number of wheat herbicides were not supported in the 91/414/EEC Review and were lost in the early stage of the review process including terbutryn, difenzoquat, methabenzthiazuron, flamprop-isopropyl and imazamethabenz-methyl (use by 30 September 2006). Later, simazine was not included in Annex 1. However these were all outclassed substances used on only a minor scale. Leading agronomists have confirmed none of these losses have had any significant agronomic impact on the wheat crop. Future Losses Unlike many other crops grown in the UK, there is a very wide selection of herbicide active substances and formulations for wheat growers to choose from. All the main herbicides listed in Table 2 have achieved Annex 1 listing with the exceptions of trifluralin (List 2), diflufenican (List 3A) and fenoxaprop (List 3A). It is known that the future of trifluralin is in doubt because of its eco-toxicity profile and the possibility of it being classified as a persistent organic pollutant (POP). The critical value of the role this herbicide has in cereal weed control (especially for resistant black-grass control) was set out very comprehensively in the WRAG document submitted to PSD in October 2005 (Response from Weed Resistance Action Group in relation to trifluralin and Annex 1, www.pesticides.gov.uk ).

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Some of the main points in this document were:

• The main value of trifluralin is that it can be used to control the important grass weeds of cereals, especially black-grass and that no herbicide resistance to trifluralin has been detected in grass weeds in the UK.

• Whilst numerous other grass weed herbicides are available they are nearly all subject to varying degrees of herbicide resistance.

• Trifluralin at c. £5 cost /ha is a low-cost herbicide treatment. Loss of trifluralin would not only remove a very valuable tool in the resistant grass weed management strategy, (in this and other crops), it would also require the substitution of more expensive alternatives.

• Increased production costs would be at a time when wheat profit margins are already under severe pressure.

• It is unlikely there will be any novel herbicides with different modes of action introduced in the short or medium term, thus the loss of trifluralin would exacerbate current resistant management problems.

At current prices, the need to substitute more expensive alternatives such as pendimethalin would give an additional treatment cost of approximately £13/ha. This would have a significant impact on profitability if wheat prices were to revert to the very low levels of c. £60/tonne as in 2005. However prices improved considerably in 2006 to over £70/tonne and in this context, an extra £13/ha in herbicide costs would be more acceptable. Whilst future wheat prices, heavily affected by global markets, are unpredictable, developments such as the increasing use of wheat for ethanol bio-fuel production may presage a period of better returns. The potential impact associated with a loss of trifluralin for herbicide resistant grass weed management per se is more serious, particularly in the case of black-grass. This is because:

• Target site resistance to the ACCase inhibitors ('fops & dims') is common and it is becoming more frequent with the sulfonylureas (SUs).

• It is known that the two resistances can occur in the same plants and there is a real possibility that an increasing number of black-grass populations would not be controlled by either herbicide group.

• The expected reduction in the maximum rate of isoproturon to 1500 g a.s. /ha in 2007 (from 2500g a.s.) is well below the rate for good black-grass control, effectively minimising its value for this use.

• The above factors would place heavy resistance selection pressure on the few remaining black-grass herbicides, tri-allate, flufenacet and pendimethalin.

• Although there is a range of cultural and integrated control alternatives to selective herbicides, these can be unreliable and are still relatively expensive or have a cost penalty, as in delayed sowing.

The complexities of resistant grass weed development and control make it impossible to quantify the potential agronomic impact of trifluralin loss. However it appears likely it could accelerate the development of multi-herbicide resistant black-grass and hence exacerbate problems of controlling this highly competitive weed. Inadequate chemical control would reduce yields, require more costly cultural alternatives and have a profound detrimental effect on the economics of winter wheat production. Diflufenican is a key component of broad-leaved weed control programmes in wheat, and it will be supported for re-registration.

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Support for fenoxaprop-P-ethyl is uncertain, but there is widespread grass weed resistance to this herbicide and any future loss would probably have minimal impact. There is also reason for concern regarding the future retention of the major wheat herbicides isoproturon, chlorotoluron and mecoprop, which are regularly detected in water and the possible impact of the Water Framework Directive. It is not known whether all the active substances on Annex 1 will achieve re-registration in the UK. There are 48 active substances currently approved (June 2006) for winter wheat in the UK (Appendix 1). There are 313 products approved (June 2006), several are low-cost off-patent herbicides sold by generic companies. There are several products containing the same single active, for example, 10 MCPA and 10 isoproturon products. Many products are formulated in mixtures of two or more active substances and where different companies are involved it is difficult to establish whether there is an aim to re-register the product after Annex 1 listings (some are a long way off) and decisions may not have been made yet. It is possible that there will be rationalisation of products and that some of them will not be re-registered in the UK for use on wheat. Dose rates and number of applications and timings could be reduced at the re-registration stage, and may have an impact on efficacy. As noted before, this is a particular concern for isoproturon, especially in the context of enhanced metabolism resistance which is already resulting in reduced efficacy. 2. Specific herbicides or herbicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties? The overriding consideration in addressing this issue for wheat is the management of prevention strategy for herbicide resistant weeds. As stated earlier a key component of this strategy, as set out in the WRAG/HGCA Guidelines document (2003), is to employ herbicides with different modes of action and avoid reliance on high resistance risk herbicides. Where target site resistance has been identified, then management of the problem is largely reliant on the use of an alternative herbicide from a different mode of action group. Whilst there are fifty active substances currently approved for winter wheat, the range of different modes of action is very much more restricted. In comparing these with the main herbicides used in wheat, it is very apparent the industry is reliant on a limited choice of different modes of action. Some of the most important of these currently used in standard grass weed control protocols for wheat are set out in Table 3. A number of the key active substances given in Table 3 are broad spectrum and important for both grass and broad-leaved weed control. Isoproturon, pendimethalin, trifluralin and flupyrsulfuron, mesosulfuron/iodosulfuron are particularly valuable in this context. For grass weed control, it would also be important to retain tri-allate and the new herbicide pinoxaden (Axial) which is particularly efficacious for rye-grass and wild-oat control.

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Table 3. Key wheat herbicide groups for the control of the main grass weed species and their mode of action (adapted from WRAG/HGCA Guidelines 2003) Mode of action Chemical family Active substance examples Product example

clodinafop-propargyl Topik ACCase inhibitors Aryloxyphenoxy-propionates ('fops') fenoxaprop Cheetah Super

Sulfonylureas flupyrsulfuron Lexus Sulfonylureas iodosulfuron/mesosulfuron Atlantis

ALS inhibitors

Sulfonylaminocarbonyltriazolinones propoxycarbazone Attribut isoproturon various Inhibition of photosynthesis at photosystem II Ureas chlorotoluron various

Inhibition of EPSP synthase Glycines glyphosate various pendimethalin Stomp Inhibition of microtubule assembly Dinitroanilines trifluralin Treflan

Inhibition of cell division Oxyacetamides flufenacet in Crystal Inhibition of lipid synthesis (not ACCase inhibition)

Thiocarbamate tri-allate Avadex

Broad-leaved weed herbicides that feature prominently in current wheat weed control protocols are: metsulfuron-methyl: this is relatively inexpensive and considered by some leading consultants to be the most useful of the broad leaved weed sulfonylureas. fluroxypyr: the leading cleavers herbicide, but also used for volunteer potato control. mecoprop-P: the most important phenoxypropionic herbicide for general broad-leaved weed control which includes activity against cleavers and several perennial dicotyledons (nearly 0.5m sprayed ha in 2004). diflufenican: a key component of the most widely used broad spectrum general weed herbicides in the 2004 CSL Survey. ioxynil/bromoxynil: this has an alternative mode of action. There are reports of recent revived interest and increase in usage for resistant /difficult to control weeds. There is also reason for concern about the major wheat herbicides isoproturon, chlorotoluron and mecoprop detected in water and the possible impact of the Water Framework Directive. It is not known whether all the active substances on Annex 1 will achieve re-registration in the UK. There are 48 active substances currently approved (June 2006) for winter wheat in the UK (Appendix 1). There are 313 products approved (June 2006), several are low-cost off-patent herbicides sold by generic companies. There are several products containing the same single active, for example, 10 MCPA and 10 isoproturon products. Many products are formulated in mixtures of two or more active substances and where different companies are involved it is difficult to establish whether there is an aim to re-register the product after Annex 1 listings (some are a long way off) and decisions may not have been made yet. It is possible that there will be rationalisation of products and that some of them will not be re-registered in the UK for use on wheat. Dose rates and number of applications and timings could be reduced at the re-registration stage, and may have an impact on efficacy. This is a particular concern for isoproturon where the maximum permitted dose rate for autumn 2007 will be 1500 g a.s./ha (it is currently 2500 g a.s./ha), especially in the context of enhanced metabolism resistance which is already resulting in reduced efficacy.

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2. Specific herbicides or herbicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

The overriding consideration in addressing this issue for wheat is the management of prevention strategy for herbicide resistant weeds. As stated earlier a key component of this strategy, as set out in the WRAG/HGCA Guidelines document (2003), is to employ herbicides with different modes of action and avoid reliance on high resistance risk herbicides. Where target site resistance has been identified, then management of the problem is largely reliant on the use of an alternative herbicide from a different mode of action group. Whilst there are fifty active substances currently approved for winter wheat, the range of different modes of action is very much more restricted. In comparing these with the main herbicides used in wheat, it is very apparent the industry is reliant on a limited choice of different modes of action. Some of the most important of these currently used in standard grass weed control protocols for wheat are set out in Table 3. A number of the key active substances given in Table 3 are broad spectrum and important for both grass and broad-leaved weed control. Isoproturon, pendimethalin, trifluralin and flupyrsulfuron, mesosulfuron/iodosulfuron are particularly valuable in this context. It would also be important to retain tri-allate for grass weed control. Table 3. Key wheat herbicide groups for the control of the main grass weed species and their mode of action (adapted from WRAG/HGCA Guidelines 2003) Mode of action Chemical family Active substance examples Product example

clodinafop-propargyl Topik ACCase inhibitors Aryloxyphenoxy-propionates ('fops') fenoxaprop Cheetah Super

Cyclohexanediones ('dims') tralkoxydim Grasp Sulfonylureas flupyrsulfuron Lexus Sulfonylureas iodosulfuron/mesosulfuron Atlantis

ALS inhibitors

Sulfonylaminocarbonyltriazolinones propoxycarbazone Attribut isoproturon various Inhibition of photosynthesis at photosystem II Ureas chlorotoluron various

Inhibition of EPSP synthase Glycines glyphosate various pendimethalin Stomp Inhibition of microtubule assembly Dinitroanilines trifluralin Treflan

Inhibition of cell division Oxyacetamides flufenacet in Crystal Inhibition of lipid synthesis (not ACCase inhibition)

Thiocarbamate tri-allate Avadex

Broad-leaved weed herbicides that feature prominently in current wheat weed control protocols are: metsulfuron-methyl: this is relatively inexpensive and considered by some leading consultants to be the most useful of the broad leaved weed sulfonylureas. fluroxypyr: the leading cleavers herbicide, but also used for volunteer potato control. mecoprop-P: the most important phenoxypropionic herbicide for general broad-leaved weed control which includes activity against cleavers and several perennial dicotyledons (nearly 0.5 million sprayed ha in 2004). diflufenican: a key component of the most widely used broad spectrum general weed herbicides in the 2004 CSL Survey. ioxynil/bromoxynil: this has an alternative mode of action. There are reports of recent revived interest and increase in usage for resistant /difficult to control weeds.

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It is known that the future of trifluralin is in doubt because of its eco-toxicity profile and the possibility of it being classified as a persistent organic pollutant (POP). The critical value of the role this herbicide has in cereal weed control (especially for resistant black-grass control) was set out very comprehensively in the WRAG document submitted to PSD in October 2005 (Response from Weed Resistance Action Group in relation to trifluralin and Annex 1, www.pesticides.gov.uk ). Some of the main points in this document were:

• The main value of trifluralin is that it can be used to control the important grass weeds of cereals, especially black-grass and that no herbicide resistance to trifluralin has been detected in grass weeds in the UK.

• Whilst numerous other grass weed herbicides are available they are nearly all subject to varying degrees of herbicide resistance.

• Trifluralin at c. £5 cost /ha is a low-cost herbicide treatment. Loss of trifluralin would not only remove a very valuable tool in the resistant grass weed management strategy, (in this and other crops), it would also require the substitution of more expensive alternatives.

• Increased production costs would be at a time when wheat profit margins are already under severe pressure.

• It is unlikely there will be any novel herbicides with different modes of action introduced in the short or medium term, thus the loss of trifluralin would exacerbate current resistant management problems.

3. Prospects for alternatives for any foreseen major gaps in herbicide availability

No foreseen major gaps have been identified for herbicides in winter wheat as a result of the 91/414/EEC review process so far. There is a need for new active substances with novel modes of action to help counter the threat of increasing herbicide resistant weed populations. However the view of WRAG (with wide representation from global agrochemical companies) is that the UK is unlikely to see the introduction of such herbicides in the short or medium term. This is despite the importance of the wheat crop as a screening target for new herbicides by international research based companies. Prosulfocarb, a newly approved herbicide in the UK has been sold in mainland Europe for over a decade and is a thiocarbamate like tri-allate. There are cultural means of grass weed control, particularly ploughing, and these are important components of the resistant management and prevention strategy. Ploughing, for example, can reduce black-grass populations by more than 80% (average 54% in recent trials). However, high costs, including escalating prices for fuel, mean that in modern low margin commercial wheat farming, ploughing will tend to be an unfavourable option. Ploughing and other cultivation techniques can also have negative environmental impacts Crop Protection Companies Mutual Recognition under 91/414 is helpful where products containing Annex 1 active substances are registered for the crop/use combination elsewhere in the N European zone but not in the UK. A new herbicide active (confidential) may soon be available for wheat via this route.

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http://www.pesticides.gov.uk/


Impact of the proposed regulation and revision of 91/414/EEC The new regulation has still to be fully defined. However it is expected to form part of the wider 'Thematic strategy for the sustainable use of pesticides'. This includes the Water Framework Directive – an area that could have the most impact on availability of some important cereal herbicides. A list of 'priority substances' have been identified under the EU Water Directive which includes isoproturon and trifluralin. These are defined as individual pollutants presenting a significant risk via the aquatic environment including waters used for the abstraction of drinking water. Other pesticides on this list have been revoked in the EEC review and it has been stated that bans on use for all remaining substances are a real probability. There are also water pollution issues with isoproturon and mecoprop, which have both (along with chlorotoluron and some other herbicides) regularly been detected in water above the 0.1 parts per billion statutory limit for drinking water. Water companies in the UK currently spend £118 m per year on removal of pesticides (and nitrates) from drinking water sources (Wakeham, 2006) - a factor that may have a significant bearing in decisions affecting the future of these key cereal herbicides.

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Pest Control in Winter Wheat

Recent changes in EU agricultural schemes, with greater emphasis on environmental protection and better knowledge on the ecology of insect pests, have led to new approaches to pest management. In particular, the use of economic thresholds to decide on the need for treatment is increasingly being adopted as a means of optimising insecticide use, cutting costs and reducing adverse environmental impacts. The following is a very brief resumé of the most important pests of winter wheat as a background to the three questions of pesticide availability addressed in this report. Further information is available in various HGCA publications especially Pest Management in Cereals and Oilseed Rape - a Guide (2003), HGCA Topic Sheets and the standard reference work ‘Crop Pests in the UK’ (Ed. M Gratwick, 1992). The wheat crop is heavily dependent on a very limited range of insecticide groups, mainly the pyrethroids. BYDV (Barley yellow dwarf luteovirus) Two different aphid species, the grain aphid (Sitobion avenae) and the bird cherry-oat aphid (Rhopalsiphum padi) are the vectors of this virus disease. The main risk factors are mild weather in the autumn and early crop emergence. Impact: early infection with BYDV causes severe stunting, excessive tillering and yellowing of the crop and even very low populations of aphids carrying the virus can cause serious economic damage. Control: is mainly with pyrethroid sprays (Table 4). Seed treatments incorporating a neonicotinoid insecticide such as imidacloprid or clothianidin can give several weeks protection. Duration of control depends on conditions but can be up to 8-9 weeks with clothianidin. Cultural control: The risk of BYDV damage can be reduced considerably by delayed sowing. Gout Fly (Chlorops pumilionis) This pest is becoming more common with earlier sowing of winter cereals and now occurs in most of England and Wales. Attack causes very serious damage to stems in early sown winter cereals. There are two generations a year, in the autumn and spring. Impact: recent HGCA funded research has indicated that most autumn infested crops can recover well, but substantial yield loss (up to 30%) can result from attacks in the spring (HGCA Topic sheet, 2005). Control: from insecticide seed treatment, such as imidacloprid, applied against BYDV vectors, will give incidental control, reducing autumn populations of gout fly and may also reduce the spring generation. Foliar sprays and seed insecticide treatments are not considered economic in the majority of cases. Cultural control: Winter wheat grown in sheltered fields near woodland should be sown after late September. Wheat bulb fly (Delia coarctata) Wheat bulb fly larvae attack shoots of wheat in the spring, causing the classic 'deadheart' symptoms by killing the central leaf. Late sowing and harder winters increase the risk of economic loss. Impact: This depends on stage of growth when the crop is attacked. Crops attacked at the single shoot stage may be totally destroyed. Well-tillered crops withstand up to 100 larvae/m2 without economic impact on yield.

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Control: Tefluthrin seed treatments are effective with later sowings but are less reliable on crops sown earlier. Chlorpyrifos and dimethoate sprays are used in late winter or early spring. There is an action threshold advice service based on egg numbers from soil sampling. Cultural control: avoidance of leaving land bare in late July and early August will reduce numbers of eggs laid in fields intended for wheat. Yellow cereal fly (Opomyza florum) Like the wheat bulb fly larvae this pest causes 'deadheart' symptoms of wheat plants and early sown crops in sheltered fields near woodlands are at greatest risk. Impact: Severe attacks occur infrequently. Most crops can withstand a considerable number of larvae by producing compensatory tillers, so the economic impact of attacks is generally low. Control: Pyrethroid sprays applied to control BYDV aphid vectors also control yellow cereal fly. Cultural control: it is reasonable to use higher seed rates to establish at least 200 plants/m2 in vulnerable situations. Crops sown after mid-October are rarely damaged. Wireworms (Agriotes spp.) These are the larvae of click beetles, which attack young wheat seedlings just below ground level killing the whole plant. Crops at highest risk are sown within two years of ploughing out pasture, but any rotation with predominate winter cropping is liable to suffer attacks, especially if grass weeds are not well controlled. Impact: Heavy infestations can cause yield losses of up to 0.6 t/ha in cereals. The action threshold for use of an insecticide treatment is 0.75 million larvae/ha based on soil sampling. Control: Seed treatment with tefluthrin, imidacloprid or clothianidin control moderate levels of wireworm attack. Cultural control: There are practices that help reduce the risk of serious wireworm attack are including a spring crop in the rotation, good control of grass weeds and avoiding grassland in the rotation. Leatherjackets (Tipula spp.) These are the larvae of crane flies that attack the roots and shoots of developing seedlings. Impact: depends on the level of infestation, which can vary considerably and is influenced strongly by rainfall in September; dry weather being unfavourable to larvae survival. Heavy levels of infestation can cause total crop failure. Control: Chlorpyrifos is the main approved chemical means of control. Methiocarb granules applied for slug control will give a reduction in leatherjacket populations. Cultural control: attacks may be largely prevented when it is possible to plough land in July or early August before the main egg-laying period. Summer aphids (Sitobion avenae and Metopolophium dirhodum) Sitobion avenae (grain aphid) is the same species that is a vector of BYDV as described earlier but Metopolophium dirhodum (rose-grain aphid) over-winters on roses. Impact: Yield losses can reach 4 t/ha, but losses of 0.25 - 1 t/ha are more usual where populations exceed threshold levels. There has been a decline in the frequency of summer aphid problems with the move away from routine prophylactic spraying of aphicides since the 1980s. This is associated with more impact from natural control factors. Considerable research work has been carried out recently under a Sustainable Arable LINK project aimed at further enhancing the control from natural aphid predators (Powell, 2006). Control: is with pyrethroids and with the selective aphicide, pirimicarb. Careful timing of sprays in relation to thresholds and weather conditions is critical in achieving economic responses. Cultural control; As indicated, natural predation from a range of arthropod species can play a major part in non-chemical control and is receiving increasing recognition.

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Orange wheat blossom midge (OWBM) (Sitodiplosis mosellana) The larvae of this pest feed on the grains of wheat during the grain filling period after emergence. Potentially damaging larval populations may be found in any field where wheat has been grown in the previous five years, with risk being increased with the intensity of wheat cropping. Impact: Attacks are sporadic, but can have very severe effects on yield in high-risk years. It has been reported that in the last serious attack year, in 2004, an estimated £6 million in value of lost yield occurred despite high use of insecticides (Crops, 2006). Control: is with carefully timed spray applications of chlorpyrifos or lambda-cyhalothrin (new 2006). Chlorpyrifos is the preferred insecticide because unlike pyrethroids, it kills larvae and eggs (as well as adults) and is, to some extent, more selective. Timing of sprays is critical and pheromone traps are now used to determine high-risk periods and when economic threshold levels may be reached. Cultural control: Further development of integrated pest management strategies for OWBM is the subject of a current HGCA/Defra funded Sustainable Arable LINK programme (Project No. 3121). There are now five winter wheat varieties listed in the HGCA Recommended List for 2006/07 with resistance to Orange Wheat Blossom Midge. Grey field slug (Derocerus reticulatum) This is the only slug of economic importance in cereals. Impact: Winter wheat is highly vulnerable to slug damage (more than winter barley and oats). Slugs kill seeds by eating the embryo and attacks after germination kill seedlings by destroying the growing parts. Risk of damage is highest on heavier wetter soils. Control: is with molluscicides of methiocarb or metaldehyde although the level of control achieved is limited. The neonicotinoid seed treatments imidacloprid and clothianidin are known to give some protection against slug damage. There are action thresholds based on numbers caught in refuge traps. Cultural control: Cultivation in dry conditions can reduce populations by physical damage and desiccation. Sowing seed at least 12mm deep reduces the risk of damage as does good soil consolidation of the seedbed after sowing by rolling. Insecticides (excluding grain storage) and molluscicides for winter wheat There are currently 17 different insecticide active substances (excluding seed treatment) and five molluscicides substances approved for winter wheat. With the exception of some substances used on a very limited scale such as rotenone, these are listed in Table 4 together with the usage in 2003/04. The most important single use was autumn application of pyrethroids for BYDV aphid vector control accounting for over 50% of the insecticide treated area. The second most important usage in 2004 was for the orange wheat blossom midge (32% of application) in what was an exceptionally high incidence year for the pest. In 2006, lambda-cyhalothrin received approval for wheat blossom midge control. Prior to that the only approved insecticides for the pest was chlorpyrifos, although pyrethroids were probably also used in conjunction with spraying for summer aphids.

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Table 4. Winter Wheat: Insecticides/Molluscicides approved 2006; Chemical group; Review status; Aim re-registration in UK wheat; Pest; Area treated with insecticides/molluscicides on winter and spring wheat 1,981,661 ha grown in GB 2004 (Source: CSL Pesticide Usage Survey 2004) Insecticides / Molluscicides approved 2006

Review status Aim re-registration UK wheat

Pest Usage 2004

(spray ha) Carbamates Pirimicarb Annex 1 √ aphids 34,634 Organophosphate Chlorpyrifos Annex 1 - wheat bulb fly, aphids, thrips, wheat blossom

midge, yellow cereal fly, frit fly, leather jackets 137,496

Dimethoate List 2 - aphids, wheat bulb fly 88,328 Pyrethroids Alpha-cypermethrin Annex 1 - aphids, yellow cereal fly 46,222 Bifenthrin List 3A √ aphids Beta-cyfluthrin Annex 1 √ aphids Cyfluthrin Annex 1 √ aphids Cypermethrin Annex 1 √ aphids, yellow cereal fly 1,155,286 Deltamethrin Annex 1 √ aphids, yellow cereal fly 128,606 Esfenvalerate Annex 1 √ aphids 203,069 Flonicamid New pending √ aphids Lambda-cyhalothrin Annex 1 √ aphids, yellow cereal fly, orange wheat blossom

midge (new 18 April 06) 442,925

Lambda-cyhalothrin/pirimicarb. Annex 1/Annex 1 √ / √ aphids

Tau-fluvalinate List 3B √ aphids 215,296 Zeta-cypermethrin List 3A √ aphids 169,191 Other insecticides 18,660 All insecticides 2,636,713 Molluscicides Metaldehyde List 3A √ slugs 154,084 Methiocarb List 2 not decided(√ N) slugs 34,946 Thiodicarb non-inclusion slugs Other molluscicides, repellants 15,454 - Company request confidentiality; √ yes; x no; (√ N) aim re-register in N Europe. Also rotenone. Insecticidal seed treatments In 2003, one seed treatment containing the insecticide imidacloprid in combination with two fungicides was the third most widely used in terms of treated area (Table 6). The insecticidal seed treatment tefluthrin was used on a very limited scale (less than 2% of the grown area of wheat). A new combined insecticide/fungicide seed treatment containing clothianidin/prothioconazole ('Redigo Deter') was introduced in 2006. 1. The likely impacts of 91/414/EEC review process on insecticide and molluscicides availability for UK winter wheat.

Losses There have been no losses of any agronomic significance for insecticides and molluscicides in the 91/414/EEC review process to date, and the majority are now in Annex 1. Impact None.

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Future losses? The likely impact of the review process on pesticide availability is impossible to predict at this stage. In terms of usage the most important substances, the pyrethroids used for BYDV vector control are in Annex 1 as is the new seed treatment insecticide clothianidin used primarily for the same purpose (but also for slug control). Chlorpyrifos, which is critically important for a number of major pests, particularly orange wheat blossom midge and leatherjackets, is also on Annex 1. Dimethoate (List 2) is important – it is the only insecticide available that is effective once wheat bulb fly damage is seen, although the cost effectiveness of treatments is inconsistent. No decision has been made on tefluthrin (List 3B).. Molluscicide thiodicarb failed Annex 1 inclusion. There has been no decision yet on metaldehyde (List 3A) or methiocarb (List 2). 2. Specific insecticides or molluscicides or groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

It would be undesirable to lose any of the insecticides and molluscicides available for use in winter wheat since the existing range is already limited, especially in the context of different modes of action available for the major pests. It is considered essential to maintain: Metaldehyde (List 3A) and methiocarb (List 2) molluscicides Seed treatments containing the neonicotinoid clothianidin, and the pyrethroid tefluthrin with their different modes of action. Pirimicarb (Annex 1) for selective control of summer aphids. Pyrethroids (most of these in Annex 1) especially for the critically important control of BYDV aphid vectors as an alternative or to supplement seed treatment control. Lamba-cyhalothrin is important as an alternative to chloryrifos for Orange Wheat Blossom Midge, although it is generally recognised to be less effective (see below). Chlorpyrifos for a range of important pests, especially for Orange Wheat Blossom Midge, leatherjackets and wheat bulb fly. It would be desirable to retain dimethoate (List 2) because it is the only insecticide available that is effective once wheat bulb fly damage is seen. This would also avoid too high a reliance on one product in the event of supply problems (as reported with chlorpyrifos for 2006 despite the large range of generic products approved). 3. Prospects for alternatives for any foreseen major gaps in insecticide and molluscicides availability

There are no losses in the review process so far. The key insecticides chlorpyrifos, the major use pyrethroids and the new neonicotinoid seed treatment insecticide are already included in Annex 1 and there is no expectation of major gaps opening as a result of the ongoing process. However, a gap analysis (not shown) for insecticides includes a need for novel insecticides with different modes

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of action for resistance strategies especially for wheat bulb fly and summer aphid control. The situation with control of OWBM has improved in 2006 with the approval of lambda-cyhalothrin for this use. Although chlorpyrifos is regarded as technically superior because of less critical timing of use with greater persistence and selectivity, it does provide an alternative treatment in years of heavy OWBM attack when there is a history of supply shortfall for chlorpyrifos. Moreover there are now five wheat varieties on the HGCA Recommended List with resistance ratings for orange wheat blossom midge. There are also reported to be promising trial results with a different class of insecticide which could gain approval within the next 3 years (J Oakley, ADAS, pers. comm.). The label approval for slug control with clothianidin seed treatment has provided an alternative substance and mode of action for this important pest in wheat. At the moment the UK regulatory system allows Mutual Recognition of on-label approvals under the existing directive for the same crop/use combination in another member state in the same climatic zone, but it is not possible for a major crop such as winter wheat with a crop area exceeding 50,000ha. This could be a useful route for spring wheat. It is not permitted for approvals off-label (there are some systems in other Member States). The possibility could be explored, however. Impact of the proposed regulation and revision of 91/414/EEC The comments made in the Executive summary apply to winter wheat:

• Mutual Recognition could be helpful if products containing Annex 1 active substances (excluding candidates for substitution) are registered on-label for the crop/use combination elsewhere in EU Member States in the same climatic zone but not in the UK. This could be helpful considering the importance of wheat in other central zone countries.

• The loss of National Provisional authorisations may have a negative impact on the

availability of pesticides for wheat by delaying decisions on new actives pending a decision on Annex 1 listing.

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Disease control in Wheat

So far the 91/414/EEC review process has had no significant agronomic impact on the availability of pesticides for wheat diseases. Therefore the following is a very brief resumé confined to the most economically important diseases as a background to the other issues of this study. Foliar Diseases Cultural or non-chemical control is not considered separately for foliar diseases because nearly all wheat varieties require a significant fungicide input to achieve their full yield potential, even when they may have a high resistance ranking for a specific disease (Clark, 2006). Septoria leaf blotch (Mycospaerella graminicola) Better known as Septoria tritici, this is the UK's most important wheat foliar disease, with sources of infection occurring in all crops every year. Impact: if not controlled, Septoria can routinely reduce yields by 1 - 2 t/ha. On susceptible varieties in severe disease seasons the yield loss can be as much as 3 to 5 t/ha (c. 40 - 60% for an average yielding crop of 8 t/ha). Control: relies on protectant and eradicant fungicides applied at critical times in the growth development of the wheat crop. A feature of this disease is that it has a relatively long latent period (2 - 3 weeks) after initial infection before visible symptoms appear. This makes the azole group of fungicides with a degree of 'kick-back' eradicant activity a crucial component of control programmes. There is a history of fungicide resistance development with this disease and recent evidence shows a downward drift in performance of azole fungicides against S. tritici (Clark, 2006) although field control remains good at label doses. Resistance of Septoria to the strobilurin fungicides was noted in 2001 and increased rapidly, becoming widespread by 2004. Septoria nodorum This is also called glume blotch, but it can affect both ears and leaves. It is mainly restricted to the southwest but outbreaks can be severe. Impact: is potentially the most damaging to yield of the diseases that affect both ear and leaves, with losses up to 70%. Control: is with fungicides applied after ear emergence. Yellow rust (Puccinia striiformis) This can be very serious in certain years and areas where susceptible varieties occupy a high proportion of the wheat area (especially in eastern England) or when varietal resistance breaks down. The disease is favoured by cool conditions of 10° - 15°C. Impact: can cause severe reductions in yield in individual crops especially when both foliage and ears are infected. Control: is achieved principally with conazole and strobilurin fungicide sprays, but some seed treatments are useful in providing a degree of insurance against yellow rust infection in autumn and spring. No resistance has been found to morpholine or strobilurin fungicides. Brown rust (Puccinia triticum) This is most prevalent in the southeast and east of England. The disease develops rapidly at high temperatures (15° - 20°C) and therefore usually affects crops later in the season, after ear emergence. Impact: When combined with ear infections, brown rust can cause large yield losses.

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Control: is offered by a wide range of different fungicide groups, but as with yellow rust, the triazoles and strobilurins are particularly important. Again some seed treatments offer a degree of protection. Powdery mildew (Blumeria graminis) This can develop over a wide range of conditions, but incidence is sporadic. Most rapid development takes place at a temperature range of 15° - 22° C but prolonged high temperatures retard development. The disease is favoured by dense vegetative growth often associated with high nitrogen and seed rates. Impact: Although very visible, impact on yields is generally much less than those of other foliar diseases. Ears may be infected but this does not cause large yield losses. Control: is with fungicides often applied early on when mildew is present to prevent build up of the disease within the crop. A very wide range of fungicides with different modes of action is approved. However with many disease cycles each season there is an inherently high resistance risk with this disease. Strobilurins, are no longer effective because of widespread resistance. Ear diseases Generally ear diseases can have serious effects on grain quality through grain shrivelling or discolouration. Some of the foliar diseases can affect the ear as has been described earlier, although this is rarely the case with Septoria tritici. Specific ear diseases are: Sooty moulds These are caused by a mixture of fungi mainly Cladosporium and Alternaria species. Impact: Sooty moulds cause little yield loss but severe grain discolouration affects marketability (and hence crop value), which is especially important for milling wheats. Strobilurins offer control. Fusarium ear blights These are due to infection with a range of Fusarium species and Microdochium nivale. Impact: The main concern in recent years has been about the link with Fusarium infection to mycotoxin contamination of grain. This is in the context of EU legislation (July 1), which imposes a tolerance limit on mycotoxins in grain for human consumption. However, recent results from a four-year research study have confirmed a generally very low incidence of mycotoxins in UK wheat (Edwards, 2006). Control: In high-risk years, ear blights may be reduced by the application of fungicides applied after ear emergence. Whilst affording protection against ear diseases, they are often part of the disease control programme designed to ensure the flag leaf is fully protected against foliar diseases. However there is only a small window of opportunity for control around anthesis, so timing is difficult. The most commonly used materials are tebuconazole and metconazole, but efficacy is limited even when well-timed applications are made. Cultural control: Resistant varieties provide a potential means of reducing Fusarium ear blight (FEB), but there is a lack of knowledge of the genetics of resistance and most UK wheat varieties are susceptible. Improving breeding techniques for FEB resistance is the subject of a current LINK project. Root and stem based diseases Take-all, eyespot, Fusarium foot rots and sharp eyespot are all significant diseases in this category, but the two most important are take-all and eyespot.

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Take-all (Gaeumannomyces graminis) Take-all is caused by a soil borne fungus, which attacks the roots and sometimes the stem base at any stage of growth. Infection limits root development typically giving patches of stunted plants that ripen prematurely (whiteheads). Impact: Take-all is the major cause of 'second wheat' syndrome, when yields of the second wheat crops are frequently 10 - 15 % lower yielding than first wheats grown after a break crop. The disease becomes progressively more severe in the third and fourth successive crops. Most damage occurs on lighter soils. Control: Until relatively recently, there were no effective fungicide treatments and control depended essentially on crop rotation. There are now two seed treatment fungicides which reduce the effect of take-all in moderate risk situations where disease pressure is not too severe. There is also one strobilurin (azoxystrobin), foliar fungicide, which can help suppress take-all. Cultural control: is with the use of crop rotations where wheat (or barley) is not grown for a year or more than two successive crops. Continuous wheat can be grown exploiting the 'take-all decline' phenomenon, but there is still a significant yield penalty compared to first wheat crops. Maintaining good soil structure, drainage and nutrient status help reduce the effects of take-all. Eyespot (Oculimannicula spp.) Eyespot forms lesions at the stem base of wheat plants restricting nutrient and water uptake. The risk of infection is increased by wet spring weather, ploughing in some situations, a preceding cereal crop in the rotation and by early-sown crops, which are exposed to infection for longer. Impact: Eyespot can be very damaging and depress yields by 10 - 20 %. Severe infection causes lodging, premature ripening and poorly filled ears. Control: A range of fungicides with different modes of action are available, but applicaton must be made before a specific growth stage (GS 33) after which there is insufficient spray penetration of the canopy to reach stem bases. There are some triazoles with very good activity ratings. Farmers use mainly prothioconazole or epoxiconazole/boscalid for control. Cultural control: requires an integrated approach of using eyespot resistant varieties, avoiding early sowing and using wider rotations. Seed-borne diseases and Ergot Details of these diseases are comprehensively covered in the HGCA guide Wheat Seed Health and Seed-borne Disease (2006). The main diseases are covered in this summary of which Microdochium seedling blight and bunt are the most important. Loose smut (Ustilago nuda) This is characterised by a mass of black fungal spores replacing grain. Impact: potentially a very damaging disease, but in practice in the UK it is now of very low economic importance due to the success of strict seed certification control and standards. Control: Seed certification and use of resistant varieties have reduced loose smut to levels that do not normally require the applicaton of seed treatments for this specific disease. Bunt (Tilletia tritici) Bunt is primarily seed-borne although less commonly infection can occur from the soil. This is potentially the most important seed-borne disease of wheat. The risk of infection is greater if seed is repeatedly sown without a fungicide seed treatment. Impact: if left to build up by not using seed treatment, bunt can cause complete crop failure. Even at low levels of infection in the field, grain may become so contaminated that it is impossible to sell, especially for milling purposes.

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Control: is with surface acting fungicide seed treatments, most of which are broad spectrum, controlling several other diseases. However if soil-borne bunt is a risk only some seed treatments, which control both seed and soil-borne infection must be used. Cultural control: Seed can be tested for bunt and if results indicate a low risk, seed can be sown untreated. Early sowing reduces the impact of seed-borne bunt, but this is of little value if the soil-borne bunt is of concern because infection of this form is favoured by early drilling. Microdochium seedling blight (Microdochium nivale) This is the main seed-borne disease affecting crop establishment. It is particularly serious if seedbed conditions are poor. Impact: Serious attacks kill seedlings prior to emergence and weaken emerging plants. Seedling loss can result in below optimal plant populations and cause significant yield losses. Control: is with broad-spectrum seed treatments that are generally very effective. Seed can be tested for the disease and seed treatment avoided if it is absent. Ergot (Claviceps purpurea) Ergot is a very common disease of grasses and cereals and is spread by 'ergots' (sclerotia) as a contaminant of grain. Risk factors include grass weeds on the farm, especially black-grass, and cool wet conditions during flowering. Impact: Infection has little direct effect on yield, but sclerotia contaminants of grain contain large amounts of poisonous alkaloids. These pose a serious risk to animal and human health and contaminated grain is unsaleable or requires cleaning at extra cost. No ergot is tolerated in milling wheat and feed contracts set a limit of 0.001% by weight. Control: is by effective seed cleaning. Fungicide sprays in the field cannot control Ergot, although some seed treatments prevent germination of sclerotia. Cultural control: Ergots are not viable for more than one year, so ploughing or a one-year break from cereals gives good control of ergot in the soil. Controlling grass weeds, especially black-grass in and around crops also helps reduce sources of infection and spread of the disease. Fungicides for winter wheat A list of the 41 currently approved (June 2006) foliar fungicide active substances is given in Appendix 2. There are 417 fungicide products approved for winter wheat not including seed treatments. Of these: 41 are chlorothalonil alone and there are 19 chlorothalonil mixtures; 19 products contain epoxiconazole alone, and there are 43 epoxiconazole mixtures. There is a very wide selection of fungicide active substances and formulations for wheat growers to choose from. The main fungicides, together with the usage figures in 2003/04 (CSL data), are shown in Table 5 illustrating the relative importance of different substances. For clarity, the diseases controlled by each formulation have been omitted, but an up to date activity chart for each fungicide is given in the HGCA Wheat Disease Management Guide (2006).

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Table 5. Main fungicides used on winter wheat in 2004 (main = on at least 10% of the crop area 1,981,661 ha grown in GB 2004); Review status; Aim re-registration for UK wheat; Activity; area treated in 2004 (Source CSL Pesticide Usage Survey data, 2004) Fungicides approved 2006 (complete List Appendix 2)

Review status Aim re-registration UK

wheat

Activity Usage 2004 ( spray ha)

Azoxystrobin New Annex 1 √ strobilurin 532,439 Chlorothalonil Annex 1 √ chlorophenyl 2,045,622 Dimoxystrobin/epoxiconazole New Annex 1/List 3A - / √ strobilurin/conazole 192,535 Epoxiconazole List 3A - conazole 1,819,227 Epoxiconazole/fenpropimorph List 3A/List 3A - / - conazole/morphiline 291,827 Epoxiconazole/fenpropimorph/kresoxim-methyl

List 3A/List 3A/Annex 1

- / - / - conazole/morpholine/strobilurin 685,931

Epoxiconazole/kresoxim-methyl List 3A/Annex 1 - / - conazole/strobilurin 374,274 Epoxiconazole/pyraclostrobin List 3A/New Annex 1 - / - conazole/strobilurin 280,731 Fenpropimorph List 3A - morpholine 174,391 Metconazole List 2 - conazole 200,605 Quinoxyfen New Annex 1 - quinoline 332,331 Tebuconazole List 3B not decided conazole 553,778 Trifloxystrobin New Annex 1 √ strobilurin 357,483 All fungicides 10,213,102 Notes: other fungicides, excludes seed treatments, - Company request confidentiality; √ yes In 2003/2004 wheat crops received on average three foliar fungicide applications which relates to the main T1, T2, T3 timings recommended in wheat disease control programmes. The most important timing is the T2 application to maximise disease control on the flag leaf and over 60% of fungicides were applied at that time in the CSL data for 2003/2004. General disease control was cited for 66% of the total area treated. Where sprays for specific diseases were cited, Septoria tritici was the most important at 16%. Table 5 shows that in 2003/2004, the most widely used fungicides were chlorothalonil, epoxiconazole, epoxiconazole/fenpropimorph/kresoxim-methyl, tebuconazole and azoxystrobin. With the widespread resistance of Septoria to strobilurins, the latter use is likely to have declined in 2005 with a commensurate increase in triazoles, (especially the new prothioconazole), and chlorothalonil. Seed treatments As shown in Table 6 there is a comprehensive range of seed treatments available. These vary in spectrum of activity from single disease activity (silthiofam) up to eight diseases in one formulation (fuberidazole/triadimenol) and include two insecticide/fungicide combinations and a single insecticide treatment (tefluthrin). Details of activity spectrum are given in the HGCA Wheat Seed Health and Seed-borne Diseases Guide. The most frequently used seed treatments in 2003 were bitertanol/fuberidazole (Sibutol) and fludioxonil (Beret Gold) accounting for 39% and 20% of the area grown respectively. Only 5% of wheat seed was untreated. A new combined insecticide/fungicide seed treatment containing clothianidin/prothioconazole ('Redigo Deter') was introduced in 2006.

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Table 6. Winter Wheat: Seed treatments approved 2006; Review status; Aim re-registration UK wheat; Activity; Usage on 1,981,661 ha grown in GB 2004 (Source CSL Pesticide Usage Survey 2004) Seed treatments approved 2006

Review status Aim re-registration UK wheat

Activity Usage 2004 (treated ha)

Fungicides Bitertanol/fuberidazole List 3A/List 3A √ / √ conazole/benzimidazole 773,119 Carboxin/thiram List 3B/Annex 1 √ / √ carboxamide/dithiocarbamate 178,441 Fludioxonil List 3A √ cyanopyrrole 387,459 Fluoxastrobin/prothioconazole New pending/ New

pending √ / √ strobilurin/triazole New

Fluoxastrobin/prothioconazole/tebuconazole

New pending/ New pending

√ / √ / √ strobilurin/ conazoles New

Fluquinconazole List 3A - triazole 1,528 Fluquinconazole/prochloraz List 3A/List 3B - / - triazole/conazole 51,059 Fuberidazole/triadimenol List 3A/List 3A √ /not decided benzimidazole/conazole 71,359 Guazatine List 3B √ guazatine 35,069 Guazatine/triticonazole withdrawn use by Aug 2006

List 3B/ Annex 1 guazatine/conazole

Prochloraz/triticonazole List 3B/ Annex 1 - / - imidazole/conazole Prothioconazole New pending √ triazole Silthiofam New Annex 1 √ carboximide 149,395 Fungicides / insecticides Bitertanol/fuberidazole/imidacloprid all List 3A √ / √ / √ conazole/benzimidazole/neonicotinoi

d 183,436

Clothianidin/prothioconazole Annex 1/ New pending √ / √ neonicotinoid/conazole Fuberidazole/imidacloprid/triadimenol List 3A/List 3A √ / not

decided / √ benzimidazole/neonicotinoid/ conazole

71,359

Prothioconazole/clothianidin New pending/New Annex 1

√ / √ triazole/neonicotinoid

Insecticides Clothianidin Annex 1 √ neonicotinoid Tefluthrin List 3B √ soil acting pyrethroid 38,735 Unspecified and other seed treatments 186,165 All seed treatments 2,061,626 Usage is for all wheat; - Company request confidentiality; √ yes 1. The likely impacts of 91/414/EEC review process on fungicide availability for UK winter wheat Losses So far the 91/414/EEC review process has had no impact on fungicide availability for wheat. Triadimefon approval has been revoked but this was an outclassed conazole and there are many better alternatives. Impact None. Future losses? It is difficult to predict what impact the ongoing review process may have on future availability of 41 active substances currently on the list of UK approved fungicides. Many fungicides have achieved Annex 1 inclusion (Table 5 and full list Appendix 2). However, at the time of writing none of the critically important azole fungicides had been Annex 1 listed. Whilst there are a very

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many azoles approved for wheat, they vary considerably in their range of activity and level of efficacy, with epoxiconazole and prothiaconazole being especially important for S. tritici control. Septoria leaf blotch is the most important single disease of wheat in the UK and since the breakdown in strobilurin activity on this disease, control depends almost entirely on certain conazoles and chlorothalonil (on Annex 1). It is probably no exaggeration to say that the loss of either of these would result in very serious yield losses and be disastrous for the UK wheat industry. Whilst wheat prices and supply are a function of the global market, such a scenario could seriously impact on farm incomes and make the UK very much more dependent on imports. There are two cereal fungicides remaining in List 1 of the Review - carbendazim and flusilazole that were supported for wheat for Annex 1 inclusion and have UK approvals but are not as widely used. These are Commission proposals are that these active substances should be included for Annex 1 for cereal uses although some other crops will not, but decisions have not been made yet (June 2006). There are 417 fungicide products (June 2006) approved for winter wheat (excluding seed treatments) and several are low-cost off-patent herbicides sold by generic companies. There are also several products containing the same actives and formulations, for example, 41 chlorothalonil products alone and 19 chlorothalonil mixtures; 19 products containing epoxiconazole alone, 43 epoxiconazole mixtures. Many products are formulated in mixtures of two or more active substances and where different companies are involved it is difficult to establish whether there is an aim to re-register after Annex 1 listing (some are a long way off) and decisions may not have been made yet. It is possible that there will be rationalisation of products and that some of them will not be re-registered in the UK for use on wheat. However, there is a very wide selection of fungicide active substances and formulations, including several new ones, for wheat growers to choose from and there is likely to be further development for the large wheat market. 2. Specific fungicides or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Retaining fungicides with different modes of action for each of the main diseases is a critical consideration. This is necessary in order to implement resistance management and prevention strategies. Seed treatments The two leading broad-spectrum fungicides bitertanol/fuberidazole (demethylation inhibitor) and fludioxonil (cyanopyrrole) are from different fungicide groups. These are critically important to retain for control of the main soil-borne diseases of bunt and microdochium seedling blight. Important alternative modes of action seed treatments for these diseases are the guanidines and the carboxamide/dithiocarbamate provided by carboxin/thiram ('Anchor'). The new insecticide/fungicide seed treatment containing clothianidin/prothioconazole will also be important for bunt (and loose smut) control as well as insecticidal uses. For take-all suppression it would be desirable to retain the conazole fluquinconazole and silthiofam in the alternative thiophene-carboxamides group. Foliar and ear fungicides All disease control programmes in cereals rely on the azoles to provide the structure around which programmes can be designed. They are therefore vitally important to retain especially for Septoria

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tritici control when there are no alternatives with eradicant activity. For the other main foliar diseases, rusts, mildews and eyespot, they are an essential component of formulation mixtures with fungicides from groups with other modes of action, especially the strobilurins and morpholines. The most important and/or effective azoles are epoxiconazole, prothioconazole and tebuconazole. The protectant, chlorothalonil needs to be maintained especially as a crucial component of programmes for Septoria tritici control. Chlorothalonil is a multi-site activity fungicide playing a key role to maintain field activity of the azoles especially for Septoria tritici control (chlorothalonil usage was over 2 million sprayed ha in 2003/04). Part of the attraction of this fungicide is also undoubtedly its low cost in the context of the current low margins in cereal growing. It would be important to maintain this fungicide. Other important fungicide groups/ fungicides to maintain are:

• Strobilurins: for yellow and brown rust control and for the physiological yield enhancement that may be obtained under some conditions.

• Morpholines: different chemistry from the azoles. Most useful for powdery mildew control, despite the occurrence of some partial resistance.

• Proquinazid and the quinolene, quinoxyfen: for mildew control, providing a different mode of action to the morpholines and azoles.

• Dithiocarbamates: have relatively low levels of activity against the important foliar and ear diseases but they offer an alternative mode of action for resistance management for disease control with increasing resistance problems in other groups.

• Prochloraz: a fungicide with DMI mode of action like the azoles, but from a different chemical family (imidazole), has a wide spectrum of activity. It is still used for eyespot control in the UK but there is widespread resistance in France.

• Boscalid (with a different mode of action) for Septoria tritici and eyespot control. 3. Prospects for alternatives for any foreseen major gaps in fungicide availability

There are no foreseen major gaps in fungicide availability as a result of the 91/414/EEC review process to date and there is a wide range of fungicides available. The critical decision yet to be made is for Annex 1 inclusion of the conazole fungicides that are so crucial for all cereal disease programmes. However the size and value of the European cereal fungicide market, as a whole means there is likely to be very full support from the major agrochemical companies to achieve Annex 1 inclusion. No new cereal fungicides offering different modes of action are likely to become available in the very near future. However, some agrochemical companies are re-evaluating older fungicides to check for use against Septoria, and new actives with novel chemistry to control major cereal foliar diseases are being sought. A recent analysis (Paveley, 2006) concludes that the arable industry is currently too dependent on fungicides and that a better balance needs to be struck between genetics and chemical control. The HGCA recommended list of winter wheat varieties (2006/07) provides a good choice of cultivars with relatively high resistance rankings for the important wheat diseases. However, levels of genetic resistance are not sufficient to provide adequate control without fungicides and most varieties require a significant fungicide input to achieve their full potential yield, as stated earlier. With

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rapidly improving genetic breeding techniques now available, there is a reasonable expectation that better and sustainable genetic resistance to cereal diseases will be achievable in the future.

Plant Growth Regulation

Plant growth regulators (PGRs) are used in wheat crops to control lodging where the crop permanently leans or in the worst case lays horizontally on the ground. This normally takes place after ear emergence when either the stem buckles between the internodes or where the root anchorage system fails. The risks of lodging are influenced by a complex of different factors including variety choice, weather, soil types and nutrient status, date of sowing and eyespot infection. Impact: Occurrences of severe lodging in the UK are, on average, every 3 - 4 years when overall 15-20% of the whole wheat area lodges. Grain yield and quality losses, increased combining time and drying costs are all important impacts. The earlier lodging occurs, the greater the effect on yield. Lodging can have a particularly severe impact on the premiums for milling wheats and overall costs of a lodged crop of milling wheat have been estimated in recent work (Berry, 2006) to be £300/ha. Table 7. Cost of lodging in a milling wheat crop of 8 t/ha yield potential Factor Cost (£/ha) 2 t/ha yield reduction 150 Loss of quality premium 90 Drying cost from 18 - 15% 35 30% additional combining time 25 Total 300

Control: of lodging is achieved by an integrated approach which takes account of risk factors, but use of plant growth regulators applied to the crop one to three times play a major role. A method of assessing the risk of lodging in relation to the different factors involved is given in the HGCA Guide: Avoiding Lodging in Winter Wheat Practical Guidelines, (2005). In low risk situations with short/average straw strength varieties not sown early, no PGRs would be indicated or a single low dose of chlormequat applied as an insurance. At the other end of the scale, for crops with good emergence sown in early to mid-September up to three separate applications of different PGRs might be applied e.g. chlormequat at growth stage (GS) 30, a tank-mix of chlormequat + trinexapac-ethyl at GS 31-32 and finally 2-chloroethylphosphonic acid (ethephon)/mepiquat chloride at GS 37- 45. Cultural control/reducing risk: hinges on the choice of variety in relation to a calculation of the risk factors. There is a wide selection of wheat cultivars in the HGCA recommended list for 2006/07 with high ranking for resistance to lodging, including several with the highest resistance score of 9. The most effective strategy against lodging is to avoid sowing lodging-susceptible varieties early, not to use high seed rates, (especially if soil nitrogen residues are high), and to make the appropriate use of PGRs.

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Plant Growth Regulators for Wheat PGRs approved for winter wheat for 2006 and the usage in 2004 are shown in Table 8. Table 8. Winter Wheat: Plant growth regulators approved 2006; Review status; Aim re-registration UK wheat; Usage on 1,981,661 ha grown in GB 2004 (Source CSL Pesticide Usage Survey 2004) Plant growth regulators approved winter wheat 2006 Review status Aim re-

registration UK wheat

Usage 2004 (spray ha)

2-chloroethylphosphonic acid (ethephon) Annex 1 √ 26,718 2-chloroethylphosphonic acid/mepiquat chloride Annex 1/List 3A √ / - 182,399 Chlormequat List 3B - 1,675,608 Chlormequat /2-chloroethylphosphonic acid/mepiquat chloride List 3B/Annex 1List 3A - / √ / - 42,209 Chlormequat/mepiquat chloride List 3B/List 3A - / - 65,297 Chlormequat/2-chloroethylphosphonic acid List 3B / Annex 1 - / - 71,321 Chlormequat/choline chloride. List 3B 272,264 Chlormequat/imazaquin List 3B/List 3B - / - 269,451 Mepiquat chloride/prohexadone-calcium List 3A / Annex 1 (new) ? Trinexapac-ethyl Annex 1 √ 379,614 Other growth regulators 11,047 All growth regulators 2,995,929 Usage is for all wheat; - Company request confidentiality; √ yes ;Choline chloride no longer classified as a.s. so choline chloride formulated mixtures omitted. Chlormequat alone and in mixtures with other PGRs clearly dominates growth regulator usage, with this PGR used on its own accounting for 50% of the area treated with growth regulators. However the use of 2-chloroethylphosphonic acid/mepiquat has continued to rise since 1994 according to the CSL data. Most growers applied between one to two sprays. Residues of chlormequat and mepiquat are sometimes detected in wheat and although they are below the MRL and do not pose a risk, the Food Standards Agency (FSA) suggest that measures should be taken to reduce them. 1.The likely impacts of the 91/414/EEC review process on plant growth regulator availability for UK winter wheat

Losses There have been no losses of active substances as a result of the review process. Choline chloride is no longer classified as an active substance for plant protection. It does not now appear on product labels although according to BASF, formulations are unchanged. Impact None. Future losses? It is difficult to judge the likely impact of the review process on PGR availability for the UK winter wheat crop, at this stage only 2-chloroethylphosphonic acid and trinexapac-ethyl have Annex 1 inclusion. Dose rates and number of applications and timings may be reduced at the re-registration

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stage, when and if Annex 1 listing is achieved, and this may have an impact on efficacy. It is notable that one company dominates the market with a number of similar products that are alternatives for very similar agronomic use (e.g. chlormequat). This indicates there could be losses of approved products and on-label uses as companies rationalise their product ranges. Chlormequat is the single most important PGR, both alone and in formulated mixtures, being used on over half of the PGR sprayed hectarage. A decision on this key substance (List 3B) has yet to be made. 2. Specific plant growth regulators it would be desirable to maintain from the agronomic perspective to avoid major difficulties

It would be desirable to maintain: Chlormequat the single most important PGR as indicated, and it is probably the one PGR that could be considered essential. It is relatively inexpensive, but it must be applied before the third node is visible. Chlormequat is often applied conveniently as a split dose with T0 and T1 fungicide applications and some agronomists use no other PGRs in winter wheat where lodging risk is low to moderate. The only significant disadvantage compared to other PGRs is the restricted timing window and poor rain fastness, requiring a minimum 6 hour period without rain after application. 2-chloroethylphosphonic acid alone (or in a formulated mixture with mepiquat chloride) is useful when a late application is required as part of a sequence as it can be applied up to just before the ear is visible (GS 49) as a second or third application of a PGR in high risk situations. It is regarded as the having the best efficacy for the late stage application and higher risk situations, but is substantially more expensive than chlormequat Trinexapac-ethyl was widely used in wheat in 2004, on just less than 380,000 sprayed ha (Table 8). It is an alternative to chlormequat with a similar technical profile, but it would be desirable to retain trinexapac-ethyl. It is supplied by a different manufacturer from several of the other substances. It is also widely used in tank-mixes with chlormequat to boost the activity in higher lodging risk situations where the substantially higher cost of 2-chlorethylphosphonic acid-containing PGRs are not considered to be economically justified. 3. Prospects for alternatives for any foreseen major gaps in plant growth regulator availability

There are no foreseen major gaps so far and no new cereal PGRs known to be in late stage development trials, but the large cereal market would provide an opportunity for new products.

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REFERENCES

HGCA and Link Projects: HGCA/Defra Sustainable arable LINK Project No. 3121 HGCA Managing and preventing herbicide resistance in weeds. WRAG guidelines. 2003. HGCA Guide: Avoiding Lodging in winter wheat practical guidelines. 2005 HGCA Review of HGCA - funded weed research (including LINK projects) 1994 - 2005. C Edwards, HGCA, Feb.2006. HGCA Project Report 370 (2005) Cost-effective weed control in cereals using vision-guided inter-row hoeing and band spraying systems. HGCA Recommended List 2006 / 07 for cereals and oilseeds. HGCA The wheat disease management guide. Spring 2006, 2nd edition. HGCA Pest management in cereals and oilseed rape - a guide. Autumn 2003. HGCA Wheat seed health & seed-borne diseases - a guide. Summer 2004. HGCA Orange wheat blossom midge - assessment and control. Spring 2005. Topic Sheet No. 17 Brome control in winter cereals. Autumn 1998. Topic Sheet No.38. Dealing with wheat bulb fly. Summer 2000. Topic Sheet No.87 Controlling gout fly on wheat. Summer 2005. Topic Sheet No.88 Determining eyespot risk in winter wheat. Autumn 2004. Other references: CROPS 20 May (2006) Wheat blossom midge. Midsummer night's midge, 8. Reed Business

Information, Sutton, UK. GRATWICK M (1992) Crop Pests in the UK. Ed. M Gratwick. Chapman & Hall, London, UK. BERRY P (2006) Arable 1. Lodging. In: Farmers Weekly 5 May 2006. 72-73. Reed Business

Information, Sutton, UK. CLARKE JH (2006) Rotation: vital for weed management and biodiversity. HGCA R & D

Conference 2006, Arable Crop Protection in the balance: Profit and the Environment. 14.1-14.12.

CLARK WS (2006) Foliar disease management strategies in cereals: current challenges. HGCA R & D Conference 2006, Arable Crop Protection in the balance: Profit and the Environment,7.1-7.8.

EDWARDS S (2006) Fusarium, pink grains and mycotoxins in wheat: an issue for farmers and the feed and food industries. HGCA R & D Conference 2006, Arable Crop Protection in the balance: Profit and the Environment.9.1-9.8.

GARTHWAITE DG, THOMAS MR, ANDERSON H & STODDART H (2005) Arable crops in Great Britain 2004. Pesticide Usage Survey Report 202. Central Science Laboratory, Sand Hutton, York, UK.

MARSHALL EJP, BROWN V, BOATMAN N, LUTMAN P & SQUIRE G (2001) Current weed control and its impact. In: The impact of herbicides on weed abundance and biodiversity. PN0940, A report for the UK Pesticides Safety Directorate, 48-61. IACR-Long Ashton Research Station, UK

MOSS SR et al. (2005) The current status of herbicide - resistant grass and broad-leaved weeds of arable crops in Great Britain. Proceedings of the BCPC Congress - Crop Science and Technology 2005, 1, 139-144.

MOSS SR (2006) Herbicide resistance: new threats, new solutions? HGCA R & D Conference 2006,Arable Crop Protection in the Balance: Profit and the Environment, 12.1-12.9. HGCA, London, UK.

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POWELL W (2006) Pest management outlook for cereals and oilseeds based on recent and new research. HGCA R & D Conference, 2006, Arable Crop Protection in the Balance: Profit and the Environment, 10.1-10.9. HGCA, London, UK.

NIX J (2005) Farm Management Pocketbook, 33rd edition, 2006. Imperial College Wye. Andersons Centre, Melton Mowbray, UK.

PAVELEY N (2006) Is disease management sustainable? HGCA R & D Conference, 2006 Arable Crop Protection in the Balance: Profit and the Environment, 5.1-5.12. HGCA, London, UK.

ORSON JH & HARRIS D (1997) The technical and financial impact of herbicide resistant black-grass (Alopecurus myosuroides) on individual farm businesses in England 1997. Proceedings of the BCPC Conference - Weeds 1997, 3, 1127 -1133.

WAKEHAM H (2006) The Water Framework directive and farming: tackling diffuse pollution. HGCA R & D Conference, 2006, Arable Crop protection in the balance: Profit and the Environment, 3.1 - 3.4. HGCA, London, UK.

ACKNOWLEDGEMENTS The help and contributions of staff from the following organisations are gratefully acknowledged: especially Jim Orson of The Arable Group (TAG), BBSRC Rothamsted Research, Hampshire Arable Systems (Crop Consultancy), Frontier Agriculture Ltd., Home Grown Cereals Authority (HGCA), the National Farmers Union and a number of the major agrochemical companies.

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Appendix 1. Winter Wheat: Herbicide active substances approved 2006; Review status; Aim re-registration for wheat UK; Activity Herbicide / desiccants approved 2006


wheat

Activity

Total weeds Diquat/paraquat Annex 1/Annex 1 √ / √ bipyridyls Glyphosate Annex 1 √ phosphonic acid Glufosinate-ammonium List 2 not decided phoshinic acid Grass weeds Clodinafop-propargyl Annex 1 √ phenoxypropionic acid Diclofop-methyl only in mixture List 3A/List 3A √ phenoxypropionic acid Fenoxaprop-P-ethyl List A not decided phenoxypropionic acid Iodosulfuron-methyl-sodium Annex 1 √ sulfonylurea Mesosulfuron-methyl Annex 1 (new) √ sulfonylurea Pinoxaden New pending √ phenylpyrazolin Propoxycarbazone-sodium Annex 1 √ sulfonylaminocarbonyltriazolinone Tralkoxydim List 3A √ oxime Tri-allate List 3B √ thiocarbamate Broad-leaved weeds (and some grasses) Amidosulfuron List A √ sulfonylurea Bromoxynil Annex 1/Annex 1 √ HBN Chlorotoluron Annex 1 √ urea Clopyralid Annex 1 - picolinic acid Bentazone only in mixture Annex 1 - diazinone Bifenox List 3A √ diphenyl ether Bromoxynil Annex 1 √ HBN 2,4-D Annex 1 √ aryloxyalkanoic acid 2,4-DB Annex 1 √ aryloxyalkanoic acid Carfentrazone-ethyl Annex 1 √ triazolinone Dichlorprop-P List 2 √ benzonitrile Dicamba only in mixtures List 3B x arenecarboxylic Diflufenican List 3A √ anilide/furanone Florasulam Annex 1 - triazolopyrimidine Flufenacet only in mixtures Annex 1 √ oxyacetamide Flupyrsulfuron-methyl Annex 1 √ sulfonylurea Fluroxypyr Annex 1 - aryloxyalkanoic acid Flurtamone only in mixtures Annex 1 √ furanone Ioxynil only in mixtures Annex 1 √ hydroxybenzonitrile Isoxaben List 3B - amide Isoproturon Annex 1 √ urea Linuron only in mixtures Annex 1 √ urea MCPA Annex 1 √ phenoxyyacetic acid MCPB Annex 1 √ phenoxybutyric acid Mecoprop-P Annex 1 √ aryloxyalkanoic acid Metsulfuron-methyl Annex 1 √ sulfonylurea Pendimethalin Annex 1 - dinitroaniline Picolinafen Annex 1 - aryloxypicolinamide Prosulfocarb List 3A √ thiocarbamate Sulfosulfuron Annex 1 √ sulfonylurea Thifensulfuron-methyl Annex 1 √ sulfonylureas Triasulfuron Annex 1 - sulfonylurea Tribenuron-methyl Annex 1 √ sulfonylurea Trifluralin List 2 - dinitroaniline

Usage is for all wheat; - Company request confidentiality; √ yes; x no. Cinidon-ethyl approved but not marketed; Methabenzthiazuron withdrawn; Imazamethabenz-methyl non-inclusion, not supported in Review, use by 30 September 2006 Many products are formulated in mixtures of two or more active substances and where different companies are involved it is difficult to establish whether there is an aim to re-register the product after Annex 1 listings (some are a long way off) and decisions may not have been made yet.

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Appendix 2. Winter Wheat: Fungicide active substances approved 2006; Review status; Aim re-registration for UK wheat; Activity Fungicides active substances in products approved 2006


wheat

Activity

Acibenzolar-S-methyl New Annex 1 x benzothiadiazole Azoxystrobin New Annex 1 √ strobilurin Boscalid only in mixture New pending / List 3A - piperidine Bromuconazole not marketed List 3A conazole Carbendazim List 1 - benzimidazole Chlorothalonil Annex 1 √ chlorophenyl Cyflufenamid New pending √ amidoxine Cyproconazole List 3B √ conazole Cyprodinil New Annex 1 √ pyrimidine Difenoconazole List 3B √ conazole Dimoxystrobin only in mixture New Annex 1 - strobilurin Epoxiconazole List 3A - conazole Famoxadone only in mixture New Annex 1 √ strobilurin Fenbuconazole List 3A √ conazole Fenpropidin List 3A √ piperidine (morpholine) Fenpropimorph List 3A - morpholine Fluoxastrobin new pending √ strobilurin Fluquinconazole List 3A - conazole Flusilazole List 1 √ conazole Flutriafol List 3B √ conazole Iprodione Annex 1 - dicarboximide Kresoxim-methyl only in mixtures Annex 1 - Mancozeb Annex 1 - dithiocarbamate Maneb Annex 1 - dithiocarbamate Metconazole List 2 - conazole Metrafenone New pending - benzophenone Picoxystrobin New Annex 1 √ strobilurin Potassium hydrogen carbonate List 4 commodity √ inorganic Prochloraz List 3B - conazole Propiconazole Annex 1 √ conazole Proquinazid New pending √ quinazolinone Prothiaconazole New pending √ conazole Pyraclostrobin New Annex 1 - strobilurin Quinoxyfen New Annex 1 - quinoline Spiroxamine New Annex 1 √ spiroketal amine Sulphur List 4 √ sulphur Tebuconazole List 3B not decided conazole Tetraconazole List 3A √ conazole Trifloxystrobin New Annex 1 √ strobilurin excludes seed treatments, sulphur - mainly applied as a nutrient; - Company request confidentiality; √ yes; x no; (√N) re-register N Europe Many products are formulated in mixtures of two or more active substances and where different companies are involved it is difficult to establish whether there is an aim to re-register the product after Annex 1 listings (some are a long way off) and decisions may not have been made yet.

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OILSEED RAPE

Most recommendations for the crop are based on information from research funded by farmers through the HGCA statutory Levy and/or commissioned by Defra. The cost of on-going projects (all HGCA crops) is £2.7million HGCA plus co-sponsors £7.9million. Most of the current R & D projects are for cereals, disease management and resistance and so far none have been undertaken as a result of any impact of 91/414/EEC. The annual HGCA R & D budget is £2.4million/annum (variety trials not included), knowledge transfer £400K.

Background

Crop Area and Use The total UK area of oilseed rape (including non set-aside and set-aside) was 534,000 ha in 1998 but declined to 402,000 ha in 2000. Since then there has been a steady increase, reaching a 5-year high of 593,000 ha in 2005. Industry estimates that the UK area will be unchanged for 2006 but could increase in future. In contrast, the EU area is expected to increase by around 6% - this is claimed to be due to biofuel demands. In 2005 the area of oilseed rape was only 32% that of wheat and 20% of the total cereal area. The area grown on non set-aside land was 519,000 ha in 2005. Most of this was grown for food and 99,350 ha were grown for biodiesel under the new Energy Aid Scheme, attracting EU aid of 45 euros/ha for biodiesel production (RPA Figures). Oilseed rape oil from UK crops is mainly used for human consumption, and is regarded as a healthy option for human nutrition because it is high in unsaturated fats and omega 3. Three-quarters of this market uses refined oil direct from the crusher, the remainder undergoes hydrogenation and is destined for margarine and other “solid” uses. There are UK assurance schemes to meet consumers’ quality demands. Production of high quality oil with high oleic and low linolenic oil from a spring rape variety is being developed – there is an interest from the food industry in reducing trans fatty acids. The HGCA is funding work to investigate alternative uses. Oilseed rape meal is used predominantly in compound animal feeds. The area grown on set-aside land was 74,000 ha in 2005, an increase compared to previous years. This includes oilseed rape for industrial use, provided the whole crop must be contracted with, and delivered to, a first processor. Two types are grown: high erucic acid rape (HEAR) to produce specific industrial oils and, mainly, double low (spring sown). Yields of the former are lower. In addition oilseed rape is grown on set-aside land for biodiesel, using feed varieties, but it is not possible to quantify the area. Impurities from weed seeds such as charlock may also affect quality for processing for biodiesel. It is estimated that the total area grown for biodiesel was 29% of the UK oilseed rape area in 2005 (D Turley, CSL, pers. comm.). The potential for biofuel crops and environmental impact was reviewed by Turley et al., 2006. So far, most biodiesel has been exported. The expansion will depend on location of processing plants. Between 5 and 15% of oilseed rape is spring sown and the area varies annually, often depending on the success of establishing winter crops. The main UK growing areas are the East Midlands and Eastern Region and the South East, the next largest were Yorkshire & the Humber, the South West, Scotland and the West Midlands.

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Rotation Rotations were four years between rape crops but as the area increases, the years between rape crops decreases – rape every two years is becoming common in some regions. The forecasts (R Elsdon, United Oilseeds, pers. comm.) are that rotations 1 in 3 of winter oilseed rape, winter wheat and either set-aside or a profitable spring break crop, possibly spring beans are the most likely. The implications of this change for pest, disease and weed occurrence under the new tight rotation are that charlock, herbicide resistant black-grass, slugs and winter stem weevil/flea beetle are likely to pose the greatest threats. The need for pesticides is likely to increase. A possible fall of 10-30% in cereal production has been predicted as a result of the Single Farm Payment system, which also seems likely to further drive farmers towards simpler rotations. Most rotations will still be based on winter crops, with less area devoted to break crops and more to cereals. Such predominantly cereals rotations will exacerbate weed problems, especially of herbicide-resistant grass weeds. Profitability Average yields (5-year mean 2001 – 2005 for England) were 3.28 t/ha for winter sown oilseed rape and 1.9 t/ha for spring rape but pesticide inputs are lower for the spring crop. For both crops herbicides may account for 65% of spray costs. The assumed price for the 2006 (harvest year) crop is £145/tonne and Gross Margins could be £235/ha for winter and £115/ha for spring rape (Nix, 2005). Crops for energy use are eligible for the EU energy crop supplement of about £15/tonne above feed price. There are environmental advantages of leaving winter stubble and drilling spring crops and spring cropping may increase if the Single Farm Payment provides incentives to do so but at the moment winter oilseed rape is more profitable. Pesticide inputs for feed and non-feed oilseed rape including the biofuel crop are expected to be similar. Pesticide use in surveys referred to later was for the large food production area. Winter oilseed rape is a profitable crop in its own right – it is no longer considered as a break crop and the area is likely to increase. In addition, more rape may be grown for biodiesel in future. Oilseed rape will be grown more frequently, in tighter rotations. Oilseed rape establishment Changes in methods of establishing the rape crop i.e. autocasting rapeseed as the previous cereal is harvested (Freer, 2002), have implications for pesticide use. Slugs, grass weed and volunteer cereals are the main problems. An HGCA survey suggested that there were fewer broad-leaved weeds. The Autocast system achieves cheaper, quicker establishment than with conventional cereal drills – it consists of a seed hopper attached behind the combine header; a fan and manifold that distribute seed to spreading plates, and seed is metered with a land wheel. It is useful on heavy soil types with a good surface tilth. Autocast and broadcasting establishment methods each cost under £40/ha, while disc and plough-based systems exceeded £100/ha. Ploughing offers control of resistant black-grass and volunteer cereals but farmers often choose not to plough to save costs. Ploughing or minimum cultivation is still popular on the lighter and some medium soils. Winter oilseed rape is drilled at the end of August or in early September on close rows 115-200 mm apart.

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Weed control in oilseed rape

Oilseed rape – a grower’s guide, HGCA (2005) summarises weed management advice based on HGCA-funded oilseed rape R&D. Clive Edwards, HGCA, in February 2006 reviewed HGCA-funded weed research 1994-2005 (including LINK projects) to inform farmers of research findings. The long-term agronomic consequences of growing rape more frequently in tighter rotations with cereals are unknown, but it is anticipated that charlock could become more widespread. Farmers are also encouraged to manage cereals for biodiversity and charlock (and chickweed) are highly desirable as a food source for insects and birds (SAFFIE). Oilseed rape growth is rapid and it competes strongly with weeds both in the autumn and spring but crops with low vigour or poor establishment are vulnerable to weed competition. Early-sown crops tend to be more vigorous than those sown late. ‘Canopy management’ in oilseed rape, where crops are managed so they are less dense and produce fewer pods but higher yields, may mean that crops are more sensitive to weed competition and additional herbicide applications may be required. Impacts of weeds

• on yield (cleavers, chickweed, volunteer cereals). • cleavers cause harvesting difficulties and also contaminate produce. • where broad-leaved weeds are not controlled in oilseed rape, weed seeds return to infest the

following crop - cleavers in winter rape and also common poppy, which cannot be easily controlled in oilseed rape and similarly charlock in the spring sown crop. However, if the following crop is a cereal there are several herbicide options.

• Seeds of cruciferous species (charlock and wild radish) affect quality for crushing and are difficult or impossible to separate from the oilseed rape sample and there is a price deduction where admixture exceeds 2%. The processor may also reject produce.

• In rape grown for seed production some cruciferous weed species such as charlock and wild radish are scheduled in the Seed Regulations. These can only be rogued with extreme difficulty.

There have been several studies on the impact of weeds. A research review of weed control in oilseed rape (Lutman et al., 1991) concluded weed control was uneconomic in many winter crops, but oilseed rape presents a good opportunity to control weeds, especially herbicide-resistant grasses (with propyzamide, carbetamide) inherited from cereals grown in the same rotation. Weed control is often unnecessary in spring oilseed rape unless establishment has been poor. Volunteer cereals, particularly barley, which grows vigorously in autumn, are the most serious problem in winter oilseed rape but experiments have shown that vigorous crops can tolerate high populations without yield loss. Economic weed control thresholds for volunteer barley vary from 100 plants/m² for early sown crops, down to only 15 plants/m² for crops that are late sown or with poor vigour. Black-grass is also competitive if large numbers emerge at the same time as the crop. A project (Lutman et al., 1995) on weed control in winter oilseed rape investigated: effects of broad-leaved weeds on yield, effects of crop vigour on weed competition and the possibility of predicting yield losses. Cleavers were very highly competitive and yield losses of 5% were caused

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by less than 10 plants/m² and in two experiments by less than 2 plants/m². Cleavers also caused crop contamination: less than 5 plants/m² resulted in more than 4% admixture and expensive cleaning would be needed. A dense mat of cleavers plants on top of the rape canopy interfered with harvesting. Therefore threshold levels for cleavers are low and if plants are easily found within the crop, they should be controlled. Chickweed, which grows vigorously in winter, had a large effect on yield compared with scentless mayweed, which was not competitive. At several sites 10-20 chickweed plants/m² in the autumn reduced yields by 5% or more, but had less effect in very vigorous crops. In crops of low vigour in autumn and winter, weed control is needed because of the risk of yield losses. Mayweeds can affect backward crops. Sowthistles commonly infest rape crops but there are no data on thresholds and their impact is probably from seed return rather than effect on yield. Other weeds were ranked in multi-species trials - poppy and charlock were also highly competitive. Charlock is more of a problem in spring rape, although some plants will germinate in the autumn and over-winter in the field. The plants can be killed by frosts but agronomists report that in recent years this has not been the case particularly if vigorous rape plants shelter the weed overwinter. A study of arable weed seed production and seed persistence by Lutman & Freeman, 2002 showed charlock produces fewer but larger seeds than most common weed species, (250 – 765 /plant in spring rape), and that the average estimated decline rate in disturbed soil is c. 37% per year. In a situation where it is uncontrolled and if other species are, in a rotation of oilseed rape, wheat, set-aside (or spring beans) it could become a problem. Control Considering the crop area, the options for broad-leaved weed control are very limited, probably because the focus is on volunteer cereal and grass weed control. HGCA Topic Sheet No. 35 gives guidance on cost-effective weed control, so does Davies (2005). The area treated with glyphosate used both pre-drilling to clean-up weedy cereal stubbles and as a pre-harvest desiccant, continues to rise. In autocast crops where rape is sown at the same time as cereal harvest there is little opportunity to do so before the rape germinates. This may mean greater pressure on post-emergence graminicide ‘fops’ and ‘dims’. However, where there is no soil disturbance, grasses and volunteer cereals germinate on the soil surface and residual propyzamide is particularly effective. A significant agronomic benefit of growing oilseed rape is that herbicides can be used to control competitive grass weeds as well as volunteer cereals. This is particularly important for black-grass, wild oats and Italian rye-grass that are difficult to control elsewhere in the rotation, because of increasing resistance to ‘fop’ and ‘dim’ herbicides. There is no known resistance to herbicides propyzamide, carbetamide or trifluralin. Propyzamide is the most commonly used post-emergence residual herbicide after the crop reaches the 3-leaf stage. The CSL pesticide usage survey (Table 1) showed it was used on 28% of the crop area in 2004 mainly for grass weeds and volunteer cereals. Post-emergence graminicide options include: propaquizafop - the most popular choice used at half dose rate or less and more than one application, fluazifop-p-butyl, tepraloxydim, cycloxydim, and quizalofop-p-ethyl. Survey data for herbicide use suggest that there is an increasing reliance on post-emergence fops and dims to control volunteer cereals, in 2004, 52.8% of the oilseed rape area grown was treated once, 20.3% twice and 1.9% three times.

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Less is done to control broad-leaved weeds although there is currently a range of herbicides to control most weed species. Residual herbicide metazachlor is used alone pre-emergence or as a split dose pre- and post-crop-emergence or at half dose rate, or less, in tank-mix with trifluralin. Trifluralin is cheap and is used in combination with metazachlor to extend the weed spectrum, including black-grass and improve control of poppy. Common poppy is only controlled pre-emergence with metazachlor. Activity of residual pre-emergence herbicides is reduced on dry or cloddy seedbeds (although so are weed numbers) and where some materials are absorbed onto straw residues. The selectivity of metazachlor pre-emergence depends on drilling depth of the crop and therefore it is not safe to use on broadcast crops and on light soils it can be leached by heavy rainfall and cause damage to drilled crops. Metazachlor and trifluralin do not control charlock, or other cruciferous species. Cyanazine is used post-emergence and more recently bifenox, a cereal herbicide, now has a Specific Off-Label Approval (SOLA) for use in oilseed rape. Cleavers are controlled with quinmerac formulated with metazachlor, or with clomazone and the large use of these herbicides, applied to 28% of the oilseed rape area, suggests that there are cleavers problems inherited from the previous cereal crop. Quinmerac improves poppy control. Clomazone also controls hedge mustard, (which is not controlled by metazachlor), but it does not control charlock (Appendix). Picloram in formulation with clopyralid also controls cleavers post-emergence and mayweeds. Mayweeds and creeping thistle are controlled with clopyralid post-emergence. Both control sowthistles, which are becoming an increasing problem (or are more noticeable in the crop than other weeds). The options for weed control in spring oilseed rape are limited, although there are opportunities for a clean-up with glyphosate, and cultivations prior to drilling. Polygonums and charlock are more likely to infest spring rape. Trifluralin is widely used and is effective on Polygonum species and any spring-emerging black-grass. Many herbicides commonly used in winter oilseed rape are not approved for use in spring-sown rape (propyzamide, carbetamide, clopyralid/picloram, metazachlor/quinmerac, metazachlor/dimethenamid-p). This is partly because of the risk of damage (e.g. propyzamide) where there is a shorter interval before the following winter wheat is sown or because the small area of spring rape does not warrant the cost of development. A sequence of trifluralin pre-sowing followed by metazachlor pre-emergence is used. Desiccation Most crops are swathed before combining, but about 33% are desiccated using diquat or glyphosate (Table 1). The desiccant is used as a pre-harvest aid rather than for desiccation of green weed. Herbicides for oilseed rape Herbicides and desiccants approved for oilseed rape for 2006 and the usage in 2003/2004 are shown in Table 1. The weed spectrum controlled by some of these herbicides is shown in the Appendix. Oilseed rape crops received on average three herbicides in 2003/2004. A new product, Springbok (metazachlor/dimethenamid-p), was registered for UK winter oilseed rape in June 2006 will improve control of problem weeds such as crane’s-bill and shepherd’s-purse compared with metazachlor. A new post-emergence graminicide quizalofop-p-tefuryl, was also registered.

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Table 1. Herbicides and harvest aids approved for oilseed rape 2006; Review status; Aim re-registration UK; Activity; area sprayed with herbicides oilseed rape (498,155 ha grown) in Great Britain 2004 (source CSL Pesticide Usage survey, 2004) Herbicides approved for oilseed rape 2006


Activity Usage 2004 (spray ha)

Total weeds and harvest aids Glufosinate-ammonium List 2 √ phosphinic acid Glyphosate Annex 1 √ phosphonic acid 309,662Grass weeds Cycloxydim# List 3A - oxime 78,150 Fluazifop-P-butyl# List 3A √ phenoxy-propionic acid 71,784 Propaquizafop# List 3A √ phenoxy-alkanoic acid 240,099 Quizalofop-p-ethyl# List 3B √ aryl phenoxypropionic acid Quizalofop-p-tefuryl# List 3B √ aryl phenoxypropionate Tepraloxydim# New Annex 1 - oxime 67,972Broad-leaved weeds and grasses Bifenox SOLA List 3A √ diphenyl ether Carbetamide (winter) List 3A √ residual carbamate Clomazone List 3A √ isoxazolidinone 27,764 Clopyralid Annex 1 - translocated piclonic 39,205 Clopyralid/picloram (winter) Annex 1/List 3B - / - translocated piclonic/pyridine carboxylic acid Cyanazine (winter) until 31 December 2007

Not supported triazine 19,437

Metazachlor List 3A - anilide 162,110 Metazachlor/quinmerac (winter) List 3A/List 3B - / - anilide/quinolinecarboxylic acid 111,976Metazachlor/dimethenamid-p (winter) List 3A/new Annex 1 - / - anilides Napropamide (winter) List 3A amide Propachlor List 3B x chloroacetanilide Propyzamide (winter) Annex 1 - amide 139,401 Pyrdate SOLA until 1 January 2007 Annex 1 √ brassicas pyridazine Trifluralin List 2 - dinitroaniline 163,120 Desiccants/harvest aids Diquat Annex 1 √ bipyrilidium 13,423 Glufosinate-ammonium List 2 not decided (√ N) phosphinic acid Glyphosate Annex 1 √ phosphonic acid See above- Company request confidentiality; √ yes; x no; (√ N) aim re-register in N Europe; The future of trifluralin is doubtful ; #ACCase inhibitor, all HRAC ‘Group A’ Non-chemical control The earliness of sowing of winter rape excludes the option of a stale seedbed to reduce weeds emerging with the crop. However, the approach can be of benefit where rape is following a fallow and weeds such as charlock and volunteer rape are a potential problem. Mechanical weeding is not used in oilseed rape because it is expensive. It is not an option in broadcast crops and wider rows than are currently used would be needed for inter-row hoeing Early inter-row hoe cultivations are used in organic winter oilseed rape in some countries, but this technique causes damage once the crop starts to cover the row. Flexible-tine weeders give poor control of charlock and other species with a strong taproot. Ploughing before sowing the winter crop avoids volunteer cereals, and reduces numbers of black-grass and other grass weeds but there has been a reduction in ploughing because of cost considerations. As resistant grass weeds develop on the farm there will be a point where it will be necessary to switch from herbicides to ploughing. There may be a move towards cultural methods of grass weed control in response to the herbicide restrictions. Orson & Harris, 1997, demonstrated that while the adoption of ploughing and delayed drilling results in an increase in costs and does not

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maximise margins in the short-term it is a better long-term option if it prevents the full expression of resistance. There are opportunities for removal of weeds including grasses with cultivations in the spring-sown rape but a change from winter to spring crop would mean a reduction in Gross Margin of £120/ha. Charlock occurs in spring and winter-sown rape so such a change would not provide an answer. Oilseed rape volunteers Oilseed rape volunteers have become an increasing and persistent problem in other broad-leaved crops. Harvesting techniques that avoid seed return and allow lost seed to germinate with subsequent cultivation (as opposed to seed burial which would aid survival) will prevent the volunteer problem to some extent. Isolation of industrial rape crops with high levels of erucic acid from edible crops will minimise cross-pollination and avoid volunteers from seed carry-over that could cause contamination. This will also be relevant if ‘designer rapes’ are grown for specific oil contents e.g. for high value pharmaceutical use. Genetically Modified Herbicide-Tolerant Oilseed rape In the future, weed control in oilseed rape could be simplified by the introduction of genetically modified varieties that are tolerant of herbicides such as glufosinate or glyphosate. Breeding programmes for winter and spring varieties are well advanced. However, at present GM crops are not acceptable to some sectors of the public and there are grower concerns regarding seed longevity. There is also concern that if genetically modified (GM) herbicide tolerant crops are introduced and if there is gene flow to related wild species that these and volunteers will be difficult to control. Volunteers from a crop tolerant to more than one herbicide will further complicate weed control. If, in the future GM crops are introduced, control of modified rape volunteers elsewhere in the rotation would require careful planning. Research funded by Defra as part of the farm-scale evaluations, has detected gene transfer from GM herbicide tolerant oilseed rape, to its weedy relative, charlock, in one plant. Charlock is an important weed of oilseed rape and other crops and the acquisition of herbicide tolerance by charlock would make weed management more difficult. 1. The likely impacts of the 91/414/EEC review process on herbicide availability for UK oilseed rape

1.1. Losses Cyanazine was not supported in the 91/414 EEC review but there was a derogation for use in winter oilseed rape until 31 December 2007. It is not approved for spring rape. It was only used on 3.9% of the area grown in 2004. Cyanazine applied post-emergence, controls charlock - other rape herbicides are ineffective. In the past benazolin was used, but it was revoked and could not be used after 2003. The new product Springbok for oilseed rape containing dimethenamid-p/metazachlor covers a broad-spectrum but the combination is unlikely to give adequate control of charlock.

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1.2. Impact

• There is a risk of processors rejecting crops infested with seeds of spring oilseed rape volunteers, and brassica weeds such as charlock. The seeds are difficult or impossible to separate from the oilseed rape sample and either cause toxicity in oil products, or affect the purity of specific oil-products used in food or industrial processes. In the EU, buyers are becoming increasingly discerning about oil quality. Trade between farmers and crushers, is usually based on the contract FOSFA 26A, which sets a legally binding framework for both buyers and sellers. Terms and conditions include minimum quality specifications. Seeds of cruciferous species (e.g. charlock and wild radish) affect quality for crushing by increasing glucosinolate levels in meal and this is detrimental to monogastrics. Meal should contain no more than 25µml/microgram of glucosinolates. There are price deductions for seed admixture. The FOSFA contract 26A: where seed admixture exceeds 4% by weight (R Elsdon, United Oilseeds, pers. comm.) the crop is rejected. The crusher may reject produce if weed seeds adversely affect oil content or cause taint or discolouration of the oil.

• If the crop is rejected the financial loss would be for average yields £470/ha (winter rape) or

£290/ha (spring rape). Assuming 20,000 ha of winter rape are currently affected by charlock, (cyanazine area sprayed, CSL survey 2004), this equates to £9,400,000 per annum.

• Rotations of 1 year in 2 or 1 year in 3 oilseed rape crops are becoming common (HGCA),

and if charlock is not controlled, it sets seed to infest the next crop. In addition farmers are encouraged to increase biodiversity by leaving charlock as a desirable food source for insects and birds in cereals. Charlock is likely to increase and become a problem in rape crops, affecting quality.

• Alternatives have been sought and there is a SOLA (winter and spring rape) for bifenox, a

diphenyl ether, on List 3A of the Review process. Bifenox controls charlock. It is applied at 5-6 true leaves, is used at grower’s risk and there has been some damage in crops that are not well waxed. Some agronomists are reluctant to advise its use, so bifenox may not be a complete solution to the problem (although cyanazine also caused crop damage under similar conditions). The company aims eventually to have an on-label recommendation for bifenox. We do not know the future of bifenox List 3A in the 91/414 Review. The new product for oilseed rape containing dimethenamid-p/metazachlor (Springbok) gives some improvement on charlock but the combination is unlikely to give adequate control.

1.3. Future Losses Trifluralin (List 2) inclusion on Annex 1 is doubtful and there is a potential impact if it is lost. It continues to be strongly supported by Dow AgroSciences. Trifluralin, a dinitroaniline (MoA K1) is on List 2 of the EC Review, was supported for use in S European crops but there has been no decision yet on whether it will achieve Annex 1 listing. A new fish toxicity study indicates there is only a low risk to fish but there are risks to aquatic organisms, and discussions about whether it is a Persistent Organic Pollutant. If it is included on Annex 1, regulatory authorities in some of the current northern zone Member States may not permit re-registration. Trifluralin products are cheap, c. £5/ha, and are used on more than 30% of oilseed rape crops, often in combination with lower than recommended dose-rates of metazachlor for broad-leaved weed control according to the 2004 CSL Survey. Cost of metazachlor low dose + trifluralin is c. £38/ha.

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• Loss of trifluralin would lead to increased costs for producers of oilseed rape and reliance for example on metazachlor (broad spectrum) ½ dose + clomazone, cost £64, or £55/ha for the full dose of metazachlor alone.

• If trifluralin were not available, there would be no control of knotgrass, black bindweed, fat-

hen, fumitory in spring rape, or pansy, fumitory in poorly established winter rape. In tank-mix, it improves control of poppy

• Many herbicides commonly used in winter oilseed rape are not approved for use in spring-

sown rape (propyzamide, carbetamide, clopyralid/picloram, metazachlor/quinmerac). This is partly because of the risk of damage (e.g. propyzamide) where there is a shorter interval before the following winter wheat is sown or because the small area of spring rape does not warrant the cost of development. A sequence of trifluralin pre-sowing followed by metazachlor pre-emergence is used. Trifluralin is needed for spring-emerging resistant blackgrass and broad-leaved weeds.

• Trifluralin is of value for the management of herbicide resistant grass-weeds and it is an

important product for use in oilseed rape where black-grass resistance is increasing. No resistance to trifluralin has ever been detected in grass-weeds in the UK (Moss & Clarke, 1994; James, Kemp & Moss, 1995; Heap, 2006). It is therefore a useful tool for resistant black-grass control and is cheaper than propyzamide, a benzamide also with MoA K1 (£42 - £51/ha). If trifluralin is lost there will be more use of propyzamide, thus increasing production costs by £37/ha. A key strategy for resistance management is to avoid over reliance on high resistance risk herbicide groups, thus trifluralin is the choice for use in mixture or sequence with various partners or target site (e.g. cycloxydim, tepraloxydim – both widely used in oilseed rape production) http://www.pesticides.gov.uk/rags.asp?id=714 as promoted by WRAG.

• The Advisory Committee on Pesticides (ACP) has now advised that PSD take a more

restrictive regulatory approach to the management of herbicide resistance in grass weeds. This will include statutory restrictions on the use of herbicides that act as ACCase or ALS inhibitors and extend the restrictions already imposed on some individual products to all similar herbicides. The most significant usage of sequential applications of products containing ACCase inhibitors (‘fops’ and ‘dims’) is in oilseed rape where they are used to control successive flushes of volunteer cereals. Survey data suggest that there is an increasing reliance on these post-emergence ‘fops’ and ‘dims’ to control volunteer cereals - 507,620 ha were sprayed in 2004, and of the oilseed rape area grown, 52.8% was treated once, 20.3% twice and 1.9% three times. In 2004 propaquizafop - the most popular choice, was used at half dose rate or less and more than one application.While the restrictions would preclude the use of two applications of a product containing the same ACCase inhibiting active substance, a sequence of two different ACCase inhibitors would be possible. Thus a sequence of a ‘fop’ followed by a ‘dim’ or a sequence of two different ‘fops’ would be allowed. Alternatively growers could use a product containing an alternative mode of action such as propyzamide (or trifluralin). The aim is to implement the proposed changes to labels for autumn 2006.

Currently there are few herbicides available for winter oilseed rape and even fewer for the spring crop. Decisions on Annex 1 inclusion for most of the important herbicide active substances (Table 1) have not been made: several graminicides, trifluralin (List 2), metazachlor (List 3A), metazachlor/quinmerac (List 3B) (winter) and clomazone (List 3A). It seems likely that older active substances will be supported with acceptable data packages and be re-registered for oilseed

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http://www.pesticides.gov.uk/rags.asp?id=714


rape, in N Europe and the UK because oilseed rape is becoming an important EU crop for biofuel as well as for feed purposes. However, dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy.

2. Specific herbicides and desiccants it would be desirable to maintain from the agronomic perspective to avoid major difficulties There are very few herbicides approved for winter oilseed rape and fewer still for the spring crop. Herbicides with alternative modes of action are important for resistance strategies. It is important to maintain the following: Trifluralin (see above) Graminicides ‘fops’ and ‘dims’ will still be important for volunteer cereal control but there will be restrictions (see above). Propyzamide, an amide MoA code L is on Annex 1 for uses including seed brassicas. Re-registration in the UK will be sought for oilseed rape (winter). Risk mitigation for operator safety, birds and mammals is needed. There is no evidence of grass weed resistance to this herbicide (Edmonds & Caseley, 1997). It is needed for control of grass weeds becoming resistant to ‘fop’ and ‘dim’ herbicides (Pollak & Collings, 2003). The technical and financial impacts of herbicide-resistant black-grass have been assessed by Orson & Harris, 1997. Metazachlor (List 3A), a chloroacetanilide for broad spectrum broad-leaved weed control, and metazachlor/quinmerac (List 3B), which gives additional cleavers control; metazachlor/ dimethenamid-p (Annex 1) better control of difficult weeds shepherd’s purse, cranesbill and may offer some slight improvement on charlock. Clomazone (List 3A) for control of cleavers and a few other species. Clopyralid (Annex 1) is useful for mayweeds and thistle control. Bifenox (List 3A) may be a suitable alternative to cyanazine for control of charlock. Glyphosate (Annex 1) is the most widely used cheap herbicide to clean up stubbles and for desiccation. Diquat (Annex 1) has already been re-registered for desiccant use in oilseed rape. 3. Prospects for alternatives for any foreseen major gaps in herbicide availability 3.1. Alternatives A ‘Gap Analysis’ (Tables 2 and 3) shows the critical herbicide gaps * * *, where there are, or soon will be no control measures at all.

a. Charlock: A sulfonylurea, ethametsulfuron (Muster 75DF) from Dupont controls charlock, pennycress, wild mustard, cranesbill and others, is registered for use in oilseed rape in Canada but not in the EU. However there are restrictions for following crops.

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b. Thistles: aminopyralid, a grassland herbicide is very effective on Compositae including thistles is in development as a mixture (not safe to rape) but it will not be available alone thus clopyralid will continue to be the solution.

Dimethachlor (List 3B) is approved for broad-leaved weed control in Germany for oilseed rape, if included in Annex 1 it will be re-registered in N Europe.

c. Resistant black-grass: no other class of compound has so far been developed – propyzamide, carbetamide and trifluralin remain the best options. Herbicides are under constant scrutiny http://www.pesticides.gov.uk/rags.asp?id=714 by Steve Moss (Rothamsted Research, BBSRC), and WRAG. The UK is unlikely to see the introduction of new herbicides with different modes of action in the short or medium term, and reliance will continue to be placed on effective current herbicides. Thus the removal of trifluralin would only exacerbate the current resistance management problems of grass weeds.

A UK Off–label Approval http://www.pesticides.gov.uk/applicant_guide.asp?id=1226, based on recognition of on-label approval in another (current Northern zone) member state and where there is an extant on-label approval for the use of the same product on another edible crop in the UK, is not possible for a major crop. These arrangements only apply to applications for off-labels for minor crops of areas less than 50,000 ha. This rules out oilseed rape as a whole, but could perhaps be a useful route for spring rape. There is little herbicide development for oilseed rape because it is competitive and has a lower requirement for weed control. This may change as the area and weed problems increases. If Herbicide-Tolerant rape is grown there will be no further herbicide development for conventional rape. Introduction of Genetically Modified Herbicide-Tolerant rape crops seems unlikely in the near future in the UK because of concerns about seed longevity and consumer opposition.

3.2. Impact of the proposed regulation and revision of 91/414EEC

• There may be a reduction in pesticide development in the future resulting from the impact of cost/patent arrangements in a new regulation 91/414/EEC and this is likely to affect oilseed rape – a minor crop in global terms.

• The new regulation is expected to form part of the wider “Thematic Strategy for the

sustainable use of pesticides” which includes the Water Framework Directive. There are concerns regarding water issues with some oilseed rape herbicides: Trifluralin is classed as a Priority Substance (pesticide) “ …..individual pollutants presenting a significant risk to or via the aquatic environment, including such risks to waters used for the abstraction of drinking water” and it presents a risk to the aquatic environment. It is one of the three remaining pesticides listed (isoproturon (Annex 1), chlorpyrifos (Annex 1), trifluralin (List 2 pending a decision)) that have not been revoked in the EC Review. Metazachlor has been found in groundwater above the 0.1 µg/L drinking water limit, (but so have other pesticides), and propyzamide and carbetamide were problematic in surface water in one catchment area in 2004/2005. Increased area of any crop where only a few herbicides are used, risks exceedance of the 0.1 µg/L level for individual actives.

Other potential mpacts are shown in the Executive Summary

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http://www.pesticides.gov.uk/applicant_guide.asp?id=1226

Table 2. Gap Analysis (winter oilseed rape): Herbicides Weeds/weed species

Application timing

Gap Status Current approved solution

Comments Solution non-chemical

Solution chemical UK

Solution chemical another MS

R & D? Residues data?

grasses & annual BLW

pre-em / residual

* * trifluralin, metazachlor, metazachlor /quinmerac, metazachlor/dimethenamid-p clomazone, propachlor

Trifluralin under review. If it disappears, cost of weed control increases. More reliance on herbicides containing metazachlor.

Wider rows inter-row hoe but ineffective in a wet autumn.

Increase metazachlor water problems?

-

Resistant black-grass

pre-em / residual

* Propyzamide,carbetamide,

Trifluralin under review. Removal would exacerbate the current resistance management problems of grass weeds.

trifluralin

- -

Established BLW except composites

post-em * * * Propyzamide, carbetamide; Bifenox SOLA

cyanazine goes after 31 Dec 2007; pyridate will now be available (Belchim), Propyzamide & carbetamide inadequate BLW control but effective on chickweed. Bifenox requires well-waxed crop 6 leaves.


- - -

Compositae Post-em * * Clopyralid Only clopyralid, (benazolin lost before Review) - -

Volunteer spring rape, charlock and runch

Post-em * *? Bifenox SOLA Cyanazine lost after 31 Dec 2007suppresses/checks, vol OSR, more information needed on bifenox. Earlier pre-em treatments have little or no activity.


- - -

BLW broad-leaved weeds Key to Gap Analysis Tables:

* * gap no immediate problem but future situation vulnerable

* * * critical gap, where there are, or soon will be no control measures at all, or where the available control measures are inadequate. Solution non-chemical - is this effective/reliable? yes/no

Solution chemical registered in the UK - please state chemical

Solution chemical another MS - in another Member State, say which chemical and where registered

Efficacy trials? – yes/no; Residues trials? - yes/no

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Table 3. Gap Analysis (spring oilseed rape): Herbicides Weeds/weed species

Application timing


Comments Solutionnon-chemical




grasses & annual BLW

pre-em / residual

* * Trifluralin, metazachlor, clomazone, propachlor

Trifluralin under review. If it disappears cost weed control increases and reliance on metazachlor (broad spectrum) + clomazone

Wider rows inter-row hoe. Crop sown too early for stale seedbed

- -

BLW except composites

post-em * * * Pyridate Bifenox SOLA

Pyridate now sold by Belchim, also risk of crop damage. Increased reliance on pre-emergence trifluralin if it achieves Annex 1 list & metazachlor, bifenox require well-waxed crop

.. - -

Compositae post-em * * Clopyralid Only clopyralid, (benazolin lost before Review) - -

Charlock and runch

post-em * *? Bifenox SOLA more information needed on bifenox; Earlier pre-em treatments have little or no activity

Wider rows inter-row hoe but ineffective

- -

BLW broad-leaved weeds

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Pest control in oilseed rape

Pest monitoring, economic treatment thresholds, as well as decision support systems have been developed for oilseed rape, mainly funded by growers levy through HGCA. A current EU-funded ‘MASTER’ project on integrated pest management of six major oilseed rape pests is aimed at developing strategies that maximise the effect of biological control agents and predators (Powell, 2005). The oilseed rape crop relies heavily on pyrethroids to control aphid, pollen beetle, cabbage seed weevil cabbage-stem flea beetle and pod midge and some pirimicarb is also used. Cabbage aphids (Brevicoryne brassicae) Cabbage aphids overwinter on brassica plants. Impact: may cause direct damage in spring, reduce yields and carry viruses, e.g. turnip mosaic virus and cauliflower mosaic virus. Control: in spring with a primicarb spray + wetter in winter rape if over 13% of plants are infested, or in spring rape if over 4% of plants are infested. Pyrethroids may not control cabbage aphid. Non-chemical control: The parasitoid, Diaeretiella rapae normally provides good control. Peach-potato aphid (Myzus persicae) Impact: this pest feeds on a oilseed rape and many other crops and weeds. Usually only very heavy aphid infestations cause direct damage. Numbers may increase following serious outbreaks of insecticide-resistant aphids on potatoes. In Scotland some oilseed rape crops have failed and were ploughed in (S. Foster, Rothamsted Research, pers. comm.). Aphids transmit the Beet Western Yellow virus, which causes temporary reddening of infected plants in spring. Virus infections have been low in recent years. Aphids that colonise crops in autumn may have survived through many generations on treated crops. This leads to high levels of insecticide resistance, and restricts insecticide choice. Three forms of insecticide resistance (Foster et al., 2000) occur in the UK and elsewhere:

• Kdr resistance to pyrethroids • MACE resistance to pirimicarb • E4 strains resistant to pyrethroids, pirimicarb and OPs.

Control: Neonicotinoid seed treatments, such as beta-cyfluthrin/imidacloprid, currently control all resistant forms for several weeks following emergence. Careful stewardship to ensure the lasting efficacy of this new class of insecticides is needed and a new Sustainable Arable LINK project (LK0953, ‘Stewardship of Neonicotinoid Insecticides’) is to monitor the incidence of resistance in M. persicae in the UK and investigate conditions where resistance is most likely to arise. Cabbage stem flea beetle (Psylliodes chrysocephala) The pest originally attacked mustard and brassica seed crops in East Anglia. It has now spread to other areas of England, and Wales and is increasing in Scotland. In recent years warmer autumns have favoured egg-laying and early hatch of larvae and this trend could continue. Shorter rotations will increase incidence of this pest. Impact: Large numbers of adults feeding in the autumn kill plants, occasionally causing total crop failure. Crushers may reject seed contaminated with the pest. Control measures applied at the threshold of five larvae per plant has given a mean yield response of 0.34 t/ha. Control: Beta-cyfluthrin/imidacloprid seed treatment reduces adult feeding and numbers of eggs laid. One spray with a pyrethroid controls feeding adults and larvae that have not entered the main stem. The threshold for application of a pyrethroid to control feeding adults is when adult flea beetle have eaten over 25% of leaf area at 1-2 true leaf growth stage, over 50% at 3-4 true leaf stage

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or if crop growth is slower than it is being destroyed. Where no adult spray is used then the threshold to control larvae is when there are over 5 larvae per plant or over 50% petioles damaged. Insecticide treatments are often combined with a herbicide and/or fungicide to reduce spray application costs, usually in October before the necessity for cabbage stem flea beetle can be assessed. The level of larval infestation becomes apparent in November/December. Work by Green, ADAS in HGCA Project 3023, showed that catches of the beetle in water traps could predict the need for control during October Non-chemical control: delayed sowing reduces risk – the numbers of adults attracted and eggs laid are reduced. The main natural enemy is the wasp Tersilochus microgaster, which parasitises larvae in spring. However all parasitoids may be vulnerable to pyrethroids. Parasitoids remain as pupae in the soil until the next crop, and may be damaged by ploughing. Minimum cultivation after rape favours parasitoid survival. Other flea beetles are controlled with pyrethroids. Pollen beetle (Meligethes aeneus) Pollen beetles lay eggs in flower buds, the larvae cause damage by feeding on pollen in the flowers. Impact: Loss of pod sites from pollen beetle damage are sometimes severe, but yield reduction in winter rape is rare because crops usually compensate by producing more and larger seeds on lower racemes. However, varietal associations and restored hybrids may lose more yield because male fertile plants are attacked and cross pollination is reduced. ‘Canopy management’ techniques currently advocated to optimize pod numbers could increase the risk. Spring crops are much more vulnerable than winter crops because they are less able to compensate for loss of pod sites. Control: with a pyrethroid spray and a neonicotinoid (new approval). Action thresholds are: if there are more than 15/plant during green/yellow bud stage, more than 5/plant for backward crops, or more than 2/plant for varietal associations in winter oilseed rape; over 3/plant at green bud stage (1/plant in Scotland). Resistant strains of beetles have appeared in France and Sweden. Only pyrethroids were approved therefore there was a risk of resistance developing in the UK and control failures to establish the level of resistance of the population required investigation. A new insecticide, with a different mode of action, effective on pollen beetle has been approved 2006 –thiacloprid (with oil O-TEQ) product Biscaya. Non-chemical control: spring crops should be sown as early as possible. Natural enemies are three wasp parasitoids, and their survival is improved by minimum cultivation after oilseed rape is harvested. There are also promising results with an insect-killing nematode, and use of turnip rape as a trap crop for beetle pests such as pollen beetle (EU-funded MASTER project). Other less important pests, are all controlled with pyrethroid sprays where necessary: Cabbage seed weevil: at present may be of economic importance only in the north of England and Scotland, and in spring rape. Control when thresholds are reached. Brassica pod midge lays its eggs in holes left behind by cabbage seed weevil, in developing pods and the pest can severely reduce yields of spring rape. Midges migrate into the rape crop and therefore headlands are affected most. Cabbage stem weevil Can reduce seed filling and kill plants in severe cases. Rape winter stem weevil Large numbers may stunt the crop. Non-chemical control: Pest control measures can be reduced considerably if predators and parasitoids are present. These beneficial organisms come from the previous season’s rape crops and are encouraged by minimum tillage.

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Molluscs Slugs are major pests of oilseed rape and shorter rotations in future will increase risk of slug attack. The problem was recently reviewed (HGCA Topic Review: Slug Management, 2006) and there will be an EU review of molluscicides in two years time. Germinating seedlings are highly vulnerable to feeding by slugs (especially Deroceras reticulatum, also Arion, Milax and Tandonia spp.), but seeds are not attacked. The growing point of a germinating oilseed rape shoot is above ground (unlike cereals) and surface-feeding slugs can kill plants. Traps to assess slug activity just before, or after, cereal harvest, are recommended but uptake of trapping is poor at a busy time of year. There is also difficulty with interpretation of results. The Rothamsted slug population model could provide early warning of slug risk at a regional level but it is difficult to forecast weather accurately. A soil test developed in the HDC Project FV 225 HortLINK project (Hort 219) CSA 5465 for brassicas may be useful for oilseed rape. Impact: serious damage occurs up to the 4 true-leaf stage. Thresholds are 4 per trap. Current chemical control: with metaldehyde, methiocarb, thiodicarb broadcast pellets. Bait pellets often do not give adequate protection to plants, and pose an environmental hazard (HGCA). It is standard practice to add slug pellets with the seed where rapeseed is autocast. Minimum tillage is widespread but there are different viewpoints on the implications of this establishment technique on slug management. Other means of control are the subject of investigation including seed treatments (HGCA project 2719). Reducing risk: Shallow cultivation after harvest to incorporate crop residues reduces slug numbers, especially in dry conditions. Drilling in a fine consolidated seedbed will prevent slugs accessing seedlings before emergence. Insecticides for oilseed rape Insecticides approved for oilseed rape for 2006 and insecticide usage for 2003/2004 are shown in Table 4. In winter oilseed rape there are usually two insecticide applications the first in the autumn, mainly September to November with a second between March and June. Table 4 shows cypermethrin accounted for the majority of autumn applications in 2004. Most sprays are for control of pollen beetle (36% of the treated area) or cabbage stem flea beetle (28%), aphids (13%). In 2006, a new insecticide formulation of thiacloprid with O-TEQ oil is approved (single application) for pollen beetle control. The oil improves retention on waxy-leaved crops. There was also a new approval for slug control with thiodicarb, another carbamate but it has now failed Annex 1 inclusion.

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Table 4. Insecticides and Molluscicides approved for oilseed rape 2006: Review status; Aim re-register oilseed rape UK; Pest; Activity; Usage on oilseed rape area grown in Great Britain 498,155 ha 2004 (spray hectares) (source CSL Pesticide Usage survey, 2004) Insecticides and Molluscicides approved for oilseed rape 2006

Review status Aim re-register oilseed

rape UK

Pest Activity Usage 2004 (spray ha)

Insecticides Neonicotinoid Thiacloprid New Annex 1 √ pollen beetle Contact & systemic chloronicotinyl Carbamate Pirimicarb Annex 1 √ aphid midge contact, fumigant and translaminar # carbamate 10,232Pyrethroid Alpha-cypermethrin Annex 1 - beetle midge weevils contact and ingested pyrethroid 103,170 Bifenthrin List 3A √ beetle midge weevils contact and residual pyrethroid. Cyfluthrin (winter) Annex 1 √ beetle non systemic pyrethroid Cypermethrin Annex 1 √ beetle midge weevils contact and ingested pyrethroid 385,509 Deltamethrin Annex 1 √ aphid beetle midge weevils contact and ingested pyrethroid 48,007 Lambda-cyhalothrin Annex 1 √ aphid beetle midge weevils contact and ingested . broad spectrum. pyrethroid 115,168 Lambda-cyhalothrin/pirimicarb

Annex 1/Annex 1

√ / √ aphid beetle midge weevils systemic, contact and stomach activity. pyrethroid /carbamate

Tau-fluvalinate List 3B √ aphid beetle contact pyrethroid 52,439 Zeta-cypermethrin List 3A √ beetle midge weevils contact and stomach activity. pyrethroid 91,141Molluscicides Metaldehyde List 3A √ slugs snails molluscicide bait 104,560 Methiocarb List 2 not decided (√

N) slugs snails carbamate 16,712

Thiodicarb non-inclusion slugs snails carbamate - Company request confidentiality; √ yes; (√ N) aim re-register in N Europe; # Myzus persicae resistance reported in some areas. Seed Treatments Insecticidal seed treatment beta-cyfluthrin/imidacloprid is widely used on oilseed crops (Table 5). In 2004, seed treatments beta-cyfluthrin/imidacloprid, thiram and iprodione accounted for 63%, 54% and 54% of the area grown respectively. Approximately 9% of the area of oilseed rape was sown with untreated seed and 29% of all oilseed rape sown in England & Wales was farm-saved from the previous harvest. Table 5. Seed treatments approved for oilseed rape 2006; Review status; Aim re-register for UK oilseed rape; Pest or Disease; Activity; Usage on oilseed rape area grown in Great Britain 498,155 ha in 2004 (spray hectares) (Source CSL Pesticide Usage survey, 2004) Seed treatments approved for oilseed rape 2006

Approval status Aim re-register for UK oilseed rape

Pest or disease Activity Usage of seed treatments 2004

Fungicide seed treatments Iprodione Annex 1 - Alternaria dicarboximide 271,240 Metalaxyl (spring) use by 31 Jan 2006 Non inclusion Annex 1 Prochloraz/thiram (winter only) List 3B/Annex 1 √ Phoma conazole/dithiocarbamate Thiram Annex 1 √ Damping off dithiocarbamate 271,355Insecticide seed treatments Beta-cyfluthrin/imidacloprid Annex 1/List 3A √ / not decided beetles pyrethroid/neonicotinoid 311,620Molluscicide seed treatments Methiocarb List 2 not decided (√ N) slugs carbamate 806 - Company request confidentiality; √ yes; (√ N) aim re-register in N Europe

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1. The likely impacts of the 91/414/EEC review process on insecticide and molluscicide availability for UK oilseed rape

1.1. Losses All insecticides and molluscicides were supported in the 91/414/EEC review, and most insecticides are included on Annex 1. 1.2. Impact None so far. 1.3. Future losses? It is difficult to predict the likely impact of the review process on pesticide availability for UK oilseed rape. Most insecticides are included on Annex 1 (Table 4). Insecticidal seed treatment beta-cyfluthrin (Annex 1)/imidacloprid is important and very widely used. The decision on imidacloprid (List 3A) has not yet been made. There will be some use of thiometoxam on imported seed in the UK in autumn 2006 and thiomethoxam is now on Annex 1. There is no decision yet on the molluscicides metaldehyde (List 3A) and methiocarb (List 2) in the review, but thiodicarb (new UK approval for rape 2006) has failed Annex 1 inclusion. At re-registration stage data may be required for each crop use of metaldehyde and this is likely to be generated for oilseed rape - an important market. We do not yet know whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could also be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. 2. Specific insecticides or molluscicides or groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

It would be desirable to maintain: Metaldehyde (List 3 A) and methiocarb (List 2) molluscicides Neonicotinoid seed treatment, beta-cyfluthrin/imidacloprid (Annex 1/List 3A), is needed for Cabbage stem flea-beetle control and it currently controls all resistant forms of peach potato aphid for several weeks following emergence. Pirimicarb (Annex 1) for control of brassica aphid Pyrethroids (most of them on Annex 1) are essential for control of other pests (cabbage-stem flea beetle, pollen beetle, cabbage seed weevil and pod midge). Thiacloprid (new Annex 1) needs to be maintained for pollen beetle control to avoid resistance.

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3. Prospects for alternatives for any foreseen major gaps in insecticide and molluscicide availability

3.1. Alternatives Gap Analysis (not given) for control of the main pests of oilseed rape: Cabbage stem flea beetle, Pollen beetle, Cabbage seed weevil and Pod midge, show that there are no gaps – insecticides approved are adequate, particularly now that thiacloprid is approved for Pollen beetle. However, new insecticides with different modes of action would be useful for resistance strategies. New chemistry will be available in the future. Molluscicides: No seed treatment is yet approved for slugs and there would be a benefit if less active substance is needed for efficacy, but seed treatments incur cost ahead of knowing whether there is a problem. However, forecasting could be used to determine instances in which treated seed is justified. A methiocarb spray is approved in the Netherlands. Future possibilities could include beta-cyfluthrin/clothianidin seed treatment. The oilseed rape crop relies heavily on pyrethroids and pirimicarb to control aphid, pollen beetle, cabbage seed weevil and pod midge. Pollen beetle (Meligethes aeneus): there is no resistance yet to pyrethroids in the UK but there is a risk, as in France. The new approval of thiacloprid for pollen beetle will be useful and only one spray is permitted (strategy to avoid resistance). Insecticides are being developed in other crops including vegetable brassicas (HDC project by Dr Rosemary Collier at Warwick HRI, Wellesbourne) and may be useful for oilseed rape.

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Disease control in oilseed rape

Disease monitoring, economic treatment thresholds, as well as decision support systems have been developed for oilseed rape and funded by HGCA and Defra. HGCA project 3200 (2005-2009) will assess new fungicides and dose rate responses for oilseed rape for control of the three main diseases. The status of fungicide resistance in the UK is not known but it is important to reduce the risk of it developing by using fungicide mixtures and fungicides with different modes of action. Estimates of national yield losses suggest that stem canker and Light leaf spot are the most important diseases; together they have caused yield losses of up to £80 million/annum in recent years. Losses of as much as £40 million/annum were attributed to Light leaf spot, but data from CSL show that losses have declined since the 1995 peak. Losses from Sclerotinia are up to £1.5 million Turner et al., in 2002, reviewed pest and disease problems in oilseed rape. The important diseases and their impact on oilseed rape yields are described below. Clubroot is also occasionally seen. Many more diseases occur in oilseed rape but cause more problems in vegetable leaf, head and flower-head brassicas because they reduce quality. Sclerotinia stem rot (Sclerotinia sclerotiorum) Sclerotinia is a potentially damaging disease in oilseed rape as well as peas, potatoes and various horticultural crops. The risk of infection increases where there are short rotations of susceptible crops and it occurs in warm, unsettled weather during flowering. Impact: the incidence of stem rot in winter oilseed rape in England was 2-4% in Defra surveys. This equates to a 1-2% yield loss. A few crops suffer severe attacks every year. The CSL survey suggests that in 2004, of the area treated with fungicides, 17% was for Sclerotinia control. Sclerotia resting bodies survive in the soil for several years and it is important to control the disease in oilseed rape so that other susceptible crops in the rotation are not affected. Control: with protectant fungicides (Table 7) applied early to mid-flowering. A wide range with different modes of action is approved. In the absence of satisfactory disease risk tests, spraying decisions are based on an assessment using the Sclerotinia Decision Guide http://www.hgca.com. A diagnostic test is being developed. Non-chemical control: wider rotations. Light leaf spot (Pyrenopeziza brassicae) Light leaf spot occurs in cool wet autumns and springs and can result in decreased plant populations, seed numbers per plant or decreased thousand seed weights. The severity of infection differs between seasons, regions and individual crops. The disease is more prevalent in Scotland. A survey in Scotland showed there was no significant influence on the sensitivity of isolates when related to the previous fungicide history of the crop from which they were sampled (Burnett, 2003). The CSL website, developed with HGCA funding http://cropmonitor.co.uk/ provides an interactive crop-specific forecast of the risk to winter oilseed rape crops from light leaf spot. Impact: the average yield reduction is 1–1.5 t/ha but yield losses of up to 3 t/ha are possible as a result of severe infection on a susceptible variety (Freer et al., 1998). Control: fungicide programmes for the control of light leaf spot do not always guarantee a yield response but omitting them where disease pressure is high can result in large yield losses. The threshold to justify a second spray is when 25% of plants are infected at early stem extension. Non-chemical control: resistant varieties. However, fungicide sprays may still be needed where disease pressure is high (e.g. Scotland, northern and western England). Phoma leaf spot and Phoma stem canker Phoma leaf spot is an important disease in winter rape in England and tight rotations will increase incidence. It survives on debris from the previous crop, airborne spores infect oilseed rape crops in

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http://cropmonitor.co.uk/


autumn and it is spread by rain-splash. If not controlled, infections result in Phoma stem canker in the following summer. A project ‘Effects of geographical location on Phoma stem canker and subsequent yield in oilseed rape crops in the UK’ may explain variation in results for fungicide application. Impact: if left untreated Phoma infections can cause 0.5–0.7 t/ha yield loss. Effects of geographical location on disease and yield of oilseed rape crops in the UK is the subject of a new HGCA project. Control: a wide range of fungicides with different modes of action is approved and sprays such as difenoconazole or flusilazole are applied in autumn, when 10–20% of plants are infected. A second fungicide spray is often applied when there is re-infection by Phoma or Light leaf spot, between December and late February in England. Non-chemical control: rotations. There are no resistant varieties. Fungicides for oilseed rape Fungicides approved for 2006 are shown in Table 7 and usage in 2003/2004 in Tables 7 and 8. Table 7. Fungicides approved for oilseed rape 2006; Review status; Aim re-register UK oilseed rape; Disease; Activity; Usage of fungicides on oilseed rape area 498,155 ha grown in Great Britain 2004 (source CSL Pesticide Usage Survey 2004) Fungicides approved for oilseed rape 2006

Review status Aim re-register UK oilseed rape

Disease Activity Usage 2004 (spray ha)

Azoxystrobin New Annex 1 √ Sclerotinia systemic translaminar & protectant strobilurin

499

Boscalid New pending - Sclerotinia Anilide 138,819 Carbendazim List 1 - (Light leaf spot) benzimidazole 146,411 Carbendazim/flusilazole List 1/List 1 √ / √ Sclerotinia Phoma (canker)

Light leaf spot Benzimidazole/systemic, protective & curative conazole

192,998

Carbendazim/vinclozolin List 1/ List 1 - / - Sclerotinia Light leaf spot Anilide/ protectant dicarboximide Chlorothalonil Annex 1 √ Light leaf spot Phoma

Downy mildew Botrytis protectant chlorophenyl. 1,416

Chlorothalonil/metalaxyl (winter) until 28 Dec 2006

Annex 1/non inclusion

Cyproconazole (winter) List 3B (√ N) Phoma Contact & systemic conazole Difenoconazole List 3B √ Light leaf spot Phoma diphenyl-ethertriazole protectant &

curative 48,012

Famoxadone/flusilazole New Annex 1/ List 1 √ Light leaf spot Phoma strobilurin/ systemic, protective & curative conazole

20,232

Flusilazole List 1 √ Light leaf spot systemic, protective & curative conazole 116,481 Iprodione Annex 1 - Sclerotinia Botrytis protectant dicarboximide with some

eradicant activity Iprodione/thiophanate-methyl

Annex 1/Annex1 - / - Sclerotinia Light leaf spot Phoma Botrytis

protectant dicarboximide with some eradicant activity/

49,834

Mancozeb Annex 1 - Downy mildew dithiocarbamate protectant 1,442 Maneb Annex 1 - dithiocarbamate protectant Metconazole Annex 1 - Sclerotinia Light leaf spot

Phoma conazole 65,474

Prochloraz List 3B - Sclerotinia Light leaf spot Phoma Botrytis

Protectant & eradicant conazole 14,411

Prochloraz/propiconazole List 3B/Annex 1 - / (√ N) Light leaf spot Phoma Systemic conazoles 1,768 Prochloraz/tebuconazole List 3B/List 3B - / ? Sclerotinia Systemic conazoles Propiconazole Annex 1 (√ N) Light leaf spot systemic, curative & protective conazole Prothioconazole (winter) New pending √ Sclerotinia systemic, protective & curative triazole Prothioconazole/tebuconazole (winter)

New pending/List 3B

√ / √ Sclerotinia Light leaf spot Phoma

triazoles

Tebuconazole List 3B not decided Sclerotinia Light leaf spot Phoma PGR

systemic conazole 101,910

Vinclozolin List 1 - Sclerotinia Botrytis protectant dicarboximide - Company request confidentiality; √ yes; (√ N) aim re-register in N Europe; Metalaxyl until 31 Jan 2006 Non inclusion; no longer marketed for oilseed rape but still extant: Carbendazim/iprodione, Carbendazim/prochloraz (winter), Carbendazim/tebuconazol

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There are usually two applications of fungicides in oilseed rape, in autumn and/or in spring. In 2004, 17% of the treated area was specified as for Sclerotinia, Light leaf spot 17% and Phoma 14% (CSL Pesticide Usage Survey). Sulphur was applied to 25,089 ha to correct sulphur deficiency in oilseed rape. Carbendazim and flusilazole, either alone or together in formulation, were used extensively on a large percentage of the rape crop (Table 8) at less than the full label dose rate, and with one or two applications. Boscalid was also widely used. Tebuconazole is also used as a plant growth regulator. 1. The likely impacts of the 91/414/EEC review process on fungicide availability for UK oilseed rape

1.1. Losses So far, the 91/414/EEC review process has had no impact on fungicide availability for UK oilseed rape. 1.2. Impact None. 1.3. Future losses? There is no decision yet on some triazole fungicides, including tebuconazole (List 3B) also used as a plant growth regulator, cyproconazole (List 3B) and prothioconazole (‘new’ active). Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. At the time of writing, no decision has been reached on carbendazim, flusilazole or vinclozolin remaining on List 1. Carbendazim and flusilazole are widely used in oilseed rape (Table 7). The fungicides were supported for use in oilseed rape for Annex 1 inclusion and have UK approvals. There has been no agreement so far between Member States, and the case has gone to the EU Council for these and other List 1 active substances. Commission proposals were that all these actives should be included on Annex 1 for use in oilseed rape although some other crops should not, but decisions will not be made until September 2006. Views of the crop sector have been sought by PSD. The most important of these for oilseed rape is flusilazole, a systemic, protective and curative conazole used alone or in mixture for control of the main oilseed rape diseases. Flusilazole continues to be strongly supported by DuPont. Vinclozolin is seldom used in oilseed rape and if it does not achieve Annex 1 listing other alternatives are available. Light leaf spot (Pyrenopeziza brassicae) Light leaf spot can result in decreased plant populations, seed numbers per plant or decreased thousand seed weights. The severity of infection, however, differs between seasons, regions and individual crops and the disease is more prevalent in Scotland. Impact: the average yield reduction is 1–1.5 t/ha but yield losses of up to 3 t/ha are possible as a result of severe infection on a susceptible variety (Freer et al., 1998). Losses of as much as £40 million/annum have been attributed to light leaf spot, but CSL data show that losses have declined since the 1995 peak.

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Strains of this disease resistant to MBCs (carbendazim, thiophanate-methyl) are common in the UK and these fungicides are ineffective against these strains. Strobilurin fungicides offer little control of Light leaf spot in winter oilseed rape and are not approved for this use, and iprodione and vinclozolin, have limited effect. Several fungicides with different modes of action are approved, but flusilazole and the formulation with carbendazim are very widely used (Table 8). Table 8. Usage of fungicides on oilseed rape area grown 498,155 ha grown in Great Britain in 2003/2004 (Source CSL Pesticide Usage Survey)

Formulation area treated (ha)

Weight of a.s. applied (kg)

Proportion of fungicide-treated

area

Proportion of census area

treated

Average number of applications (where applied)

Average proportion of full

label rate

Carbendazim/flusilazole 192,998 29,608 0.21 0.31 1.24 0.51

Carbendazim 146,411 43,867 0.16 0.26 1.15 0.60

Boscalid 138,819 31,534 0.15 0.28 1.00 0.91

Flusilazole 116,481 12,926 0.12 0.20 1.16 0.55

Tebuconazole 101,910 17,349 0.11 0.19 1.15 0.68

For 10 to 15 years, winter oilseed rape growers have been reliant on triazoles, e.g. tebuconazole. In Scotland, strains of Light leaf spot less sensitive to triazoles make control more difficult. In high-risk areas, robust rates of tebuconazole or flusilazole/carbendazim are currently advised at the first signs of Light leaf spot. The new prothioconazole/tebuconazole is likely to be an alternative, although it is too soon to have a comparison of efficacy. HGCA project 3200 will assess new fungicides and dose rates for the three major diseases of oilseed rape. Phoma leaf spot and Phoma stem canker Phoma leaf spot is an important disease in winter rape in England and tight rotations will increase incidence. If not controlled the infections result in Phoma stem canker in the following summer. Impact: if left untreated Phoma infections can cause 0.5–0.7 t/ha yield loss. A wide range of fungicides with different modes of action is approved and sprays such as difenoconazole or flusilazole are applied in autumn, when 10–20% of plants are infected. A second fungicide spray is often applied when there is re-infection by Phoma or Light leaf spot, between December and late February in England. Famoxadone/flusilazole and carbendazim/flusilazole are approved for Phoma and Light leaf-spot. Therefore triazole fungicides particularly flusilazole and formulations continue to be the main defence against Light leaf spot and Phoma in the near future. The new prothioconazole/ tebuconazole may be the best alternative. Because no satisfactory alternatives to triazoles are available, it is essential that strategies are adopted to ensure they remain effective. The impact of 91/414/EEC if flusilazole fails Annex 1 inclusion: it will be even more important that growers adopt strategies to avoid resistance and for Crop Protection Companies to develop new fungicides with a different mode of action. 2. Specific fungicides or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Fungicides with alternative modes of action are important for resistance strategies. The status of fungicide resistance to oilseed rape in the UK is under review.

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It would be desirable to maintain the following: Seed treatments: Thiram, iprodione. Foliar sprays: Light leaf spot: the use of anti-resistance strategies are very important in prolonging the useful life of fungicides, even once resistance in the pathogen has started to develop. Mixtures or alternations of fungicides with different modes of action in a spray programme are an important defence against the development of fungicide resistance. It is important to keep triazoles, particularly prothioconazole/tebuconazole and flusilazole for Light leaf spot). In 2004, flusilazole and carbendazim/flusilazole, were used extensively, with one or two applications being applied to almost a third of the area grown at lower than label dose rates. Tebuconazole is used as a plant growth regulator as well as for disease control. Protectants Strobilurins and Boscalid; and the new prothioconazole with curative action need to be maintained for Sclerotinia. In France, fungicide resistance has impaired Sclerotinia control in oilseed rape, particularly when using MBC fungicides (carbendazim) alone. The status of fungicide resistance in the UK is not known but it is important to reduce the risk of it developing by using fungicide mixtures and fungicides with different modes of action. Iprodione/thiophanate-methyl (both Annex 1) declining in importance but could be needed if resistance develops. 3. Prospects for alternatives for any foreseen major gaps in fungicide availability

3.1. Alternatives There were no losses in the review, but new fungicides with different modes of action are needed for resistance strategies. Gap Analysis (not shown) for fungicides for the main diseases of oilseed rape: Light leaf spot, Phoma (canker/dark leaf spot), Sclerotinia, Alternaria show that currently there are no gaps – fungicides approved are adequate. Fungicides with alternative modes of action to triazoles are needed for Scotland, where strains of Light leaf spot less sensitive to triazoles are developing. Carbendazim/flusilazole is widely used in oilseed rape for Light leaf spot. If flusilazole fails Annex 1 inclusion, prothioconazole is likely to be used alone and it will be even more important that growers adopt strategies to avoid resistance and for Crop Protection Companies to develop new fungicides with a different mode of action. a. Sclerotinia: protectants boscalid and azoxystrobin do not control the disease. The ‘new’ triazole prothioconazole offers control and is a significant addition to fungicides for Sclerotinia. There is a submission for approval of the new fungicide cyprodinil/fludioxonil for control of Sclerotinia in some higher value crops, but there are no plans for introduction into oilseed rape. b. Plant Growth Regulator trinexapac (Annex 1) may be useful for canopy management of oilseed rape - the company aims to re-register in N Europe for oilseed rape and cereals, and UK cereals. Global fungicide development overall does not appear to have decreased so far (Phillips McDougall, ECPA conference, November 2005).

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REFERENCES

HGCA and Link Projects: HGCA (2005) Oilseed rape – a grower’s guide. HGCA-funded weed research (including LINK projects) 1994-2005 review, C Edwards (February,

2006) HGCA Project 3200 will assess new fungicides and dose rates for the three major diseases of

oilseed rape. HGCA Project 3023: Revised thresholds for cabbage stem flea beetle in winter oilseed rape. HGCA Project 2617 (2002-2006) Sustainable Arable Farming For an Improved Environment

(SAFFIE) HGCA Project Report OS32 (1998) Dormancy and persistence of volunteer oilseed rape HGCA Project Report OS57 (2002) The further development of seed treatments to control cabbage

stem flea beetle and other pests in winter oilseed rape. Sustainable Arable LINK project LK 0965 / HGCA 3035: Integrated management of herbicide

resistance. Sustainable Arable LINK project LK 0953. Stewardship of Neonicotinoid Insecticides. Sclerotinia Decision Guide http://www.hgca.comTopic Sheet No. 85 (2005) Integrated Slug control in winter oilseed rape. Topic Sheet 24 (1999) Dormancy and persistence of volunteer oilseed rape Other references: DAVIES K (2005) Weed management in winter oilseed rape crops. Technical Note TN578, SAC,

Edinburgh, UK. EDMONDS J & CASELEY JC (1997) The role of propyzamide in mangement of herbicide

resistant black-grass in oilseed rape. In: Proceedings 1997 Brighton Crop Protection Conference - Weeds, Brighton, UK, 351 – 357.

FOSTER SP, DENHOLM I & DEVONSHIRE AL (2000) The ups and downs of insecticide resistance in peach-potato aphids (Myzus persicae) in the UK. Crop Protection 19, 873-879.

FREER JBS, GLADDERS P, HARDWICK NV & SUTHERLAND KG (1998) The effect of site, season and cultivar on disease management strategies for winter oilseed rape grown in England and Scotland. In: Proceedings 1998 Brighton Crop Protection Conference – Pests and Diseases, Brighton, UK.

GARTHWAITE DG, THOMAS MR, ANDERSON H & STODDART H (2005) Arable crops in Great Britain 2004. Pesticide Usage Survey Report 202. Central Science Laboratory, Sand Hutton, York, UK.

HEAP I (2006) International survey of herbicide-resistant weeds hhtp://www.weedscience.com JAMES EH, KEMP MS & MOSS SR (1995) Phytotoxicity of trifluoromethyl and methyl

substituted dinitroaniline herbicides on resistant and susceptible populations of black-grass (Alopecurus myosuroides). Pesticide Science 43, 273-277.

JONES N & SIMPSON N (2005) Messages from SAFFIE - modified weed control strategies to enhance biodiversity.

LUTMAN PJW et al., (1991) Research Review OS2 (1991) Weeds in oilseed crops. LUTMAN PJW & FREEMAN S (2002) Population dynamics of arable weeds: seed production

and seed persistence. IACR –Rothamsted, 26-27. LUTMAN PJW, BOWERMAN P, PALMER GM, ANDREWS F & WHYTOCK GP (1995)

Project Report OS15 (1995) Cost-effective weed control in winter oilseed rape. MOSS SR & CLARKE JH (1994) Guidelines for the prevention and control of herbicide-resistant

black-grass (Alopecurus myosuroides Huds.) Crop Protection 13 (3), 230-234. Updated on website http://www.pesticides.gov.uk/rags.asp?id=714

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NIX J (2005) Farm Management Pocketbook 33rd edition 2006. Imperial College, Wye. Andersons Centre, Melton Mowbray, UK.

ORSON JH & HARRIS D (1997) The technical and financial impact of herbicide-resistant black-grass (Alopecurus myosuroides) on individual farm businesses in England. In: Proceedings of the BCPC Conference – Weeds 1997, 3, 1127-1133.

POLLAK R & COLLINGS LV (2003) Kerb (propyzamide), its role in reducing Alopecurus myosuroides seedbanks in arable crops. Aspects of Applied Biology 69, Seedbanks: Determination, Dynamics & Management, 63-67.

POWELL W (2005) Pest management outlook for cereals and oilseeds based on recent and new research. In: Proceedings HGCA Conference, Arable crop protection in the balance: Profit and the environment, 10.1- 10.9.

TURLEY DB, BOATMAN N & McKAY H (2005) Environmental impacts of cereal and oilseed cropping in the UK and assessment of the potential impacts arising from cultivation for liquid biofuel production. Research Review 54, HGCA, London.

TURNER JA, ELCOCK SJ, WALTERS KFA, WRIGHT DM & GLADDERS P (2002) A review of pest and disease problems in winter oilseed rape in England and Wales. In: Proceedings of the BCPC Conference – Pests and Diseases 2002, 2,555-562.

Appendix: common weed names are according to Dony et al. (1986); Latin names Stace (1997) DONY JG, JURY SL & PERRING FH (1986) English Names of Wild Flowers, 2nd edition. The

Botanical Society of the British Isles. STACE C (1997) New Flora of the British Isles 2nd edition. Cambridge University Press,

Cambridge, UK. Appendix: Blue text actives unsupported; pink text Annex 1 doubtful.

ACKNOWLEDGEMENTS

The help and contributions from the following organisations are gratefully acknowledged: Home Grown Cereals Authority (HGCA), The Arable Group (TAG), BBSRC Rothamsted Research, Weed Resistance Action Group, Agricultural Industries Confederation Ltd (AIC), National Farmers Union (NFU), Environment Agency (EA), The Voluntary Initiative, Crop Protection Association (CPA), United Agricultural Products - Europe (UAP), European Crop Protection Association (ECPA) and Crop Protection Companies.

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89

Appendix. Weed Susceptibility to herbicides for Oilseed Rape; Key: S = susceptible; MS = Moderately Susceptible; R = Resistant; MR = Moderately Resistant; Blue text actives unsupported; pink text Annex 1 doubtful. trifluralin clomazone propachlor metazachlor metazachlor metazachlor metazachlor/ quinmerac clopyralid bifenox cyanazine Common name Latin name Pre-plant Pre-weed em Pre-weed em Pre-weed em Pre-weed em Post-weed em Pre-weed em Post-weed em Post weed-em Post weed-em Post weed-em 2.3 L/ha 0.25 L/ha 9.0 L/ha 2.5 L/ha 1.5 L/ha 2.5 L/ha 2.0 L/ha 2.0 L/ha 0.5 L/ha 1.0 L/ha 1.0 L/ha Bindweed black Fallopia convolvulus S MR R MS MS S S Bugloss Anchusa arvensis S S Charlock Sinapis arvensis R R R MR MR S S Chickweed, common Stellaria media S S S S S 4 TL S Cot R S Cleavers Galium aparine R S S MS MR S 2 whorls S 2whorl R Corn marigold Chrysanthemum segetum R S S 2 TL S Corn spurrey Spergula arvensis MS S MS S Crane's-bill, cut-leaved Geranium dissectum S MR Cot MR S MR Deadnettle, henbit Lamium amplexicaule S MS S Dead-nettle, red Lamium purpureum MS S S S S 2 TL S Cot MS S S Fat-hen Chenopodium album S MS MR MS S S Fool's parsley Aethusa cynapium R S S Forget-me-not, field Myosotis arvensis S S 2 TL S MS S Fumitory, common Fumaria officinalis MS R R R R R S? S Gallant -soldier Galinsoga parviflora S Groundsel Senecio vulgaris R S S S S 2 TL S S S Hemp-nettle, common Galeopsis tetrahit S S MR S S Knotgrass Polygonum aviculare S MR R R R R MS S Mayweed, scented Matricaria recutita R R S S S 4 TL S 4 L S R S Mayweed, scentless Tripleurospermum inodorum R R S S S 4 TL S 4 L S R S Nettle, small Urtica urens MS MR S MS S Nightshade, black Solanum nigrum R MS S Orache, common Atriplex patula MS R MR S S Pansy, field Viola arvensis S S MR R MS S S Parsley piert Aphanes arvensis S S S R MR Pennycress, field Thlaspi arvense R R R R R S Persicaria, pale Persicaria lapathifolia S MS MR S Pimpernel, scarlet Anagalis arvensis S R S Pineappleweed Matricaria discoidea R R S S S R S Poppy, common Papaver rhoeas MS R S MS S 2 L MS S Redshank Persicaria maculosa S S R MS MR S Shepherd's-purse Capsella bursa-pastoris R S S S S S MR S Sow-thistle, smooth Sonchus oleraceus R MS MS S S Speedwell, common, field Veronica persica S S S S S 2 TL S 2 L S S Speedwell, ivy-leaved Veronica hederifolia S S S S 2 TL S S Sun spurge Euphorbia helioscopia MS R Thistle, creeping Cirsium arvense R R S Wild radish Raphanus raphanistrum R S R S Annual meadow grass Poa annua S MS S S S 2 L S S Blackgrass Alopecurus myosuroides S S S S 2 L S MS Brome, barren Anisantha sterilis MS MS Wild-oat Avena fatua MS R MR R Vol Potatoes Solanum tuberosum MS


SUGAR BEET Applied research and information technology transfer for sugar beet in the UK is principally the function of the British Beet Research Organisation (BBRO). This organisation is owned jointly by the processors, British Sugar plc and the National Farmers Union. It is funded by a contractual levy paid 50/50 by the growers and British Sugar. The levy fund is currently of the order of £2m / year of which approximately £1.2 - £1.3 million is spent on crop research. Work commissioned by BBRO is carried out by a range of contractors, with Broom's Barn Research Station, an internationally recognised centre of expertise on sugar beet research, regularly undertaking the majority of projects.

Background

Crop area The area of sugar beet was 196,000 ha in 1995 but there has been a continuing reduction – 169,000 ha in 2002, 154,000 ha in 2004 and a decline to approximately 148,000 ha in 2005 (Defra, 2006). All sugar beet is now grown in England, principally in the Eastern counties. The industry is currently going through a major upheaval as a result of recent reform of the EU sugar regime. The full outcome of this is still not known, but prices will be cut drastically and there may be further contraction in the area grown. Economics/ profitability Sugar beet has been regarded as a generally profitable crop with significantly higher returns than combinable arable crops such as wheat (Nix, 2005). However a feature of the industry is the enormous variation in yields per ha with the top 10% of growers achieving more than 75 t/ha and the lowest 10% yielding less than 45 t/ha (average 60 t/ha). With the drastic reduction in prices expected from the reform of the sugar regime, it is predicted that only growers able to achieve average yields of 70 t/ha or more are likely to be viable. There will be restructuring, but the UK sugar beet industry is one of the most efficient in Europe and is well placed to respond to the new economic pressures. The crop is likely to continue to retain its important place in British agriculture, although levels of profitability are anticipated to reduce more in line with those achieved in other arable crops such as cereals and oilseed rape. Rotations Sugar beet would normally be grown in a rotation of not closer than one in three years, usually with winter wheat and other combinable crops. There are, however a very wide range of different rotations and some beet is grown in rotations of one in eight or more. As a spring sown broad-leaved root crop, sugar beet plays a key role as a break crop in rotations that tend to be dominated by cereals, especially winter wheat. The two crops differ in the range of pests, diseases and problem weeds and valuable opportunities are provided in the autumn preceding a sugar beet crop to control difficult grass weeds in particular. Yields of winter wheat are often 20% higher where it is sown after an effective break crop, for example early-lifted sugar beet (May & Champion, 2005).

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Weed Control in Sugar Beet

The following is a brief summary of some of the main aspects of current weed control practice in sugar beet. More detailed information including weed/herbicide susceptibility charts and costs is available from the technical publications of British Sugar plc in conjunction with the British Beet Research Organisation (BBRO) and on the excellent industry website www.uksugarbeet.co.uk. A comprehensive review of the principles of sugar beet weed control is given in the latest Weed Management Handbook (Knott, 2002). Sugar beet is very susceptible to competition from weeds at the early stage of growth from emergence until the crop has eight true leaves. Tall, early-emerging weeds are particularly competitive whilst late-emerging weeds are unlikely to compete with the crop. The weed spectrum tends to be dominated by annual broad-leaved species. There are fourteen commonly occurring broad-leaved weeds identified in the Weed Management Handbook. On mineral soils, knotgrass, black-bindweed and fat-hen tend to be important; whilst on heavier or more organic soils, cleavers, redshank and volunteer oilseed rape are common problems. Annual grass weeds are generally less important, the most common being annual meadow-grass and spring wild-oats. As a component of rotations mainly dominated by winter wheat, herbicide tolerant black-grass can occur and difficult cereal weeds such as cleavers are a common problem. Volunteer potatoes can be a serious problem in rotations that have included this crop. Weed beet (Beta vulgaris) can be a major problem, especially in shorter rotations where there is only a two or three year break between beet crops. Impact: Reduced yields of beet are the critical problem arising from uncontrolled weeds in modern systems. In a recent article (Crops, 2005), a specialist agronomist cited losses of 30%. The British Sugar/BBRO publications cite one tall weed per square metre can reduce crop yield by 10%. High standards of weed control will become even more important as the reform of the sugar regime drives up the minimum yield levels required for viable production. Control: Herbicides are the standard method of weed control in sugar beet. These are commonly applied in a programme of repeat low dose, low volume applications. This comprises a sequence of treatments, each consisting of two or more tank-mixed herbicides (typically three to five including adjuvant). On average, a sequence of four sprays is applied, depending on soil type and weed spectrum. The particular combination of pre-emergence and/or post-emergence herbicides selected depends on the broad-leaved weed spectrum present, and there is a relatively wide range of suitable selective herbicides to choose from (Table 1). Pre-emergence herbicides are generally used to provide some flexibility in the timing and selection of post-emergence treatments. The FAR technique uses a lower dose mixture of herbicides based around phenmedipham, ethofumesate, a residual herbicide (chloridazon or lenacil) and adjuvant oil. The sequence begins as soon as weeds appear and subsequent sprays are applied at weekly intervals. Most annual and perennial grass weeds are controlled pre-drilling with contact herbicides such as glyphosate or the bipyridyls and/or post-emergence with specific selective graminicides. Control of weed beet is achieved by a combination of various methods including tractor hoeing, weed wipers with glyphosate or cutting.

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http://www.uksugarbeet.co.uk/


Use of glyphosate on genetically modified (GM) sugar beet cultivars resistant to the total post-emergence herbicide glyphosate has proved a valuable weed control technique, but is unlikely to be accepted in the UK in the foreseeable future. Cultural Control: As a row crop grown on mainly lighter soils, sugar beet affords the option of inter-row weed control by tractor hoeing. In the past a combination of mechanical hoeing with intra-row band spraying was employed. However this is labour and energy intensive and less cost effective compared to chemical control. Tractor hoeing is now a less common practice except where weed beet and sometimes other pernicious weeds are a particular problem (May, 2005). Herbicides for Sugar Beet Some of the approved herbicides for 2006 and usage of the most important top 17 in 2004 are shown in Table 1. There are currently (June, 2006) 26 approved active substances including glufosinate-ammonium, quizalofop-p-tefuryl, quizalofop-p-ethyl, chlorpropham and quinmerac not listed in Table 1. There are some 32 different beet herbicide products on the market containing one or more of these chemicals, including 5 different chloridazon mixtures and lenacil/triflusulfuron-methyl. Table 1. Sugar beet: Some of the herbicides approved 2006; Review status; Aim re-registration in UK; Usage on 153,896 ha grown in GB in 2004 (Source CSL Pesticide Usage Survey 2004) Some of the herbicides approved 2006

Review status Aim re-register UK sugar beet

Activity Usage sprayed ha

2004 Top 17 by area sprayed Total weeds Diquat/paraquat Annex1/Annex 1 √ / √ contact bipyridyls 2,134 Glyphosate Annex 1 √ translocated phosphonic acid 71,039 Grass weeds Cycloxydim List 3A - translocated oxime 11,484 Fluazifop-p-butyl List 3A √ translocated phenoxpropionic 6,279 Propaquizafop List 3A √ foliar phenoxy alkanoic acid 6,804 Tepraloxydim New Annex 1 - translocated oxime 17,356 Broad-leaved weeds (and some grasses) Chloridazon List 3A - residual pyridazinone 75,755 Clopyralid Annex 1 - picolinic acid 103.818 Ethofumesate Annex 1 √ benzofuran 118,085 Lenacil List 3B √ uracil 66,692 Metamitron List 3B √ carbamate 236,666 Phenmedipham Annex 1 √ carbamate 208,379 Phenmedipham/ethofumesate Annex 1/Annex 1 √ / √ carbamate/benzofuran 94,413 Phenmedipham/desmedipham Annex 1/Annex 1 √ / √ contact carbamate 57,687 Phenmedipham/ethofumesate/desmedipham Annex 1 √ / √ / √ contact carbamate 55,060 Triflusulfuron-methyl List 3A √ sulfonylurea 87,474 Trifluralin List 2 - dinitroaniline 17,904 - Company request confidentiality; √ yes In 2004, the sugar beet crop received five herbicide sprays on average, reflecting wide use of the FAR system. As shown in Table 1, the leading products were metamitron, phenmedipham, ethofumesate, clopyralid, phenmedipham/ethofumesate mixtures and triflusulfuron-methyl. There was also very considerable usage of chloridazon, and phenmedipham/desmedipham mixtures. Glyphosate was used pre-sowing on 46% of the crop area. Most herbicides were used for general weed control (47%) or broad-leaved weed control (27%). The CSL survey records that applications for specific weed problems such as volunteer potatoes, cleavers, fat-hen and grasses account for less than 10% of usage in each case. However these are still critically important treatments in situations where such weeds need controlling.

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1. The likely impact of the 91/414/EEC review process on herbicide availability for UK sugar beet

Sugar beet yields suffer severely from weed competition and good weed control will become even more critical for the industry in the future as the reform of the EU Sugar regime means that only those growers achieving higher yields of 70 t/ha plus are likely to survive, as indicated earlier. Losses No sugar beet herbicides have been lost as a result of the review process so far. The industry currently has a wide selection of different active substances and formulations to select from and there are no important gaps in the spectrum of weed control required. Future losses With the notable exceptions of chloridazon and triflusulfuron-methyl the majority of the most important herbicides is now included on Annex 1 with most companies confirming support for re-registration. Although the sugar beet area will decline in Europe as a result of the reformed sugar regime, it will still remain a major crop in northern Europe and it would appear likely that all the main herbicides will be re-registered for sugar beet with opportunities for mutual recognition across the zone. At re-registration stage there will be restrictions on dose-rates and timings on two of the key beet herbicides, ethofumesate and metamitron that could compromise herbicide efficacy. There are precedents in Denmark, for dose-rate restrictions. It is likely that ethofumesate will be restricted to 1000g a.s./ha for the sugar beet crop and can only be applied to the field once in three years - this could affect other crops grown in the same rotation (there are SOLAs for several crops including onions, where 1,393 ha were sprayed with ethofumesate in 2003). Metamitron dose rate will be restricted to 3,500g a.s./ha/per sugar beet crop. It is however difficult to speculate on the impact of such potential restrictions at this stage. A reversion to the technique of intra-row band spraying with inter-row tillage might be possible in some circumstances. Trifluralin (List 2) is probably the one substance least likely to achieve Annex 1 listing and the implications of this potential loss are described below. 2. Specific herbicides or herbicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties As has been pointed out previously, the loss of any herbicide is highly undesirable. This is because even if it has a similar weed control spectrum to others, any loss, particularly of a substance with a different mode of action, increases the resistance selection pressure on the remaining herbicides. The crucially important herbicides for sugar beet are clearly indicated in Table 1. For broad-leaved selective weed control ethofumesate, metamitron, phenmedipham and chloridazon are all critically important. Lenacil is used on a smaller scale than the others but is a

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particularly strong agent against black-bindweed and brassicas. It has a different mode of action and is therefore important to minimise the risk of herbicide resistance development. Lenacil is also suited for use on heavier soils where cleavers thrive. Glyphosate and the bipyridyls are the most important herbicides for pre-drilling and pre-emergence total weed control. They play a critical role in controlling the grass weed legacy of preceding cereal crops, including resistant black-grass. Glyphosate is also very important as the only herbicide for control of weed beet (using weed wipers) and its importance is likely to increase commensurate with a higher incidence of herbicide resistant black-grass and wild-oats. Other key more target specific herbicides are triflusulfuron-methyl for control of cleavers, clopyralid for volunteer potatoes and thistles and the 'fop' and 'dim' selective grass weed herbicides of which propaquizafop and cycloxydim are the most important. However, tepraloxydim is reported as an increasingly popular choice particularly as it has some activity against 'fop/dim' resistant black-grass, when applied to small plants that are actively growing (M Lainsbury, pers. comm.). Trifluralin rarely receives a mention in any of the literature on weed control in beet crops, although the CSL data records a use on nearly 18,000 sprayed ha in 2004. Grass weeds in sugar beet can normally be well controlled by glyphosate in the autumn and the range of selective graminicides. Ethofumesate plus metamitron will give control of black-grass and wild-oats (including herbicide resistant strains) whilst these weeds are small. The value of trifluralin is more important in other crops for the management of herbicide resistant grass weeds, especially resistant black-grass. The latter does normally occur in sugar beet crops but the opportunities for control by autumn cultivation and the use of total herbicides, plus the useful grass weed activity of ethofumesate indicates its loss would have less impact than for other crops in the rotation. 3. Prospects for alternatives for any foreseen major gaps in herbicide availability There are no foreseen major gaps for herbicide availability in sugar beet at the present time. Whilst this is the case there is some concern in the industry that there are no novel sugar beet herbicides on the near horizon. Many agrochemical companies do not include sugar beet in their primary screens for new pesticides. Development of a new selective herbicide depends on the chance of a molecule selective to a major world crop such as cotton also being suitable for sugar beet. The likelihood of this happening is declining as more resource is concentrated by such global companies on the use of genetically modified herbicide resistant crops for weed control. There is the possibility of easier access to herbicides approved for sugar beet in other EU Member States in the same climatic zone through Mutual Recognition. For example the isomer s-metolachlor (new Annex 1), approved in other Member States for use in sugar beet and maize, but metolachlor is not a new active – it was reported in 1974. Dimethenamid-p (new Annex 1), approved in the Netherlands and Belgium could also be useful. Dimethenamid is also an old active, the isomer is new.

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Pest Control in Sugar Beet

The most important pests of sugar beet controlled by pesticides are green aphids, a soil complex of springtails, symphylids and millipedes and free-living nematodes that cause Docking disorder. In some situations or years leatherjackets, wireworms and spider mites may cause serious damage. Only these pests are briefly described in this section. Full details of all pests of significance in sugar beet are described in the UK Sugar Beet website: www.uksugarbeet.co.uk and can be supplemented with fuller reference works such as Crop Pests in the UK (Gratwick, 1992). Springtails, symphylids and millipedes These pests are most damaging on organic and silty soils. They usually occur together in mixed populations. Impact: Feeding damages seedling roots and the emerging young shoots up to the 2-leaf stage. In high infestation situations crop stands can be drastically reduced. Control: with seed treatments imidacloprid or tefluthrin. Tefluthrin is the better product where populations are high but it does not control beet foliage pests. A new and very effective seed treatment, clothianidin/beta-cyfluthrin was introduced in 2005. Cultural control: Plant debris and organic matter in the soil can diminish crop damage, as can the avoidance of organic or heavy silty soils. Green aphids The two most important aphids in sugar beet are the peach potato aphid (Myzus persicae) and the potato aphid (Macrosiphum euphorbiae). Both species appear very similar in the field, although M. persicae is the more important of the two. Impact: Direct feeding damage rarely occurs but these two species are very efficient vectors of the viruses that cause virus yellows, namely beet yellow virus (BYV), beet mild yellowing virus (BMYV) and/or beet chlorosis virus (BChV). Further information on virus yellows is given in the section on diseases. Control: The standard method of control for the majority of the sugar beet crop is seed treatment with the neonicotinoid seed treatment imidacloprid. This gives control of aphids for up to 10 weeks after sowing and hence reduces primary infection of virus yellows. Alternatives are to use foliar sprays of pirimicarb, triazamate or pyrethroid but all these insecticides have problems with resistant populations and pyrethroids give inadequate foliar cover. Triazamate has been withdrawn by the company and is not supported in the EC review. Control after the 16-leaf stage is not required. Cultural control: Plant breeding work is ongoing to select resistant cultivars to virus yellows. However this is intrinsically difficult because of the need for multiple resistance to all three virus types. Docking Disorder/Free-living nematodes. (Trichodorus, Paratrichodorus spp. or Longidorus spp.) Docking Disorder is characterised by irregularly stunted plants, frequently with fangy roots. It is caused by stubby-root or needle nematodes, and is confined to sandy or sandy peat soils. Approximately 15% of the sugar beet growing area in the UK is at risk. Impact: Feeding of nematodes on beet seedlings injures the roots, can decrease growth rate and creates large variation in plant size. If a large proportion of plants is affected especially in wet years, yield losses can be as high as 30%. Control: Preventative treatment with granular nematicides such as oxamyl is essential in sandy soils where there is a history of Docking disorder damage. Unlike the potato crop there is little or no contention regarding the relative efficacy of the different nematicides in comparison with aldicarb in sugar beet and no published evidence of any difference between oxamyl and aldicarb for this

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specific use. This may be because the critical period for control is at an early stage of beet growth (A Dewar, pers. comm.). Cultural control: There are no real alternatives to chemical control apart from avoiding susceptible sandy soils. Wireworms (Agriotes spp.) Wireworms are an uncommon pest of sugar beet and do not affect more than 5% of the sugar beet cropping area. They are associated with rotations containing grassland but there is some evidence of increasing incidence in non-grass rotations, possibly linked with grass weeds in cereals (the so called arable wireworm). Impact: The most serious damage is caused to young seedlings and plants can be killed completely by wireworms feeding on the hypocotyls. Control: The soil applied carbamate insecticides carbosulfan and oxamyl give some limited control of wireworms, as does the pyrethroid component in the new seed treatment clothianidin/ beta-cyfluthrin. It is very probable that tefluthrin seed treatment also has a degree of activity for control of this pest although there is no label claim (A Dewar, pers. comm.). Cultural control: There are no fully effective alternatives to the use of insecticides. Even the conventional method of avoiding close rotations with grassland is of little value with the low occurrence of grass farming in the Eastern counties and the increasing incidence of the arable wireworm. Leatherjackets (Tipula spp.) Leatherjackets are the larvae of crane flies. They usually feed on the surface of the soil, severing the hypocotyls of seedlings. They are generally a minor pest although sporadic outbreaks, which can be quite serious, do occur in some years. Impact: Severe infestation kills seedlings and causes bare patches in fields that can affect yield. Control: There is only one approved insecticide, chlorpyrifos, that is recommended as a post-emergence spray as soon as leatherjacket damage occurs. Some secondary control is provided with methiocarb granules applied for slug control. Leatherjackets have been identified by British Sugar in the PSD Minor Use Network ‘gap analysis' as a pest with potential problems of control because of lack of any alternative to chlorpyrifos. Cultural control: There is no reliable effective alternative to insecticides, although cultivation may help decrease leatherjacket populations. Spider mites (Tetranychus urticae) Two-spotted spider mites are associated with hot dry conditions and are a much more common and serious problem in Spain and France. In the UK incidence is very sporadic with a significant outbreak not usually more than 1 year in 10. The worst affected areas are crops on unirrigated lighter soils and especially on headlands, which is where the spider mites overwinter. Impact: Feeding damage on leaves causes yellowing and eventually these leaves fall off. This can have a serious effect on yield. It is possible the similarity of spider mite damage and virus yellows may mean previous incidence and impact of the disease may have been underestimated. Control: There are currently no recommended acaricides for use on sugar beet in the UK. British Sugar have identified spider mites as a 'minor use gap'. Cultural control: There are substantial differences in variety sensitivity to spider mites that may have a part to play in the development of any future integrated control strategy. Insecticides and nematicides for sugar beet Details of insecticides, nematicides and the minor use of molluscicides are given in Table 2. Sugar beet crops received on average much less than one insecticide spray in 2004. Most foliar sprays are made for the control of the aphid vectors of sugar beet virus yellows. Pirimicarb was the

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single most important foliar insecticide for aphid control but was used on only 8% of the total sugar beet area. Triazamate was also a leading aphicide in 2004 (4% of area) but was withdrawn by the manufacturer in 2005, with a grower use-up period until 4 January 2007. Aldicarb was the leading nematicide granule used for Docking disorder but the CSL survey for 2004 cites its use on only 4% of the sugar beet area. Oxamyl applied as a granule for the same target was used on 3% of the area grown. The latter is likely to increase following the revocation of the aldicarb approval in 2004 but will still be confined to the relatively small area of soils where Docking disorder is prevalent. Table 2. Sugar beet: Insecticides, nematicides and molluscicides approved 2006; Review status; Aim re-registration for UK sugar beet; Usage on 153,896 ha grown in GB 2004 (spray ha) (Source CSL Pesticide Usage Survey 2004) Insecticides, nematicides and molluscicides 2006


sugar beet

Pest Activity Usage 2004

spray ha Insecticides Chlorpyrifos Annex1 - leatherjackets organophosphate Cypermethrin Annex 1 √ cutworms/caterpillars pyrethroid 4,560 Deltamethrin Annex 1 √ flea beetles, caterpillars pyrethroid 335 Dimethoate List 2 - leaf miners organophosphate 851 Lambda-cyhalothrin Annex 1 √ flea beetles, leaf miners pyrethroid 5,353 Lambda-cyhalothrin/pirimicarb Annex 1

/Annex 1 √ / √ flea beetles, leaf miners, green

and black aphids pyrethroid/carbamate

Pirimicarb Annex 1 √ green and black aphids carbamate 13,443 Triazamate # Not

supported aphids carbamoyl triazole

Zeta - cypermethrin List 3A √ cutworms, caterpillars pyrethroid Nematicide & insecticides Benfuracarb List 2 √ Docking disorder vectors, leaf

miners, millipedes, pigmy beetle, springtails, symphylids

carbamate

Carbosulfan List 2 √ Docking disorder vectors, aphids, flea beetle, mangold fly, millipedes, pigmy mangold beetle, springtails, symphylids and wireworms

carbamate

Oxamyl Annex 1 √ Docking disorder vectors, aphids, marigold fly, millipedes, pygmy beetles

carbamate

Molluscicides Metaldehyde List 3A ? slugs carbamate 1,319 Methiocarb List 2 not decided/(√ N) slugs carbamate 551 # no longer marketed blue text Approvals will be revoked. Use-up date by 4 January 2007; - Company request confidentiality; √ yes; (√ N) aim re-register in N Europe Seed Treatments Seed treatments dominate the use of insecticides in sugar beet. This is primarily due to the highly effective use of imidacloprid applied in this way for the control of the green aphid vectors of virus yellows and hence of virus yellows as a disease. It also gives control of the common sugar beet soil pests, plus activity against wireworms and leatherjackets. In 2004, imidacloprid seed treatment was applied to some 75% of the sugar beet grown. Tefluthrin as a seed treatment for the soil pest complex was used on a further 4-5.5% (British Sugar figures are lower than those of CSL) of the area grown (Table 3). All sugar beet seed has a standard treatment of thiram and hymexazol (see section on diseases).

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Table 3. Sugar beet: Seed treatments approved 2006; Review status; Aim re-registration UK sugar beet; Activity and usage on 153,896 ha grown in GB 2004 (treated ha) (Source CSL Pesticide Usage Survey 2004)

Approval in UK 2006 Review status Aim re-registration UK sugar

beet

Disease/pest Activity Usage 2004

treated ha

Fungicides Hymexazol List 3B √ black leg isoxazole all seed Thiram Annex 1 √ Phoma dithiocarbamate all seed Insecticides Clothianidin/beta-cyfluthrin Annex 1/Annex 1 √ / √ aphid vectors of beet virus

yellows, symphylids, springtails, millipedes, wireworms, leatherjackets, pygmy beetle, leaf miners and flea beetles

neonicotinoid/pyrethroid

Imidacloprid List 3 A not decided aphid vectors of beet virus yellows and soil pests. not wireworms and leatherjackets

neonicotinoid 114,948

Tefluthrin List 3B √ pygmy beetle, springtails, symphylids, millipedes,

pyrethroid 8,537

- Company request confidentiality; √ yes 1. The likely impacts of the 91/414/EEC review process on the insecticide and nematicide availability for UK sugar beet

Losses The two widely used sugar beet pesticides that have been affected by the Review process in this sector are the nematicide aldicarb and the selective aphicide, triazamate. A decision not to include aldicarb in Annex 1 was made in March 2003. It could only be used until the end of 2007 in crops where there was a derogation for an ‘Essential Use’. No Essential Use derogation was requested for UK sugar beet and in September 2003 UK approvals for sugar beet were revoked. There was a grower use-up period until September 2004, so 2005 was the first year the product was unavailable for actual use. Triazamate was withdrawn by the manufacturers in 2005, but was still available for the 2006 season under the use-up period arrangements expiring in January 2007. Impacts Loss of aldicarb

• In the relatively small area of infected soils requiring nematicide granular treatment for the control of Docking disorder, aldicarb has been replaced by the alternative granular nematicides oxamyl, and to a lesser extent, benfuracarb and carbosulfan. These chemicals have a comparable degree of activity against the free-living nematodes attacking sugar beet, and no adverse impacts of aldicarb loss have been evident as far as Docking disorder control is concerned (A Dewar, pers. comm.).

• There has been an increase in pesticide treatment costs for growers previously using aldicarb

who did not use imidacloprid seed treatment for aphid control. This is because the replacement oxamyl gives a shorter period of early aphid control (about 3 - 4 weeks, up to

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about the 2-leaf stage) compared to the 6 - 8 weeks control achieved with aldicarb. With aldicarb only one subsequent foliar spray of an aphicide would be necessary in a normal year. With oxamyl a similar period of protection against aphid attack and virus control could require two applications of foliar insecticides. However this impact would be of minor significance in the context of the small area concerned (< 10% sprayed with aphicides in 2004) and the main method of aphid control now is with neonicotinoid seed treatments, on some 74% of crops treated in 2005 (Dewar et al., 2005). These treatments give up to 10 weeks protection from aphids and, unlike the foliar aphicides, at the present time they control M. persicae populations resistant to one or more of the known resistant mechanisms.

• It is considered only a matter of time before the development of M. persicae populations that

are resistant to neonicotinoid seed treatments. The withdrawal of aldicarb means it will not be possible to revert to this previous method of control which was widely used in the past. The only alternative insecticides for the control of aphids are now pirimicarb and pyrethroids/pirimicarb mixtures but both can give unreliable control because of insecticide resistance (Dewar, 2006). MACE resistance to dimethyl carbamates pirimicarb and triazamate is now widely occuring, but aldicarb controls these resistant aphid, thus the loss of aldicarb has compromised resistance strategy options for the control of MACE as well as low-level esterase (R1) resistant M. persicae (S Foster, pers. comm.).

Loss of triazamate

• This carbamate foliar insecticide is still available in 2006 so the impact of withdrawal can only be assessed subjectively. However the technical profile of triazamate is almost identical to that of pirimicarb although triazamate has the advantage of longer persistence (reflected in a higher single treatment cost/ha.). Both pirimicarb and triazamate are subject to the same M. persicae resistance mechanisms, especially MACE. With such similar characteristics it can be expected that pirimicarb will be substituted for triazamate and there will be very little impact in this particular crop.

2. Specific insecticide or insecticide / nematicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

The sugar beet industry can ill-afford to lose any of the very limited range of active substances listed in Table 2. With the widespread resistance to pirimicarb and pyrethroids and the potential threat of future resistance to imidacloprid and other new neonicotenoid seed treatments there is strong need for new active substances with different modes of action. Unfortunately the novel azomethine aphicide pymetrozine, recently approved for potatoes, has poor activity when used in sugar beet as it is deactivated by the metabolism of this particular crop species. It will be desirable to retain all the existing foliar insecticides in Table 2. With the lack of any alternative to chlorpyrifos for leatherjacket control, the retention of this organophosphate is essential. All the granular soil applied nematicides/insecticides are carbamates with a similar spectrum of activity although only oxamyl is approved for early aphid control and therefore will be the most important to retain. It is absolutely crucial to maintain approvals for the neonicotinoid and neonicotinoid/pyrethroid based seed treatment products, imidacloprid and clothianidin/beta-cyfluthrin.

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It is probably desirable to retain tefluthrin seed treatment for that sector of the market that requires a high standard of soil pest complex control but prefers to control aphids with foliar sprays as and when necessary, rather than use neonicotinoid based seed treatments as a prophylactic. Although slugs are normally a very minor problem, it will be desirable to maintain at least one molluscicide. Methiocarb would probably be the preferred option because of its secondary activity against leatherjackets. 3. Prospects for alternatives for any foreseen major gaps in insecticide / nematicide availability

There are currently no foreseen major gaps in the insecticide/nematicide availability for the UK sugar beet crop which have resulted from the 91/414 EEC review process. Minor use gaps, such as acaricides, have been identified in the ongoing project co-ordinated by the PSD Minor Use Network but none of these are directly attributable to the review process to date. There is an expectation that a newseed treatment thiamethoxam/tefluthrin (from Syngenta) will be approved for use in beet in 2006 and introduced in 2007. Thiomethoxam is now on Annex 1. The area of major concern is the lack of any insecticides with novel chemistry that could be used to combat aphid vectors of virus yellows, because at some stage in the future they are expected to develop resistance to the neonicotinoid seed treatment. With the high incidence of aphid populations already resistant to carbamate, organophosphate and pyrethroid insecticides the industry is dangerously reliant on this one area of chemistry to combat a virus disease complex that can be devastating. It has been noted elsewhere in studies on other crops that global insecticide development overall appears to have slowed down. This together with the imminent contraction of the sugar beet industry in the UK and the rest of Europe does not auger well for the development of new sugar beet insecticides.

Disease control in sugar beet

The following is a brief overview of the important diseases of sugar beet in which pesticides have a role to control. A fuller coverage of all significant diseases is given in the UK Sugar Beet website, www.uksugarbeet.co.uk. Blackleg There are three agents of this disease that attack germinating seeds and young seedlings. Seed-borne blackleg is caused by Phoma betae. Soil-borne blackleg is the result of infection with either Aphanomyces cochlioides or, less importantly, Pythium spp., which are widespread in sugar beet soils. Impact: Germinating seeds may be killed below ground or the young seedlings may 'damp off' soon after they emerge. This could lead to thin stands below the optimum plant population. The incidence of seed-borne blackleg is probably now rare and seed treatment may be unnecessary, although the standard thiram seed treatment provides a relatively low cost insurance (M Asher, pers.

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comm.). In contrast, soil-borne blackleg is more important especially for late sown beet under warmer soil conditions. Control: It is standard practice in the UK for all seed to be treated with two fungicides: thiram for Phoma control and hymexazol for soil-borne blackleg. Cultural control: There are no proven alternatives to chemical control at the present, but with the probable very low incidence of Phoma the development of a routine seed test could be a future option to minimise the use of thiram. Soil-borne blackleg is less prevalent under cooler soil conditions from earlier sowing (now being encouraged) but this is not always practicable. Downy mildew (Peronospora farinosa.) This disease occurs only sporadically. When severe attacks occur early in the season they are normally traceable to infection in over-wintering plants. Beet plants growing at cleaner-loader or clamp sites and in set-aside following a beet crop are the main sources of infection Impact: Infection at critical times can reduce yields and root juice purity (Scopes & Ledieu, 1979), but infections rarely reach levels of economic significance (Byford, 1996 cited by Asher & Ober, 2005). Control: There are no approved fungicides at present, although there are certainly fungicides available that could be registered if the disease became more important. Current control depends on good crop hygiene to prevent the development of over-wintering beet host plants. There is probably a reasonable level of resistance in common beet varieties otherwise the disease would be more important. This is likely to be a selection factor in breeding new varieties. However, specific testing for downy mildew is no longer carried out by the National Institute of Agricultural Botany. (NIAB). Virus yellows This is the single most important disease of sugar beet. As described in the Pest Control section, it is transmitted mainly by green aphid vectors especially Myzus persicae and comprises a complex of beet yellows virus (BYV), beet mild yellowing virus (BMYV) and / or beet chlorosis virus. (BChV). The sources of the virus vary according to the types. They are mostly from over-wintering beet or beet related plants; in the case of BMYV, hosts include many common weeds. The level of infection risks from virus yellows varies according to a number of factors. These include the severity of the preceding winter and the number and size of local aphid populations over wintering on host plants such as winter rape and vegetable brassicae. Viruses are transmitted to young beet plants in spring/early summer by winged aphids with the spread within the crop depending on the number of incoming aphids and the movement of winged and wingless aphids between plants. Impact: Early infection can decrease yield by 40 - 50 % and nearly all the sugar beet area is subject to infection risk. Control: As described in the pest section, control of virus yellows is now very heavily dependent on seed treatment with imidacloprid. This is a highly efficacious method, killing aphids up to 10 weeks after sowing and preventing secondary infection of the two most important viruses, BMYV and BChV. Yield improvements of up to 28% have been obtained in a four year evaluation programme and the product has no effect on beneficial non-target organisms. Similar results have been obtained with a new seed treatment clothianidin/beta-cyfluthrin introduced in 2005 (Dewar et al., 2005). An alternative control method is to use post-emergence insecticide sprays of pirimicarb alone or in combination with a pyrethroid, but these have become unreliable due to a high incidence of green aphid insecticide resistant populations. Cultural control: There are no complete alternatives to chemical control but measures aimed at the destruction of the over-wintering sources of the BYV and BChV from beet in clamps, cleaner-loader sites and on set-aside land will effectively reduce the level of virus available for vector transmission in the spring. Little can be done about BMYV infection sources as this virus over-winters on numerous weed species and hence this virus is more widespread.

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Powdery mildew (Erysiphe betae) This disease over-winters on Beta species, especially the coastal sea beet Beta maritimae and spreads by airborne spores inland onto the sugar beet crop. It is the foliar fungal disease that is most widespread and severe in sugar beet. Severity and occurrence of attack varies, with survival being reduced by cold winters. Varieties differ in susceptibility with new Rhizomania resistant cultivars having low levels of resistance to powdery mildew. Impact: Powdery mildew infection in late summer can reduce yields by up to 15% but this will depend on infection pressure. Yield responses in recent evaluation trials with triazole fungicides gave on average 13.8 % increase in yield in two severely infected sites and 5% in trials with low infection (Asher & Ober, 2005). Control: Powdery mildew is controlled by foliar applications of fungicides. Until 1997 sulphur was used almost exclusively, but this has now largely been replaced with triazoles and several new fungicides including a strobilurin/triazole combination. Improved yield responses with the newer fungicides are, at least in part, associated with enhanced green leaf retention in the autumn. Rust (Uromyces beticola) and Ramularia leaf spot (R. beticola) Both these foliar disease can be widespread but rarely reach levels of economic significance. Most common beet varieties have had reasonable levels of resistance, but this is changing with the introduction of new Rhizomania resistant cultivars, which so far have relatively low levels of rust resistance. Control can be achieved with triazole fungicides used for mildew control and this may become more important if new cultivars continue to be introduced with low levels of genetic resistance. Cercospora leaf spot (Cercospora beticola) This is a major disease in warmer climates. Although it is seldom seen in the UK the predicted change in climate to hotter drier summers as a result of global warming could increase disease risk in the UK. A number of effective fungicides are approved in the Netherlands and France. Fungicides for sugar beet The foliar fungicides currently approved are given in Table 4, seed treatment fungicides in Table 3. Table 4. Sugar beet: Fungicides approved 2006; Review status; Aim re-registration UK sugar beet; Usage on 153,896 ha grown in GB 2004 (spray ha) (Source CSL Pesticide Usage Survey 2004) Fungicide approved 2006 Review status Aim re-

registration UK sugar beet

Disease Activity Usage 2004

spray ha Cyproconazole List 3B (√ N) powdery mildew, rust &

Ramularia conazole 25,494

Difenoconazole/fenpropidin List 3B/List 3A √ / √ powdery mildew, rust & Ramularia

conazole/morpholine (new 2005)

Flusilazole/carbendazim List 1/List 1 √ / - powdery mildew, rust & Ramularia

conazole/benzimidazole 22,331

Flusilazole List 1 √ powdery mildew, rust & Ramularia

conazole 17,523

Propiconazole Annex 1 (√ N) powdery mildew, rust & Ramularia

conazole

Sulphur Commodity List 4H √ powdery mildew inorganic 5,542 Triadimenol # List 3A x powdery mildew, rust triazole Quinoxyfen Annex 1 - powdery mildew quinoline 8,814 Pyraclostrobin/epoxiconazole New Annex 1/List 3A - / - powdery mildew, rust &

Ramularia strobilurin/conazole 3,108

√ Yes; x No; (√ N) aim re-register in N Europe; - Company request confidentiality; Red text UK approval revoked (only sold in mixtures for cereals) # no longer marketed, use-up date Dec. 2008

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In 2004 sugar beet crops received on average a single fungicide spray application and as has been standard practice for some time, all seed was treated with thiram and hymexazol. Cyproconazole was the most important fungicide, being used on 16% of the sugar beet crop, with flusilazole/carbendazin having only a slightly smaller share at 14%. The CSL survey information indicated that over 50% of sprays were applied for general diseases control (powdery mildew, rust and Ramularia control), but the most important target would almost certainly have been mildew control in most cases. 1. The likely impacts of the 91/414/EEC review process on fungicide availability for UK sugar beet

Losses Industry specialists consider there have been no fungicide losses of any significance so far in the review process. Triadimenol is only sold by Bayer and the approval expires in Jan 2007. The major potential impact from the loss of aldicarb for controlling virus yellows disease vectors is covered in the section on pest control. Future losses As stated in other sections, it is difficult to predict the likely impact of the ongoing review process on fungicide availability for the sugar beet industry as it is unknown if substances still under review (Tables 3 & 4) will achieve Annex 1 listing. It is also unknown whether those fungicides on Annex 1 will be re-registered in the UK or N.Europe. There are two fungicides remaining in List 1 of the Review that are important for sugar beet (Table 4) - carbendazim and flusilazole that were supported for sugar beet for Annex 1 inclusion and have UK approvals. The Commission proposals are that these actives should be included on Annex 1 for use in sugar beet although some other crops should not, but decisions have not been made yet (June 2006). Flusilazole continues to be strongly supported by DuPont. Although not a direct result of the review process there are some health and safety and disposal issues regarding the application to seed of the seed treatment thiram that might affect future availability. However the probably low occurrence of the one specific seed-borne disease that is the target of thiram, indicates such a development would have little impact. A positive impact of the likely revision of the 91/414 EEC review to allow for Mutual Recognition would be to facilitate the registration in the UK of Cercospora leaf spot fungicides should this disease become more prevalent, as it is in the Netherlands. 2. Specific fungicide or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

The one major foliar disease of sugar beet, powdery mildew, requires a range of fungicides with different modes of action to minimise the risk of resistance development.

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It is crucial to retain the triazoles of which cyproconazole and flusilazole are the most important. The newly introduced formulated mixture of flusilazole/fenpropidine (Spyrale) is claimed to have considerably higher efficacy against powdery mildew and rust than other products and has the advantage of a morpholine component from the resistance strategy perspective. Other substances with different modes of action should be retained are the quinoline quinoxyfen and especially sulphur, which until 1997 was the principal fungicide for mildew control. There is no known occurrence of powdery mildew resistance to sulphur so it could be important if there was any future requirement to manage fungicide resistance to this disease. The seed treatment for soil-borne blackleg control with hymexazol is critically important. Before its introduction blackleg damage occurred in approximately one third of sugar beet soils. The causal agents together occur on c. 45% of such soils. Moreover there is no alternative reliable method of control. It will be desirable to retain thiram but this is considered very much less important for reasons explained earlier. 3. Prospects for alternatives for any foreseen major groups in fungicide availability

No foreseen major gaps were identified in this study. This is considered likely to remain the case for the foliar diseases because fungicides developed for the main wheat diseases such as mildew and rust are also likely to be suitable for sugar beet. There is less concern about the potential for foliar disease resistance development to modern fungicides compared to cereals. This is because, as a solely spring-sown crop in north Europe, there is no 'green bridge' for the survival of resistant populations. There is no known reason why hymexazol should become unavailable as a result of the review process. However there is considerable concern that this is the only available substance for the control of a very important disease, the lack of any reliable alternative control method and no indications or any new substances or development to take its place. As a disease favoured by warmer soil conditions, the expectation of climate changes and milder early springs may increase the importance of this pathogen.

REFERENCES UK Sugar Beet website. www.uksugarbeet.co.ukCROPS, 11 March (2006) t weed control essential’, pp 20-23. Reed Business Information,

Sutton, UK. DEWAR AM, HAYLOCK LA, GARNER BH, SANDS RJN & PILBROW J (2005) Neonicotinoid

seed treatments - the panacea for most pest problems in sugar beet. Aspects of Applied Biology 76, Production and Protection of Sugar Beet and Potatoes, 3 – 12.

FOSTER SP (2005) Insect resistance in the UK: the current situation. Aspects of Applied Biology 76, Production and Protection of Sugar Beet and Potatoes, 181-182.

GARTHWAITE DG, THOMAS MR, ANDERSON H & STODDARD H (2004) Arable Crops in Great Britain. Pesticide Usage Survey Report 202. Central Science Laboratory, Sand Hutton, York, UK.

GRATWICK M (1992) Crop Pests in the UK. Ed. M Gratwick. Chapman & Hall, London, UK.

‘Bee

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KNOTT CM (2002) Weed control in arable and field vegetable crops. In: BCPC Weed Management Handbook, 359 - 398. Ed. RL Naylor. Blackwell ScienceLtd., Oxford, UK.

MAY MJ & CHAMPION GT (2005) Options for further improving the environmental impact of sugar beet crops. Aspects of Applied Biology 75, Production and Protection of Sugar Beet and Potatoes, 63-69.

NIX J (2005) Farm Management Pocketbook 33rd edition 2006. Imperial College Wye, Andersons Centre, Melton Mowbray, UK.

SCOPES N, LEDIEU (1989) Pest and Disease Control Handbook 3rd edition. BCPC, Thornton Heath, UK.

ACKNOWLEDGEMENTS The help and contributions from Dr Alan Dewar, Dr Mike Asher, Mike May and Dr John Pidgeon of the Broom's Barn Research Station, Phillip Ecclestone of British Sugar plc, Dr Steve Foster of Rothamsted Research, Martin Lainsbury formerly of The Arable Group (TAG) and technical staff of several of the major crop protection companies are gratefully acknowledged.

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FORAGE MAIZE Most recommendations for the crop are based on information from research funded by farmers’ annual subscription to the Maize Growers Association (MGA). It is not a statutory levy. The R & D budget for the maize crop is £10,000/annum, and is considerably lower than that of levy bodies HGCA and HDC. Maize Growers Association website: www.maizegrowersassociation.co.uk

Background

Crop Area and Use In 1989 the UK maize area was only 24,782 ha. Following the introduction of early-maturing maize varieties adapted to lower light levels and lower temperatures, suitable for use in the UK, the maize area increased dramatically and the growing region extended northwards. The crop is currently grown on 131,000 ha (Defra June 2005 UK census) - an increase of 11.4% from the previous year, and a fivefold increase from 1989 to 2005. In 2005, maize was grown mainly for cattle feed: forage 124,000 ha and it is estimated by the MGA that 7,000 ha of grain maize was grown and is used for chicken and pigeon feed. Maize is also grown alone, or in a crop mix, to provide game cover, but there are conflicting estimates regarding the area grown for this purpose and 10,000 ha has been suggested (based on seed sales for this purpose). Maize is grown mainly in southern counties with around 40% in South Western region, 24% in Midlands & Western region and 17% in South Eastern region (CSL, 2002). Seed is sown in late March to mid April or even into May when soil temperatures should be a constant 8ºC at sowing depth. Maize flowers in late July in southern England and further north, during August. It is usually harvested in October or earlier in warm years. The UK area is small in comparison with other EU member states - the area of forage maize is c. 1,500,000 ha in France, 1,170,000 ha in Germany. France has the largest grain maize area 1,750,000 ha. In future, as a result of climate change, warmer weather conditions could be more favourable to both the UK grain crop (and to forage in northern areas). Earlier varieties and development of machines that can cope with wet conditions have also improved prospects for grain maize but drying costs are high in a wet harvest season. Livestock farmers currently rely on imports of 1.4 million tonnes p.a. of grain maize. However, although the maize crop is successful there are concerns that it may not survive in the UK because affordable crop protection products will not be available in future (S Draper, MGA, pers. comm.). Rotations The Maize Growers’ Association (MGA) survey in 1998, showed that 80% maize was in rotation, 20% was in continuous maize and the MGA suggest that the ratio probably remains the same. Maize has been grown not only for the feed value, but also as a place in the rotation as an environmentally friendly crop to allow for the dispersal of FYM and slurry within the legislation regarding Nitrate Vulnerable Zones (NVZs).

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Where, on livestock farms, maize is grown in rotation after maize it is possible to plant rye-grass, which is grazed in spring until late March then ploughed for sowing maize again in mid-April. Thus, maize and rye-grass crops alternate. On mixed farms, a winter cereal, probably wheat can follow maize where harvest is early. Maize is grown continuously on fields that are not accessible for grazing because of logistical problems for movement of livestock. In addition, the value of maize for stock-feed is also higher than alternative fodder crops. UK maize is also grown continuously because it is relatively late harvested in October, often a period of high rainfall, and a winter cereal crop cannot be sown because the land is too wet. If spring cereals are sown there can also be a serious yield loss due to the poor soil structure caused by harvesting maize under wet soil conditions. So far, maize has been continuously cropped without too many pest and disease problems but new ones (Diabrotica virgifera virgifera) may mean this will change in the future. Environmental impact Soil compaction resulting from late harvested (October) maize leads to soil erosion and diffuse pollution through surface run-off. Surface run-off in trials quantified by the Institute of Grassland and Environmental Research (Defra Study SP0404, 2001) showed that once the land is compacted through harvesting maize, the run-off increases dramatically, but that most run-off can be stopped by deep cultivation and cropping with an autumn crop. Undersowing with grass 10 weeks after maize provides ground cover after maize harvest and also reduces erosion. The atrazine applied to maize checks grass growth long enough to avoid competition. This technique would not be successful with other maize herbicides. Maize therefore needs to be harvested in September to allow time for the cultivations and drilling the autumn cereal crop. This may conflict with the aim of getting the best quality maize silage to produce the maximum yield of milk, because the maize silage Dry Matter (DM) may be lower than the required 30% DM (Draper, 2002). Research at the Centre for Dairy Research (CEDAR) funded by the MGA over a four-year period, shows wide variations in the response of maize quality in terms of dry matter to milk production. There is better correlation with starch - when maize silage drops below 25% starch then serious losses in milk yield may occur. Above 25% there appears to be only a small effect on milk yield. The starch concentration of the maize silage would be a better indicator of when to harvest maize, but this requires laboratory testing, which is expensive, not practical and gives variable results. The MGA also analysed the economic effect of improved soil structure on maize and wheat yields when maize is harvested earlier, compared to loss in maize silage quality (Draper, 2002). For an average yielding dairy herd the effect of harvesting maize earlier is cost neutral. For the higher yielding dairy herd there is a cost but this may be mitigated by not harvesting at the extremes and once the starch reaches 25% there appears to be no effect. Draper concluded that, given better analysis, then it may be possible to harvest the maize earlier without any significant loss in milk production, thus both the environment and the farmer would benefit. Earlier drilling and the use of early-maturing hybrid varieties provide opportunities for earlier harvests. The aim should be to harvest by the end of September at the latest. The Single Payment Scheme: Cross Compliance Guidance, Defra, 2006 gives guidelines for soil management in maize.

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Profitability Maize has been one of the most profitable crops to grow but the costs of growing will increase following the loss of atrazine. In the UK, yields are around 40t/ha, average variable costs £225/ha and silage maize is valued at c. £25/tonne (at 30% dry matter) (Nix, 2005). Maize is usually used on-farm. Standing maize crops are typically sold for between £425 and £525/ha but can range from £250 – £800/ha depending on potential yield and demand. In France, in a warmer climate, yields are higher, 35t/ha to more than 50t/ha, obtained using high yielding cultivars and high inputs. Following decoupling in the CAP reform there is no longer an area payment. The average costs of maize production, following the introduction of the Single Payment Scheme (SP), are given by Morgan, MGA, 2005: utilisable tonne of DM was £47/tonne pre-SP and is now £55/tonne post SPS. Cross Compliance measures - soil management, avoiding maize-growing on fields at risk from soil erosion or run-off are key factors regarding Single Payment and Entry Level Schemes.

Pesticide availability for maize and Maximum Residue Levels

• There are very few (16) crop protection active substances available for UK forage maize - 11 herbicides, 0 fungicides, 4 insecticides and 1 seed treatment.

• Maize crops are widely grown in S Europe therefore most residues data are generated in that

area, mainly in southern France. In France, a large number of crop protection products/mixes are available for maize.

• After Annex 1 listing it is likely that some products available now will not be re-registered

for the UK. However there are data for some crop protection products for N Europe (e.g. Germany) and Mutual Recognition could be a useful route to obtain access to pesticides needed. In the draft regulation of the 91/414 revision it is proposed that France is included in the South Zone and Mutual Recognition will not be possible directly from S Europe. Mutual Recognition will not apply to plant protection products containing a candidate for substitution.

• Off–label Approvals http://www.pesticides.gov.uk/applicant_guide.asp?id=1226 based on

recognition of approvals in other (current Northern zone) member states are not possible for a major crop. The use of the pesticide on the crop must have an on-label approval in the Member State in which the use is approved. There must be an extant on-label approval for the use of the same product on another edible crop in the UK. These arrangements only apply to applications for off-labels for minor crops of areas less than 50,000ha and do not apply to major crops including forage maize. There can be no extrapolations from cereals (in the same crop group hierarchy). Could a minor use be considered? Could grain maize be considered a minor crop with c.7,000 ha grown in 2005 ?

• Specific Off-Label Approvals (SOLAs) may be possible where there is no on-label approval

for the crop of a suitable pesticide to control an economically damaging pest, disease or weed. The cost to the growers of generating residues data (if needed) is likely to be

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prohibitive for this sector - the research budget for maize pesticides is small, approximately £2,000/annum.

• The new Regulation (EC) No 396/2005 of the European Parliament and of the Council on

maximum residue levels (MRLs) of pesticides in or on food and feed of plant and animal origin and amending Council Directive 91/414/EEC comes into force possibly 2007. UK/EU MRLs for forage maize are already set for prosulfuron, chlorpyrifos, fluoroxypyr and pendimethalin at the Limit of Quantification. This may preclude late sprays of chlorpyrifos to control Diabrotica. A key feature of the new controls is the establishment of Annex I to the Regulation, containing a commodity list of foods and feeds for which MRLs will be set, and it will provide for MRL controls to be extended to animal feeds, including grass in the future.

• A submission for registration of Genetically Modified glyphosate-tolerant varieties has been

made in some Member States, but not the UK because the late maturing varieties concerned are unsuitable. If GM H-T maize is widely grown in the future there will be little herbicide development in conventional crops.

Weed control in forage maize Maize is drilled in late April/May, on very wide rows 750 mm, to suit seed drills. Recent trials have shown that higher starch yields are obtained by using higher seed rates (130,000 seeds/ha) and closer row widths i.e. rows 375 mm apart, or using the French system with alternate rows at 375 mm and 750 mm. Better suppression of weeds may also be achieved. Maize is slow growing initially when temperatures are low and it seldom forms a complete canopy before the end of July. Spring emerging annual weeds can smother maize at early growth stages and perennial species, particularly common couch, can cause suppression. Even when mature the canopy allows light penetration and weeds grow beneath it. The initial concept of weed critical periods was published by Nieto et al., 1968 and showed that weeds in maize need to be removed from the crop 10-12 days after germination and also that weeds emerging 30 days after germination had little impact. Thus the crop had a critical weed free period lasting from 10-30 days after germination. It is therefore important to remove weeds early with effective residual herbicides. Impact: of weeds in maize is on yield and on feed value. The forage harvester collects both crop and weed matter for ensiling, thus the nutritive value of the fodder will be reduced if weeds are present. Some weed species for example, deadly nightshade, (but not black nightshade after ensiling) are toxic to animals. Weeds may also delay harvest. Recent trials by the MGA showed that a cheap treatment programme with atrazine and bromoxynil improved starch yields by 69% compared with untreated plots with high weed populations. There is very little information on yield reductions caused by weeds in maize or on the competitive impact of different weed species on the crop – in comparison with cereals, funding is very limited. Control: is with herbicides and most UK approvals are for forage maize. The main weeds controlled by herbicides are shown in the Appendix. The last CSL Pesticide Usage Survey for maize showed that in 2002 that herbicides were used on over 96% of the maize crop (Table 1), and there were at least two applications. Glyphosate was applied to clean up emerged weeds before cultivating and sowing.

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Atrazine, the main herbicide (Table 1) used for grasses and a wide spectrum of broad-leaved weeds, was applied post- as well as pre-emergence. Atrazine can be incorporated into the seedbed prior to drilling. In exceptionally dry weather control will be reduced although this can be limited by incorporating the atrazine. Where black nightshade is a problem atrazine will not persist long enough into the growing season to achieve acceptable long-term control of this weed, and some strains are resistant. Resistant weeds to atrazine may build up on fields that have had more than two applications of the chemical. Bromoxynil, a contact-acting HBN herbicide, was introduced in 1997, and is widely used for sites with black-nightshade problems and for general broad-leaved weeds, but there is a risk of scorch therefore timing and weather conditions are critical. Bromoxynil was applied to nearly half the area grown in 2002, and a tank-mix with atrazine was often used. Bromoxynil can cause scorch in bright sunlight. Atrazine and bromoxynil are the standards for cheap weed control in maize and both are used at lower dose rate than the label recommendation. Bromoxynil dose rate is varied according to species and weed size. Pendimethalin, applied pre-emergence, is more expensive than atrazine, is less effective under dry soil conditions as is frequently the case in May. However, if soil moisture is adequate, it controls black-nightshade and gives season-long control. Other herbicides approved are bromoxynil/prosulfuron, bromoxynil/terbuthylazine. Several other herbicides are applied post-emergence but they only solve specific weed problems: pyridate (for black-nightshade, fat-hen and cleavers); fluroxypyr for volunteer potato suppression, cleavers and docks; clopyralid for creeping thistles and mayweed and rimsulfuron (forage maize) can be used, on named varieties only, before the four collar growth stage of the crop, for cleavers and some annual broad-leaved weeds. Nicosulfuron applied post-emergence, is used mainly for grass weed control including couch grass. However, it has a residual effect and grass cannot be sown in the autumn following maize. There are guidelines for resistance management: only one sulfonylurea can be applied per year. There are SOLAs for Flexidor 125 (isoxaben) for maize grown for game cover and for Bema (pendimethalin) for forage maize. Herbicides no longer approved: cyanazine was not supported in the EC Pesticide Review 91/414 and could no longer be used after 31 December 2003; in 2004 atrazine and simazine failed to achieve Annex 1 listing (Table 1) and could not be used after 10 September 2005. Cyanazine and simazine were not widely used in maize. There were no derogations for any of these herbicides for ‘Essential Uses’ in maize. Lentagran (pyridate) is no longer sold by Syngenta and the grower use-up period is until 1 January 2007. It will be sold by Belchim in other crops but may not be available for maize in future. New post-emergence herbicides have been registered for forage maize. In 2005, mesotrione alone (Callisto) foliar-acting and in January 2006, a formulation of mesotrione/terbuthylazine (Calaris) with foliar and soil residual activity, were approved for maize. Mesotrione is a triketone which disrupts development of plant pigments – its’ mode of action is different from other herbicide groups and there is no known cross resistance in weeds which exhibit reduced sensitivity to other herbicides. Terbuthylazine, a triazine with residual activity, inhibits photosynthesis. Mesotrione and terbuthylazine have different modes of action and there is no known cross resistance between them, or between the groups of herbicides to which each belongs and this will reduce the likelihood of resistance development. There are guidelines for resistance management. Weed control can be reduced if strains of individual weed species develop that are less sensitive to a specific herbicide or herbicide group. The use of mesotrione (Callisto) in programmes or tank-mixes with herbicides possessing a different mode of action will reduce the likelihood of resistance developing in broad-leaved weeds e.g. fat-hen, black nightshade and common amaranth. At the present time, triketones

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(e.g. mesotrione) are not approved in crops other than maize and therefore crop rotation will also delay the onset of any resistance. Where continuous maize is grown the use of mesotrione for more than two seasons should be avoided. With a limited range of herbicides available this may not be possible. PSD are to impose statutory restrictions on the use of herbicides that control grass weeds and that act as ALS inhibitors (nicosulfuron and rimsulfuron) approved for use in forage maize. No usage data are available for nicosulfuron because it was only approved in 2004 but data for rimsulfuron, (which is seldom used), indicate that it is only applied once per crop. The use of ALS inhibitors for grasses in maize forage crops is not likely to be affected by the restrictions. Non-chemical weed control: Maize is grown on wide rows and can be mechanically weeded. More than one pass would be needed because soil disturbance stimulates further flushes of weed. Repeated cultivations may have adverse effects on soil structure. Guidelines for organic maize production suggest 2 - 3 passes of inter-row hoes costing £34.75/ha per pass. Maize is relatively heat tolerant and flame weeding can be done at 5 cm and 25 cm crop height, costing around £92/ha per pass. Inter-row cultivation equipment from Garford Farm Machinery, Deeping St. James, Lincs., using vision guidance technology has been evaluated in maize. For maize grown on dairy farms this is likely to be done by a contractor. Herbicides for maize Atrazine was the main herbicide used in maize - applied to 124,845 ha in 2002, it was usually applied pre-emergence but there were sometimes post- as well as pre-emergence applications. Applications were at a lower dose rate than the label recommendation, i. e. 1.06 kg a.i. /ha (2.0 L/ha product) in 2002. Table 1. Herbicides approved for maize 2006; Review status; Aim re-registration UK maize; herbicide group; usage of herbicides on maize grown 120,996ha in Great Britain in 2002 (source CSL Pesticide Usage Survey) Herbicides approved for maize 2006 except blue text

Review status Aim re-registered for UK maize

Herbicide group Usage 2002 (spray hectares)

Total weed Glyphosate Annex 1 √ phosphonic acid 25,626Grasses/Broad-leaved weeds Atrazine revoked Non inclusion Annex 1 triazine 124,845 Bromoxynil Annex 1 √ HBN 57,780 Bromoxynil/prosulfuron Annex 1/new Annex 1 √ / √ HBN/sulfonylurea 4,550 Bromoxynil/terbuthylazine Annex 1/List 3B √ / (√ N) HBN/triazine Clopyralid Annex 1 - picolinic 877 Cyanazine/pendimethalin revoked Non inclusion/on Annex 1 triazine/dinitroaniline 3,237 Fluroxypyr Annex 1 - aryloxyalkanoic acid 4,651 Isoxaben SOLA game cover only List 3B - amide Mesotrione New Annex 1 √ triketone Mesotrione/terbuthylazine New Annex 1/List 3B √ / (√ N) triketone/triazine Nicosulfuron * List 3A √ sulfonylurea Pendimethalin Annex 1 - dinitroaniline 14,819 Pyridate# use by 1 January 2007 on Annex 1 pyridazine 5,216 Rimsulfuron* Annex 1 √ sulfonylurea 3,722 Atrazine and cyanazine revoked; # pyridate no longer sold for maize; *ALS inhibitor, HRAC‘Group B’; - Company request confidentiality; √ yes; x no; (√ N) aim re-register in N Europe

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1. The likely impacts of the 91/414/EEC review process on herbicide availability for UK forage maize

1.1 Losses Cyanazine was not supported in the Pesticide Review 91/414/EEC and in 2004 atrazine and simazine failed to achieve Annex 1 inclusion (Table 2). Growers could no longer use cyanazine after 31 December 2003, atrazine and simazine after 10 September 2005. Cyanazine and simazine were not widely used in maize. There were no derogations for ‘Essential Uses’ of cyanazine, simazine or atrazine in maize thus little time to find alternatives. Ireland, Spain and Portugal have derogations for ‘Essential Use’ in maize until 31 December 2007. 1.2. Impact Loss atrazine

• Weeds in maize reduce yields and feed value. The forage harvester collects both crop and weed matter for ensiling, thus the nutritive value of the fodder will be reduced if weeds are present. Some weed species for example, deadly nightshade, (but not black nightshade after ensiling) are toxic to animals. Weeds may also delay harvest. Recent trials by the MGA showed that a cheap treatment programme with atrazine and bromoxynil improved starch yields by 69% compared with untreated plots with high weed populations but there is very little information on reductions of yield caused by weeds in maize, or on the competitive impact of the different weed species. In comparison with cereals, research funding is very limited.

• Atrazine was the main herbicide used in maize (applied to 124,845 ha in 2002), it was

usually applied pre-emergence, but sometimes post-emergence as well. Atrazine (residual and contact-acting) covered a broad-spectrum of grasses and broad-leaved weeds and provided season-long weed control of most species encountered (Appendix). The few weeds that escaped (black nightshade) were controlled post-emergence with bromoxynil. It could be soil-incorporated and it performed better than pendimethalin in the dry soil conditions often encountered in May. Pendimethalin, the other pre-emergence alternative, is less effective on grasses and mayweeds and groundsel. Where maize was grown under plastic, atrazine applied before drilling was the most active material.

• It is not possible to assess the impact of loss of atrazine on weed control on farms at this

stage because there was still a grower use-up period for 2005. • There is no direct replacement for atrazine - all the other approved herbicides are for post-

emergence application although some have residual activity as well. It is important to remove weeds early to avoid competition. None so far has been as effective as atrazine on grasses and broad-leaved weeds (Appendix 1). This means that several sprays may be needed post-emergence and there are restrictions on late timings. Post-emergence mesotrione/terbuthylazine (approved January 2006) and bromoxynil/prosulfuron and may cover an adequate broad-leaved weed spectrum including mayweeds and black-nightshade with the former and the latter controls knotgrass as well. Knotgrass is not controlled by mesotrione and it is moderately resistant to mesotrione/terbuthylazine. However, there are restrictions on the number of sulfonylurea applications (one per year) and this means that if

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grass weeds are present (controlled with nicosulfuron) then bromoxynil/prosulfuron cannot be used for broad-leaved weeds, and therefore a choice has to be made – either grass or knotgrass control. Mesotrione/terbuthylazine does not control grasses except annual meadow-grass. There are also restrictions with following cropping and a particular disadvantage of nicosulfuron, which has some residual activity, is that grass cannot be sown in the autumn following maize. In addition some spring-sown vegetable crops follow maize (mainly grain) in the rotation, but vegetable crops must not be sown within 18 months of application and this is a limitation for grain maize.

• Maize is grown on wide rows and can be mechanically weeded but it more expensive (see

below). More than one pass would be needed because soil disturbance stimulates further flushes of weed. Repeated cultivations may have adverse effects on soil structure.

• The research budget for maize herbicides is small, approximately £2,000/annum. There is an

ongoing cost for a search for alternatives to atrazine. Whilst chemical manufacturers carry out a limited amount of research to register new actives, there is a requirement for more financial investment in the maize crop that currently is fragile and likely to be made more so by the huge increase in chemical costs.

• The greatest impact from the loss of atrazine will be on increased costs of weed control and

this will have an impact on the crop profitability in 2006. Atrazine was first reported in 1957 - new chemistry will be more expensive to cover the cost of development and increased ecotoxicology data required for registration.

The following are based on 2005 prices: atrazine was £7 - £11/ha depending on dose rate 2.0 - 3.0 L/ha. Other herbicides are all more expensive and also depend on dose: new mesotrione/terbuthylazine with foliar and residual activity for 2006 will be approximately £28.50 to £43/ha, post-emergence bromoxynil/prosulfuron £23.50/ha, bromoxynil alone £21.75/ha. For grass weeds nicosulfuron costs £23/ha, unless common couch is the target £35/ha. The next generation of herbicides will be even more expensive. In 2005 weed control cost: Atrazine alone £7/ha + farm application cost £8.50/ha = £15.50/ha If black nightshade was a problem a programme would be atrazine 2.0 L/ha followed by, or in tank-mix with, bromoxynil 2.5 L/ha £21.75 + two applications £17/ha (total £46/ha) / or one application cost £8.50/ha (total £37.50). In 2006 weed control will cost: including application will be at least £51.50 to £80/ha or more assuming both grass and broad-leaved species were present. If mayweed escaped control then clopyralid would be used as well. Non-chemical weed control costs: are higher than for weed control with herbicides. The cost of tractor hoeing is on average £34.75/ha per pass (Nix, 2005). Two or three passes would be needed £69.50 or £104.25/ha. The Dairy sector In round figures, the number of producers in the UK has fallen from 35,000 in 1995 to 20,000 in 2005. A revised survey for Defra by Colman & Yaqin Zhuang, was published in July 2005. The authors found that more dairy farms cease production between April 2003 and April 2005 than had intended to do so when originally surveyed, and there was a higher concentration of more profitable and

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larger herds among those that quit. Furthermore, 8.7% of the remaining producers have stated the intention to quit in the next five years and 8.4% are uncertain of their future. The rate of growth of milk output of continuing producers in the sample has been insufficient to offset that lost from producers ceasing production. The scale of the exodus suggests that there will be a more significant downturn in milk production in England than previously projected, while in Wales the decline may be less than previously projected. Total UK output is expected to fall to around 13.3 billion litres in 2007/8, as against a national quota at that time of 14.41 billion. The survey did not include the impact of increased production costs with loss of atrazine. The UK dairy sector is generally less reliant on forage maize than some other major milk producing countries, however it is an essential part of winter rations for many producers. Atrazine has an ‘Essential Use’ derogation until 31 December 2007 in Ireland, Spain and Portugal - this undermines the UK's competitive position in the EU dairy market (NFU). Milk at 18 p/L is being produced at cost – the significant increase in herbicide costs or reduction in yield of maize if weeds are not controlled will compound the severe financial pressure being experienced by the majority of dairy farmers. Dairy farmers are unlikely to be able to pass these additional costs on to consumers because of the competitive nature of the dairy market, it is more likely that this will give further encouragement to dairy farmers to cease milk production which in turn may impact on the sustainability of the dairy supply chain. 1.3. Future losses? It is difficult to predict the likely impact of the review process on pesticide availability for the UK maize. Most maize herbicides are now included in Annex 1, except for nicosulfuron and terbuthylazine where decisions have not yet been made (Table 2). It is not known whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could also be losses of approved products. 2. Specific herbicides it would be desirable to maintain from the agronomic perspective to avoid major difficulties

A range of herbicides is needed for maize to cover the weed spectrum. Resistance strategies and other restrictions mean that options are limited. It would be desirable to maintain the following: Glyphosate non-selective herbicide for use pre-cropping. It is important to retain the HBN herbicide bromoxynil for black nightshade control. Bromoxynil, is on Annex 1, and the aim is for re-registration for UK maize. Although some of the newer herbicides are effective they are more expensive and in some cases have other drawbacks (see Gap Analysis, Table 2). Bromoxynil/prosulfuron is needed as the only herbicide that controls knotgrass because the activity of pendimethalin is poor in dry soil conditions. Mesotrione/terbuthylazine will be essential for control of black nightshade, mayweed and orache as these are major weeds of the maize crop. Nicosulfuron will be essential for grass weed control. Clopyralid needs to be maintained for mayweed control.

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3.1. Alternatives A ‘Gap Analysis’ (Table 2) shows the critical herbicide gap * * *, where there are, or soon will be no control measures at all. There is urgent need for a new broad-spectrum residual herbicide as effective as atrazine. It is too soon to say whether mesotrione/ terbuthylazine approved in the UK in January, 2006, will fill the gap but knotgrass control is poor. Where forage maize is grown continuously on the same sheltered field, repeated use of atrazine in has led to a build-up of black nightshade, which it does not control. The MGA (S Draper, MGA, pers. comm.) noted that this has led to development of herbicides for nightshade control and these may not be appropriate after the loss of atrazine. Polygonums are likely to present a problem for the future.

There are two new promising herbicides a. and b. in the pipeline for UK maize, possibly c:

a. pre-emergence flufenacet/isoxaflutole (not a sulfonylurea) is to be submitted for UK registration for annual grass and broad-leaved weeds, including mayweeds.

b. post-emergence sulfonylurea-based foramsulfuron/isoxadifen/iodosulfuron also for

annual grass and broad-leaved weeds, including mayweeds.

c. s-Metolachlor (on Annex 1) may be re-registered for maize in N Europe, possibly UK.

d. Dicamba (List 3B) – the aim is re-registration for maize in N Europe not in the UK. Other factors

• Maize occupies 1240,000 ha, thus UK off-label approvals based on recognition of approvals in other (current Northern zone) member states are not possible where a crop area exceeds 50,000 ha. It could be a useful route for grain maize.

• Mutual Recognition could be very helpful in gaining access to new products for forage

maize if the crop/use is on-label in another member state in the same zone (currently Northern).

• Maize is an important crop world-wide and new herbicides are being developed elsewhere.

However, the area in N Europe is relatively small compared with wheat and this may deter registration to some extent.

• Genetically modified herbicide (glyphosate, or glufosinate) tolerant forage maize varieties

have been developed and Bt maize is already grown in the EU. Weed control could be simplified with GM Herbicide-Tolerant maize. A submission by Monsanto for registration of glyphosate GM tolerant varieties has been made elsewhere in the EU, but not the UK because the late maturing varieties concerned are unsuitable. Acceptance of GM crops by some sectors in the UK seems unlikely in the near future. If GM H-T maize is widely grown in the future there will be little herbicide development for conventional maize crops. It is also worth noting that global Crop Protection Companies are investing millions of Euros in

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development of biotechnology traits and that some of this investment is re-directed away from traditional agrochemical investment.

• Globally there appears to be a reduction in herbicide development for maize. In the period

1990-1999 when 10 maize herbicides were introduced, only 4 new herbicide active substances were introduced over the period 2000-2004, and only 3 are now in R & D (Phillips McDougall, ECPA conference, November 2005).

3.2. Impact of the proposed regulation and revision of 91/414EEC

• Mutual Recognition of products containing Annex 1 active substances (excluding candidates for substitution) registered for the crop/use combination elsewhere in the proposed Central zone but not in the UK could be helpful for maize.

Key to the Gap Analysis Tables: * * gap no immediate problem but future situation may be vulnerable

* * * critical gap, where there are, or soon will be no control measures at all, or where the available control measures are inadequate.

Solution non-chemical - is this effective/reliable?




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Table 2. Gap Analysis Maize: Herbicides

# can add mesotrione (or sulcotrione but no UK registration ); BLW broad-leaved weeds

Weeds/weed species controlled

Application timing

Gap Status

Current approved solution



Solution chemical another MS R & D? Residues data?

Couch grass Rye-grass Black-grass Volunteer cereals

pre-em / residual

* * * None as effective as atrazine?

Used to be controlled by atrazine, only pre- emergence herbicide left is pendimethalin poor control of some grasses. Mesotrione/terbuthylazine(residual) only controls annual meadow-grass.

none none pre-em flufenacet /isoxaflutole (non sulfonylurea) to be submitted for UK reg for annual grass & BLW including mayweeds

Yes

Mayweed, polygonums

* * * None as effective as atrazine

Weeds becoming an increasing problem with no atrazine available. Pendimethalin poor control because soil conditions dry. Mesotrione/terbuthylazine may be better on mayweed.

none possibly mesotrione/ terbuthylazine

pre-em flufenacet /isoxaflutole (non sulfonylurea) to be submitted for UK reg for annual grass & BLW including mayweeds

Yes

Couch grass Rye-grass Black-grass Volunteer cereals

post-em * * * nicosulfuron (Samson)

Gives good control but has a residual effect which means that after the maize crop, grass cannot be sown in the autumn, or spring sown vegetables the year after.

Tractor hoeing

none Post-em foramsulfuron/isoxadifen/ iodosulfuron, sulfonylurea based to be submitted for UK reg for annual grass & BLW including mayweeds #

Yes

Mayweed, thistles post-em * * clopyralid (Shield) Foliar-acting - only works on emerged mayweed cannot be used past the 8 leaf stage of the maize crop

Tractor hoeing

none

Black nightshade and other BLW

post-em * * bromoxynil alone; bromoxynil /terbuthylazine

Maize very dependent on bromoxynil (Table 1), will it be re-registered for UK maize? If withdrawn, the maize crop may be uneconomic to produce.

Tractor hoeing

Polygonums (knotgrass and redshank)

post-em * * * bromoxynil/ prosulfuron (Jester)

Jester gives good control but these weeds cannot be controlled where grass weeds are present as the Samson required to control grass weeds means that Jester cannot be used in the same calendar year. Therefore a choice has to be made –either grass or polygonum control. Where Jester is used problem with subsequent cropping.

Tractor hoeing

none Post-em foramsulfuron/isoxadifen/ iodosulfuron, sulfonylurea based to be submitted for UK reg for annual grass & BLW including mayweeds #

Yes

Black-nightshade, fat-hen, cleavers

* * pyridate (Lentagran) No longer sold but can still be used until 1 January 2007, not sold for maize in future

Vol potatoes post-em * * fluroxypyr (Starane) Generally poor control of volunteer potatoes Tractor hoeing

none

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Pest Control in forage maize

Frit fly, leatherjackets and wireworm are the most common pests of maize. Frit fly (Oscinella frit) Frit flies overwinter in grasses or cereal shoots, pupating in March or April and the adult flies emerge in spring. The frit fly attacks the developing seedling and destroys the growing point. Impact: yield loss. Heavy infestations can destroy the majority of a crop. Control: is with seed treatments applied before the seed is imported. Chlorpyrifos applied to the soil at crop emergence is approved for frit fly control. Leatherjackets (Tipula spp.) Leatherjackets attack developing seedlings. The pest is often suppressed if emergence coincides with a period of heavy rain or irrigation. Impact: crop loss. Control: In the past Gamma-HCH and chlorpyrifos were used on about 3.2% of the area of maize grown for the control of wireworm or a combination of wireworm and leatherjackets in maize crops drilled after grass. The final approval for use of gamma-HCH on maize expired on 20 June 2002. Methiocarb is approved for their control in maize. Western corn rootworm (Diabrotica virgifera virgifera) This is an alien pest of maize from North America. The area of maize suitable for development of Diabrotica depends on climate. However, the beetle is known to have spread very quickly throughout mainland Europe. In the absence of maize, a small proportion of the larval population can survive on a few known alternate hosts, which include wheat (Triticum aestivum), although the pest is less productive here. Diabrotica virgifera virgifera was first found in the UK in 2003 on farms in the vicinity of Heathrow and Gatwick airports. It is a notifiable pest. Extensive national monitoring, using pheromone traps, is undertaken but in 2004 the pest was not detected in any new locations. Monitoring in 2005 (www.defra.gov.uk/planth/diab.htm) showed that no beetles were found in those fields where beetles had been trapped in 2004, confirming the effectiveness of crop rotation as the recommended control measure against this pest. A significant increase in beetle numbers was recorded in the Heathrow area despite the use of insecticide-treated maize seed. Particularly high numbers of beetles were confirmed on a new outbreak farm near Heathrow airport. Although Diabrotica was found in new locations some were not sampled in 2003-04 and populations may have existed previously. It is too soon to say whether Diabrotica is increasing its range in the UK. Information on this pest and Pest Risk Analysis (PRA) are shown on the website www.defra.gov.uk/planth/newsitem/diab2.htm. The PRA (Diabrotica virgifera virgifera) (MacLeod et al., 2004) gives data from a simulation model: a slow rate, where there is a statutory campaign against Diabrotica, is expected to range from a minimum of 0 km per year; typically be 20 km/year and have a maximum of 40 km/year; a fast rate of spread, where no statutory action is taken, is expected to have a minimum spread of 60 km per year and a maximum of 100 km/year. The simulation model also combined the maximum area that could be occupied within each year and used the rate of spread to determine the actual area infested each year. A report by ADAS for Defra Plant Health Division, 2004 gives an economic assessment of rotational measures against Diabrotica virgifera virgifera in UK maize crops. Impact: The adult beetle feeds on flowers, but it is the feeding damage to roots by larvae and the resulting susceptibility to lodging, and in severe cases plant death, that is more significant in forage

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maize. It is too soon to assess the impact of this pest in the UK on maize yield. Evidence from European countries suggests it takes a number of years of growing continuous maize in a field before populations of Diabrotica build up to densities sufficient to cause economic damage. At least five years was suggested in the PRA. The European Confederation of Maize Growers, 2004 suggested that where present, the pest causes a loss of up to 80 % of the crop. To estimate the potential economic impact of this pest on UK maize growers, if no statutory action were taken, it was assumed that there would be a range of yield losses of 10 to 30% (see PRA). Statutory control measures for Diabrotica continue in the outbreak area and they recommend avoiding continuous maize and using a crop rotation (the larvae starve if no maize roots are available) and avoiding maize as a game cover crop. Although growers have been advised to rotate maize game cover, or to plant alternatives, this has proved difficult for some, because it is often planted on small areas of land that are unsuitable for cropping Control with insecticide: An on-label approval for chlorpyrifos in maize already existed, and a SOLA was obtained to target Diabrotica. It was sprayed on maize stubble in 2003, but since then no recommendations have been made for foliar applications to maize for Diabrotica control. The Plant Health Service obtained a SOLA for lambda-cyhalothrin for use on maize, specifically for eradication/containment of the alien adult beetle, but efficacy was poor. There is a practical difficulty with making foliar spray applications against Diabrotica in the UK: by the time adult beetles emerge from the soil and become active in the crop, the crop is already too tall for treatment with conventional sprayers and it is also difficult for sprays to reach the target. The situation is different in the warmer parts of Europe (e.g. Hungary and Italy) where the pest is already established, because the beetle emerges earlier in the year. Insecticidal seed treatments are needed to control this pest. Little or no work has been done in this country and there are no UK approvals for application of any seed treatments (except thiram) for maize. Work in southern Europe suggests that higher doses are required for this pest than are currently applied. Available seed treatments on imported seed may lack adequate persistence for effective use under UK conditions (PRA), imidacloprid and thiamethoxam seed treatments are effective for about three weeks from planting. Clothianidin is more persistent and may be more effective, lasting for up to six weeks. Soil applied insecticides to control the larvae are also effective. Chlorpyrifos has been effective against adults, both in US and European trials - where for control purposes, it is recommended that a chlorpyrifos product (with a 21-day harvest-interval) is applied every 4 weeks until October. Specialist spray machinery may be required in a tall maize crop late in the season. This equipment is unlikely to be available to many maize growers and would increase variable costs. Of the insecticides approved for use in the UK, only chlorpyrifos has been shown to be effective against Diabrotica. Chlorpyrifos (an organophosphate) is on Annex 1 (for grape vines) but future availability of chlorpyrifos products in the UK cannot be assured. Carbosulfan (List 2 of the Review) and bifenthrin (List 3A) are also used in some Member States - neither is approved for maize in the UK but they could be applied to wheat in the rotation. Aphids Aphids are not usually a problem in forage maize. The bird cherry aphid (Rhopalosiphum padi) is the main species responsible for damage in grain maize – it feeds on the tassels, affecting pollen flow to the silks and moves down to the developing cob. It can cause poor grain set and yield loss. Control: a pirimicarb spray is recommended at thresholds where over 10 aphids are found on the tassel or ear in grain maize. At this stage, high clearance sprayers are needed but may not be available.

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Molluscs Slugs (Derocerus and Milax spp.) may cause problems to the emerging plants by shredding the leaves and the growing point. Impact: plant loss and yield loss. Control: maize growers are reliant on molluscicide (methiocarb) seed treatment on imported seed. Slug monitoring with traps is an important part of slug control. Control in the crop is usually only warranted at the seedling stage. There is a limited choice of active ingredients for the control of slugs (metaldehyde and methiocarb) but many products. In 2002 molluscicide pellets, mainly metaldehyde were applied to 4.8% of the crop area. Molluscicide usage continues to increase and more use is recorded in wet seasons. Insecticides and molluscicides for maize Insecticides and molluscicides for maize approved for 2006 and the usage on forage maize in the last CSL srvey for 2002 are shown in Table 3. There are no new insecticides or molluscicides approved for maize as of June 2006. In 2006 the position remains the same for seed treatments. Table 3. Insecticides, molluscicides and repellents approved for maize 2006; Review status; Aim re-registration UK forage maize; Usage of herbicides on maize grown 120,996 ha in Great Britain in 2002 (Source: CSL Pesticide Usage survey, 2002) Insecticides, molluscicides & repellents 2006

Review status Aim re-registered UK

maize

Pest Activity Usage 2002 (spray hectares)

Insecticides Organophosphate Chlorpyrifos Annex 1 - leatherjackets contact and ingested organophosphorus

insecticide and acaricide 1,409

Carbamate Pirimicarb Annex 1 √ aphid contact and fumigant carbamate Molluscicides/ repellents Methiocarb List 2 not decided (√

N) slugs, also reduces leatherjackets

carbamate 278

Metaldehyde List 3A √ slugs 4,687 also nicotine, rotenone, natural plant extract; - Company request confidentiality; √ yes; (√ N) aim re-register in N Europe

Seed treatments Table 4. Fungicide & molluscicide seed treatments approved for maize 2006; Review Status; Aim re-registered UK forage maize; Activity; Usage of seed treatments on maize grown 120,996 ha in Great Britain, 2002 (hectares), all except thiram are on imported seed. Fungicide & molluscicide seed treatments approved for maize 2006

Review status Aim re-registered UK maize

Activity Usage 2002

Fungicide seed treatments Fludioxonil/metalaxyl revoked List 3A/non inclusion - 2,006 Fludioxonil/metalaxyl-M List 3A/new Annex 1 x Cyanopyrrole/ phenylamide 11,444 Thiram Annex 1 √ protectant dithiocarbamate 40,680Molluscicide & repellent seed treatments Anthraquinone no longer available Commodity List 4E quinone 2,921 Methiocarb List 2 not decided (√ N) carbamate 73,873 - Company request confidentiality; √ yes; x no; (√ N) aim re-register in N Europe

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Only thiram is approved to treat maize seed in the UK. It is uneconomic for a single chemical to be applied, thus other seed treatments with several actives are applied prior to importation. In the 2002 CSL Pesticide Usage Survey (Table 4), the most extensively used seed treatments were with methiocarb 39%, thiram 22% and fludioxonil/metalaxyl-M 6% of the seed-treated area. Maize is prone to attack by birds but anthraquinone bird repellent (seed treatment) is no longer available. 1. The likely impacts of the 91/414/EEC review process on insecticide and molluscicide availability for UK forage maize

There is very little use of insecticides in forage maize. Maize insecticides were supported in the 91/414/EEC review because there were uses in several other crops. So far no active substances have been lost through failure to achieve Annex 1 listing. There is a limited choice of active ingredients for the control of slugs. Decisions on Annex 1 for metaldehyde (List 3A), methiocarb (List 2) have not been made. 2. Specific insecticides, molluscicides or groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

It would be desirable to maintain the following: Imported seed treatments containing clothianadin or thiometoxam, both new on Annex 1,are essential to control frit fly, leatherjackets and wireworm, and a molluscicide (methiocarb) is also essential for slug control in maize. (Gap Analysis Table 6) Continued availability of seed treatments is dependent on re-registration in other countries. The crop is grown in wetter areas of England (South West, West Midlands) and usage of slug pellets is higher in wet seasons. It would therefore be desirable to maintain a UK approval for molluscicide bait (metaldehyde) although usage is low – it was applied to 3.9% of the crop area in 2002 .Chlorpyrifos (organophosphate), now on Annex 1, is used for control of common pests of maize frit fly, wireworm and leatherjackets but it is less effective than some seed treatments on imported seed. It appears to be the only insecticide currently approved in the UK that could give some control of Diabrotica. (Pirimicarb is needed for aphid control in grain maize.) 3. Prospects for alternatives for any foreseen major gaps in insecticide availability

3.1. Alternatives

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A ‘Gap Analysis’ (Table 5) shows the critical insecticide gap * * *, where there are no control measures at all. Effective means of control for Diabrotica is urgently needed. If the area of grain maize increases aphicides with different modes of action from pirimicarb may be needed for resistance management. These could be available by Mutual Recognition. Lambda-cyhalothrin and pymetrozine have SOLAs for use in sweetcorn. New seed treatments: thiometoxam (new on Annex 1) and clothianidin (new on Annex 1). Both are new neonicotinoid active substances. Clothianidin seed treatment is being submitted for UK registration at two dose rates: standard for wireworm and a higher premium dose rate for Diabrotica. This may be the most effective solution. Bifenthrin soil treatment is used in some other Member States to control Diabrotica. Chromobacterium suttsuga a USDA Biopesticide has been developed for Diabrotica.

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Table 5. Gap Analysis Maize: Insecticides (there is no current requirement for Nematicides)

Poncho (clothianidin) belongs to the neonicotinoid group of active ingredients, new on Annex 1. Submitted for UK registration. Poncho Beta (beta-cyfluthrin/clothianidin) is registered for sugar beet in UK Cruiser (thiometoxam) a neonicotinoid insecticide, new on Annex 1

Pest

Application timing (seed, soil or foliar treatment)






Frit fly, wireworm. leather jackets

soil * * chlorpyrifos Pest control is poor with this product and high environmental risk. Currently growers importing treated seed to counteract the problem. Products not cleared to betreated in this country.

none clothianidin (Poncho) or thiometoxam (Cruiser) (imported seed treatment)

clothianidin seed treatment standard wireworm rate to be submitted for UK registration

Yes

Aphids in grain maize

crop * * pirimicarb More aphicides needed (lamda-cyhalothrin and pymetrozine have SOLAs for sweetcorn)

none Most aphicides

Diabrotica v v seed * * * Nothing Currently growers importing treated seed to counteract the problem. The products are not cleared to be treated in this country. Higher rates required for this pest and difficult to get variation in rates applied from the continent

none Poncho or Cruiser (imported seed treatment)

clothianidin seed treatment premium rate for diabrotica to be submitted for UK registration

Yes

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Disease control for forage maize There are no fungicides approved for maize in the UK, and it would not be practical to spray tall maize crops if disease occurs late. There may be some varietal field resistance to diseases. There are very few significant maize diseases. Common maize rust (Puccinia sorghi) is occasionally seen in the UK, but is of no economic importance to the forage maize crop. (There are a number of rust resistant sweetcorn varieties). Maize eyespot Maize eyespot is caused by the fungus Aureobasidium zeae. Symptoms occur primarily on older leaves, the initial symptoms being small, water soaked or chlorotic circular spots and the tissue at the centre of the spot later dies. The spot is surrounded by a yellow halo that can be seen clearly when the leaf is held up to the light. Spots may coalesce into large necrotic areas and the entire leaf dies. These symptoms can be confused with physiological leaf spots. The disease overwinters on crop debris and its development is favoured by wet weather. It could be more common in continuous maize. Impact: it has occasionally been found (in 2002) at significantly levels serious enough to cause crop failures. 1. The likely impacts of the 91/414/EEC review process on fungicide availability for UK forage maize

No fungicide is approved in the UK except thiram seed treatment, thus no impact. 2. Specific fungicides or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Thiram approval for seed treatment needs to be maintained. Although it is seldom used now, it will be required for addition to an insecticide seed treatment available in future. 3. Prospects for alternatives for any foreseen major gaps in fungicide availability

Maize eyespot: Currently there are no fungicides available for the maize crop in the UK (Gap Analysis, Table 7) This disease is unlikely to be a problem in the rest of Europe because it is prevalent in mild, wet, summer months - conditions typical only in the UK. Fungicide development and registration in the main EU maize growing areas is therefore unlikely. However, fungicides approved for cereals may be appropriate (e.g. prothioconazole) and a SOLA may be possible for this minor use but residues data would be required. No work has yet been done and funding would be needed.

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Table 6. Gap Analysis Maize: Molluscicides & Bird Repellents Pest (Latin name)


Gap Status






slugs soil * * metaldehyde, methiocarb

Very dependent on metaldehyde for slug control, some methiocarb used

none - - -

birds seed * * * anthroquinone Birds are a problem in maize crops. Anthraquinone repellent on some imported seed may not be available in future.

none - - -

Table 7. Gap Analysis Maize: Fungicides none approved Disease


Gap Status






maize eyespot

* * * none New disease in a few crops, already found at significantly serious levels causing crop losses. No fungicides approved for the maize crop. Prevalent in mild wet conditions in the summer months in the UK. Unlikely to occur in the rest of Europe so no research, or Mutual Recognitions of fungicide solutions. R & D needed.

none None, a minor use in a major crop – is a SOLA possible using a cereal fungicide? eg seed treatment prothioconazole?

unlikely none

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SWEETCORN

This crop is not included in the remit for this project but there are some interesting comparisons with maize. Sweetcorn, unlike maize, is a minor crop (1,100 ha in 2003). It is in the cereal crop hierarchy. There have been spin-offs from European maize pesticide development, but there may be fewer actives available in future. If residues data are not available for this edible crop from elsewhere in N Europe, they are generated in the UK and funded by growers through the Horticulture Development Council (HDC). HDC members can find the sweetcorn Gap Analysis on the HDC website. As a minor crop, sweetcorn has several SOLAs for crop protection chemicals, including lambda –cyhalothrin for frit fly control and pirimicarb and pymetrozine for aphid control. For weed control there is derogation for “Essential Use” for atrazine in sweetcorn and growers can use it until 31 December 2007. The on-label approval for bromoxynil/prosulfuron has not been maintained. Sweetcorn has SOLAs (January 2006) for bromoxynil, fluroxypyr, pendimethalin, mesotrione alone or in a formulation with terbuthylazine, nicosulfuron. The vegetable crop has a few more crop protection solutions than maize. However there is concern regarding weed control after 2007 when atrazine is no longer an option.

REFERENCES

ADAS (2004) Economic assessment of the rotational measures within the EC control measures

against Diabrotica virgifera in UK maize crops. Report by ADAS for Defra PHD, March 2004. 29pp.

COLMAN D, YAQIN ZHUANG D (2005) Changes in England and Wales dairy farming since 2002/03: A Resurvey. Http://www.defra.gov.uk/

DEPARTMENT FOR ENVIRONMENT, FOOD AND RURAL AFFAIRS (Defra), (2001) Soil erosion control in maize. Project SP0404 by the Institute of Grassland and Environmental Research (IGER).

DEPARTMENT FOR ENVIRONMENT, FOOD AND RURAL AFFAIRS (Defra) (2006) Maize and other forage crops. In: Single Payment Scheme: Cross Compliance Guidance for Soil Management 2006 edition. p F27-28. Defra publications, London, UK.

DRAPER S (2002) Maize Quality at what cost to the environment? European Maize Conference 2002. Http://www.maizegrowersassociation.co.uk/_Attachments/106_101CMS.htm accessed February 2006

GARTHWAITE DG, THOMAS MR (2002) Grassland & Fodder Crops in Great Britain. Pesticide Usage Survey Report 188. Central Science Laboratory, Sand Hutton, York, UK. Defra publications, London. Http://www.csl.gov.uk

MACCLEOD A et al. (2004) Pest Risk Analysis for Diabrotica virgifera virgifera. Revision number: 1. Central Science Laboratories, Sand Hutton, York

MAIZE GROWERS ASSOCIATION website: Http://www.maizegrowersassociation.co.uk MORGAN J (2006) Costs of Forage Production following decoupling and the introduction of

the Single Payment Scheme (SPS). Economic Technical Note – November 2005 MGA Office. website: Http://www.maizegrowersassociation.co.uk

NIETO JH, BRONDO MA & GONZALEZ JT (1968) Critical periods of the crop growth cycle for competition from weeds. PANS (C) 14, 159-166.

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NIX J (2005) Farm Management Pocketbook 36th edition 2006. Imperial College, Wye. Andersons Centre, Melton Mowbray, UK.

In the text and Appendix common weed names are according to Dony et al. (1986); in Appendix Latin names according to Stace (1997). DONY JG, JURY SL & PERRING FH (1986) English Names of Wild Flowers, 2nd edition. The


Cambridge, UK.

ACKNOWLEDGEMENTS

The help and contributions from the following organisations are gratefully acknowledged: Maize Growers Association (MGA), Central Science Laboratory, Plant Health Group (CSL), Agricultural Industries Confederation Ltd (AIC), Defra Plant Health Division, National Farmers Union (NFU), Institute of Grassland and Environmental Research (IGER), United Agricultural Products - Europe (UAP) and Crop Protection Companies.

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Appendix. Weed Susceptibility to herbicides for Maize. Key: S = susceptible; MS = Moderately Susceptible; R = Resistant; MR = Moderately Resistant at product dose rates

atrazine pendimethalin mesotrione mesotrione/terbuthylazine nicosulfuron bromoxynil bromoxynil/prosulfuron clopyralid Pre/Post-em Pre-em Post-em Post-em Post-em Post-em Post-em Post-weed-em Common name Latin name 3.0 L/ha 3.75 L/ha 0.75 L/ha 1.0 L/ha 1.5 L/ha 2.5 L/ha 0.5 kg/ha 0.5 L/ha Amaranth, common Amaranthus S Bindweed black Fallopia convolvulus MS S MS S S MS Bugloss Anchusa arvensis S Charlock Sinapis arvensis S S S S Chickweed, common Stellaria media S S S S S S Cleavers Galium aparine R S Corn marigold Chrysanthemum segetum S S S Deadnettle, henbit Lamium amplexicaule S S S S Dead-nettle, red Lamium purpureum S S S S S S Dock, broad-leaved Rumex obtusifolius R Fat-hen Chenopodium album S S S S MS S S Fool's parsley Aethusa cynapium MS Forget-me-not, field Myosotis arvensis S S S Fumitory, common Fumaria officinalis MS MS Gallant -soldier Galinsoga parviflora S Groundsel Senecio vulgaris S R S S S Hemp-nettle, common Galeopsis tetrahit S S S S Knotgrass Polygonum aviculare R S MR MS S Mayweed, scented Matricaria recutita S MS S S S S Mayweed, scentless Tripleurospermum inodorum S MS S S S S Nettle, small Urtica urens S S Nightshade black Solanum nigrum S* S S S MS S S Orache, common Atriplex patula MS S S MS S S Pansy, field Viola arvensis MS S S S S Parsley piert Aphanes arvensis S S Pennycress, field Thlaspi arvense S S S S Persicaria, pale Persicaria lapathifolia MS S MS S MR Pimpernel, scarlet Anagalis arvensis S Pineappleweed Matricaria discoidea S MS S Poppy, common Papaver rhoeas S S Redshank Persicaria maculosa MS S S MS S S MR Shepherd's-purse Capsella bursa-pastoris S MS S S S Sow-thistle, smooth Sonchus oleraceus S S Speedwell, common, field Veronica persica MS S S S Speedwell, ivy-leaved Veronica hederifolia MS S Sun spurge Euphorbia helioscopia R Thistle, creeping Cirsium arvense R S Wild radish Raphanus raphanistrum S Annual meadow grass Poa annua S S S S Blackgrass Alopecurus myosuroides S S Couch, common Eltrigia repens MR S Wild-oat Avena fatua MS S Vol OSR Brassica napus MS S S R Vol Potatoes Solanum tuberosum MS

* inherited-resistant populations of black-nightshade have built up on fields cropped continuously with maize; # nicosulfuron also controls Volunteer cereals, ryegrass; blue text failed Annex 1

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POTATOES The principal organisation responsible for initiating and funding applied research on the potato crop is the British Potato Council (BPC). This is a statutory levy organisation financed by growers and by trade purchasers of the crop. Minimising the impact of pests and diseases is considered to be of crucial commercial significance by BPC and is one of the priorities in their corporate plan. The R & D budget for 2006/2007 is approximately £1.5m.

Background Crop area and use The potato crop in the UK is divided into the ware crop grown for human consumption either as fresh or processed product and the smaller but high value seed crop, some of which is exported. Ware crops are grown as first earlies, second earlies or main crop but the difference between these classes is becoming less distinct. In 2004 there were 149,000 ha (field area) of potatoes including seed crops grown in the UK and in 2005 there were 137,000 ha (Defra, 2006) (BPC figures are lower than this because only planted area from registered growers is recorded). The average UK production of potatoes per annum is fairly constant and was 6.3 million tonnes in 2005. Potato production accounted for just 3% of all the UK cropped area in 2005. The majority of potatoes are now grown on light to medium texture soils with irrigation, particularly in the Eastern counties of England and Scotland. The seed crop is predominantly grown in Scotland with some 12,000 ha (more than 80%) out of the total 14,322 ha seed crops planted (BPC) in 2005. Average yields of potatoes have increased greatly with improved husbandry methods with average increases of 0.52 t/ha/year over the last decade (M Storey, 2005) and were 45.1 t/ha for the UK maincrop in 2005. Currently the market split for processed and fresh potatoes has stabilised at about 50/50, following a period when there was a trend demanding more processed crop. Economics/profitability Potatoes are a relatively intensive arable crop with high production costs and high outputs per ha. Average variable costs per ha for main crop ware potatoes for 2006 are predicted to be £2,225 compared to £635 for sugar beet and £250 for winter wheat. Gross margins forecasts per ha were £1300, £1100 and £285 respectively (Nix, 2005). There has been a trend for declining average prices for growers over the last ten years. The average price of £157/t in 1994 compares to just £92/t in 2004, and although more growing on contract has increased security of payments, there is still serious financial pressure on growers (Storey, 2005). Profitability depends on a multitude of factors particularly yield and the price obtained for a crop which can range from £300/t for premium quality salad potatoes to around £80/t for the processing crop. Quality of produce is a crucial factor. Rotations Traditionally potatoes have been grown on wide rotations of at least 1 in 5. This is still considered desirable and reflects the most common practice. Any closer rotations are associated with increased risks from a number of soil-borne pests and pathogens, particularly potato cyst nematode (PCN) and

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diseases such as stem canker and black scurf (Rhizoctonia solani). Build up of volunteer potatoes (groundkeepers) can also be a serious problem where closer rotations e.g. double cropping is practiced. The increasing pressure from large corporate purchasers to reduce pesticide usage strongly favours wide rotations. As a spring crop, potatoes have a valuable place in arable rotations in providing an opportunity to control difficult weeds such as perennial grasses during the autumn. So does sugar beet, and with the expected decline in the area, weed control could become more difficult for potatoes. Pesticide availability for potatoes and Maximum Residue Levels There are currently (April 2006) 74 different approved active substances (excluding the protected crop). Many of these are in formulated combinations, especially for fungicides. These comprise 20 herbicides (including 4 desiccants), 30 fungicides, 18 insecticides and nematicides, 3 molluscicides and 3 sprout suppressants. The potato crop has no shortage of active substances in the foliar fungicide, insecticide and the herbicide sectors. New actives are regularly being introduced particularly for foliar fungicides and insecticides. There are however concerns about the limited range of actives for the control of nematodes (especially after the ‘Essential Use’ derogation for aldicarb expires). Some concern is also expressed about the limited range of sprout suppressants, storage fungicides and the chances of Annex 1 listing of sulphuric acid in the EEC Review. However views varied greatly according to the industry sector. Half the industry in the non-processing sector, for example have virtually ceased using sprout suppressants (D Hudson, pers. comm.). With the financial support available from the BPC, the generation of data for Specific Off-Label Approvals for minor uses is an option available, where a need is identified. UK and/or Codex MRLs have been set for some 37 of the approved active substances. However a major factor in the use of pesticides in ware potatoes is the very strong influence of major purchasers and their dislike of pesticide residues in food crops, even when residues are well within MRL levels. This can severely limit the options open to growers for particular crop protection needs. Maleic hydrazide for example is one of only two approved substances for sprout suppression in processed ware potato stores but residues in the tubers mean that it is infrequently used for this purpose. The 0.5 mg/kg MRL for aldicarb is currently under review. A proposal by the European Commission to set all MRLs for aldicarb to the level of determination (effectively zero, ruling out its use in potatoes) is being considered by the European Food Safety Authority (EFSA).

Weed control in potatoes Historically potatoes were regarded as a weed-cleaning crop. Standard cultivation in wide rows facilitated frequent mechanical and hand cultivation and, once established, the dense foliar canopy suppresses weeds. However repeated cultivations cause root damage and yield loss and now weed control is almost exclusively achieved with the use of herbicides. Impact: of weeds is primarily on yield because the crop has a high demand for nutrients and water, and is sensitive to competition. A wide range of trials have shown yield losses attributable to weeds

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can be very high, with some research citing from 36 to 54% (Knott, 2002). Actual yield losses from weed competition depend on many factors, but they are greatest from early emerging weeds. In addition to yields, weeds also influence tuber size and quality and affect the ease of harvesting. Certain weed species act as hosts for migratory nematode pests, and Rhizoctonia and Colletorichum coccodes diseases. Weeds may also be implicated in the survival of pathogenic Erwinia spp. Control: of weeds is with a wide range of herbicides with different modes of action and used at different stages of weed and crop growth. Common practice on mineral soils is to use a tank-mix of a contact herbicide with a residual product shortly before the beginning of crop emergence. Most ‘critical period’ studies indicate that one effective treatment can be adequate to prevent yield loss, although in practice more than one application is often necessary. Soils with a high organic content, or very light sandy soils, can limit the choice, efficacy and rate of herbicides used. Choice may also be limited by variety grown because some varieties are sensitive to specific herbicides. A very wide range of weeds needs to be controlled, but there are many herbicides available to cover the spectrum, especially in ware crops, with no serious gaps identifiable. However pre-emergence residuals sometimes do not perform well because of adverse soil conditions and post-emergence herbicides are needed for weeds that escape control. However, the range of options is limited in efficacy, crop safety and there may be restrictions on post potato cropping. The options for seed crops are more limited than for ware production because effects on foliage from post emergence herbicides mask symptoms of virus infection. Most herbicide applications are for the control of broad-leaved weeds. The increasing incidence of cleavers, creeping thistle and coltsfoot can be a problem in maincrop potatoes. Perennial weeds are more difficult to manage, but there are some options for these to be controlled in preceding crops. The main use of glyphosate for potatoes is in the preceding autumn to control perennial weeds, particularly grasses. Cultural control: The control of weeds by mechanical cultivation only, is practised in organically grown crops using a combination of gas burners, harrows and ridgers pre-emergence and inter-row cultivations post-emergence. However this is more expensive, less effective and subject to yield reductions from root damage. It is also precluded from some common commercial systems notably production of early potatoes under plastic film or fleece protection. Mechanical cultivation may be inhibited under high rainfall conditions and prevent weed control at critical times, especially on heavier silt soils. A combination of mechanical tillage and herbicide use is practised especially on organic and sandy soils that limit herbicide options. Herbicides for potatoes The 2004 CSL Pesticide Usage Survey reported 68% of the ware crop area treated was for general weed control, 21% for pre-harvest desiccation, 8% for broad-leaved weeds and just 2% for grasses, with an average of 3 applications on ware crops. The main herbicides used in 2004 (desiccants excluded) are given in the following Table 1. It is notable that metribuzin use has declined considerably since 2000. The area treated then was c. 41,000 ha. There were substantial increases in linuron and diquat/paraquat use in this time. There are 15 herbicide active substances approved for potatoes, excluding the desiccants diquat, sulphuric acid, carfentrazone-ethyl and glufosinate-ammonium (although the latter two also have some use as herbicides).

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Table 1. Potatoes: approved herbicides; Review status; Aim to re-register in potatoes UK; herbicide activity and usage on 142,953 ha of crop grown in GB 2004. Top 7 a.s with > 1000 sprayed ha (Source CSL Pesticide Use Survey 2004)

Herbicides approved 2006 Review status Aim re-registration UK potatoes

Herbicide activity Usage 2004 (sprayed ha)

>1000ha Total weeds Diquat/paraquat Annex 1/Annex 1 √ / √ bipyridyls 89,879 Glufosinate-ammonium Annex 1 not decided phosphinic acid Glyphosate Annex 1 √ phosphonic acid 31,266 Paraquat Annex 1 √ bipyridil Grass weeds Cycloxydim* List 3A - oxime Propaquizafop* List 3A √ phenoxyl alkanoic acid 1,863 Quizalofop-p-tefuryl* List 3B √ aryl phenoxyproprionic acid Broad-leaved (and some grasses) Bentazone* Annex 1 - diazinone Clomazone* List 3A √ isoxazolidinone 5,526 Linuron Annex 1 √ rate restricted 950 g a.s.

/ha/year. urea 101,100

Metribuzin* List 2 √ rate restricted triazinone 22,965 Metribuzin/flufenacet* List 2/new Annex 1 √ triazinone/ oxyacetamide Pendimethalin* Annex 1 - dinitroanaline 5,943 Prosulfocarb List 3A √ thiocarbamate Rimsulfuron List 2 √ sulfonylurea All herbicides 339,552

*Not on potato seed crop; - Company request confidentiality; √ yes; 1. The likely impacts of the 91/414/EEC review process on herbicide availability for UK potatoes Losses Cyanazine, monolinuron, sethoxydim and terbutryn were unsupported in the EC Pesticide Review 91/414 and are no longer available. The loss of these herbicides in the initial stages of the review process is not considered to have had any significant impact on the agronomy of these crops. They were used on only relatively small areas at that time and their demise has not left any significant gaps in the weed control spectrum as far as agronomy is concerned. However monolinuron, albeit more expensive, was an alternative to linuron, which is now the single most important potato herbicide so any threat to the future availability of linuron would be much more serious because of the earlier withdrawal of monolinuron. Furthermore, variety-specific responses to other herbicides in combination with low temperatures may affect leaf formation sufficiently to compromise statutory seed crop inspection and certification. The anticipated rate restriction of linuron to 950 g a.s./ha/year (current authorised maximum rate of 2250 g a.s./ha/year) will be insufficient alone on heavier soils. This will mean tank-mixes with other more expensive herbicides such as pendimethalin are needed to reinforce activity and it is estimated this could increase treatment costs by up to 25% on such soils (L Sykes, pers. comm.). However according to Makhteshim-Agan (UK), the majority of growers already use lower rates of linuron in combination with other herbicides in order to improve the spectrum of weed control, especially against black-bindweed.

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At product re-registration stage there will be dose-rate restrictions for metribuzin (because of water issues) and the maximum permitted will be 525 g a.s./ha pre-emergence, 350 g a.s./ha post-emergence. Data from CSL Pesticide Usage Surveys also suggest that both linuron and metribuzin are used at around half the full label dose rates. Future losses As applies to other crops, the likely impact of the review process on future availability is difficult to judge. As indicated in Table 1, four of the top seven herbicides all have Annex 1 listing, whilst the next two most widely used are pending. As with all Annex 1 listings, there is no certainty that the chemicals will subsequently be re-registered for use on potatoes in the UK or other N European zone countries. Table 1 shows the intention of agrochemical companies to support re-registration. 2. Specific herbicide and herbicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties As applies generally in crops, a range of herbicides is needed to cover the weed spectrum and herbicides with different modes of action are important for resistance strategies. Mechanical cultivation is a fall-back method that may be used in some circumstances, but it is considerably more expensive than using herbicides and there are other limitations as described in the cultural weed control section. It would be desirable to maintain the following: Linuron. This substance is used on over 29% of the total treated area. In Scotland it is applied on 80% of the seed crop treated area, reflecting the limited range of other herbicides that can be used on the seed crop. Linuron is the single most important herbicide, with very wide spectrum of control including cleavers. It is also relatively cheap at £12-24/ ha. Diquat/paraquat. Usually applied as a formulated mixture and often in tank mixes with residual herbicides to provide contact activity on emerged weeds. Unlike several other herbicides there are no variety or soil type restrictions which make it an extremely versatile combination. Accounted for over 26% of the sprayed area in 2004. Metribuzin is still the third most important herbicide used in potatoes. It has valuable persistent residual activity and will control most weed species including volunteer oilseed rape and fumitory. Glyphosate is essential for the control of perennial weeds surviving into the autumn from the previous crop. It is particularly valuable for grasses including herbicide resistant species that are an increasing problem, as well as thistles and other perennial broad-leaved weeds Clomazone pre-emergence and rimsulfuron post-emergence, are needed to control cleavers and some other weeds. Post-emergence herbicides rimsulfuron and bentazone have also been identified as important to retain for situations where low soil moisture has resulted in inadequate residual activity and poor pre-emergence weed control. Rimsufuron has systemic foliar activity, no variety restrictions and controls difficult weeds in addition to cleavers, such as volunteer oilseed rape and a range of late emerging weeds. There are no restrictions post potato cropping after bentazone, thus it is a useful alternative to rimsulfuron, especially in brassica production areas. Pendimethalin may be needed to reinforce the activity of linuron on heavier soils when the maximum rate of linuron is reduced to 950 g a.s./ha. /year. The same might apply to prosulfocarb.

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3. Prospects for alternatives for any foreseen major gaps in herbicide availability There are no major foreseen gaps in herbicide availability as a result of the 91/414 EEC review process to date although for some varieties, there is a concern that the need for tank-mixes of other active substances with linuron may cause difficulties within seed production – most are not approved. Prosulfocarb (first announced in 1987), a thiocarbamate from Syngenta is the most recent introduction. It has UK approval (2006) for cereals and for use in potatoes. Prosulfocarb controls only a limited range of grasses and broad-leaved weeds pre-emergence or early post-emergence, including black-grass, annual meadow-grass and cleavers. It is therefore recommended for use in tank-mixes to reinforce or supplement the activity of other herbicides metribuzin and linuron. Specialist potato agronomists consulted were not aware of any new herbicides at a late stage of development.

Pre-harvest haulm destruction It is standard practice to destroy the haulm of potato crops before harvesting. This is done chemically with desiccants or to a lesser extent by mechanical flailing. Efficiency of desiccation is affected by timing in relation to crop growth stage and by the type of cultivar. Impact/reasons: Haulm destruction pre-harvest is carried out in order to:

• kill weeds to facilitate mechanical harvesting. • encourage changes in the tuber (skin set) that give it some protection against damage and

disease entry. This is essential for tubers going into store and for some markets where the crop is sold directly from the field.

• to restrict and help manage tuber size. • reduce the spread of blight (Phytophthora infestans) and Erwinia spp. from foliage to tubers. • prevent aphid-borne virus in seed crops. • meet the quality requirements of the end markets.

Methods: Chemical desiccation is the most common method and is regarded as essential in seed crops, especially because of the critical requirements needed to control virus infection and to determine seed tuber size as accurately as possible. More than a single application may be necessary. Haulm destruction by specialised mechanical flailing machines is used to a limited extent in the UK although it would the conventional method for organic crops. Flailing may be used alone or in combination with chemical desiccants. Desiccants for potatoes The use of desiccants is dominated by the commodity product sulphuric acid and by diquat. CSL figures on sprayed ha for 2004 are 60,924 ha and 71,192 ha respectively in 2004. There were two other substances approved, namely glufosinate-ammonium (also used as a herbicide) and carfentrazone-ethyl, but use was minor compared to sulphuric acid and diquat (Table 2).

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Table 2. Potatoes: Desiccants approved 2006; Review status; Aim to re-register UK potatoes; Activity; Usage in 2004 on 142.953 ha of potatoes in GB (Source: CSL Pesticide Usage Survey, 2004) Desiccants approved 2006 Review status Aim to re-register

UK potatoes Activity Usage 2004

Spray ha Sulphuric acid Commodity List 4H √ inorganic acid 60,928 Diquat Annex 1 √ bipyridyl 71,192 Glufosinate-ammonium$ List 2 not decided phosphinic acid Pyraflufen-ethyl* New Annex 1 √ phenylpyrazole Carfentrazone-ethyl$ New Annex 1 √ triazolinone √ yes; * not seed potatoes; $ flail first on seed crops Sulphuric acid is a leading desiccant (particularly for seed potatoes in Scotland) for a number of reasons. Although expensive, requiring specialist equipment and normally contractor applied, sulphuric acid gives very rapid and reliable desiccation of foliage (and weeds), it has no soil moisture restrictions and is considered to be the least difficult means of controlling tuber size. In 2004, of the approximately 61,000 total sprayed ha 64% was used on seed potatoes. Use on ware potatoes has been declining but sulphuric acid is still regarded as the most appropriate desiccant for dense-canopied crops on wetter, heavier soils where mechanical haulm destruction would cause soil damage. Diquat has a similar level of usage to acid, but is considerably less popular for the Scottish seed crop. It has the advantage of not requiring specialist contractor equipment, but it cannot be used under dry conditions when the soil moisture deficits exceed a certain level (depending on soil and crop type) because there is a risk of tuber damage. Foliage desiccation is slower than with acid and diquat can be less effective under some conditions, particularly in vigorous immature crops. Glufosinate-ammonium can only be used on crops that are beginning to senesce and on seed potatoes the crop must be flailed first, a technique that is believed to increase tuber disease infection and it is therefore unattractive to seed producers. It can be used in dry conditions but not when the soil is exceptionally wet/saturated. Like glufosinate-ammonium, carfentrazone-ethyl is also used on a limited scale for haulm destruction and again has to be used in combination with flailing for seed crops. On ware crops it is normally applied as a second treatment (T2) after flailing or use of acid or another desiccant. It also has the disadvantage of not controlling grass weeds. However use of carfentrazone-ethyl is increasing on ware crops grown under purchaser protocols that prohibit sulphuric acid. Pyraflufen-ethyl is a new active substance on Annex 1 (product OS 159 marketed by Ceres Management Alliance Ltd. approved for desiccation in potatoes (not seed) 2006. 1. The likely impact of the 91/414/EEC review process on desiccant availability for UK potatoes Diquat, carfentrazone-ethyl and the new approved pyraflufen-ethyl are on Annex 1, whilst decisions on glufosinate-ammonium and sulphuric acid have not yet been made. Diquat is the leading desiccant on the world market for a range of crops, with production and sales dominated by a leading international agrochemical company, Syngenta. The company has indicated its intention to support re-registration in the UK. For these reasons and the dominant market share it has in the UK and elsewhere in Europe, problems of future availability are considered unlikely.

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The situation with sulphuric acid is very different and future availability is more uncertain and dependent on the EC review process. There is UK strong support in principle, from a consortium of 4 main manufacturers (National Sulphuric Acid Association) orchestrated under the auspices of the Chemical Industry Association (CIA). However, as a commodity chemical, the profit margins for manufacturers are small compared to those for specialist pesticides and their desiccant market share is likely to continue declining - usage was down 32% from 1994 to 2004). Continued support will depend very much on the cost of any necessary new data packages identified by the French rapporteurs (K Bull & L Sykes, pers. comm.). Sulphuric acid also suffers from an image problem in that it is highly corrosive, a registered poison and it is used in very large quantities. A number of the major retail purchasers have excluded it from their grower protocols for ware potatoes and this disaffection trend is likely to be contagious. There is also a 'critical mass' dimension. The bulk-handling requirement with specialised equipment and storage facilities means the provision of a spraying service is capital intensive for the contractor and will not be profitable below a certain minimum volume of demand. In 2004 sulphuric acid accounted for 36% of the total weight of active substances used, in GB, but for only 0.1% of the pesticide-treated area (CSL Pesticide Usage Survey, 2004). This was used almost entirely for the desiccation of approx. 61, 000 ha of potatoes. A cynical but plausible view expressed by a major Scottish spray contractor was that because of the very high quantities used, retailers and others would see this as an easy target to dramatically reduce pesticide usage. It will not have escaped the notice of antagonists that the UK and Ireland are the only EU states with approvals for sulphuric acid. Use on ware crops is on the decline as a result of retailer purchaser pressures and there are already many seed and ware producers managing without this desiccant. In the author's opinion the retailer factor alone is likely to lead to a situation where contractor services for the ware crop and the small seed crop in England may be withdrawn. Carfentrazone-ethyl will be supported for UK potatoes. The decision has not yet been made on re-registration of glufosinate-ammonium as a desiccant, but the relatively small usage and label constraints for potato desiccation suggests a vulnerability to rationalisation if significant costs are involved. 2. Specific desiccants it would be desirable to maintain from the agronomic perspective to avoid major difficulties For the reasons outlined previously, pre-harvest haulm destruction by chemical desiccation is now a very important part of most potato production on a commercial scale and it would be desirable not to lose any of the very limited range of desiccants available. Both diquat and sulphuric acid are considered to be essential for seed crops, especially the latter in the case of the Scottish seed producers. Diquat and carfentrazone -ethyl are probably the most important to keep for the ware crop now that purchaser protocols are reducing the demand for sulphuric acid. Pyraflufen-ethyl is a new desiccant (active from FeinChemie, marketed by Ceres Management Alliance Ltd.) approved for potatoes 2006. It is too soon to assess importance to the grower. Possible climate changes resulting in hotter drier summers and potential water shortages for irrigation underline the importance of alternatives to diquat, especially where retailer protocols prevent use of sulphuric acid or a contractor service is not available.

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3. Prospects for alternatives for any foreseen gaps in desiccant availability The possible loss of sulphuric acid could be covered in many circumstances by the substitution of diquat. This is the case for other European potato producers. However, any such loss would hit the high value Scottish seed production crop hard because sulphuric acid has a reputation of giving a technically superior performance on this crop under Scottish conditions compared with diquat. This is partly because crops mature later in the north and a very fast speed of haulm kill is needed to maximise of tuber disease control, which is particularly critical in a seed crop. Glufosinate-ammonium and carfentrazone-ethyl are generally not considered as suitable substitutes in this crop situation when used alone. However, there is an increasing adoption of using two or three treatments in sequence and these materials could have a place in a programme with diquat. Pyraflufen-ethyl is new and is not approved for seed crops, and it is too soon to assess its performance in commercial ware crops. As indicated earlier, there are restrictions for use of diquat under dry conditions. Whilst a high proportion of the crop is now grown under irrigation, water shortages could still prevent diquat use at the optimum time in a dry year and/or when high temperature/high wind conditions favour rapid transpiration. Moreover the Scottish seed growers may have less access to irrigation than the major ware crop areas in Eastern England. Failure to stop growth to control tuber size at the required time can have a critical impact on the crop value in both ware and seed production. Mechanical flailing is normally an alternative to chemical desiccation on lighter soils only. On heavier silt soils it can cause serious soil damage and compaction that in turn can result in serious problems with harvesting. At up to £100/ha it is also an expensive option and has serious disadvantages as described earlier. In actively growing crops, haulm can re-grow after flailing and a subsequent desiccant treatment will often be required to achieve more complete desiccation, or even burning with the use of tractor mounted propane gas equipment. Non-chemical haulm destruction is generally very much less efficient in terms of time, costs and disease control and can be considered very much more environmentally damaging in terms of emissions and energy use (especially where gas burners are used) and risks of soil damage and compaction. There are no indications of any new desiccants under development. Impact of the proposed regulation and revision of 91/414EEC

• Comparative assessment and substitution may lead to the substitution of more hazardous pesticides which contain an active substance listed in Annex 1D with alternative products which present significantly less risks to health or to the environment. This will take into consideration the chemical diversity of the active substances, which should be adequate to minimise the occurrence of resistance in the target organism.

The health and safety profile of sulphuric acid suggest if it is listed in Annex 1, it could be a contender for Annex 1D. If this transpired, the shorter registration period associated with this category could be a deterrent argin commodity product by manufacturers.

to support of a low m

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Pest Control in Potatoes

Pests of importance in potatoes are potato cyst nematode (PCN), migratory nematodes, transmitting spraing (Tobacco Rattle Virus), aphids (particularly in seed potatoes), wireworms, cutworms and slugs. Potato cyst nematode (Globodera rostochiensis and G pallida) This is the single most important and widely distributed pest of potatoes in the UK, affecting both yield and quality. Of the soils suitable for growing potatoes it is estimated that some 67% are infested with PCN, requiring the use of nematicides, even with the use of rotations of 1in 5 or 6. Despite the availability of a range of nematicides for PCN control the prevalence of this pest in the UK is increasing with a population shift to G. pallida, the more difficult to control of the two species. Impact: On most soils the potential yield loss caused by PCN in fields with even low or moderate infestations, averages 6 t/ha for every 10 'full' cysts/100g soil. A full cyst contains 50 or more eggs (Gratwick, 1992). In susceptible cultivars the effect of high PCN infestation without chemical control has been described as catastrophic. A recent Bayer sponsored survey (Anon., 2005) indicated that PCN cost the industry approximately £15m each year. Control: Most effective control is an integration of crop rotation, nematicides with tolerant and resistant varieties where appropriate. Chemical control is normally required for economic production, usually with the incorporation of nematicide granules. Nematicides currently approved are aldicarb, ethoprophos, oxamyl and fosthiazate and the soil injected nematicide, dichlorpropene (Table 3). Aldicarb has been the predominant chemical of choice as it is regarded as (but not proven to be) the most efficacious and cost effective. Essential use support documentation indicates figures of about 15,000 kg a.s. sold in 2003/04 for PCN control. Non-chemical control: Resistant and tolerant varieties, and long rotations complement chemical control but are not a substitute for nematicide use. Considerable research in alternative technologies is ongoing, including the use of a biological control method employing a solanaceous trap crop (to trigger egg hatching). A system using the trap crop Solanum sisymbrifolium is now commercially available (Greenvale & Bransoms) and marketed as Decyst or Foil-cyst Migratory/stubby root/ free-living nematodes (FLN) Species of stubby root nematodes (Trichodorus and Paratrichodorus) can transmit Tobacco Rattle Virus (TRV), which causes tuber symptoms known as spraing. Stubby root nematodes mainly occur on light sandy soils and the problem is therefore less widespread than PCN. Impact: FLN can reduce yield (poorly documented), but it is the necrotic marks in the tuber flesh that make tubers unacceptable for sale and they are impossible to grade out. TRV is particularly damaging to the potato cultivars favoured by the processing industry, and it is thought between 8 to 12% of this crop currently suffers damage. FLN and spraing tends to be less of a problem with the non-processing crop, which is grown more on other soil types, although nearly all of the early non-processing crops are grown on sandier soils. Control: Nematicides only give a reduction in spraing symptoms. Where fields have been identified with a high risk of spraing infection chemical treatment has to be combined with the use of varieties that are not spraing sensitive. However the most important processing varieties are particularly sensitive to spraing. The major nematicides currently used and approved for spraing reduction are aldicarb, oxamyl and fosthiazate. Dichloropropene gives some control of migratory nematodes but has no label claim for spraing control. Before 2005, oxamyl did not have high rate

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recommendation specifically for spraing suppression. Aldicarb is the industry standard and is generally regarded by many as the most effective of the nematicides available. Although solid evidence for this widely held belief is considered by specialist advisors to be limited, there is a natural reluctance to change products when control failure can result in a complete crop loss. Non-chemical control. As the spraing virus infests many common weeds, good weed control between potato crops may help. Most effective control again requires an integration of cultural methods, variety choice and use of nematicides. Reliable diagnostic tests are now available to identify the presence of TRV and to assess risk. Aphids In the UK the species most commonly found on potatoes are Macrosiphum euphorbiae (the potato aphid) and Myzus persicae (the peach potato aphid). Impact: Aphids can cause loss of yield either by direct feeding damage when aphids are present in large numbers or more seriously in seed crops, by the transmission of viruses such as leaf roll virus and potato virus Y. Crops grown from seed must be protected from aphids from emergence until haulm destruction. On ware crops aphids are now considered to be less important than was previously thought. The Assured Produce Protocol for potatoes (www.assuredproduce.co.uk) suggests that control of aphids on ware crops is unnecessary in most years and they need only be sprayed if numbers increase rapidly before the end of July. Recent ADAS work indicates spray threshold levels should also be raised (Parker, 2005). Control: There are currently eight different active substances approved for aphid control, including the recent addition of the neonicotinoid, thiacloprid (Table 3). Both aldicarb and (to a lesser extent), oxamyl, give a useful control of early aphids that enhances their value when used for nematode control. Aphid resistance to insecticides: Since the 1970's there have been increasing problems with resistance to insecticides in Myzus persicae. This virus vector species has now been identified with 3 different types of insecticide resistance known as esterase or E4, MACE and knockdown (Kdr). Recent aphid surveys show very high levels of M. persicae with Kdr resistance to pyrethroids whilst pirimicarb gives no control of MACE resistant aphids. There are now three newer insecticides that currently have no problems with any of these resistant mechanisms: pymetrozine, flonicamid and thiacloprid. These provide opportunity for alternation of products where more than a single spray is required in order to minimise the risk of further resistance development. Non-chemical control: Some varieties are less susceptible to feeding damage and the use of virus-free seed reduces the risk of virus spread in seed crops, but control measure still rely essentially on insecticide use. Hand-rogueing and particularly crop isolation are used in seed crops. Cutworms Cutworms are the larvae of noctuid moth species of which the most important is Agrotis segetum. Although attacks can be severe, incidence is infrequent and is usually confined to unirrigated, light-land soils. Impact: Feeding larvae in the tubers produce irregular holes which severely reduce tuber quality. Secondary damage may follow from pathogens or other insects. Control: is currently with chlorpyrifos and three pyrethroids (Table 3). However approval for the former was revoked in September 2005 and the use-up period expires at the end of September 2006.

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Only the pyrethroid component of the lamda-cyhalothrin/ pirimicarb formulation would have activity against cutworms. The HDC has developed a dynamic model to give optimum spray timings when pheromone traps warn of pest attacks. Non-chemical control: The risk of damage can be reduced by good weed control, but particularly by well-timed irrigation. Wireworms (Agriotes / Athous spp.) These are traditionally associated with planting into land within 4 years of a grass ley, especially in South West England. However there is now an increasing problem with 'arable wireworm' in crops following cereals over a much wider area, including the Eastern counties. Impact: Damage affects crop quality and very low levels (less than 5%) can preclude crops from most markets. Control: Chemical control is important because there are no resistant varieties and cultural control by avoiding the planting of potatoes within 4 years of a grass ley is of diminishing value because of the arable wireworm. There are only two insecticides currently approved; ethoprophos and fosthiazate (Table 3) and these can both give very poor control (D Hudson, pers. comm.). Non-chemical control: The most effective method is to avoid growing potatoes in infested fields, but finding such opportunities is increasingly difficult and there are no reliable means of identifying infested fields. Pheromone traps to help quantify adult click beetles are currently under evaluation. Repeated disturbance of the soil with cultivation can help, as can earlier harvesting before larvae start to actively feed on tubers in the late summer/early autumn. There is some SAC research evidence that iso-thiocyanates contained in certain cruciferous plants may be useful for the control of wireworms (R Clayton, pers. comm.). Molluscs Slugs (Arion hortensis and Milax spp.) can be a serious problem in crops grown on heavy cloddy soils. Impact: Tuber damage or its extent is difficult to predict, but can be limited by lifting the crop as early as possible. Control: Slug pellets broadcast over the rows can help to reduce damage. Test baiting is used to assess slug activity and may assist in the timing of pellet application. Molluscicides currently approved are methiocarb, metaldehyde and thiodicarb (Table 3). Non-chemical control: a variety of cultural methods can be used to help reduce slug populations such as site and variety selection, producing a fine tilth and lifting the crop as early as possible but these measures are not always practical options.

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Nematicides, insecticides and molluscicides for potatoes The current range of these pesticides available in the UK is shown in Table 3. Table 3. Nematicides, insecticides and molluscicides approved for potatoes 2006; Review status; Aim re-registration UK potatoes; Usage on approx. 143,000 ha grown in GB in 2004 ( Source: CSL Pesticide Usage Survey 2004)

Nematicides, insecticides and molluscicides 2006

Review status Aim re-registration UK potatoes


Nematicides / insecticides Aldicarb Essential use Expires 31 December 2007

Non inclusion

nematodes and aphids organophosphate 9,184

1,3-dichlorpropene List 2 - nematodes halogenated hydrocarbon

Flonicamid New pending √ aphids including resistant types carboxamide New Lambda-cyhalothrin Annex 1 √ aphids pyrethroid 64,658 Nicotine List 4C √ aphids alkaloid Rotenone List 4C √ aphids botanical Oxamyl# Annex 1 √ nematodes (and aphids) carbamoyloxime Pirimicarb Annex 1 √ aphids carbamate 90,277 Pymetrozine Annex 1 √ aphids including resistant types pyridine azomethine 21,207 Thiacloprid Annex 1 √ aphids including resistant types chloronicotinyl New Ethoprophos List 2 √ wireworms and nematodes. organophosphate Fosthiazate New Annex 1 √ wireworms and nematodes organophosphate Chlorpyrifos* Use by 30 September.2006

Annex 1 cutworms organophosphate

Cypermethrin Annex 1 - cutworms pyrethroid 13,552 Deltamethrin SOLA Annex 1 x Colorado beetle pyrethroid Zeta-cypermethrin List 3A √ cutworms pyrethroid 943 Lambda-cyhalothrin/pirimicarb Annex

1/Annex 1 √ / √ aphids and cutworms pyrethroid/carbamate

Molluscicides Metaldehyde List 3A √ slugs (specific) carbamate 66,849 Methiocarb List 2 not decided

UK, (√ N) slugs (some cutworm control) carbamate 68,908

Thiodicarb non-inclusion slugs

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carbamate 13,539 (includes

insect repellent)

- Company request confidentiality; √ yes; (√ N) re-registration N Europe; Nicotine & rotenone also an approved insecticides; * Use revoked September 2005; #not seed crops

1. The likely impacts of the 91/414/EEC review process on nematicides, insecticides and molluscicides availability for UK potatoes Losses The major area of concern to the industry in this sector is the loss after 2007 of aldicarb for PCN and particularly FLN, and spraing control. Aldicarb failed to achieve Annex 1 inclusion in the 91/414/EEC Review. An ‘Essential Use’ derogation was granted but expires in December 2007 (sale and supply must cease by 30 June 2007). The very limited range of wireworm insecticides also requires consideration, although no losses are anticipated at present.

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Impact PCN is the most important pest of potatoes as described earlier. The industry standard for control has been aldicarb but this will be unavailable to potato growers for use after 2007. Aldicarb was also the leading nematicide for the control of the less widespread problem of migratory nematodes and the suppression of spraing transmitted by these vectors. The case for the retention has been set out in the documentation submitted to seek derogation (Information Report on Essential Uses www.pesticides.gov.uk). This case was made when there was uncertainty about Annex 1 listing for the two alternative granular formulations, oxamyl and fosthiazate. However these two nematicides are now listed, providing more confidence in their future availability and chances of re-registration in the UK. Moreover, both oxamyl and fosthiazate now have an additional label approval for reduction of spraing in addition to use for PCN, giving fosthiazate and oxamyl, the same range of nematicide use approval as aldicarb. In addition to oxamyl and fosthiazate there are two other nematicides for PCN control: 1,3-dichloropropene and ethoprophos, although the former is a soil fumigant requiring specialist contractor application and is a very expensive and problematic treatment. A strong point made for aldicarb in the case presented to the EU to obtain Essential Use derogation was the serious cost penalty that would be incurred by the industry in substituting oxamyl, which is intrinsically less effective on both nematodes and aphids in terms of rate of a.s. /ha. This applied particularly to the control of FLN and spraing control where oxamyl was considerably more expensive. A Bayer sponsored survey of the industry in 2005 (Anon., 2005) indicated that growers and potato agronomists seriously lacked confidence in the capacity of alternative nematicides to match the performance of aldicarb, especially for the control of FLN and spraing in the sensitive but popular processing varieties grown on susceptible soils. This survey used economic modelling to predict that if FLN could not be properly controlled, then there would be a massive reduction in UK potato production of c. 149,000 tonnes, import substitution, a loss of over £50m in retail terms of production in the UK and nearly a 1000 job losses. The view of an independent, specialist potato consultant was that the arguments in this document were very weak and not substantiated for either PCN or FLN. DuPont have recently carried out development work with oxamyl, claiming comparable control of FLN and spraing suppression at their rate of 210 g product/100m furrow to the aldicarb rate of 128 g product/100m of furrow. At the time of writing it has not been possible to access this data although there is no reason to doubt it, as it would have been required to support the new approval. Bayer were also unable to provide any trials results comparing the new higher rate of oxamyl with aldicarb for spraing suppression on the grounds that recent work had yielded insufficient data. The new oxamyl rate is now a label recommendation. DuPont have also adjusted their product pricing so these two rates are now roughly equivalent in cost. As indicated earlier, Syngenta also now have a label recommendation for use of fosthiazate to control FLN and suppress spraing. Ongoing research (LINK) is evaluating drip irrigation technology as a delivery system for the improved targeting and control of nematodes in potatoes with oxamyl. This may have the potential to enhance cost efficiency for this nematicide. The impact of aldicarb loss cannot be assessed objectively until this actually happens after 2007. A very good indication should be available during 2007 because the use of aldicarb is likely to be minimal next year (see below). There are portents of the likely scenario. The industry is currently adjusting to the impending loss, and aldicarb sales for PCN control in potatoes are reportedly reduced considerably already,

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especially in the non-processing sector. There is a widespread antipathy to aldicarb by the major retailer purchaser companies of fresh ware potatoes. At least three of the largest companies have protocols that restrict aldicarb use to FLN/spraing control only (i.e. not for PCN control), and two others do not permit any use. It appears that the non-processing part of the industry, representing some 50% of potato production (but where FLN and spraing affects a smaller potato area), has accepted the move from aldicarb with minimal impact, although many involved will need a further year or more of using alternative nematicides to be confident of the change. DuPont claims they now have 80% of the nematicide market on ware potatoes in Scotland, almost exclusively for the control of FLN/spraing suppression (N Beadle, pers. comm.). The main use of aldicarb is now considered to be largely in the processing crop where there has been particular industry concern at moving away from aldicarb for FLN and spraing control. This is in the context of a higher proportion of lighter soils where FLN/ spraing are prevalent and where sensitive cultivars such as Pentland Dell and Russett Burbank in particular predominate. There is a consensus in the industry that use of aldicarb in 2007 will be minimal because of residue concerns for tubers stored into 2008 and treatment records that buyers may interpret as the crop having been treated with an illegal substance. Although residues very rarely occur and the MRL would in any case be valid for crops treated legally in 2007, the perception is unlikely to change. In effect, aldicarb is being phased out of use by the industry in 2006. Two potato consultants have stated there is strong evidence to show there is no difference between granular nematicides for PCN control and consider the impact of the loss of aldicarb for this sector is likely to be minimal. However this is contentious and other consultants disagree. There is wide agreement that the evidence and commercial experience of oxamyl and fosthiazate for control of spraing and/or FLN control is still limited. It will not be until after wide substitution in 2007 and acceptable field performance, that the processing industry in particular be confident in the change, and judgement on impact cannot be assessed until then. Overall, it now appears there is a reasonable chance the demise of aldicarb will have very much less impact on crop agronomy and costs than was previously thought. Future losses? Wireworms. The concern in the case of wireworms is that there are only two insecticides approved for control, ethoprophos and fosthiazate. Both have the support of major agrochemical companies and have much larger markets for PCN control suggesting reasonable prospects for continued availability. The loss of either product would create a monopoly situation. Reliance on one essential chemical for the control of this important pest would cause concerns on future resistance strategies, price and availability. Nicotine (List 4) has so far been supported in the review, although it may be that the package is insufficient. The view of the industry was sought in late May 2006 on the importance of nicotine and if support were withdrawn, would there be a need for an ‘Essential Use’ derogation? Nicotine usage in potatoes is not identified separately in the CSL Pesticide Usage Surveys indicating only very minor usage. There is a possibility to extend the use of nicotine as an ‘Essential Use’ derogation if there is a very clear need for it to be available in the short term. A case has been made to PSD (D Richardson) and Essential Uses will be sought. Molluscicides are widely used in potatoes. Thiodicarb failed Annex 1 inclusion, and there is no decision yet on the alternative molluscicides metaldehyde (List 3A) and methiocarb (List 2).

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2. Specific nematicides, insecticides, molluscicides or groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties It would be desirable to maintain the following: For PCN and spraing vector control the continued availability of the nematicides fosthiazate and oxamyl is considered crucial. It would also be desirable to maintain the availability of 1,3-dichloropropene, which has a different mode of action from the two carbamates. There is a strong view in the industry that it would be prudent to permit the use of aldicarb for a further period until there is widespread agreement that FLN and spraing control with oxamyl and fosthiazate is acceptable. The nematicides, fosthiazate and ethoprophos are also considered crucial as the only two products approved for wireworms. Although an infrequent pest, the approved pyrethroids are important as the only insecticides that will be available for cutworm control after the loss of chlorpyrifos for ware potatoes in 2006. There are concerns that climate change may increase the frequency of cutworm-favourable conditions. Resistance management for Myzus persicae control is crucial and requires a range of different insecticides with distinctly different modes of action. The newer insecticides flonicamid, pymetrozine and thiacloprid are particularly valuable in this context as they have no resistance problems yet. It will be desirable to maintain pirimicarb (despite problems with MACE and E4 resistance in some populations) because of its particularly high selectivity in situations where natural aphid predators are present. At least one molluscicide is needed and it would be desirable to maintain both metaldehyde and methiocarb. The latter has the added advantage of providing some control of cutworms. However methiocarb has a maximum application rate per hectare that many growers find inadequate. In such situations the availability of another molluscicide facilitates a follow up treatment. 3. Prospects for alternatives for any foreseen major gaps in nematicide, insecticide and molluscicide availability Alternatives As has been described, the one potential major gap resulting from the 91/414 EEC review process would occur if the alternative nematicides that are now approved for FLN and spraing control fail to perform as well as aldicarb when they are used on a wide commercial scale. There is however a reasonable expectation this will not be the case. There are no indications of any new nematicides becoming commercially available in the short to medium term.

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However, considerable research in alternative technologies is ongoing, including the use of a biological control method employing a solanaceous trap crop to trigger egg hatching. A system using trap crop Solanum sisymbrifolium is now commercially available (Greenvale & Bransoms) and marketed as Decyst or Foil-cyst. Whilst not related to legislation, it was reported in the course of this study that the existing wireworm and slug control substances regularly give growers very inadequate control.

Disease control for potatoes Blight (Phytophthora infestans) Late potato blight is by far the most serious threat to commercial potato production, requiring multiple applications of foliar fungicides on practically all crops every year. Recent studies indicate that the aggressiveness of blight populations has increased as a result of new strains emigrating here from other countries (Bradshaw & Bain, 2005). Impact: The disease can have a drastic effect on yield by causing premature defoliation of the crop and by transmission of the disease to tubers (tuber blight). Bradshaw in a recent paper (Bradshaw & Bain, 2005) cited previous work reporting yield losses of up to 50% depending on the timing of the disease in relation to crop development. Control: A programme of routine fungicide sprays is essential and will continue to be the method of control for the foreseeable future. Decision support systems can accurately predict blight timing and have the potential to reduce the number of sprays per season. Non-chemical control. Although a range of commercial potato cultivars is available with varying degrees of resistance as shown in the BPC IVT listings, this is only of value to the extent of potentially reducing the amount and frequency of fungicide use. Moreover the most popular cultivars are more susceptible to blight and the planted area of these varieties has increased considerably over recent years. Genetic resistance can be unstable with the appearance of new blight strains. Blight fungicides Fungicides currently approved for late blight are listed in Table 4. There is an extensive range of over 20 different active substances currently approved for blight control. A high proportion of these are in formulated mixtures and there is a history of new actives being regularly added to the list. Table 4 shows the market is currently dominated by cymoxanil/mancozeb (41,7871 sprayed ha) and fluazinam (322,043 sprayed ha, but cyazofamid, dimethomorph/mancozeb, various dithiocarbamates (e.g. mancozeb) and cymoxanil/famoxadone also account for very large sprayed areas. In 2004 just cymoxanil/mancozeb (mixture) and fluazinam alone accounted for ca. 50% of all the sprayed hectarage of fungicides in potatoes.

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Table 4. Fungicides approved for late blight control in potatoes; Review status; Aim re-registration UK potatoes; Activity and usage on approx. 143,000 ha grown in GB in 2004 (Source CSL Pesticide Usage Survey 2004) Blight fungicides 2006 Review status Aim re-

registration UK potatoes


Benthiavalicarb-isopropyl/mancozeb New pending √ valinamide/dithiocarbamate New Copper products List 3A √ copper Chlorothalonil Annex 1 √ chlorophenyl 18,121 Chlorothalonil/mancozeb Annex 1/Annex 1 √ chlorophenyl/dithiocarbamate Cyazofamid Annex 1 √ cyanoimidazole-sulfonamide 133,257 Cymoxanil List 3B √ urea Cymoxanil/famoxadone List 3B/Annex 1 √ urea/ strobilurin 71,283 Cymoxanil/mancozeb List 3B/Annex 1 √ urea 417,871 Cymoxanil/chlorothalonil List 3B/Annex 1 √ urea Dimethomorph/mancozeb List 2/Annex 1 - cinnamic acid 88,695 EBDC (various dithiocarbamates) Annex 1 (mancozeb) - dithiocarbamates (mancozeb)87,200 Fenamidone/mancozeb New Annex 1/Annex 1 √ strobilurin/dithiocarbamate New Fenamidone/propamocarb hydrochloride New Annex 1/List 2 √ strobilurin / carbamate New

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Fluazinam List 3A √ pyridinamine 322,043 Fluopicolide/propamocarb hydrochloride New pending/List 2 √ acylpicolide#/carbamate Benalaxyl/mancozeb Annex 1/Annex 1 √* / √ phenylamide/dithiocarbamate Metalaxyl-M/mancozeb New Annex 1/Annex 1 √ / √ phenylamide/dithiocarbamate 45,200 Metalaxyl-M/fluazinam New Annex 1/List 3A √ / √ phenylamide Propamocarb hydrochloride/mancozeb List 2/Annex 1 not decided carbamates Propamocarb hydrochloride/chlorothalonil List 2/Annex 1 not decided carbamate/chlorophenyl Zoxamide/mancozeb New Annex 1/ Annex 1 - benzamide/dithiocarbamate 63,810 - Company request confidentiality; √ yes; * eventually to be replaced by curalaxyl (new pending); # new MoA; propineb approved but not marketed 1.The likely impact of the 91/414/EEC review process on blight fungicide availability for UK potatoes Losses The only active substances of significance to have been lost in this sector are the fentin (tin) products. At the time this was considered by some to be a major loss to the industry because of their strength in controlling potato tuber infection in the mature crop. In fact this has not been the case because of the availability of alternatives, including new products with novel chemistry, affording good tuber blight control (Bradshaw & Bain, 2005). Examples are fluazinam, which is a standard part of the mid- and late-season spray programme recommended by leading specialists because of its good zoospore and soil activity in reducing tuber blight. Recent BPC funded trials comparing a range of blight fungicides showed the lowest level of tuber infestation were where cyazofamid, fluazinam and dimethomorph/mancozeb were used as late season sprays (Bradshaw & Bain, 2005). Future losses? It is difficult to judge the likely impact of the review process on blight fungicide availability for the UK potato crop because some of the key substances do not yet have Annex 1 inclusion. Dose rates and number of applications and timings may be reduced at re-registration stage when and if Annex 1 listing is achieved and this may have an impact on efficacy. There could be losses of approved products and on-label uses as companies rationalise their product ranges. However with an armoury of over twenty different active substances approved and the regular introduction of new fungicides some losses could probably be absorbed with minimal impact.

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2. Specific blight fungicides or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties With the extreme importance of blight as the major disease of potatoes it is crucial to maintain a wide range of substances with different modes of action. This is not only to minimise the risk of fungicide resistance but also to provide the different types of activity required at different stages of crop growth in order to maximise disease control. Any list of desirable chemicals to retain is somewhat arbitrary. However based on the above considerations it is suggested a minimum list of essential blight fungicide active substances should include the following: mancozeb alone and in mixtures

Resistance prevention (multi-site activity) especially as a component of mixtures with systemic fungicides. Also very cost effective alone.

fluazinam Good foliar and tuber blight control. Second most used active. cymoxanil mixtures One of the most cost effective and widely used groups. Cymoxanil/

mancozeb used on 85% of ware and 75% of seed area grown. Has eradicant 'kickback' activity and a long history of use without resistance problems.

metalaxyl-M mixtures Has systemic activity - valuable during early season periods of rapid growth.

propamocarb mixtures Systemic but non-phenylamine type (resistance prevention) cyazofamid Highly effective under late-season high disease pressure. Strong tuber

blight protection. 3. Prospects for alternatives for any foreseen major gaps in blight fungicide availability Alternatives With the very wide range of chemistry and products available, no gaps were identified. New fungicides continue to be introduced. Syngenta's mandipropamid is reported as very promising and could be approved and commercially available in 2007. Potato blight control benefits from the importance of grapevine diseases as a primary screen for research based agrochemical companies where fungicides for that crop are often suitable for potatoes also.

Seed and soil borne disease controlled by seed or ware tuber treatments Seed potatoes and harvested ware crop tubers suffer from a very wide range of diseases. Important diseases that can be controlled with fungicides include: Stem canker/black scurf (Rhizoctonia solani) Dry rot (Fusarium spp.) Silver scurf (Helminthosporium solani) Black dot (Colletotrichum coccodes) Skin spot (Polyscytalum pustulans) Gangrene (Phoma exigua)

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Details of all the differing specific disease symptoms, impacts and control measure are too extensive and complex to describe in a review of this nature. Such information is readily available in standard references such as the Assured Produce Protocol and the BPC website (www.potato.org.uk). Many of these diseases can have a major impact on the all important quality factor of skin finish. This can be absolutely critical for the price received for a crop. Good skin disease control can make the difference between an £85+/t quality ware crop and £10/t stock-feed. The prevalence of such diseases is illustrated by a LINK funded survey completed in 2000 which found 59 % of crops infected with black scurf, 56% infected with black dot and 72% infected with stem canker. (LINK Project Report 1993-2000 No HP0123T; www.defra.gov.uk

) Resistance of potato varieties to diseases was recently reviewed by Thomas et al., (2005). None of the new cultivars showed a high level of resistance to black dot, black scurf or silver scurf. However several of the new varieties, for example Paramount, were consistently more resistant to skin spot, and resistance was reported to be relatively stable over a three-year testing period. Fungicides for seed and soil-borne diseases The most significant diseases that can be controlled with fungicides and the fungicides approved are given in Table 5. Application timing varies with the different chemicals: post-harvest, at dressing or applied at the time of planting/pre-planting. A more recent addition to this list is azoxystrobin that is now approved for black dot and black scurf control by soil application. (Annex 1 listed). However azoxystrobin is only approved for use on seed for ware production, not on seed for seed production. Thiabendazole and imazalil are the only two fungicides approved for treatment of ware potatoes going into store. There is known resistance to thiabendazole and probably with imazalil but this appears to have been contained by the use of imazalil/thiabendazole formulated mixture. When used on ware potatoes, both active substances leave residues that are unacceptable to some ware purchasers. CSL statistics for the whole of GB show that 35% of the 372,762 t of seed potatoes were treated with storage fungicides in 2004. Of the treated tonnage, 91%, 7% and 2% were treated with imazalil, thiabendazole and 2-aminobutane (2-AB) respectively. In Scotland (producing more than 80% of seed potatoes in the UK), 40% of the seed crop was treated with fungicides in 2004 and of this only 1% was treated with 2-aminobutane (SASA Pesticide usage in Scotland. Potato stores 2004. www.sasa.gov.uk

). The total tonnage of seed potatoes treated with fungicides in GB declined markedly by 25% between 2002 and 2004. The total weight of ware potatoes stored from the 2004 harvest was just over 4 million tonnes and the CSL survey estimated that nearly half (48%) received no chemical storage treatment atall.

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Table 5. Fungicides approved for tuber-borne disease control in seed potatoes; Aim to re-register UK potatoes; diseases controlled; Activity; Usage on seed potatoes as % of total tonnage treated with fungicides (Source CSL Usage Survey Potato Stores in GB, 2004)

Fungicides 2006 Review status Aim re-registration UK potatoes

Disease Activity % of seed

treated 2-Aminobutane Essential use until 31 Dec 07

Non-inclusion skin spot, gangrene alkylamine 2

Azoxystrobin (seed for ware production only)

Annex 1 √ black dot black scurf strobilurin

Flutolanil List 3A √ black scurf and stem canker (Rhizoctonia) anilide oxathiin Imazalil* Annex 1 √ done gangrene, dry rot, silver scurf, skin spot (not

Rhizoctonia) conazole 91

Imazalil/thiabendazole* Annex 1/Annex 1 √ dry rot, gangrene, silver scurf, skin spot, stem canker

Iprodione Annex 1 - black scurf and stem canker dicarboximide Pencycuron List 3A not decided black scurf and stem canker urea Pencycuron/imazalil List 3A/Annex 1 not decided silver scurf (applied planting/pre-planting) urea/conazole Thiabendazole* Annex 1 √ silver scurf, dry rot, gangrene, skin spot,

black scurf and stem canker benzimidazole 7

Toclofos-methyl List 2 √ black scurf and stem canker organophosphate *also approved for use on ware potatoes; - Company request confidentiality; √ yes 1. Likely impacts of the 91/414/EEC review process on seed and soil borne disease control fungicides available for UK potatoes Losses The major concern expressed for this specialist sector was the loss of 2-aminobutane (2AB) after the expiry of the ‘Essential Use’ derogation in 2007. This is for the control of skin spot (Polyscytalum pustulans), although 2AB also controls gangrene (Phoma exigua). Skin spot damages the eyes on a seed crop and it is therefore essential to control the disease when present. Infected seed will lead to disease in the ware crop produced from the seed, which has a major impact on quality and acceptability of the crop. Peroxyacetic acid (List 4), approved in the UK to control pathogens on potato tubers pre-planting, has not been supported and use will subsequently cease. Peroxyacetic acid offers a large contribution to disease control and resistance management strategies (R Clayton, BPC, pers. comm.). The industry was consulted in May 2006 about the importance of peroxyacetic acid. There is a possibility to extend the use of peroxyacetic acid as an ‘Essential Use’ derogation if there is a very clear need for it to be available in the short term. A case has been made to PSD and an Essential Use will be sought. Impact The major commercial variety, King Edward, is especially susceptible to skin spot. A unique feature is that 2AB is the only fumigant formulation used to treat potatoes grown for seed. The fumes penetrate dust and soil on the seed surface and it is thus very effective. It also has the advantage of facilitating early treatment after harvest and storage without further handling. With alternative fungicides such as imazalil, treatment is often delayed until after the seed comes out of store and the disease would have had the chance to develop and penetrate the surface cells. In seasons when the crop is lifted wet and soil coverage is high, 2AB is the only chemical that works in these conditions. However this application method requires the use of contractor application in special stores that can

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be sealed. This factor, perhaps together with the broader spectrum of control offered by imazalil (plus silver scurf and dry rot) and because 2-aminobutane is no longer approved for use in ware potatoes or mixed ware/seed crops, may help explain declining use of 2-aminobutane even in 2004, a wet year. Use of 2-aminobutane may now be confined to seed for export - an important market. Possible consequences of 2-aminobutane loss have been discussed with several industry specialists: Rob Clayton BPC, Stuart Carnegie of the Scottish Agricultural Science Agency (SASA), David Hudson, an independent consultant and Peter Harkett, Chief Agronomist of McCain. The impacts are regarded as very difficult to assess objectively until after 2007 when 2AB is no longer available to the industry. There was no consensus, but Rob Clayton gives a possible scenario:

• An increase in the incidence of the disease associated with the substitution of alternative chemicals such as imazalil, which are known to be less effective, particularly because of the difficulty of achieving correct loading rates and good coverage under commercial conditions. There is anecdotal evidence of increasing disease prevalence coinciding with the decline in 2AB use at the early stages of the seed multiplication process.

• Considerable extra capital investment by growers and processors in equipment and stores is needed to implement more integrated control strategies.

• More cost for processors from the high peelings wastage associated with skin spot infection.

The disease penetrates the skin to 6 - 7 mm that results in 3 - 4 % loss of volume in a crop for processing. In practice crops with significant skin spot are likely to be rejected, rather than re-adjusting peeling procedures in a production line.

• A need to substitute alternative less susceptible, but less market acceptable cultivars in place

of the sensitive King Edward variety. This could have a detrimental effect on prices because of the strong brand image value of King Edwards as a major commercial variety.

• A higher risk of disease resistance development from the increased selection pressure placed

on imazalil and a compromisation of resistance strategies.

• Increased use of chemical sprout suppressants as an unintended consequence of using higher temperatures in store to inhibit disease development.

A contrary view expressed strongly by David Hudson is that the very low usage of 2AB on seed crops described earlier (only 1% of the 40% of the crop treated in Scotland with any fungicide) actually reflects a much lower background level of the disease as a result of substantial and improved practices in seed crop management in recent years. These include:

• Growing on more favourable lighter soils and locations that facilitate earlier harvesting with

less time for any disease to develop. • More dedicated seed crops that are lifted earlier than a mixed seed/ware crop.

• More attention to proper curing and improved stores with better ventilation.

• A reduction in the multiplication time period for seed stock from 7-10 years to 3-4 years

giving less chance for any infection to build up before ware use.

• A consolidation of the seed growing industry with a smaller number of more technically advanced growers adopting integrated control measures to minimise the risk of infection.

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2. Specific fungicides or fungicide groups for treatment of seed and soil borne diseases that it will be desirable to maintain from the agronomic perspective to avoid major difficulties Retention of imazalil would be desirable as the most important treatment for both seed and ware disease control. With the limited range of other fungicides available in this sector is also considered desirable to retain thiabendazole, iprodione and azoxystrobin to provide different modes of action for disease resistance management. This would be mainly for the seed and processing sectors since these fungicides are not used at all in the pre-packing market. 3. Prospects for alternatives for any foreseen major gaps in fungicides for seed and soil borne diseases The only foreseen gap is for skin spot control in seed potatoes, where alternative fungicides are generally less effective. This applies especially on crops harvested under difficult wet conditions when alternative fungicides are ineffective. There is some concern about the lack of alternative chemistry to imazazil and thiabendazole as storage fungicides in ware potatoes. However as indicated earlier, the pre-packing industry has not used these actives for over five years without too many problems, including storage at 2.5°C of very skin spot susceptible varieties. Alternatives Skin spot is only a significant problem in the UK and Scandinavia so it is improbable agrochemical companies would be screening chemicals for that use. The efficacy of alternative chemicals continues to be evaluated in SAC trials sponsored by the BPC www.potato.org (Hilton & Wale, 2006). There are some compounds showing activity in these early screening trials, e.g. boscalid/pyraclostrobin, but there are no alternative new chemicals to 2AB likely to be available in the near future. BPC have invested heavily in developing alternative control strategies for skin spot and the emphasis is now on an integrated approach to disease management, involving improved seed stock selection, better store hygiene, early crop harvest, improved curing techniques and improved chemical application methods for the alternative chemicals plus the use of resistant varieties. This approach offers good prospects in some areas more than others. Early harvesting for example is not always practical and may adversely affect yields. Other aspects involve very considerable capital investment in new equipment and stores but these are not options for all growers. Off–label Approvals based on Mutual Recognition of approvals (although none are known) in Member States in the same zone may be possible for a minor crop such as seed potatoes, of area less than 50,000 ha. There must be an extant on-label approval for the use of the same product on another crop in the UK.

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Growth regulators

Growth regulators chemicals are used for two purposes; sprout suppression of ware potatoes in store and to provide some degree of control of volunteers (groundkeepers) from potatoes that remain in the field after harvesting. Sprout suppression The period of dormancy that follows harvesting of mature tubers varies considerably depending on factors such as variety, degree of mechanical damage, tuber infection and particularly store temperature. All potatoes going into store for any significant period will normally need some chemical or other means of suppressing sprout development. Impact: Sprouting of potatoes has a number of detrimental consequences on crop value. There is a loss of marketable weight through transpiration, softening of the tissues, shrinking, poor fry colours and a reduction in nutritive value. Losses in marketable weight can be as high as 10% and quality is severely compromised. Control: The standard methods of suppressing sprout growth are with growth regulator chemicals and/or low temperature stores. However, low temperature storage is unsuitable for processing crops because it affects the cooking quality. Low temperature storage can also increases the risk of certain diseases. Chemical growth regulators as sprout suppressants are therefore predominantly used in processed crops. With fresh produce stored at low temperatures, suppressants may still play a role to supplement low temperature. However there is an issue of residues (except from ethylene) and storage chemicals are not acceptable to some retailers despite correct application procedures leaving residues within the maximum residue limits. As indicated earlier in this report, there is increasing pressure from retailers to avoid the use of any storage chemical for fresh potatoes. In processing crops that have to be stored for any significant period, use of chemical suppressants is difficult to avoid although a carefully managed integrated approach can minimise the need. Non-chemical sprout control; as indicated, the main alternative is the use of low temperature stores, but these are only suitable for non-processing crops. Whilst chemical suppressants may sometimes be needed to supplement cold temperatures, in most seasons it is possible, to avoid chemical use altogether. This is by use of an integrated approach of variety choice, timing of sale, harvest and store management strategy. Growth regulators for sprout control There are currently three chemicals used to suppress sprouts approved in the UK: chlorpropham (CIPC), maleic hydrazide and ethylene (Table 6). Ethylene acts by modifying the storage atmosphere. The CSL survey for potato stores in GB (2004) shows that of the ca. 2 million tonnes of ware potatoes treated, 95% was treated with chlorpropham and just 1.4% with ethylene (Table 6). No figures are given for maleic hydrazide which is known to be little used, because it penetrates the skin and tends to leave relatively higher levels of residues, which are not readily removed by washing and peeling. These are always within the MRL but are not acceptable to many retail purchasers.

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Ethylene potato store treatment systems are now commercially available. However, they are confined to use in low temperature non-processing potato stores because of concerns regarding fry-quality effects. There is some Canadian research work indicating possible use in processing potato stores under a special application regime (D Hudson, pers. comm.). Use of ethylene in potato stores is still very much on a limited scale because the systems are not yet fully proven.

Table 6. Sprout suppressants approved for potatoes 2006; Review status; Aim to re-register for UK potatoes; Activity; % usage of different sprout suppressants on the 2.1 million tonnes of ware potatoes treated with all chemicals (Source CSL Usage Survey: Potato stores in GB, 2004) Suppressants approved 2006

Review status Aim re-register for UK potatoes

Activity % of ware treated

chloropropham (CIPC) Annex 1 √ carbamate 95 Ethylene Commodity List 4G √ ethylene 1.4 Maleic hydrazide Annex 1 √ pyridazinone √ Yes Volunteer suppression by foliar application of maleic hydrazide Volunteer potatoes resulting from unharvested tubers are a major problem in succeeding crops. Maleic hydrazide sprayed onto the haulm when it is still actively growing can be a useful part of an integrated programme for the control of volunteers in ware crops. However some retailer protocols prohibit this use and performance tends to be unreliable. 1. The likely impacts of the 91/414/EEC review process on growth regulators availability for UK potatoes Losses The Approval of tecnazene was revoked in the early stage of the review but with the availability of alternative chemicals, this had negligible impact. Both chlorpropham and maleic hydrazide have achieved Annex 1 listing. The decision on Annex 1 listing of ethylene (List 4) is still pending, but this commodity chemical is being supported. In addition all the Crop Protection Companies concerned have indicated they intend to apply for re-registration for the approved uses on potatoes (Table 6). 2. Specific growth regulator and regulator groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties It is considered essential to maintain chlorpropham and ethylene .It would, however be the preferred to retain all three currently approved growth regulators for the reasons given:

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Chlorpropham (CIPC)

Most widely used product. The relatively low residues are almost entirely restricted to the skin and can be removed by washing and peeling. Essential for processing crop as there are no fully acceptable alternatives available at present. Ease of application by fogging.

Maleic hydrazide Provides an alternative to chlorpropham for the processed crop in stores that are unsuitable for fogging. It has limited usage because it penetrates potato flesh and leaves relatively high residues that are unacceptable to some retailers. However, this is currently the only proven alternative to CIPC. Although there are other means of control, applied in the field, it can be a useful tool as part of an integrated strategy for controlling the major problem of volunteer potatoes.

Ethylene Crucial advantage in that treated produce is residue-free and it can be used in low temperature stores for non-processing crop. Further development required. Unsuitable for processed crop at present.

3. Prospects for alternatives for any foreseen major gaps in growth regulator availability No foreseen major gaps were identified in this study. Maleic hydrazide use in the field is only part of an integrated programme for volunteer potato control. Maleic hydrazide use is precluded by some crop protocols, but there is a growing concern that in milder winters, frost damage, a natural part of integrated volunteer control, is becoming less frequent. There is a view that maleic hydrazide is not essential, but others disagree however, and an alternative is being sought. Syngenta are reported to be evaluating trinexapac-ethyl for use as a sprout suppressant, but if this leaves significant residues it would have the same market acceptability problems as maleic hydrazide.

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REFERENCES ANDERSON HM, GARTHWAITE & THOMAS, MR (2005) Potato Stores in Great Britain 2004.

Pesticide Usage Survey Report 205. Central Science Laboratory, Sand Hutton, York, UK. http://www.csl.gov.uk

ANON. (2005) The economic case for the continuing availability of Temik for the UK potato market. Bayer internal report on restricted access (available to PSD). ASSURED PRODUCE (2006) Crop Specific protocols potatoes. Control document No. 00043/06. http://www.assuredproduce.co.uk BRADSHAW NJ, BAIN RA (2005) Potato blight control - is a sustainable approach a realistic option? Aspects of Applied Biology 76, Production and Protection of Sugar Beet

and Potatoes, 183 - 190. GUNN JS (1990) Crop Protection Handbook - Potatoes. Ed. JS Gunn. BCPC, Bracknell, UK. GARTHWAITE DG, THOMAS MR, ANDERSON H & STODDART H (2005) Arable Crops in

Great Britain 2004. Pesticide Usage Survey Report 202. Central Science Laboratory, Sand Hutton,York,UK. http://www.csl.gov.uk

GRATWICK M (1992) Crop pests in the UK. Ed. M Gratwick. Chapman and Hall, London, UK. HILTON A & WALE S (2006) To evaluate novel and existing fungicide seed tuber treatment

applied just prior to planting for the control of skin spot. http://www.potato.org.ukKNOTT CM (2002) Weed control in arable and field vegetable crops. In: BCPC Weed

Management Handbook, 359 - 398. Ed. R L Naylor. Blackwell Science Ltd, Oxford. UK. NIX J (2005) Farm Management Pocketbook 33rd edition 2006. Imperial College Wye,

Andersons Centre, Melton Mowbray, UK. PARKER WE (2005) The direct feeding effects of aphids (Macrosiphum euphorbiae and

Myzus persicae) on the yield of potato crops in the UK. Aspects of Applied Biology 76, Production and Protection of Sugar Beet and Potatoes, 167-174.

Information Report on Essential Uses. Http://www.pesticides.gov.uk STOREY RMJ ( 2006) Challenges to sustainable potato production in Great Britain. Aspects of

Applied Biology 76, Production and Protection of Sugar Beet and Potatoes, 105-107. STRUTHERS G (2005) Pesticide use in Scotland. Potato stores 2004. Scottish Agricultural Science

Agency, Edinburgh, UK. http:/www.sasa.gov.uk THOMAS JE, GANS PT, & KENYON DM (2005) Resistance to disease in commercial potato

cultivars and its use in disease management. Aspects of Applied Biology, 76, Production and Protection of Sugar Beet and Potatoes, 121-126.

LINK Project Report 1993-2000 No. HP0123T. Http://www.defra.gov.uk

ACKNOWLEDGEMENTS The help and contributions from Rob Clayton and Mike Storey of the British Potato Council, David Hudson of David Hudson Potato Services, Stuart Carnegie of SASA, Peter Harkett of McCain Foods Ltd., Les Sykes of Frontier Agriculture Ltd., Chris Ursell of CU Consulting, Martin Gibbard of MG Consulting and staff of several of the major crop protection companies are gratefully acknowledged.

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Arable Crops FIELD PEAS and BEANS

Recommendations for the crop are based on information from research funded by the Processors and Growers Research Organisation (PGRO) levy. A levy of 50p per tonne plus VAT is collected from the trading of combining peas, field beans and lupins and is of the order of £300,000 per annum. Near market research projects are funded, including variety, agronomy and crop protection trials. The PGRO website is: http://www.pgro.org

Background Crop Area An expansion of the area of field peas and beans followed the introduction of an EU subsidy in 1978 for home produced protein for animal feed and resulted in increased development of pesticides and varieties for these crops. Field beans (Vicia faba) occupy only a small percent of the arable area, and only 10% of the area of wheat in 2005, field peas harvested dry for animal feed peas even less, 2.3%. In 2005 the UK area of field peas including those harvested dry for human consumption was 43,000 ha, and field beans was 187,000 ha (provisional figures, Defra, 2006). In addition special varieties of peas harvested dry are grown for human consumption and the area is very variable (Basic Horticulture Statistics, Defra, 2006) the provisional area for 2005 is 11,210 ha. Field bean areas are increasing, peas decreasing - following wet conditions during pea harvests and recent clashes of harvest timing with wheat, and this trend is forecast to continue. The varieties grown in winter or spring differ in terms of winter hardiness. The relative area of winter and spring beans grown is often influenced by recent yields. In future the area of these protein crops grown will depend on profitability relative to cereals, a demand for a GM free source of vegetable protein and farmer perception of the importance of a break crop. No nitrogen fertiliser is needed for peas and beans. There are opportunities to reduce populations of resistant black-grass and other grass weeds: with propyzamide in winter beans, or trifluralin in spring and winter beans and with cultivations before spring-sown peas and beans. Most field pea and field bean crops are grown in the drier areas: the Eastern Region, East Midlands and the South East. Field beans are also grown in the South West, the West Midlands and have extended further north to Yorkshire & the Humber Region in an attempt to avoid attacks of Bruchid beetle (Bruchus rufimanus). Winter field beans are grown on heavier soils where it is difficult to achieve a suitable spring seedbed; spring beans are grown on a wide range of soil types. Beans need adequate moisture during the flowering period - the spring-sown crop is more sensitive to drought. The loss of simazine in the 91/414/EEC Review will increase costs of growing beans after 2007 and there may be a reduction in area. Field beans are not widely grown in other EU member states and this will limit pesticide development for the crop. Rotations There are no chemical control measures for the several root-infecting fungi that cause foot and root rots to peas and beans. Crop rotation is essential to reduce the build up of pests and soil-borne diseases in particular. All pea and bean crops are treated as one crop and a break of at least four

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legume-free years should be maintained between them. Peas and beans harvested dry are grown in arable rotations that may include winter wheat, and sugar beet, potatoes and oilseed rape. Profitability An EU subsidy for home produced protein for animal feed was introduced in 1978. In 1993 support was changed to an area payment and peas and beans were sold at world market prices. World prices are low and inputs need to be managed with care (Knott, 1994). Under the CAP Reform there is a EU protein supplement of 55.57 €/ha for peas and beans harvested dry and the output figures given here include this supplement. Field peas harvested at dry seed stage are grown mainly for animal feed and the price in the 2006 harvest year is assumed £84/tonne (Nix, 2005). Smaller areas of lower yielding, special varieties are grown for human consumption and pigeon feed markets. Quality samples are micronised for pet food. Prices for these crops depend on quality (freedom from pest and disease damage) and crop protection inputs are higher. There is also a wide variation in premiums depending on season, supply and demand. Premiums for human consumption marrowfat varieties range from £25 to £50/tonne. The average yield of feed peas is 3.75 t/ha, the output is £350/ha and the gross margin is about £160 /ha. National yields of peas are slightly higher than for beans. The price for field beans assumed by Nix, 2005 is £82/tonne for 2006. Average yields of winter beans (4.0 t/ha) are slightly higher than spring beans (3.7 t/ha), the outputs are £365 and £340/ha, and gross margins £240 and £220/ha respectively. Compounders do not pay premiums for protein. Most of the spring bean area is grown for high quality for the human consumption export market (premium about £12/tonne) using special varieties, and pesticide inputs are slightly higher. The cost of herbicides is currently lower for beans than peas, because simazine (£4/ha) is used on nearly all winter beans and much of the spring crop. Costs will increase after 2007 when simazine ‘Essential Use’ expires.

Weed control in Field Peas

Peas for harvesting dry are drilled on light/medium soils, on a row width of 200mm or less, as early as possible in spring. Most pea varieties are semi-leafless, stiff-strawed and resistant to lodging. Some are tall and are thus better able to suppress weeds than older varieties. Peas have slow initial growth and experiments have shown that early removal of weeds before peas are at 3-node growth stage prevents yield loss. Weeds seriously reduce pea yields and tall species that shade the crop are particularly damaging. Black-bindweed and cleavers can over-run a lodged pea crop and interfere with combining. Infestations of cleavers appear to have increased in recent years possibly due to the use of reduced dose rates of cleaver herbicides in cereals. Volunteer oilseed rape is often a problem in pea crops. Impact: yield reduction, lodged crops cause harvesting problems (Table 1), increased production costs (diquat) if a desiccant is needed to kill off green weeds which might cause harvesting difficulties andthere are also losses associated with passage of the sprayer (24m boom) of up to 0.76% (McClean, 1985). Quality is only an issue for human consumption peas but high weed populations may increase risks of Botrytis. Some weeds are hosts of Sclerotinia. Table 1 gives some indication of yield increases achieved where weeds are controlled, but there are few data and the impact of weeds on yield depends on the species and their numbers. Yield

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response must cover the cost of pesticide plus application at least, but other factors (e.g. the effect of weeds on harvesting and prevention of weed seed return) are also important.

Table 1. Impact of weeds on untreated plots compared with standard herbicide treatments on yield and harvestability of spring peas and spring and winter beans Crop Weeds/m2 %Yield increase Harvesting & other operations

Spring peas Pre-emergence terbutryn/terbuthylazine

29– 471

Range 9 –40 (8-29%loss Mean 20 (17%loss) (b)

Black-bindweed,cleavers cause crop lodging. Slower work rate, higher cost and harvest losses, desiccant costs

Spring beans simazine

20-200 79-519

Range 0 – 55 (0-36%loss) Mean 3.9 (4%) (a) Range 4 - 40 (4-29%) Mean 20 (17%) (b)

Black-bindweed, cleavers cause crop lodging. Slower work rate, higher cost and harvest losses,

Winter beans simazine

9-76 Nil (c) Black-bindweed, cleavers cause crop lodging. Slower work rate, higher cost and harvest losses,

a. Heath & Clarke, 1991 b. PGRO, unpublished trials data c. Cook et al., 1991

Control: residual herbicides are applied pre-emergence of weed and peas and control a wide spectrum of annual grass and broad-leaved weeds, including black-bindweed, which causes lodging. Pendimethalin/cyanazine and fomesafen/terbutryn also control volunteer oilseed rape, which has become a widespread and persistent problem because of the longevity of survival of seed in the soil. Other pre-emergence herbicides, available in 2005, isoxaben/terbuthylazine and linuron/trifluralin are less effective on broad-leaved weeds. Clomazone, a cleavers killer, has a limited weed spectrum.

Early post-emergence pendimethalin + bentazone (Impuls) or a tank-mix of isoxaben/terbuthylazine (Skirmish) + bentazone are both effective on very small weeds including volunteer oilseed rape. Weeds may emerge later than this in some years. Foliar-acting post-emergence herbicide tank-mixes bentazone/MCPB + cyanazine, cyanazine + MCPB/MCPA are used where dry or cloddy seedbeds would reduce residual activity, or as a follow-up treatment for weeds which escape pre-emergence control. MCPB is useful for control of docks and thistles. There are no means of suppressing volunteer potato foliage in peas. Several post-emergence graminicides (‘fops’ and ‘dims’) are available for control of annual grasses wild-oats, spring germinating black-grass and volunteer cereals. The high doses required for common couch are uneconomic. Resistant black-grass does not appear to be a problem in peas yet. Diquat desiccant costs £27/ha and is a useful harvesting aid. It is likely to become more widely used if weed control is less effective after 2007.

Herbicides Field Peas Herbicides approved for 2006 and herbicide usage in 2004, are shown in Table 2. The weed species controlled are given in Appendix 1. Of the pea herbicides registered for the UK, cyanazine, terbutryn and fomesafen (blue text in Table 2) were not supported in the EC Review and have ‘Essential Use’ derogations but can no longer be used after 31 December 2007.

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In the 2004 survey peas were treated with an average of three herbicide applications, one of them prior to drilling. Total herbicides, mainly glyphosate, and some diquat/paraquat were applied to 64.5% of the crop area before sowing or emergence of the crop. The main pre-emergence herbicide recorded was terbutryn/terbuthylazine 37.4% of the pea area pendimethalin/cyanazine on 29.7%; and these were used to control broad-leaved weeds and annual meadow-grass. Clomazone was used pre-emergence to control cleavers on 17.5% of the pea area. A large area of peas (61%) was sprayed post-emergence with cyanazine at low dose 200g/ha in tank mix with bentazone/MCPB. Cyanazine was also used at 1000g/ha in tank mix with MCPB/MCPA. Some pendimethalin (2.4% of the crop area) was applied post-emergence in tank-mix with bentazone (product Impuls). Table 2. Herbicides approved for dry harvest peas 2006; Review status; Aim re-registration UK field peas; Usage of pesticides on 62,281 ha peas grown in Great Britain, 2004 (spray hectares) (Source: CSL Pesticide Usage survey, 2004) Herbicides and desiccants approved for field peas 2006

Review status Aim re-register UK field peas


Total weeds Glufosinate-ammonium List 2 not decided (√

N) phosphinic acid

Glyphosate Annex 1 √ translocated phosphonic acid 39,602 Diquat/paraquat Annex 1/ Annex 1 √ / √ contact bipyridyls 567Grass weeds Cycloxydim List 3A - translocated oxime 6,374 Fluazifop-P-butyl List 3A √ translocated phenoxypropionic acid 3,950 Propaquizafop List 3A √ translocated phenoxy alkanoic acid 6,372 Quizalofop-p-ethyl List 3B √ translocated aryl phenoxypropionic acid Quizalofop-p-tefuryl List 3B √ translocated aryl phenoxypropionic acid Tepraloxydim New Annex 1 - translocated oxime 15,933 Tri-allate List 3B √ Residual thiocarbamate Broad-leaved (and some grasses) Bentazone Annex 1 - contact diazinone Bentazone/MCPB ## Annex 1/Annex 1 - contact diazinone/translocated phenoxy-

butanoic acid 37,977

Clomazone List 3A √ residual oxazalodinone 10,896 Cyanazine until 31 Dec 2007 Not supported contact and residual triazine 42,098 Cyanazine/pendimethalin until 31 Dec 2007 Not supported/Annex 1 residual and contact triazine/

dinitroaniline 18,515

Fomesafen/ terbutryn # until 31 Dec 2007

Not supported residual and contact diphenyl ether/triazine

Isoxaben/terbuthylazine List 3B/List 3B √ Residual amide/triazine Linuron/trifluralin Annex 1/List 2 √ / √ Residual and contact urea / dinitroaniline MCPB/MCPA Annex 1/Annex 1 √ / √ translocated phenoxybutanoic/

phenoxyacetic acid MCPA Annex 1 √ translocated phenoxybutanoic acid 837 Pendimethalin Annex 1 - residual dinitroaniline 1,468 Trifluralin SOLA List 2 - dinitroaniline 919 terbutryn/terbuthylazine until 31 Dec 2007 Not supported/List 3B residual and contact triazines 23,278Desiccation Diquat Annex 1 √ Contact bipyridyl 23,302 Glufosinate-ammonium List 2 not decided (√

N) contact phosphinic acid

Sulphuric acid List 4 √ 298 # no longer available; ## no longer marketed after 2007; - Company request confidentiality; √ yes; (√ N) aim re-register in N Europe; future of trifluralin is doubtful Graminicides (ACCase inhibitors) were applied to 52.6% of the crop area, only 1% of the crop had two applications, 0.9% had three applications. Tepraloxydim was the most popular graminicide in 2004.

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Diquat was used to desiccate 37% of the pea area, sulphuric acid on 0.47%. Sulphuric acid is rarely used and is not recommended by PGRO. In 2005 isoxaben/terbuthylazine became available again – the registration was still extant. It is approved for broad-leaved weed control pre- and post-emergence in peas. Two new pea herbicides were registered: quizalofop-p-tefuryl (Panarex) a graminicide, and linuron/trifluralin (Blois). However the future of trifluralin is doubtful. Non-chemical control: peas are able to withstand weeding with flexible tines at early growth stages along or across the rows, and later, but before flower bud stage, along the rows. A tall, stiff-strawed variety will suppress weeds. This technique is suitable for light soils. Efficacy is poor in wet conditions because weeds re-establish. The technique is not suitable for grass weeds, perennials or deep-rooted weeds such as charlock, black-bindweed, nor is it suitable to control volunteer potatoes. The cost of 2 to 3 passes is higher than the cost of herbicide + application. 1. The likely impacts of the 91/414/EEC review process on herbicide availability for UK field peas

Unless effective herbicides are available for combining peas the crop will be difficult to grow successfully in the UK, but there will be no impact from herbicide loss in mainland Europe. UK peas have been dependent on triazine herbicides but in other EU Member States different actives that were supported in the Review are approved. The gross margin is only £160/ha but peas are a useful spring break crop and no nitrogen fertiliser is used. 1.1. Losses Cyanazine, terbutryn and fomesafen were not supported in the 91/414/EEC Review. These pea herbicides (terbutryn and cyanazine for the last 25 years) have been used without obvious adverse effects on consumer or environment. There is an ‘Essential Use’ derogation for combining peas, which expires 31 December 2007. After then there will be no broad-spectrum pre-emergence herbicide for peas unless those used in France become available. In addition a decision has been made that bentazone/MCPB (Pulsar) will not be manufactured after 2007 because without cyanazine as a tank-mix partner, weed control would be poor. This is an indirect impact of the 91/414 Review. It would have been desirable to maintain products containing pendimethalin/cyanazine terbutryn/terbuthylazine and fomesafen/terbutryn for pre-emergence grass and broad-leaved weed control, including black-bindweed, which causes lodging. Fomesafen and pendimethalin also control volunteer oilseed rape, which has become a widespread and persistent problem because of the longevity of survival of seed in the soil. In 2004 the main pre-emergence herbicide recorded was terbutryn/terbuthylazine on 37.4% of the pea area; pendimethalin/cyanazine on 29.7%; and these were used to control broad-leaved weeds and annual meadow-grass. Fomesafen/terbutryn has not been manufactured for the 2006 season and is no longer be available. In field peas weeds are removed early with pre-emergence herbicides but if soil conditions are dry then a post-emergence herbicide is used. No wide spectrum herbicide will be available after 2007.

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Post-emergence herbicides are needed: where the soil is too dry for residual activity; for species that escape control with residual pre-emergence herbicides; for certain soil types (sands, <10% organic matter) where pre-emergence herbicides cause damage or are ineffective. The loss of cyanazine after 2007 will have a large impact. Table 2 shows cyanazine was the most widely used active substance (in tank-mixes with bentazone/MCPB) on peas in 2004: 61% of the crop area was sprayed post-emergence with cyanazine at low dose 200g/ha in tank mix with bentazone/MCPB. 1.2. Impact

• The impact from loss of herbicides for peas cannot be assessed nationally in terms of yield,

weed seed return or harvesting difficulties causing increased use of desiccants because Essential Uses continue until the end of 2007.

• Weeds cause yield loss in trials due to competition up to 29% (mean 17%) (Table 1). Losses

due to harvesting difficulties unless a desiccant used (diquat £27/ha + application cost).

• There are price deductions for peas contaminated with weed seeds.

• Weedy seed crops are rejected. Seed may not be marketed unless it has been officially certified. To obtain certification the seed crop must pass official field inspection and there is a general requirement that crops shall not be so weedy that a proper inspection for trueness to variety cannot be carried out.

• Growers levy through PGRO, funded projects to find alternatives.

There will be the small range of herbicides available after 2007 and peas may not be a viable crop to grow in the future unless there are alternatives. Other pre-emergence alternatives may remain after 2007 but they are less effective: isoxaben/terbuthylazine, linuron/trifluralin and clomazone (controls cleavers and a few broad-leaved weeds). Trifluralin may fail Annex 1 and/or UK registration, so might terbuthylazine. Pendimethalin is on Annex 1, but needs a partner and could be tank-mixed with any of these. The only post-emergence herbicides for broad-leaved weeds that will remain after 2007 will be: isoxaben + bentazone (early before 2nd node stage), pendimethalin + bentazone (Impuls) (early before 3rd node stage), bentazone, MCPB and MCPB/MCPA. The early post-emergence herbicides are very effective, particularly for volunteer oilseed rape control, but growers have difficulty with early applications, preferring to wait in case there is a late weed flush. Bentazone is on Annex 1 but has important weaknesses (Appendix 1): knotgrass, speedwells, annual meadow-grass, and control of large fat-hen is poor. It is useful for mayweed and cleavers control; MCPB, MCPB/MCPA are on Annex 1 but have very limited weed spectra. Tank-mixes will be used and at dose rates needed to achieve the same level of weed control they are more damaging to peas than the cyanazine + bentazone/MCPB combination. 1.3. Future losses? It is difficult to predict the likely impact of the review process on herbicide availability for UK field peas because we do not yet know whether remaining active substances (Table 2) will achieve Annex 1 inclusion - the future of trifluralin is doubtful. The few active substances on Annex 1 remaining are likely to be re-registered in the UK (or N Europe). Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on

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efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. 2. Specific herbicides / desiccants or groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

There is urgent need for new broad-spectrum pre-emergence herbicides such as those registered for peas in France (aclonifen, imazamox/ pendimethalin see Table 3). It is important to retain the few remaining (on Annex 1 unless otherwise stated): Glyphosate, non-selective herbicide pre-cropping. pendimethalin, pendimethalin + bentazone, isoxaben/terbuthylazine (both List 3B), clomazone (List 3A), bentazone, MCPB, MCPB/MCPA. Trifluralin (List 2)/linuron is also approved but the future of trifluralin is doubtful. Graminicides (all List 3) also need to be maintained and used according to the PSD resistance strategy. While the restrictions would preclude the use of two applications of a product containing the same ACCase inhibiting active substance, a sequence of two different ACCase inhibitors would be possible. A sequence of a ‘fop’ followed by a ‘dim’ or a sequence of two different ‘fops’ would be allowed. Resistant grass weeds are not yet a problem in pea crops probably because peas are not grown on heavy land where black-grass is more likely to occur. It would also be wise to maintain tri-allate (List 3B) although there is some evidence of a low level of resistance. Diquat will be essential for desiccation. It was used to desiccate 37% of the pea area in 2004 and is likely to become more widely used if weed control is less effective after 2007. 3. Prospects for alternatives for any foreseen major gaps in herbicide / desiccant availability

3.1. Alternatives A ‘Gap Analysis’ (Table 3) shows the critical herbicide gap * * *, where there are, or soon will be no control measures at all. There are two pre-emergence herbicides registered for peas in France that are potential alternatives to those lost from the UK in the 91/414 review, and residues data are available for both:

a. aclonifen + pendimethalin tank-mix b. imazamox/pendimethalin formulated product

Pendimethalin is on Annex 1 and will be re-registered for UK peas. Aclonifen and imazamox are not currently registered for any UK crop (July 2006). Aclonifen is on List 3B, rapporteur Germany and Mutual Recognition will be used to request authorisation in the UK. Imazamox is a new active

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substance on Annex 1. UK registration is being sought for the formulated imazamox/pendimethalin product.

There are no prospects of an effective, safe alternative post-emergence tank-mix to replace bentazone/MCPB + cyanazine after 2007. The former will not be manufactured after 2007 and cyanazine Essential Use expires. A UK Off–label Approval http://www.pesticides.gov.uk/applicant_guide.asp?id=1226, based on recognition of an on-label approval in another (current Northern zone) member state and where there is an extant on-label approval for the use of the same product on another edible crop in the UK, is not possible for a major crop. These arrangements only apply to applications for off-labels for minor crops of areas less than 50,000ha. This could now include field peas because the area has declined. In the past there has been a spin-off for peas and beans from soya herbicides, but since GM soya was introduced Crop Protection Companies no longer include soya in early herbicide screens. Globally there appears to be very little herbicide development compared with the period 1990-1999 when 10 herbicides for soya were introduced. A report by Phillips McDougall, given at the ECPA conference November 2005 that very few new herbicide active substances had been introduced over the period 2000-2004 (only 1 for soya), and none were in R & D.. There are a few for wheat herbicides but broad-leaved herbicides for wheat are usually damaging to broad-leaved crops. 3.2. Impact of the proposed regulation and revision of 91/414EEC General points are made in the Executive Summary. The following are relevant to peas:

• The new regulation is expected to form part of the wider “Thematic Strategy for the sustainable use of pesticides” which includes the Water Framework Directive. There are concerns regarding water issues with some pea herbicides: Trifluralin is classed as a Priority Substance (pesticide) “ ..individual pollutants presenting a significant risk to or via the aquatic environment, including such risks to waters used for the abstraction of drinking water” and it presents a risk to the aquatic environment. It is one of the four remaining pesticides listed [diuron, isoproturon (on Annex 1), chlorpyrifos (on Annex 1), trifluralin] that have not been revoked. Bentazone has been found in groundwater above the 0.1 µg/L drinking water limit.

Key to the Gap Analysis Tables: * * gap no immediate problem but future situation vulnerable






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Table 3. Gap Analysis (Combining Peas): Herbicides and desiccants Weeds/weed species

Application timing

Gap Status

Current approved solution Comments Solution non-chemical




Annual meadow-grass & broad spectrum annual BLW

pre-em / residual

* * * Opogard & Batallion (terbutryn/terbuthylazine); Reflex T (fomesafen/terbutryn); Bullet (pendimethalin/cyanazine)

Terbutryn, fomesafen cyanazine not supported in the EC Review, Essential Uses until 31 Dec 2007 Terbutryn/terbuthylazine and fomesafen/terbutryn, are the most widely used pre-emergence residual herbicides. control a wide weed spectrum including species which cause crop lodging. Pendimethalin/cyanazine fomesafen/terbutryn control black-bindweed which causes lodging) and volunteer oilseed rape.

Flexible–tine weeding poor control deep rooted weeds (oilseed rape, black bindweed) and in wett conditions

None yet Registered for peas France: aclonifen + pendimethalin orimazamox/ pendimethalin imazamox

Yes. Residues data available for both

Annual meadow-grass & limited range of annual BLW

pre-em / residual

Blois (trifluralin/linuron), Skirmish (isoxaben/terbuthylazine)

Other pre-emergence alternatives may remain but they are less effective: isoxaben/terbuthylazine and linuron/trifluralin Trifluralin may fail Annex 1 and/or UK registration, so might terbuthylazine. Pendimethalin Annex 1 SOLA will remain but needs a partner could be tank-mixed + Blois, Skirmish or Centium.

Cleavers pre-em / residual

* * Centium (clomazone) clomazone used for cleavers control. Controls a limited range of other broad-leaved weeds. Needs a partner. .

Annual BLW Early post-em / residual and foliar

Impuls (pendimethalin/bentazone); tank-mix Skirmish (isoxaben/terbuthylazine) + bentazone

Both effective but depend on spray opportunity and very small weeds and timing peas 1 to 2 nodes. Weeds may emerge later

Use instead of the later post-em treatments

None known

Annual BLW post-em / foliar

* * Fortrol (cyanazine) + Pulsar (bentazone/MCPB)

The most widely used post-em herbicides are tank-mixes of cyanazine plus Pulsar (bentazone/MCPB), or cyanazine + MCPB/MCPA Cyanazine will be lost 31 December 2007 and Pulsar will not be manufactured Bentazone is on Annex 1 important weaknesses: knotgrass, speedwells, annual meadow-grass, and control of large fat-hen is poor. Useful for mayweed and cleavers control.; MCPB, MCPB/MCPA are supported in the EC Review (List 1). These have limited weed spectra if used alone.

None found yet, bentazone + MCPB not as effective,

None found yet

.

Annual Grasses and annual meadow-grass (Not for volunteer cereals)

pre-em / residual

* * tri-allate granular soil acting thiocarbamate granules for wild oats, blackgrass and annual meadow-grass. Resistant blackgrass not yet a problem in peas but may develop in future. Important resistance strategy for grass weeds, rarely used, was difficult to obtain

Flexible –tine weeding unsuitable for grasses

Desiccant * * diquat Can be used on seed, animal feed and seed crops. Sulphuric acid approved but not recommended.


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Pest control Field Peas

Field thrips (Thrips angusticeps) The tiny black "thunderflies" feed within the enclosed leaves of the growing point just as the seedlings are emerging from the soil. Damaged leaves are pale, distorted and thickened. Impact: severe in a few situations. Control: nothing approved. Seed and foliar spray treatment is needed. Recent work has indicated that good control of thrips can be achieved with lambda-cyhalothrin. Pea and bean weevil (Sitona lineatus) Early sown crops in a dry spring can be more severely affected by pea weevil. The adults feed on the leaves leaving semi-circular notches around the leaf margins. Larvae from eggs, laid by weevils during the feeding period, feed below ground on the root nodules. Impact: on yield, by reducing the supply of nitrogen. Control: Pyrethroids offer control. Monitored by trapping – a threshold is when an average count per trap exceeds 30 weevils on one day. Cultural control: Avoid cloddy seedbeds. Pea aphid (Acyrthosiphon pisum) The large green aphids produce colonies in the growing points of peas causing flower loss and poor pod development. Aphid can also transmit viruses including pea enation mosaic virus. Impact: severe loss of yield if uncontrolled. Control: Several approved insecticides, including pirimicarb and pyrethroids, are available for control of pea aphid. There are no reports of insecticide resistant strains in the UK. Threshold for spray application is when aphids can be found on 15% of the plants as they begin to flower. A pea aphid population model (PAM) is available to aid decisions on treatment timing. Cultural control: Ladybird and hoverfly larvae predate aphids and will control low infestations. Pea moth (Cydia nigricana) Pea moth is a common pest. Peas producing flowers from mid-June onwards are vulnerable. Impact: the caterpillar feeds on peas inside the pod and spoils quality of peas for human consumption markets. The effect on yield is negligible so feed peas do not warrant sprays. Control: with pyrethroids applied to control the caterpillar as it leaves the egg and moves to the young developing pod. Monitoring is carried out using a pheromone-based pea moth trap so sprays can be timed accurately if required. Cultural control: Areas where many field peas are grown are likely to be a reservoir of moths. Pea cyst nematode (Heterodera göttingiana) Pea cyst nematode is not widespread. The root system is poorly developed, there are very few nodules present and the lemon-shaped cysts can be found embedded in the root surface. Impact: yield loss. The damage occurs in patches, and infested areas usually die prematurely. Control: no nematicides are now approved for use in peas. Cultural control: A rotation of one of the host crops in five years will help to prevent the establishment of the nematode. Once present, the cysts are very persistent and may remain viable for twenty years or longer. Slugs and snails (e.g. Deroceras, Milax and other spp.) Slug feeding can result in poor seedling establishment on wet or heavy soils with high organic matter. Slugs also attack seeds and roots. Impact: reduced plant stand.

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Control: with metaldehyde pellets if needed early in the crop growth stages. Cultural control: Soils containing high levels of organic debris including straw are most likely to harbour slugs. Avoid growing peas in close rotation with oilseed rape. Insecticides for Field Peas Insecticides approved for 2006 and insecticide usage in 2004, are shown in Table 4. There is no longer approval for any nematicide in peas and problems with nematodes in peas are uncommon, although severe in the locations where they occur. In the 2004 survey, there were at least 2 sprays of insecticides per crop. Of the insecticide-treated area, the majority of insecticides were applied for the control of aphids, which accounted for 36%, pea moth for 27%, pea and bean weevil 16%, and a combination of aphids/pea moth for 8%. Most insecticides were applied at or near the full label rate, with pirimicarb (used alone or in formulation with lambda-cyhalothrin) the most widely used insecticide, followed by lambda-cyhalothrin, the most popular pyrethroid. Cypermethrin was also widely used but it is no longer approved for field peas, only for vining peas. In 2005, triazamate was withdrawn by the manufacturer. However, this aphicide was seldom used in peas. There was a new approval for bifenthrin, an acaricide/insecticide. In 2006 there are changes to the lambda-cyhalothrin label, Minimum Harvest Interval is 25 days for peas. Table 4. Insecticides and molluscicides approved for field peas 2006; Review status; Aim re-registration UK field peas; Usage of insecticides on field peas 62,281 ha grown in Great Britain, 2004 (spray hectares) (Source: CSL Pesticide Usage survey, 2004) Insecticides and molluscicides approved for field peas 2006

Review status Aim re-register UK field peas


(spray ha)Insecticides Carbamate Pirimicarb Annex 1 √ 46,212Pyrethroids Alpha-cypermethrin Annex 1 - Pea moth Pea weevil aphid contact and ingested pyrethroid 5,948 Bifenthrin List 3A √ aphid contact and residual pyrethroid Cypermethrin Annex 1 Pea moth Pea weevil aphid contact and stomach acting pyrethroid 15,745 Deltamethrin Annex 1 √ Pea moth Pea weevil aphid

Pea midge contact pyrethroid 10,770

Lambda-cyhalothrin Annex 1 √ Pea moth Pea weevil aphid Pea midge

contact and ingested pyrethroid 28,889

Lambda-cyhalothrin/pirimicarb Annex 1/ Annex 1

√ / √ Pea moth Pea weevil aphid Pea midge

contact and ingested pyrethroid/carbamate

Fatty acids thrips aphid soap concentrate Natural Plant extracts Pea moth thrips aphid Nicotine unsupported? List 4 thrips aphid non-persistent contact alkaloid Rotenone List 4 thrips aphid natural contact insecticide of low

persistence. Triazamate withdrawn unsupported Zeta-cypermethrin List 3A √ Pea moth Pea weevil aphid contact and stomach acting pyrethroid 14,002 Molluscicides & repellents Metaldehyde List 3A ? Slugs & snails molluscicide bait 1,174

Cypermethrin is no longer approved for field peas; - Company request confidentiality; √ yes

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1. The likely impacts of the 91/414/EEC review process on insecticide/ molluscicide availability for UK field peas 1.1. Losses There were no insecticide losses in the 91/414/EEC review process, except for withdrawal of triazamate. The revocation of broad-spectrum organophosphate insecticides in the UK after the anti-cholinesterase review, has increased reliance on pyrethroids and increased the risk of developing pest resistance. 1.2. Impact So far, the 91/414/EEC review process has had no impact on insecticide availability for UK peas. Triazamate was not widely used in peas. 1.3. Future losses? It is difficult to predict the likely impact of the review process on pesticide availability for UK pea. The most important insecticides achieved Annex 1 inclusion (Table 4) but we do not yet know whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. In some seasons slugs can be a problem in peas. Metaldehyde (List 3A) is not widely used therefore a decision to re-register will depend on whether data is required for each crop/use combination. 2. Specific insecticides/molluscicides and groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

A limited range of insecticides is available for field peas. Resistance of pea aphid to pyrethroids or pirimicarb has not been found yet, but active substances with different modes of action are needed for resistance strategy. The revocation of broad-spectrum organophosphate insecticides in the UK after the anti-cholinesterase review, has increased reliance on pyrethroids and increased the risk of developing pest resistance. It would be desirable to maintain the following: Pyrethroids, particularly lambda-cyhalothrin. Pirimicarb alone or in formulation with lambda-cyhalothrin must be maintained. Molluscicide bait metaldehyde.

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3. Prospects for alternatives for any foreseen major gaps in insecticide / molluscicide availability

3.1. Alternatives Insecticides with alternative modes of action are important for resistance strategies. Gap Analysis Table 5 show the critical insecticide gaps * * *, where there are, or soon will be no control measures at all. Gaps identified for peas were not a result of insecticides lost in the EC Review. a. Field thrips (Thrips angusticeps): Fenitrothion (organophosphate) was used to control field thrips in the past and later it failed Annex 1 inclusion. Nothing is approved now. Seed and foliar treatments are needed. Good control was achieved in trials with thiamethoxam (new Annex 1) seed treatment, but this active is not approved in the UK yet. Recent work has indicated good control of thrips with lambda-cyhalothrin foliar sprays. b. Pea aphid (Acyrthosiphon pisum): a limited range of products is available compared with other crops, although no resistance in pea aphid has been found yet. Aphicides with different modes of action are available in other crops, but development is needed in peas. c. Slugs and snails: reliant on metaldehyde molluscicide bait pellet as the only means of control. An alternative solution is needed but no prospects yet. Methiocarb will be re-registered in another (current Northern zone) member state for peas. A UK Off–label Approval based on recognition of on-label approval in another EU Member State (in the same climatic zone) and where there is an extant on-label approval for the use of the same product on another edible crop in the UK, could now be useful for insecticides for field peas. Global insecticide development overall appears to have slowed down and Crop Protection Companies may be finding it more difficult to gain approvals for them. In the US reduced risk/OP alternatives are given preference. However, more insecticides are in development for fruit and vegetables than for other sectors and field peas could also benefit (Phillips McDougall, ECPA conference November 2005). 3.2. Impact of the proposed regulation and revision of 91/414EEC General comments - see Executive Summary

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Table 5. Gap Analysis (field peas): Insecticides and molluscicides

Pest (Latin name)

Application timing



Solution chemical UK Solution chemical another MS


Aphid (Acyrthosiphon pisum)

foliar ** Aphox (pirimicarb)

Limited range of products although no resistance in pea aphid yet

none Actives available but efficacy work needed

limited

Thrips (Thrips angusticeps)

foliar *** None approved

Good control in trials with thiamethoxam but not approved in UK

none Approval of thiomethoxam

yes

Slugs Bait pellets ** metaldehyde molluscicide bait: pellet, an alternative is needed.

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Disease control Field Peas

Damping-off diseases Peas sown early in cold and wet conditions are prone to pre-emergence diseases such as Pythium ultimum. Pythium affects the developing root and shoot. Impact: crop loss if seedlings may fail to emerge, or collapse shortly after emergence. Control: seed treatments containing thiram protect the seed and seedlings from infection. Foot rot/Root rot (Fusarium solani f. sp. pisi, Phoma medicaginis var pinodella/Aphanomyces euteiches) Affected plants appear in patches or along sections of rows. Plants are stunted, pale and the lower foliage may dry up. The root system may be brown and poorly developed and the base of the stem discoloured. Fusarium causes a brick-red discolouration in the vascular tissue. Infection by Phoma results in a blackening of the stem base, later plants collapse or break-off at soil-level. Aphanomyces root rot is encouraged by wet soils. Impact: yield loss - infected plants often die before pods have developed. Control: No fungicides are approved for the control of these soil-borne diseases, however, Phoma medicaginis can be seed-borne and seed treatments containing thiabendazole or fludioxonil will give some control. Cultural control: A strict rotation of is necessary to prevent the build up of these diseases in the soil. Peas and beans should be treated as one and the same crop and a break of at least four years should elapse between crops. A predictive soil test has been developed to avoid planting peas in high-risk fields. No varieties are resistant to these diseases. Leaf and pod spot (Ascochyta pisi and Mycosphaerella pinodes) The 'Ascochyta complex' of closely related fungi, is seed-borne, but M. pinodes and P. medicaginis can also survive in the soil for several years. The most common leaf and pod spotting is caused by M. pinodes. In wet weather, many small dark-brown or purple spots develop. Impact: yield loss - plants may be defoliated and patches die prematurely if infection is severe. Control: The fungi are seed-borne and if tested seed is found to be infected then seed treatments containing thiabendazole or fludioxonil should be used. To prevent leaf and pod spot developing in wet seasons, fungicides can be applied as soon as the first spots are seen on the foliage. In order to reduce pod infection, a spray should be applied as soon as the first pod is visible following a disease risk assessment. Azoxystrobin can control of leaf and pod spot, and also gives some control of grey mould (Botrytis cinerea) and Mycosphaerella blight. Cultural control: is with healthy seed and avoidance of excessive overhead irrigation during pod-set. Peas should not be grown more frequently than once in five years on the same land. Downy mildew (Peronospora viciae) The fungus is soil-borne and commonly infects seedlings before emergence. Some early maturing varieties are very susceptible to mildew and these should be avoided in high-risk fields. Impact: plant loss. If secondary infection spreads to the pods, quality is reduced. Control: there are no effective means of control once the disease has become established. Seed treatments with cymoxanil and metalaxyl M (as cymoxanil/fludioxynil/metalaxyl M) or fosetyl-aluminium are effective in preventing the initial seedling infection thereby reducing the amount of air-borne inoculum that causes the secondary infection. However the disease is already resistant to metalaxyl. Cultural control: some field pea varieties have good field resistance.

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Botrytis pod rot (Botrytis cinerea) Pod rot (grey mould) occurs in wet seasons when the flower petal sticks to the developing pods or lodges on the stems in the leaf axils. Botrytis then infects the pods, which either abort, or the seeds rot within the pods. Impact: yield loss in wet seasons, white ‘chalky’ peas reduce quality for human consumption or seed. Control: several fungicides with different modes of action are approved (Table 6) but some labels indicate only moderate control. Preventative sprays are more useful than curative treatments. Botrytis and Mycosphaerella are the main diseases of field peas. Fungicide mixtures containing chlorothalonil have produced very good responses in both control of Botrytis and Mycosphaerella and yield increases of up to 31% have been achieved in trials. In addition, a two-spray programme in these situations has resulted in a significant reduction of seedborne infection of Mycosphaerella after harvest. Sclerotinia (Sclerotinia sclerotiorum) The disease can affect a very wide range of crops. It causes a white mould of the stems and pods in dense crops with lush foliage. It spreads rapidly in warm humid conditions. The stems become covered with dense white mycelium and then collapse. The infection can progress to the pods. Impact: in severe cases complete crop loss. Control: iprodione is approved. Cultural control: a rotation, which allows at least three years between host crops, will prevent a build-up of the fungus in the soil. Sclerotia remain viable in the soil for several years,

Powdery mildew (Erysiphe pisi) Pea leaves and stems become covered with a white 'dusty' film late in the season and pods may become severely infected. It occurs under hot dry conditions in the day, and high humidity at night. Impact: delayed maturity and harvesting, failure of infected pods to fill adequately reduces yield. Control: no fungicides are approved in peas for the control of powdery mildew. Where a risk of powdery mildew is anticipated cyproconazole/chlorothalonil, at this time, will significantly reduce the risk of serious infection. Metconazole is approved in combining peas for Botrytis, but there are no data on Erisyphe pisi control. Cultural control: several varieties are completely resistant to powdery mildew.

Fungicides for field peas Table 6 shows the fungicides approved for 2006 and the usage in 2004. There are between one and two fungicide sprays on peas depending on seasonal weather conditions. Usually two fungicide applications are necessary to control Botrytis in a wet season. Fungicides containing chlorothalonil, azoxystrobin and vinclozolin (both applied alone) were used for disease control (mainly for Botrytis, but also for Mycosphaerella and Ascochyta) on 178% of the pea area. Usually two fungicide applications are necessary to control Botrytis. The inclusion of cyproconazole also controlled powdery mildew. There is a SOLA for iprodione in peas, but it is seldom used. Since the 2004 survey there have been new approvals for chlorothalonil/vinclozolin, chlorothalonil/pyrimethanil and for metconazole. There are also guidelines for anti-resistance strategy, particularly regarding azoxystrobin. Approval for use of carbendazim was revoked for a number of crops including combining peas in 1999 as a result of the MRL directive 98/82/EC. Rothamsted Research has shown that peas and beans suffer from sulphur deficiency in some areas and sulphur application was probably used to correct deficiency.

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Table 6. Fungicides approved for field peas 2006; Review status; Aim re-registration UK field peas; Disease; Activity; Usage of fungicides on field peas 62,281 ha grown in Great Britain, 2004 (spray hectares) (Source: CSL Pesticide Usage survey, 2004) Fungicides approved field peas 2006


field peas

Disease Activity Usage in 2004 (spray

hectares) Azoxystrobin New Annex 1 √ Botrytis Leaf & pod spot systemic translaminar and

protectant strobilurin 29,327

Chlorothalonil Annex 1 √ Botrytis Leaf & pod spot protectant chlorophenyl 68,021 Chlorothalonil/cyproconazole Annex 1/List 3B √ Botrytis Leaf & pod spot protectant chlorophenyl/contact

& systemic conazole 6,398

Chlorothalonil/pyrimethanil Annex 1/List 2 √ Botrytis Leaf & pod spot protectant chlorophenyl/anilinopyrimidine

Chlorothalonil/vinclozolin Annex 1/List 1 √ Botrytis Leaf & pod spot protectant chlorophenyl/ protectant dicarboximide

.

Iprodione SOLA Annex 1 - Botrytis Sclerotinia Stemphyylium

protectant dicarboximide with some eradicant activity

.

Metconazole Annex 1 - Botrytis Mycosphaerella conazole Vinclozolin List 1 - Botrytis Leaf & pod spot protectant dicarboximide 7,123Sulphur List 4 commodity inorganic 1,919

- Company request confidentiality; √ yes

Seed treatments In 2004 the two most important seed treatment active substances used on peas were thiram and cymoxanil/fludioxonil/metalaxyl-M, accounting for 55% and 23% of the area grown respectively. Thiabendazole applied as thiabendazole/thiram has important use as control measure against Aschochyta infection that occurs in seed crops grown in a wet year. In the 2004 survey nearly all peas, received a seed treatment prior to drilling. Table 7. Fungicide seed treatments approved for field peas 2006; Review status; Aim re-registration UK field peas; Disease; Activity; Usage of seed treatments on field peas 62,281 ha grown in Great Britain, 2004 (hectares). (Source: CSL Pesticide Usage survey, 2004) Fungicide seed treatments approved 2006

Review status Aim re-registration UK field peas

Disease Activity Usage in 2004 (ha)

Cymoxanil/metalaxyl M/fludioxonil

List 3B/ New Annex 1/List 3A

√ / √ / √ downy mildew, damping-off Ascochyta

acylanilines / cyanopyrrole 14,325

Fosetyl-aluminium SOLA Annex 1 x(crops not decided) downy mildew Systemic phosphonic acid Thiram /thiabendazole Annex 1/Annex 1 √ / √ damping-off Ascochyta protectant

dithiocarbamate/benzimidazole Thiram Annex 1 √ damping-off protectant dithiocarbamate 34,086

√ yes

1. The likely impacts of the 91/414/EEC review process on fungicide availability for UK field peas

1.1. Losses All fungicides for peas were supported in 91/414/EEC review process and so far there are no significant losses of active substances through failure to achieve Annex 1 listing (Tables 6 and 7).

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1.2. Impact So far, the 91/414/EEC review process has had no impact on fungicide availability for UK peas. Gaps identified for peas in Gap Analysis Table 8 were not a result offungicides lost in the EC Review. 1.3. Future losses? The most important fungicides achieved Annex 1 inclusion but we do not yet know whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. At the time of writing, no decision has been reached on inclusion of vinclozolin and other active substances remaining on List 1. There has been no agreement so far between Member States, and the case has gone to the EU Council. It was not supported for use in peas for Annex 1 inclusion but it has UK approval. The Commission proposal is that vinclozolin should be included on Annex 1 for use in some other crops but not for peas. Views of the crop sectors have been sought by PSD Decisions have not been made yet (June 2006). Usage of vinclozolin is greater in field peas than on vining peas but if vinclozolin is lost other alternatives are available. There is a SOLA for iprodione (list 1 originally) spray in combining peas (Table 6). Residues data for some older SOLAs may not satisfy modern EC standards – a PSD study of data in archives, covering List 1 actives, suggests that new data may be required to set MRLs to support some minor crops/uses. List 2 (fosetyl-aluminium seed treatment Table 7) and some list 3 actives will be studied later. The impact will be on cost to the grower through PGRO levy to maintain these uses. 2. Specific fungicides or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

It would be desirable to maintain the following: All Seed Treatments Cymoxanil/fludioxonil/metalaxyl-M. Cymoxanil is particularly important for downy mildew control because some strains are already resistant to metalaxyl. Downy mildew cannot be controlled with available foliar applied fungicides. Fosetyl–aluminium as an alternative for downy mildew control needs to be maintained. Thiram/thiabendazole is required for Ascochyta control in some seasons. Thiram only prevents damping off disease but it is a cheap seed treatment for varieties that have good field resistance to downy mildew and for seed not infected with Ascochyta.. Foliar sprays There is a limited range of fungicides available for field peas, although more than for vining peas. To avoid resistance to diseases it would therefore desirable to maintain: Chlorothalonil and chlorothalonil mixtures are the most important, Azoxystrobin, Triazoles cyproconazoles, metconazole Iprodione SOLA for Sclerotinia

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3. Prospects for alternatives for any foreseen major gaps in fungicide availability

A limited range of fungicides is available for field peas, and more are needed with different modes of action for resistance strategy. 3.1. Alternatives Gaps (Gap Analysis, Table 8) identified requirements for new chemistry not available in the UK for peas and beans. There are prospects for filling gaps. Mutual Recognition could be helpful. a. Downy mildew (Peronospora viciae): no means of control with foliar sprays. Actives are available in UK for other crops, but development work and residues data are needed. b. Powdery mildew (Erysiphe pisi): Metconazole is now approved for peas for control of leaf & pod spot and it may be effective on powdery mildew but efficacy trials are needed (residues data not needed). c. Botrytis (Botrytis cinerea): several fungicides have an on-labelapproval, but only offer a reduction in disease. d. Sclerotinia ( Sclerotinia sclerotiorum): Iprodione SOLA is the only approved fungicide for this disease. Actives are available in the UK but efficacy work is needed. Cyprodonil (new Annex 1) is used in France would be a better alternative for Sclerotinia and Botrytis control. It will be re-registered in N Europe. UK Off–label Approvals based on recognition of on-label approval in another (current Northern zone) member state and where there is an extant on-label approval for the use of the same product on another edible crop in the UK, should be possible for fungicides for field peas, where the area is now less than 50,000 ha. Global fungicide development overall does not appear to have decreased so far and for the vegetable sector has even increased and this could benefit field peas (Phillips McDougall, ECPA conference, November 2005). 3.2. Impact of the proposed regulation and revision of 91/414EEC General comments see Executive Summary.

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Table 8. Gap Analysis (field peas): Fungicides

Disease (Latin name)

Application timing





Damping-off (Pythium spp)

seed treatment ** thiram Only thiram approved in UK none alternatives required if thiram lost

none

Downy mildew (Peronospora viciae)

seed treatment ** Seed treatment cymoxanil

Only cymoxanil available, already resistant to metalaxyl

Variety resistance. Some combining pea varieties with tolerance

No other actives developed

none none


foliar *** none No approved fungicides See above Actives available in UK None in peas, efficacy data needed

Botrytis cinerea foliar ** Amistar (azoxystrobin) and others

Better control is needed. Cyprodonil ?

none Actives available in UK Cyprodonil in France

efficacy data needed

Sclerotinia sclerotiorum

foliar

** iprodione SOLA

Better control is needed. Cyprodonil ?

none Actives available in UK Cyprodonil in France

efficacy data needed

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Weed control in Field Beans

Table 1 shows the yield achieved by the use of simazine compared with untreated beans, and the effect of weeds on harvestability. Field beans have an indeterminate growth habit, older winter bean varieties are very long-strawed and thus compete well with weeds although the low plant density reduces the competitive effect early in the season. Weed problems are related to the germination periods of various species: cleavers and black-grass are an increasing problem in autumn-sown beans, although some may germinate in spring as well; black-bindweed affects the spring-sown crop. Black-bindweed and cleavers grow above the crop canopy and cause lodging and harvesting difficulties, black-bindweed and volunteer rape are still green at harvest and require desiccation and cleavers and black-grass senesce and set seed. It is therefore considered important to control these species. Common couch is often associated with field beans grown on heavy soils and volunteer potatoes can be a problem on lighter ones. Although some winter bean crops are drilled, on heavy soils the large seeds are often broadcast and then shallowly ploughed in. This ensures adequate depth protection from simazine of more than 80 mm and the surface is usually levelled before autumn herbicide application. Alternatively, early harrowing in spring can be done to encourage tillering of the crop and to remove weeds prior to treatment with simazine. Spring-sown field beans are grown on a wide range of soils and drilled as early as possible, usually on 200 mm rows. There is some interest in establishing winter and spring beans with minimum tillage and when simazine is no longer available there will be no need for 80 mm sowing depth to avoid damage. Impact: weed populations on heavy cloddy seedbeds are usually low. Some data suggest that weeds in winter beans often do not pose a threat to yield (Table 1) and significant expenditure on weed control is rarely warranted. Weeds are more damaging in the spring crop, particularly if high populations compete for moisture. However, weeds, importantly cleavers and black-grass, set seeds in beans, and return to cause weed infestations in other arable crops. Weeds also cause lodging and harvesting difficulties in spring and winter crops and may need desiccation. Control: nearly all the winter bean crop is treated with simazine, a cheap, soil-applied residual herbicide that controls many broad-leaved weeds and some grasses. There is a SOLA for pendimethalin for winter beans but this can cause damage on heavy, water-logged soils. Clomazone is applied where cleavers are anticipated. The only safe foliar-acting post-emergence herbicide is bentazone, which is relatively expensive and controls a limited weed spectrum. Field beans are grown on heavier soil types where there may be a resistant black-grass problem. There are opportunities in beans to control resistant blackgrass: with propyzamide or trifluralin, and the practice of sowing winter beans by ploughing in seed will also help reduce black-grass. So far, black-grass resistance to trifluralin, propyzamide and carbetamex has not been found (Heap, 2006) and there is an opportunity to control resistant black-grass with propyzamide (Pollak & Collings, 2003) and cheap trifluralin (James, Kemp & Moss, 1995) pre-weed-emergence. Several post-emergence graminicides are approved for use in beans. New label restrictions by PSD on these ACCase inhibitors to avoid grass weed resistance will have little impact on the field bean crop. It is not economic to use the high dose of graminicide required for perennial grasses in beans and the annual dose rate will suppress couch. The best and cheapest means of eradicating common couch is with glyphosate applied either pre-harvest in the previous cereal crop, or in autumn before sowing, or pre-harvest of beans (not seed crops).

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Desiccants are seldom used in field beans unless any green weeds are present. Most weeds senesce by harvest stage of winter and spring-sown crop but a few species such as black-bindweed will still be green and cause severe harvesting difficulties. However, the passage of the sprayer through tall winter crops causes damage and crop loss. Sulphuric acid is an approved desiccant for beans, but is not used. Because the necessary residues data have not been generated diquat is not approved for use on beans grown for human consumption and these varieties account for most of the spring bean area. Desiccant use is likely to become more important if weed control is poor after 2007. Non-chemical control: Field beans can be grown successfully without herbicides using flexible-tine weeders or with inter-row hoes where they are sown on wide rows. The crop is more tolerant of damage than peas. However, more than one pass is needed and it is a more costly, and a less effective method of weed removal than with herbicides. Herbicides for Field Beans

Herbicides approved for 2006 and herbicide use in 2004, are shown in Table 8. The weeds controlled are given in Appendix 2. The bean herbicides registered for the UK, cyanazine, terbutryn and fomesafen (blue text in Table 2) were not supported in the EC Review, simazine failed Annex 1 listing. All have ‘Essential Use’ derogations for field beans but can no longer be used after 31 December 2007. Surveys show that the use of herbicides on the area grown has increased significantly from 152% to 249% over the last ten years. More than two herbicides were applied to the field bean crop in 2004 including total herbicides glyphosate or diquat/paraquat. The use of glyphosate is increasing. In 2004, total herbicides, mainly glyphosate, and some diquat/paraquat were applied to 44.4% of the crop area before sowing or emergence of the crop. Of the bean area grown, 73% was treated with simazine pre-weed-emergence at full label rate to control a broad spectrum of weed species. Clomazone was applied pre-emergence in tank-mixes to 16.3% of the bean area for cleavers control – this suggests that cleavers were not well controlled in the previous wheat crop. Herbicides used to control black-grass were propyzamide and trifluralin pre-weed-emergence. Propyzamide is more expensive than trifluralin. Carbetamide was not widely used in 2004 although more was sold in 2005, and tri-allate has been difficult to obtain. Trifluralin is becoming more widely used on 7.7% of the crop area in 2004, because it is cheap and it is also effective on some broad-leaved weeds including fat-hen and polygonums. Post-emergence graminicides were applied to 46.8% of the bean area to control a range of grass weeds and volunteer cereals, and on 2.5% of the crop there were two applications. In 2005 isoxaben/terbuthylazine became available again – the registration was still extant. It is approved for broad-leaved weed control pre-emergence in spring beans. Two new herbicides were registered for winter and spring field beans (and peas) in 2005: quizalofop-p-tefuryl (product name Panarex) a graminicide, and linuron/trifluralin (product name Blois). However the future of trifluralin is doubtful – it may not achieve Annex 1 positive listing and even if it does, it may not be approved in some Member States. Neither linuron/trifluralin nor isoxaben/terbuthylazine are as effective on such a wide range of weeds as simazine. A new SOLA for pendimethalin in spring beans was approved in 2006. Desiccant use in field beans is low – diquat was used in only 2.2% of the crop in 2004.

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Table 9. Herbicides and desiccants approved for field beans 2006; Review status; Aim re-registration field beans UK; Activity; Usage of herbicides and desiccants on field beans 179,720 ha grown in Great Britain in 2004 (spray hectares) (Source: CSL Pesticide Usage survey, 2004) Herbicides and desiccants approved for field beans 2006

Review status Aim re-registration field beans

UK


Total weeds Glufosinate-ammonium List 2 not decided contact phosphinic acid Glyphosate Annex 1 √ translocated phosphonic acid 78,485 Diquat/paraquat Annex 1/ Annex 1 √/ √ contact bipyridyls 1,263Grass weeds Carbetamide winter List 3A √ residual pre- & post carbamate Cycloxydim List 3A - translocated oxime 23,938 Fluazifop-P-butyl List 3A √ translocated phenoxypropionic acid 5,024 Propaquizafop List 3A √ translocated phenoxy alkanoic acid 16,213 Quizalofop-p-ethyl List 3B √ translocated aryl phenoxypropionic acid Quizalofop-p-tefuryl List 3B √ translocated aryl phenoxypropionic acid Tepraloxydim New Annex 1 - translocated oxime 43,329 Propyzamide winter Annex 1 - residual amide 8,510 Tri-allate List 3B √ residual thiocarbamate Broad-leaved weeds (and some grasses) Bentazone Annex 1 - contact diazinone Clomazone List 3A √ residual oxazalodinone 29,253 Cyanazine until 31 Dec 2007 Not supported contact and residual triazine . Cyanazine/pendimethalin spring until 31 Dec 2007

Not supported/Annex 1 residual and contact triazine/ dinitroaniline 28,050

Fomesafen/terbutryn/# spring until 31 Dec 2007 Not supported residual and contact diphenyl ether/triazine Linuron/trifluralin Annex 1/List 2 √ / √ residual and contact urea / dinitroaniline Isoxaben/terbuthylazine spring List 3B/List 3B / √ residual amide/triazine . Pendimethalin winter and spring SOLAs Annex 1 - residual dinitroaniline 19,491 Simazine until 31 Dec 2007 Non-inclusion residual triazine 131,170 Trifluralin List 2 - dinitroaniline 13,784 Terbutryn/terbuthylazine until 31 Dec 2007 Not supported/List 3B residual and contact triazines Other herbicides includes mainly terbutryn/terbuthylazine & some terbutryn/fomesafenin 2004

48,276

Desiccants/harvest management Glufosinate-ammonium List 2 not decided

(√ N) contact phosphinic acid

Glyphosate Annex 1 √ contact phosphonic acid Diquat Annex 1 (√ N) contact bipyridyl 3,969

# no longer available; Future of trifluralin doubtful; blue text not supported, or failed Annex 1 listing; - Company request confidentiality; √ yes; (√ N) aim re-register in N Europe

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1. The likely impacts of the 91/414/EEC review process on herbicide / desiccant availability for UK field beans

UK field beans have been dependent on simazine for grass and broad-leaved weed control. The main impact will be on costs - simazine at £4/ha compared with a tank-mix £67/ha excluding application cost, for a crop with Gross margins £240 (winter), £220/ha spring. The loss of effective wide spectrum herbicides pendimethalin/cyanazine and terbutryn/ terbuthylazine will affect spring bean yields, increase weed seed return and reduce harvestability.

1.1. Losses Simazine failed Annex 1 listing in the 91/414/EEC Review. There is a derogation for ‘Essential Use’ in field beans until 31 December 2007. Simazine is a residual herbicide that controls a wide range of broad-leaved and grass weeds (Appendix 2). It is the most widely used herbicide for field beans - virtually all winter beans are treated with simazine, and some is used in spring beans. In total 73% of the spring and winter bean crop was treated with simazine in 2004 (Table 9). Winter beans are treated pre- or sometimes post-emergence, spring beans pre-emergence. It would have been desirable to maintain simazine, the most widely used herbicide in beans. Terbutryn, fomesafen and cyanazine were not supported in the EC Review, but have derogations for Essential Uses until 31 December 2007. Pendimethalin/cyanazine was used for spring beans, on 15.6% of the total bean area in 2004. Terbutryn/terbuthylazine is also popular in spring beans. for pre-emergence grass and broad-leaved weed control, including black-bindweed, which causes lodging. There was little use of fomesafen/terbutryn. Pendimethalin and fomesafen control volunteer oilseed rape, which has become a widespread and persistent problem because of the longevity of survival of seed in the soil. After 2007 a few pre-emergence alternatives may remain but they are less effective: isoxaben/terbuthylazine (spring beans only) and linuron/trifluralin. Trifluralin may fail Annex 1 and/or UK registration, so might terbuthylazine. Pendimethalin on Annex 1, will remain and will form the basis for weed control in winter and spring beans, but it needs a partner and could be tank-mixed with these or clomazone, which controls cleavers and a few broad-leaved weeds. Post-emergence herbicides are needed for species that escape control with residual pre-emergence herbicides; and for soils types with <10% organic matter. However the only safe post-emergence herbicide for field beans is bentazone (on Annex 1), which only controls a narrow weed spectrum, is expensive and is seldom used. 1.2. Impact

• The impact from loss of herbicides for beans cannot be assessed nationally in terms of yield, weed seed return or harvesting difficulties causing increased use of desiccants because Essential Uses continue until the end of 2007.

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• Limited data (Table 1) suggest that winter beans will not suffer yield loss, spring beans 4 – 17% loss depending on weed population and species.

• Winter and spring beans are harvested after most weeds have set seeds, which return to

infest the following crop. Cleavers are a particular problem. Field beans had been regarded as a cleaning break crop in the rotation with winter wheat but this will no longer be the case when broad-spectrum herbicides are lost.

• The cost of simazine at full dose rate is about £4/ha. After 2007 the only options for weed

control may be pendimethalin (Annex 1) SOLA (£34/ha), clomazone (£33/ha) and tank-mixes may be needed (£67/ha), but there will be some gaps in the weed spectrum shown in Appendix 2. Trifluralin (£5.70/ha) or trifluralin/linuron may not be available (see 2.).

• Propyzamide £50/ha will be used for resistant black-grass and it controls some broad-leaved

species (Appendix 2). Propyzamide and carbetamide can only be used in winter beans.

• Field beans can be weeded with inter-row hoes where they are sown on wide rows, or with flexible-tine weeders. However, it is a less effective method than with herbicides. The cost of weeding once with a steerage hoe is c. £34.75/ha and two or three passes would be needed (£69.50 or £104.75/ha).

• Black-bindweed and cleavers cause lodging and harvesting difficulties.

• In weedy crops, diquat (£27/ha) desiccant will only be used to avoid harvesting difficulties

if some species, e.g. black-bindweed are still green. The passage of the sprayer through tall winter crops causes damage and crop loss. In spring beans, mainly grown for human consumption, diquat is not approved for use because the necessary residues data have not been generated.

• Gross margins for beans are lower than for wheat or oilseed rape: £240/ha (winter), £220/ha

(spring) excluding a human consumption premium, which is not always achieved. Thus any increase in production costs will mean that beans will be even less profitable.

• Growers levy through PGRO, funded projects to find alternatives.

There are benefits for the field bean crop and it may continue to be grown:

• markets, UK for animal feed and for human consumption export, and no surpluses. • opportunities to control resistant black-grass: with propyzamide or trifluralin, and the

practice of sowing winter beans by ploughing in seed will also help reduce black-grass infestations.

• no nitrogen fertiliser is used. 1.3. Future losses? There are few herbicide options remaining for UK field beans and we do not yet know whether remaining active substances, all on List 3, clomazone, terbuthylazine, isoxaben and several graminicides (Table 9) will achieve Annex 1 inclusion. The future of trifluralin (List 2) is doubtful. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios.

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Field beans, particularly winter-sown varieties, are not widely grown in other EU countries and it is surprising that companies in many cases are aiming to re-register products in the UK or N Europe after Annex 1 inclusion (Table 9). 2. Specific herbicides/desiccants and herbicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Glyphosate non-selective herbicide pre-cropping. It vital that the few remaining herbicide are maintained: Pendimethalin on Annex 1 is essential. Isoxaben/terbuthylazine (both on List 3B) (spring beans only). Trifluralin/linuron (List 2/Annex 1). Clomazone (List 3A) for cleavers control. Bentazone (on Annex 1), will be needed for charlock control etc. It is the only post-emergence herbicide for broad-leaved weeds in field beans, others have been evaluated but are too damaging. Trifluralin (spring and winter), propyzamide (Annex 1) (winter) are needed to control herbicide-resistant black-grass in beans and as part of the management strategy for the arable rotation as a whole. There are guidelines (WRAG http://www.pesticides.gov.uk/rags.asp?id=714; Moss & Clarke, 1994) for control of resistant blackgrass. Trifluralin is therefore an important product for use in field beans grown on heavy land, where black-grass resistance is increasing. No resistance to trifluralin has ever been detected in grass-weeds in the UK (Moss & Clarke, 1994; James, Kemp & Moss, 1995; Heap, 2006). It is therefore a useful tool for resistant black-grass control and is cheaper than propyzamide, a benzamide also with MoA K1 (£42.00 - £51.00/ha). If trifluralin is lost there will be more use of propyzamide, thus increasing production costs by £37.00/ha. Trifluralin is also becoming more widely used in beans because it is also effective on some broad-leaved weeds including fat-hen and polygonums. It would also be useful to maintain tri-allate (spring and winter) although there is some evidence of a low level of resistance. Graminicides need to be maintained where there are no resistant grass weeds, to control volunteer cereals. In 2004, post-emergence graminicides, mainly tepraloxydim (Annex 1) and cycloxydim, were applied to 46.8% of the bean area to control a range of grass weeds and volunteer cereals, and there were two applications on only 2.5% of the crop. Desiccants are seldom used in field beans but harvest aids are likely to be needed if weeds become a problem after 2007: diquat, and glyphosate (both on Annex 1). Glufosinate-ammonium (List 2) is much less important.

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3.1. Alternatives A ‘Gap Analysis’ (Table 10) shows the critical herbicide gap * * *, where there are, or soon will be no control measures at all. There is an urgent need for new broad-spectrum pre-emergence herbicides and there are two pre-emergence herbicides registered for peas in France that are potential alternatives to those lost for UK field beans in the 91/414 review:

a. aclonifen + pendimethalin tank-mix b. imazamox/pendimethalin

Pendimethalin is on Annex 1. Aclonifen is on List 3B, rapporteur Germany and Mutual Recognition will be used to request authorisation in the UK for peas only.

Imazamox is a new active substance on Annex 1. UK registration is being sought for the formulated imazamox/pendimethalin product for field beans. A UK Off–label Approval based on recognition of on-label approval in another (current Northern zone) member state and where there is an extant on-label approval for the use of the same product on another edible crop in the UK, is not possible for a major crop. These arrangements only apply to applications for off labels for minor crops of areas less than 50,000 ha. This rules out field beans as a whole, but could perhaps be a route for winter or spring beans. However, there may be few opportunities because the UK is the largest producer of field beans, areas in other EU countries are small but there is increasing interest in France.

3.2. Impact of the proposed regulation and revision of 91/414EEC See general comments in the Executive Summary.

• The new regulation is expected to form part of the wider “Thematic Strategy for the sustainable use of pesticides” which includes the Water Framework Directive. There are concerns regarding water issues with some bean herbicides:

Trifluralin is classed as a Priority Substance (pesticide) “ ..individual pollutants presenting a significant risk to or via the aquatic environment, including such risks to waters used for the abstraction of drinking water” and it presents a risk to the aquatic environment. It is one of the four remaining pesticides listed (diuron, isoproturon, chlorpyrifos, trifluralin) that have not been revoked in the EC Review. Bentazone has been found in groundwater above the 0.1 µg/L drinking water limit but this is more likely to result from applications to peas. Propyzamide and carbetamide were problematic in surface water in one catchment area in 2004/2005.

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Table 10. Gap Analysis (Field Beans): Herbicides and Desiccants

Weeds/weed species

Application timing

Gap Status

Current approved solution Comments Solution non-chemical




Annual meadow-grass & annual BLW

pre-em * * * Several products (Simazine); Opogard & Batallion (terbutryn/terbuthylazine); Reflex T (fomesafen/terbutryn); Bullet (pendimethalin/cyanazine)

Simazine failed Annex 1 listing Essential Use until 31 Dec 2007 most widely used Terbutryn, fomesafen, cyanazine not supported in the EC Review Essential Use until 31 Dec 2007 All control a wide weed spectrum, all will be lost

Mwchanical weeding ineffective in a wet year, 2-3 passes needed

None yet Registered for peas France: aclonifen + pendimethalin; or imazamox/ pendimethalin imazamox new on Annex 1

Annual meadow-grass & limited range of annual BLW

Pre-em * * Blois (trifluralin/linuron); Skirmish spring (isoxaben/terbuthylazine); Stomp (pendimethalin) SOLA; Treflan (trifluralin) SOLA

Other pre-emergence alternatives: isoxaben/terbuthylazine and linuron/trifluralin may remain but they are less effective. Trifluralin may fail Annex 1 and/or UK registration, so might terbuthylazine. Pendimethalin Annex 1 SOLA will remain but needs a partner could be tank-mixed + Blois, Skirmish or Centium.

As above

Volunteer oilseed rape

pre-em * * fomesafen/terbutryn; pendimethalin/cyanazine; pendimethalin

Only pendimethalin left pre-emergence Flexible–tine weeding ineffective on rape

imazamox/ pendimethalin

Cleavers pre-em * * Centium (clomazone) clomazone used for cleavers control. Controls a limited range of other broad-leaved weeds.

Mechanical weeding ineffective in a wet year, 2-3 passes needed

Annual BLW post-em * * bentazone The only post-emergence treatment and high cost Bentazone is on Annex 1 weaknesses: knotgrass, speedwells, annual meadow-grass, and control of large fat-hen is poor. Useful for mayweed and possibly cleavers control

As above

Annual Grasses and annual meadow-grass

pre-em pre-planting

* Avadex BW (tri-allate) Kerb (propyzamide) winter Carbetamex (carbetamide) winter; Treflan (trifluralin)

All important for strategy for resistant grass weeds developing in field beans. Tri-allate difficult to obtain.

As above

Desiccant pre-harvest * * diquat Very little used in beans and cannot be used on human consumption crops (special spring sown varieties that account for most of the area).

As above Residue data for human consumption beans

No residues data



Pest control Field Beans

Stem and bulb nematode (Ditylenchus dipsaci) Stem and bulb nematode is the most damaging pest of field beans and can cause severe problems in wet seasons. The pest is seed-borne and the free-living nematode can also infest soils, thereby becoming a problem for a wide range of other crops. It occurs where farm-saved seed from an infested stock has been multiplied for several generations. Impact: it has reduced crop yields to 0.8 t/ha. Control: no nematicide is approved and none is required. Cultural control: by using nematode-free seed and crop rotation. Seed should be tested for the nematode, and only clean stocks should be sown. Pea and bean weevil (Sitona lineatus) This pest attacks spring beans and weevil causes characteristic ‘U’ shaped notches around the edges of leaves, but the main damage occurs as a result of the larvae feeding on the root nodules. Winter beans are also prone to attack but growth is too advanced in growth for the pest to affect yield. Impact: may reduce yield of spring beans if large numbers appear when plants are small. Control: with pyrethroids applied at the first sign of leaf damage and repeated after 7 to 10 days. A monitoring system for pea and bean weevil is available Field thrips (Thrips angusticeps) The tiny black "thunderflies" feed on the leaf surface of spring beans, they are seldom a problem in winter beans. In beans, the thrips feed on the leaf surface and are often more exposed than in peas. Impact: bean leaves die, growth temporarily arrested. Control: no insecticide approved but a contact pyrethroid such as lambda-cyhalothrin applied for weevil control, will provide adequate control of thrips. It is seldom necessary to spray winter beans. Black bean aphid (Aphis fabae) Spring-sown crops are usually more likely to suffer damaging attacks than winter beans. Colonies in the growing points of beans from onset of flowering result in flower loss and poor pod development. Black bean aphid (and pea aphid) are able to transmit several viruses, which add to the yield loss. Impact: severe yield loss if uncontrolled. Control: aphids can be controlled using pirimicarb as soon as 5% of the plants have been colonised. The choice is limited to insecticides that do not harm pollinating insects – thus pirimicarb is mainly used, (nicotine, fatty acids and rotenone also approved). There are no reports of insecticide resistant aphid strains in the UK yet. Bruchid beetle (Bruchus rufimanus) Adults fly to beans during flowering and lay eggs on developing pods. The larvae bore through the pod and into the seed, where they feed until mature and adults emerge from the seed leaving a hole. Impact: negligible effect on yield, no effect on animal feed quality. Bean damage from larval feeding reduces quality for export for human consumption (premium £12/tonne). Control: Lambda-cyhalothrin or deltamethrin should be applied to the crop as soon as beetles are found in the flowers, before the first eggs are laid and repeated seven days later. Molluscs Slugs (Deroceras, Milax and other spp.) Slug feeding can result in poor seedling establishment on wet or heavy soils with high organic matter. Slugs can also attack seeds and roots.

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Impact: reduction in plant stand. Control: metaldehyde pellets are applied at an early stage of crop growth. Cultural control: soils containing high levels of organic debris including straw are most likely to harbour slugs. Such debris should be well dispersed, chopped and spread or disked before ploughing in the autumn. Insecticides and molluscicides for field beans Insecticides approved for 2006 and insecticide use in 2004, are shown in Table 11. In the 2004 survey 70% of beans were treated with at least one insecticide. In 2004 the majority of insecticides were applied for the control of pea and bean weevil, which accounted for 47% of the insecticide-treated area, aphids 23%, unspecified pests 15% and bruchid beetle 13%. The use of pyrethroids has increased significantly over the last decade because most spring varieties are grown for export for human consumption and insecticides for control of Bruchid beetle are used to achieve quality. Bruchid beetle has become widespread and the area of spring beans has extended further north in an attempt to escape the pest. Table 11. Insecticides and molluscicides approved for field beans 2006; Review status; Aim re-registration UK field beans; Usage of Insecticides and molluscicides on field beans 179,720 ha grown in Great Britain, 2004 (spray hectares) (Source: CSL Pesticide Usage survey, 2004) Insecticides and molluscicides approved for field beans 2006

Review status Aim re-registration UK beans


Insecticides Carbamate Pirimicarb Annex 1 √ aphid contact pyrethroid /carbamate 56,630Pyrethroid Alpha-cypermethrin Annex 1 - pea weevil contact and ingested pyrethroid 20,073 Cypermethrin Annex 1 pea weevil contact and stomach acting pyrethroid 84,443 Deltamethrin Annex 1 √ pea weevil contact pyrethroid 41,848 Lambda-cyhalothrin Annex 1 √ pea weevil contact and ingested pyrethroid 59,596 Lambda-cyhalothrin/pirimicarb Annex 1/ Annex 1 √ / √ aphid pea weevil contact and ingested pyrethroid/carbamate Zeta-cypermethrin List 3A √ pea weevil contact and stomach acting pyrethroid 19,729 Fatty acids List 4 aphid soap concentrate Nicotine unsupported? List 4 aphid contact pyrethroid Molluscicides Metaldehyde List 3A ? slugs molluscicide bait 1,325

- Company request confidentiality; √ yes 1. The likely impacts of the 91/414/EEC review process on insecticide / molluscicide availability for UK field beans

1.1. Losses So far, the 91/414/EEC review process has had no impact on insecticide availability for UK field beans. Gaps identified for beans in Gap Analysis Table 12 were not a result of insecticides lost in the EC Review.

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The revocation of broad-spectrum organophosphate insecticides in the UK after the anti-cholinesterase review, has increased reliance on pyrethroids and increased the risk of developing pest resistance. 1.2. Impact None. 1.3. Future losses? The most important insecticides achieved Annex 1 inclusion (Table 11), but there is no decision yet on List 3A molluscicide, metaldehyde. Slugs are a problem in wet years but metaldehyde is not widely used, therefore a company decision to re-register will depend on whether data is required for each crop/use combination. We do not yet know whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. 2. Specific insecticide/molluscicide or insecticide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

A limited range of insecticides is available for field beans. Aphid resistance in beans to pyrethroids or pirimicarb has not been found yet, but active substances with different modes of action are needed for resistance strategy. It would be desirable to maintain the following: Pyrethroids, the most important is lambda-cyhalothrin for pea weevil and Bruchid beetle control. Pirimicarb (Annex 1) alone or with lambda-cyhalothrin (Annex 1) essential for aphid control. It would be desirable to maintain a UK approval for molluscicide bait metaldehyde (List 3A). In wet years and on heavier soil types slugs are a problem in field beans. 3. Prospects for alternatives for any foreseen major gaps in insecticide availability

3.1. Alternatives Most spring varieties are grown for export for human consumption and insecticides (lambda-cyhalothrin or deltamethrin) for control of Bruchid beetle are used to achieve quality. The pest lays eggs over a long period and currently several sprays are applied. A more persistent insecticide is needed. Spray application to reach the target below the crop canopy is also difficult. The Gap identified for field beans highlights the requirement for a more effective and persistent insecticide for Bruchid beetle control. Potential products and residues data are available but efficacy work needed. The Gap is not a result of insecticides lost in the 91/414 EC Review.

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Disease control in field beans

Leaf and pod spot (Ascochyta fabae = Didymella fabae) Winter beans are more prone to serious attacks, which can develop in wet conditions. The disease is almost entirely seed-borne, but infection can also be transmitted from bean volunteers. Brown spots contain distinctive black fruiting bodies (pycnidia), spores on seedlings spread by rain-splash to neighbouring plants. Impact: yield reduction where infection severe. Control: Seed treatments containing thiabendazole are only partially successful in controlling Ascochyta in the seed. Azoxystrobin reduces foliar infection. Cultural control: use only healthy seed - infected seed is unsuitable for sowing. Farm-saved seed should be tested. Resistant varieties are available. Foot rots (Fusarium solani, F. culmorum and Phoma medicaginis var. pinodella) Foot rots are soil borne and can occur on seedlings and on more mature plants, causing browning of the stem base and wilting of the leaves followed by plant death. Some varieties of spring beans are particularly prone to foot rot diseases. However, beans appear less sensitive to foot rots than peas. Impact: yield loss. Control: no chemical control. Cultural control: adequate rotation and avoidance of soil compaction. Downy mildew (Peronospora viciae) Severe infection can reduce flower numbers, and cause defoliation and death of the growing point. Impact: yield reduction Control: a seed treatment cymoxanil/metalaxyl-M/fludioxanil (SOLA) is useful in fields with a history of the disease will control mildew on newly emerged seedlings. Foliar sprays should be applied at early flowering when symptoms are first seen. Cultural control: Several new varieties, for example Fuego, have resistance to the disease. Downy mildew is soil-borne and spreads within the crop by means of air-borne spores. Avoid planting beans on fields where there is a known history of downy mildew. Chocolate spot (Botrytis fabae, B. cinerea) Winter beans are more susceptible to chocolate spot than spring beans. Symptoms appear from early flowering onwards when the first 'non-aggressive' lesions develop on the lower leaves. In cool, wet weather the lesions may enlarge to give a more damaging aggressive phase. Impact: yield reduction from severe attacks particularly if plant populations are high. Control: several fungicides approved. Early fungicide treatment is essential if the crop shows symptoms at first bud or early flower. A second spray may be required 3 to 4 weeks later if damp conditions persist. Additional sprays unlikely to be economic, and there are losses from damage caused by passage of the sprayer. Cultural control: there is no varietal resistance to chocolate spot Bean rust (Uromyces fabae) The disease is characterised by numerous reddish-brown pustules on the leaves. Early shorter-strawed varieties of spring beans are likely to suffer infection of rust in dry seasons. Rust may occasionally be damaging on winter beans. Impact: yield can be severely reduced if the plant defoliates before pods are completely filled. Control: wide range of fungicide mixtures. Treatment is unlikely to be worthwhile if infection begins when pod fill is complete and the crop is beginning to senesce. Cultural control: some varieties have a degree of partial resistance.

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Sclerotinia Sclerotinia trifoliorum may infect winter beans in damp autumn weather, and it may be associated with preceding crops containing red clover. Plants develop a watery stem rot, which spreads to neighbouring plants. Sclerotinia sclerotiorum infects spring beans (but this is very rare) and also peas, rape, linseed, lupins and some field vegetables. Impact: yield loss. Control: no fungicides approved. Fungicides for Field Beans Fungicides approved for 2006, and use in 2004, are shown in Table 12. Strains of both Botrytis spp. developed resistance to MBCs and these fungicides are no longer approved. Fungicide usage has increased in recent years. In 2004, chlorothalonil, tebuconazole and azoxystrobin were widely used and accounted for 73% of the fungicide-treated area. There was also some use of boscalid and mancozeb/metalaxyl M (a potato fungicide). Most usage, 40%, was for chocolate spot control, for downy mildew 14%. New fungicides available in 2005 were a formulation of boscalid/pyraclostrobin (Signum), and metconazole (Caramba). Table 12. Fungicides approved for field beans 2006; Review status; Aim re-registration UK field beans; Disease; Activity; Usage of pesticides on field beans 179,720 ha grown in Great Britain, 2004 (spray hectares) (Source: CSL Pesticide Usage survey, 2004) Fungicides approved for field beans

Review status Aim re-registration UK beans

Disease Activity Usage 2004 (spray ha)

Azoxystrobin New Annex 1 √ rust Ascochyta SOLA,

systemic translaminar and protectant strobilurin

48,371

Boscalid/pyraclostrobin Pending/new Annex 1 - chocolate spot rust Anilide/strobilurin Carbendazim no longer approved List 1 4,158 Chlorothalonil Annex 1 √ chocolate spot Protectant chlorophenyl 209,726 Chlorothalonil/cyproconazole Annex 1/List 3B √ chocolate spot rust chlorophenyl/conazole 28,993 Chlorothalonil/metalaxyl until 31 Dec 2006

Annex 1 √ downy mildew Chlorophenyl/phenylamide

Chlorothalonil/metalaxyl-M Annex 1/ new Annex 1 √ downy mildew chocolate spot

Chlorophenyl/phenylamide

Chlorothalonil/vinclozolin Annex 1/List 1 √ chocolate spot Chlorophenyl/dicarboximide Cyproconazole List 3B √ rust Contact & systemic conazole 11,003 Iprodione Annex 1 - chocolate spot protectant dicarboximide with

some eradicant activity 176

Iprodione/thiophanate-methyl Annex 1/ Annex 1 - chocolate spot Protectant systemic & some curative action

6,760

Metconazole Annex 1 - rust chocolate spot Systemic conazole Tebuconazole List 3B not decided rust chocolate spot Systemic conazole 72,755 Vinclozolin List 1 - chocolate spot protectant dicarboximide Sulphur List 4 commodity √ Inorganic 4,586

Carbendazim no longer approved in field beans; - Co mpany request confidentiality; √ yes

Seed treatments It is estimated that at least half of bean seed sown is farm saved from the previous harvest. Nearly all beans are sown with untreated seed, thiram was used on about 2% of the area grown in 2004. Cymoxanil/metalaxyl-M/fludioxonil SOLA seed treatment is now available to reduce seedling downy mildew infection.

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Table 13. Fungicide seed treatments approved for field beans January 2006; Review status; Aim re-registration UK field beans; disease controlled; activity; Usage of fungicide seed treatments field bean area grown 179,720 ha in Great Britain, 2004 (hectares) Seed treatments 2006 Review status Aim re-registration

UK beans Disease Activity Usage in 2004

(hectares)

Cymoxanil/metalaxyl -M/fludioxonil SOLA



acylanilines / cyanopyrrole

thiram Annex 1 √ damping-off protectant dithiocarbamate 2,927

Thiram/thiabendazole Annex 1/Annex 1 √ / √ damping-off Ascochyta protectant dithiocarbamate/benzimidazole

√ yes 1. The likely impacts of the 91/414/EEC review process on fungicide availability for UK field beans

1.1. Losses So far, the 91/414/EEC review process has had no impact on fungicide availability for UK field beans. 1.2. Impact None. 1.3. Future losses? Several fungicides achieved Annex 1 inclusion (Table 12 and 13) but there is no decision yet on Annex 1 inclusion for the important triazoles, including tebuconazole, cyproconazole and cymoxanil – all on List 3B. At the time of writing, no decision has been reached on inclusion of vinclozolin and other active substances remaining on List 1. There has been no agreement so far between Member States, and the case has gone to the EU Council. It was not supported for use in field beans for Annex 1 inclusion but it has UK approval. The Commission proposal is that vinclozolin should be included on Annex 1 for use in some other crops but not for beans. Decisions have not been made yet (June 2006). Views of the crop sectors have been sought by PSD. Vinclozolin is seldom used in field beans. If vinclozolin does not achieve Annex 1 listing, other alternatives are available. We do not know whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios.

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2. Specific fungicides or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties It would be desirable to maintain the following: Seed treatments It is essential to maintain the seed treatment cymoxanil/fludioxonil/metalaxyl-M, cymoxanil (List 3B) is particularly important for downy mildew control because some strains are already resistant to metalaxyl. To avoid disease resistance it would be desirable to maintain a range of fungicides for beans: Foliar sprays Azoxystrobin (new Annex 1) control of rust, SOLA for Ascochyta. Metalaxyl-M (new Annex 1) the only foliar spray for control of downy mildew, but some strains may be resistant. Chlorothalonil (Annex 1) alone and in formulations. Boscalid/pyraclostrobin (pending/new Annex 1) for control of rust and chocolate spot. Triazoles tebuconazole (list 3B), cyproconazole (List 3B), metconazole (Annex 1) for control of rust and chocolate spot. Iprodione (Annex 1) morpholine and iprodione/thiophanate-methyl (Annex 1) for chocolate spot. 3. Prospects for alternatives for any foreseen major gaps in fungicide availability

3.1. Alternatives Gaps identified for beans highlight requirements for new chemistry to avoid disease resistance and were not a result of fungicides lost in the 91/414 EEC Review.

a. Downy mildew (Peronospora viciae): Seed treatment cymoxanil/fludioxonil/metalaxyl-M, cymoxanil (List 3B) is particularly important for downy mildew control because some strains of the disease are already resistant to metalaxyl. Alternative seed treatments are needed for control of downy mildew but none are available and there are no current prospects. There is also a need for foliar treatments – only metalaxyl-M is available. Foliar fungicides for potatoes and vines, may have potential but efficacy work needed.

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REFERENCES

The PGRO website lists information sheets for growers: http://www.pgro.org COOK SJ, BOWERMAN P & LAVERICK RM (1991) Control of broad-leaved and grass weeds in

winter beans. Aspects of Applied Biology 27, Production and Protection of Legumes, 161-166.

GARTHWAITE DG, THOMAS MR, ANDERSON H & STODDART H (2004) Arable crops in Great Britain 2004. Pesticide Usage Survey Report 202. Central Science Laboratory, Sand Hutton, York, UK

HEATH MC, CLARKE JH (1991) Comparison of pre- and post-emergence herbicides for the control of broad-leaved and grass weeds in spring field beans. Aspects of Applied Biology 27, Production and Protection of Legumes, 167-172.

HEAP I (2006) International survey of herbicide-resistant weeds. hhtp://www.weedscience.org accessed April 2006.

JAMES EH, KEMP MS & MOSS SR (1995) Phytotoxicity of trifluoromethyl and methyl substituted dinitroaniline herbicides on resistant and susceptible populations of black-grass (Alopecurus myosuroides). Pesticide Science 43, 273-277.

KNOTT CM (1994) Weed control for peas and beans at world market prices. Aspects of Applied Biology 40, Arable farming under CAP reform, 351-360.

McCLEAN KA (1985) Pulses: Harvest management, drying and storage. Which protein crop? National Agricultural Centre Arable Crop Conference (1985). 62-80.

MOSS SR & CLARKE JH (1994) Guidelines for the prevention and control of herbicide-resistant black-grass (Alopecurus myosuroides Huds.) Crop Protection 13 (3), 230-234.


POLLAK R & COLLINGS LV (2003) Kerb (propyzamide), its role in reducing Alopecurus myosuroides seed banks in arable crops. Aspects of Applied Biology 69, Seedbanks: Determination, Dynamics & Management, 63-67.

In the text and Appendix 1 & 2 common weed names are according to Dony et al. (1986); in Appendix 1 & 2 Latin names according to Stace (1997). DONY JG, JURY SL & PERRING FH (1986) English Names of Wild Flowers, 2nd edn. The


Cambridge, UK. Appendix 1 & 2: Blue text actives unsupported or failed Annex 1;

pink text Annex 1 doubtful.

ACKNOWLEDGEMENTS

The help and contributions from the following organisations are gratefully acknowledged: Processors and Growers Research Organisation, The Arable Group (TAG), BBSRC Rothamsted Research, Weed Resistance Action Group, Agricultural Industries Confederation Ltd (AIC), National Farmers Union (NFU), United Agricultural Products - Europe (UAP), European Crop Protection Association (ECPA) and Crop Protection Companies.

red text not manufactured after 2007;

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Appendix 1 Weed susceptibility to pre- & post-emergence herbicides for field peas. Key: S = susceptible; MS = Moderately Susceptible; R = Resistant; MR = Moderately Resistant

Common name Latin name terbutryn/ terbuthylazine

fomesafen/ terbutryn

pendimethalin/cyanazine

terbuthylazine/ isoxaben

trifluralin/linuron

pendimethalin + bentazone

terbuthylazine /isoxaben

bentazone MCPB cyanazine cyanazine

bentazone/MCPB +

Bindweed black Fallopia convolvulus S S MS MS MS MS MS MS S* S S Bugloss Anchusa arvensis S S Charlock Sinapis arvensis S S MS S S/MS S S S S S S Chickweed, common Stellaria media S S S S S S MS S R S S Chickweed, mouse-eared Cerastium fontanum S MS R Cleavers Galium aparine R S S S R R MS Corn marigold Chrysanthemum segetum S Corn spurrey Spergula arvensis S MS S Crane's-bill, cut-leaved Geranium dissectum MS S S MR Deadnettle, henbit Lamium amplexicaule S S MS MS MS S Dead-nettle, red Lamium purpureum S S S MS R S S Dock, broad-leaved Rumex obtusifolius S S S Fat-hen Chenopodium album S S S R S MR MS S S S Fool's parsley Aethusa cynapium R S S S MS S R S MS Forget-me-not, field Myosotis arvensis S S R S S S Fumitory, common Fumaria officinalis S S MS R S MS S S S Gallant -soldier Galinsoga parviflora S S Groundsel Senecio vulgaris S S S S R MS R S S Hemp-nettle, common Galeopsis tetrahit S MS S S MS S MR S* S MS Knotgrass Polygonum aviculare S S S MS S S R MR S S MR Mayweed, scented Matricaria recutita S S S S MS MR S R S S Mayweed, scentless Tripleurospermum inodorum S S S S MS MR S R S S Nettle, small Urtica urens S S MS MS S S S S Nightshade black Solanum nigrum ? S MS S S R S MS Orache, common Atriplex patula S S MS MS MR S S Pansy, field Viola arvensis S S S S S S R S* S S Parsley piert Aphanes arvensis MR S Pennycress, field Thlaspi arvense S S Persicaria, pale Persicaria lapathifolia S S S S S S S Pimpernel, scarlet Anagalis arvensis S S S S R S Pineappleweed Matricaria discoidea S S S S S Poppy, common Papaver rhoeas S S MS S S S MS S S Redshank Persicaria maculosa S S S S S S S S* S S Shepherd's-purse Capsella bursa-pastoris S S MS S S S S S Sow-thistle, smooth Sonchus oleraceus S S S MS MS S* MS Speedwell, common, field Veronica persica S S MS S S S MS R S S Speedwell, ivy-leaved Veronica hederifolia R MS MS MR S S Sun spurge Euphorbia helioscopia MR R Thistle, creeping Cirsium arvense R R S S/MS R suppr S Wild radish Raphanus raphanistrum S S S S S S Annual meadow grass Poa annua S MS S R S R R S R Blackgrass Alopecurus myosuroides R R R R R MS R Brome, barren Anisantha sterilis R R R MS R Wild-oat Avena fatua MS R R R R Vol OSR Brassica napus R S MS MR MS S MS S

193

Appendix 2. Weed Susceptibility to the main herbicides for Field Beans. Key: S = susceptible; MS = Moderately Susceptible; R = Resistant; MR = Moderately Resistant Common name Latin name simazine pendimethalin/ cyanazine terbutryn/ terbuthylazine fomesafen/terbutryn clomazone propyzamide trifluralin Bentazone post-

em Bindweed black Fallopia convolvulus S MS S S MR S S MS Bugloss Anchusa arvensis S Charlock Sinapis arvensis S MS S S R R S Chickweed, common Stellaria media S S S S S S S S Cleavers Galium aparine MR MS R S MS R S Corn marigold Chrysanthemum segetum S R S Corn spurrey Spergula arvensis S S MS MS S Crane's-bill, cut-leaved Geranium dissectum MR MS S Deadnettle, henbit Lamium amplexicaule S S S MS Dead-nettle, red Lamium purpureum S S S S S MS MS Dock, broad-leaved Rumex obtusifolius - Fat-hen Chenopodium album S S S S MS S S MS Fool's parsley Aethusa cynapium MR R S S R S Forget-me-not, field Myosotis arvensis S S S S Fumitory, common Fumaria officinalis MS S S S R MS MS Gallant -soldier Galinsoga parviflora Groundsel Senecio vulgaris S S S S S R MS Hemp-nettle, common Galeopsis tetrahit S S S MS S MR Knotgrass Polygonum aviculare MS S S S MR S S MR Mayweed, scented Matricaria recutita S S S R R S Mayweed, scentless Tripleurospermum inodorum S S S S R R S Nettle, small Urtica urens S S S S MR S MS S Nightshade black Solanum nigrum S MS ? S S R S Orache, common Atriplex patula MS MS S R MS MS Pansy, field Viola arvensis MS S S S S R Parsley piert Aphanes arvensis S Pennycress, field Thlaspi arvense R S Persicaria, pale Persicaria lapathifolia S S MS S S Pimpernel, scarlet Anagalis arvensis S S S S S Pineappleweed Matricaria discoidea S S R R S Poppy, common Papaver rhoeas S S S S R MS MS Redshank Persicaria maculosa MS MS S S S S S S Shepherd's-purse Capsella bursa-pastoris S S S S R S Sow-thistle, smooth Sonchus oleraceus S S MS R MS Speedwell, common, field Veronica persica S S S S S S S MS Speedwell, ivy-leaved Veronica hederifolia MS R MS S S S MR Sun spurge Euphorbia helioscopia MR MS Thistle, creeping Cirsium arvense R R R R R suppr Wild radish Raphanus raphanistrum S S R S Annual meadow grass Poa annua S S S MS MS S S R Black-grass Alopecurus myosuroides S S S R Brome, barren Anisantha sterilis S Wild-oat Avena fatua MS S MS Vol OSR Brassica napus R MS R S S propyzamide controls volunteer cereals


194

Horticultural crop VINING PEAS Recommendations for the crop are based on information from the Processors and Growers Research Organisation (PGRO). Research is funded by a levy of 41p per tonne plus VAT, collected from the production of vining peas, green beans and broad beans. The PGRO levy is £50,000 per annum. In some cases, growers will pay two levies, notably the Horticultural Development Council (HDC) statutory levy on these crops and the PGRO voluntary levy, and in such cases, the latter is refundable. The arrangements have allowed the development of integrated and centrally managed research programmes. The PGRO website is: http://www.pgro.org

Background Crop Area The total area of vegetable crops has declined considerably, by nearly 50% or more since the late 1970s. Vining peas, harvested green for freezing and canning, represent the largest vegetable crop area after potatoes. Basic Horticultural Statistics for the UK (Defra, 2006) show that, since 1970s when the area of vining peas was over 50,000 ha, there has been a decline and estimates for 2005 suggest only 31,025 ha were grown. The decline is due to increased popularity of a very wide range of ‘fresh’ vegetables, competition from imports, the high cost of re-investment in pea harvesters (c. £250,000 each) and low prices for the crop. There have been several factory closures in the last 20 years. Vining peas for quick-freezing and canning are grown in the East of England and Scotland, close to processing factories, and top quality “150 minute” peas are grown within 40 miles. The area of picking peas for fresh market was 907 ha in 2005. Vining peas are grown according to Assured Produce protocols http://www.assuredproduce.co.uk. Retailers also have their own restricted lists of pesticides for crops and these differ between individual retailers.

Rotations Crop rotation is essential to reduce the build up of pests and soil-borne diseases in particular. There are no chemical control measures for the several root-infecting fungi that cause foot and root rots to peas, field, broad and green beans. All pea and bean crops are treated as one crop and a break of at least four legume-free years should be maintained between them. Many growers have extended their rotations with breaks of five or even six years. Vining peas are mainly grown in arable rotations that may include winter wheat, sugar beet and potatoes. Peas are grown on a range of soils: sands, light and medium soil types. The growing season is short, about four months. Sowing programmes ensure continuity of supply - vining peas are sown from February to the end of May. Profitability Vining peas are grown on contract to the processor. In the UK the national average yield (fresh weight) for the last five years has ranged from 4.3 to 5.4 t/ha. The average price for peas is approximately £210/tonne where harvesting and haulage are paid for separately. For an average yield of 4.74 t/ha, the output is £1000/ha and the gross margin is about £750/ha (Nix, 2005). The price varies with quality grade (tenderometer value). There are deductions for weedy material, pests and blemishes from diseases and where there is a risk of toxic weed contaminants, the whole crop is rejected.

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Weed Control Vining Peas

Peas have slow initial growth and at early stages are poor competitors with weeds. All weed species will have some effect on pea yield. Lawson, 1983, explored the competitive impact of weeds on this crop. The time when weeds need to be absent from the crop to ensure optimum yield is 2-3 weeks after emergence. Tall species such as fat-hen and wild-oats which shade the crop are particularly damaging. Vining peas are grown in arable rotations. Volunteer potatoes, are a serious problem and a herbicide tank-mix can only prevent formation of toxic potato berries (but the herbicide will not be available after 2007). Volunteer oilseed rape is a widespread and persistent weed. Volunteer cereals, are easily controlled with graminicides. Peas also inherit cereal weeds and these appear to have increased as a result of reducing herbicide doses to minimise costs of growing cereals. A study for Defra HH3403SX (Grundy et al., 2003) gives a representative list of common weed species that are targets for weed control in a range of vegetable crops. Impact: weeds affect quality, yield and harvestability – quality is the most important factor. Quality: The vining crop is machine harvested. Weedy contaminants such as flower or seed heads of creeping thistles, mayweeds, common poppy, sow-thistle, campion, fragments of volunteer oilseed rape and linseed capsules reduce quality of vining peas. Pineappleweed also causes taints. A very high standard of weed control is therefore necessary in the processed crop to avoid quality problems (Knott, 1997) the cost of removal in the factory is £50/tonne plus 3% crop loss. Where separation is difficult or impossible, and where the contaminant is toxic (berries of black nightshade, briony and volunteer potatoes) the crop is rejected because it poses a risk to the consumer. The quality standards have been raised in some products to what amounts to ‘nil tolerance’, for example ‘one piece of contaminant per tonne of peas for freezing’ compared with 2% some years ago. The presence of weed, or other contaminants adversely affects consumer confidence. Harvesting: weeds slow down work rate and increase costs. The impact of weeds is often dependent on harvesting method: for hand-picked peas contaminants are not such a problem, but thistles and nettles are unpleasant for pickers; intake of weedy contaminants by vining pea harvesters reduces quality and some weeds e.g. fat-hen, volunteer oilseed rape, knotgrass slow down harvesting rate. Yield reduction: some data on the effect of weeds on yield is shown in Table 1. Yield loss depends on weed numbers and weed species present and competition with the crop. Table 1. The impact of weeds on pea yield, quality and harvesting (Source crop value: Defra, Basic Horticultural Statistics, 2006)

Crop UK crop value (£ million) 2004/2005

Yield Loss Quality Harvesting & other operations

vining peas machine harvested & processed

35.2 Up to 30% (average 17%)#. Cleaning losses per tonne 3%. Crop rejection 100%.

Weed parts contaminants, some toxic. Cost cleaning £50/t

Slower work rate, higher cost and harvest losses, by-passed crops.

picking peas 3.0 Up to 100% Contaminants, some toxic.

Interfere with manual harvest (nettles, thistles)

# unpublished trials data

Control: In all vining peas weed control is based on early removal with pre-emergence herbicides except for late-drilled crops where dry soil conditions will reduce efficacy of residual herbicides, and where fewer weeds are anticipated. Residual herbicides are applied pre-emergence of weed and peas. Terbutryn/terbuthylazine controls most species and annual meadow-grass; fomesafen/ terbutryn controls volunteer rape as well. Clomazone, for cleavers, has a limited weed spectrum.

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Foliar-acting post-emergence herbicide tank-mixes bentazone/MCPB + cyanazine, cyanazine + MCPB/MCPA are used as a follow-up treatment for weeds which escape pre-emergence control, or alone as an alternative where dry or cloddy seedbeds would reduce residual activity, or where rape and cleavers are the main weeds. Early post-emergence tank-mix isoxaben/terbuthylazine + bentazone is also effective on oilseed rape volunteers. The cyanazine + MCPB/MCPA tank mix prevents formation of volunteer potato berries and is particularly important for vining peas. The timing of application is precise and related to pea growth stage. MCPB controls a limited spectrum but is useful for docks and thistles. Annual grasses: wild-oats, spring germinating black-grass and volunteer cereals are controlled with post-emergence graminicides. Non-chemical control: In most horticultural crops the costs of alternative weed control methods are higher than for weed control with herbicides. Hand labour has now become expensive and also scarce, but is sometimes needed where volunteer potato berries could become a problem. Vining peas are sown on optimum row widths of 200 mm or less, and inter-row hoeing is not an option. However, work (HDC Project FV 243, 2002) has indicated that mechanical weeding techniques can control seedling annual weeds. More than one pass is needed because soil disturbance stimulates another flush of weeds. This technique is suitable for light soils and should be carried out in dry conditions with a flexible-tine weeder either across or in the direction of the pea rows. The technique is unsuitable for grass weeds, perennials or deep-rooted weeds such as black-bindweed or charlock, and it will not control volunteer potatoes. Efficacy is poor in wet conditions because weeds re-establish. Herbicides for vining peas Herbicides approved for 2006 and herbicide usage in 2003, are shown in Table 2. The weed species controlled are given in the Appendix. Peas receive, on average, 2 herbicide sprays. The area treated with herbicides for broad-leaved weed control has increased over the last 25 years – perhaps a reflection of the ‘nil weed contaminant in frozen produce’ policy adopted by buyers. Glyphosate use has increased dramatically – it was used extensively on all crops prior to drilling or planting (on 54% of the area grown). In 2003, residual herbicides mainly terbuthylazine/terbutryn and some fomesafen/terbutryn were used pre-emergence on peas and broad beans. Cyanazine was the most important herbicide used on 59% of the total area of peas & beans grown. MCPB was also used in peas probably for oilseed rape volunteers. Of the pea herbicides registered for the UK, cyanazine, terbutryn and fomesafen (blue text in Table 2) were not supported in the EC Review and have ‘Essential Use’ derogations but can no longer be used after 31 December 2007. In 2005, isoxaben/terbuthylazine, approved for broad-leaved weed control pre-emergence, became available again – the registration was still extant. A new herbicide product was registered for vining peas in 2005, linuron/trifluralin (product name Blois) and another, linuron/ trifluralin/pendimethalin isin development. However the future of trifluralin is doubtful. SOLAs were obtained for a low dose of pendimethalin in vining peas. There is some evidence that resistant grass weeds from cereals are being carried over into vegetable crops although vining peas are spring-sown and there is likely to be inherently lower black-grass populations. To manage resistance, PSD will apply restrictions to the use of existing herbicides where there is a high resistance risk, including ACCase inhibitors ‘fop’ and ‘dim’ graminicides used in vining peas. In 2003, 10.2 % of the 39,998 ha vining pea area grown was sprayed only once with

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a fop or dim and the label restrictions will not affect peas. After 2007, a low dose of pendimethalin is expected to form the basis of weed control in peas, and it will have some activity on black-grass. Table 2. Herbicides approved for vining peas 2006; Review status; Usage of pesticides on 46,211ha peas and beans grown in Great Britain, 2003 (spray hectares). (Source: CSL Pesticide Usage survey, 2003) Herbicides approved for vining peas 2006

Review status Aim re-registered for peas UK

Activity Usage peas and beans 2003 (spray

ha)Total Weeds Glufosinate-ammonium List 2 not decided (√ N) phosphinic acid Glyphosate Annex 1 √ translocated phosphonic acid 24,904 Diquat/paraquat Annex 1/ Annex 1 √ / √ contact bipyridyls 2,667 Paraquat Annex 1 √ contact bipyridyl 55Grass weeds Cycloxydim# List 3A - translocated oxime 1,484 Fluazifop-P-butyl# List 3A √ translocated phenoxypropionic acid 53 Quizalofop-p-ethyl# List 3B √ translocated aryl phenoxypropionic acid Tepraloxydim# New Annex 1 - translocated oxime 2,914 Tri-allate List 3B √ Residual thiocarbamate Broad-leaved weeds & some grasses

Bentazone Annex 1 - contact diazinone 1,835 Bentazone/MCPB## Annex 1/Annex 1 x contact diazinone/translocated phenoxy-butanoic acid 22,785 Clomazone List 3A √ residual oxazalodinone Cyanazine until 31 Dec 2007 not supported contact and residual triazine 27,412 Fomesafen/terbutryn$ until 31 Dec 2007

not supported residual and contact diphenyl ether/triazine 8,290

Isoxaben/terbuthylazine spring List 3B/List 3B - / √ Residual amide/triazine Linuron/trifluralin Annex 1/List 2 √ / √ Residual and contact urea / dinitroaniline MCPB/MCPA Annex 1/Annex 1 √ / √ translocated phenoxybutanoic/ phenoxyacetic acid 4,735 MCPB Annex 1 √ translocated phenoxybutanoic acid 3,560 Pendimethalin SOLA Annex 1 x (-) Residual dinitroaniline 151 Terbuthylazine/terbutryn until 31 Dec 2007

Terbutryn not supported

residual and contact triazines 16,433

$no longer available; ## no longer manufactured after 2007; future of trifluralin doubtful; Active substances in blue text not supported, cannot be used after 31 December 2007; # ACCase HRAC group A; - Company request confidentiality; √ yes; x no; (√ N) re-registration N Europe

1. The likely impacts of the 91/414/EEC review process on herbicide availability for UK vining peas

Unless alternative effective herbicides are available for UK vining peas the crop will be uneconomic to grow and process, there will be factory closures and frozen and canned peas will be imported from mainland Europe, where different herbicides (active substances supported in the Review) are still available. The UK crop has been dependent on triazines. After 2007 there will be no broad-spectrum pre-emergence herbicide for vining peas unless those used in France, which include actives aclonifen or imazamox become available.

1.1. Losses Fomesafen, terbutryn and cyanazine were not supported in the 91/414/EEC Review. These pea herbicides (terbutryn and cyanazine for the last 25 years) have been used without obvious adverse

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effects on consumer or environment. There are ‘Essential Use’ derogations for vining peas, but they expire 31 December 2007. After then there will be no broad-spectrum pre-emergence herbicide for vining peas unless those used in France become available. Pre-emergence herbicides terbutryn/terbuthylazine and fomesafen/terbutryn control a wide spectrum of broad-leaved weeds, annual meadow-grass and some other annual grasses and fomesafen also controls volunteer oilseed rape. It would have been desirable to maintain these. Fomesafen/terbutryn has not been manufactured for the 2006 season and it will not be manufacture in 2007. In vining peas weed control is based on early removal with pre-emergence herbicides, except for late drillings where soil conditions are dry, or on sands or organic soils.

Post-emergence herbicides are needed for species that escape control with residual pre-emergence herbicides; for certain soil types (sands, <10% organic matter) where pre-emergence herbicides cause damage or are ineffective. A tank-mix of cyanazine + MCPB/MCPA is the only means of preventing of potato berry formation. Table 2 shows cyanazine in tank-mix with bentazone/MCPB was the most widely used active substance on peas in 2003.

A decision has been made by the manufacturer that bentazone/MCPB (Pulsar) will not be sold after 2007 because without cyanazine as a tank-mix partner, weed control would be poor. This loss is an indirect impact of the Review.

1.2. Impacts

• Quality is the most important factor for vining peas and standards have been raised to what amounts to ‘nil tolerance’ for contaminants i.e. ‘1 piece of contaminant per tonne of peas’. The presence of weed contaminants adversely affects consumer confidence. Where separation from weed contaminants is difficult or impossible, and if there is a possibility of contamination of produce with toxic weed parts (berries of black nightshade, briony spp. and volunteer potatoes) that pose a risk to the consumer the whole crop is rejected - financial loss £1000/ha (although there would be no harvesting cost). The grower may also be excluded from future contracts.

• There are price deductions for crops contaminated with weed parts. Produce for processing

will require extra cleaning in the factory costing approximately £50/tonne and there are crop losses of c. 3% associated with the cleaning process. If the level of contamination is too high, cleaning is uneconomic and the peas are rejected.

• Weedy crops are occasionally by-passed – resulting in total crop loss. Sowing programmes

ensure a continuous flow to the factory and any delays caused by slow, difficult harvesting for example, cannot be tolerated. There are crop losses associated with harvesting weedy crops.

• Weeds can also cause yield loss due to competition of up to 30%.

• Growers levy through PGRO/HDC, has funded projects to find alternative herbicides.

The only pre-emergence herbicides that may remain after 2007 will be: pendimethalin (Annex 1) low dose SOLA, possibly isoxaben/terbuthylazine (both List 3B) and clomazone (List 3A). Linuron/trifluralin is doubtful. None are as broad-spectrum and as effective as those that will be lost.

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The only post-emergence herbicides for broad-leaved weeds that will remain after 2007 will be: bentazone, MCPB and MCPB/MCPA all on Annex 1, possibly tank-mix isoxaben/terbuthylazine + bentazone (for early post-emergence application). Bentazone has important weaknesses (see Appendix): knotgrass, speedwells, annual meadow-grass, and control of large fat-hen is poor. It is useful for mayweed and cleavers control; MCPB, MCPB/MCPA are on Annex 1 but have very limited weed spectra. Tank-mixes will be used but they are more damaging to peas than the cyanazine + bentazone/MCPB combination. 1.3. Future losses? Few actives remain, we do not know whether remaining active substances for vining peas isoxaben, terbuthylazine (both List 3B) and clomazone (List 3A) will achieve Annex 1 inclusion and the future of trifluralin is doubtful. The few remaining active substances on Annex 1 are likely to be re-registered in the UK (or N Europe). Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. 2. Specific herbicide or herbicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

A range of herbicides is needed for vining peas to cover the weed spectrum. It is essential that the few remaining herbicides are retained and tank-mixes will be used to cover the weed spectrum: Glyphosate non-selective herbicide pre-cropping. Pendimethalin SOLA, isoxaben/terbuthylazine, clomazone, bentazone, MCPB, MCPB/MCPA perhaps linuron/trifluralin. Graminicides, particularly tepraloxydim and cycloxydim also need to be maintained and used according to the PSD resistance strategy. It is unlikely that two applications would be made in a short season crop such as vining peas. The restrictions would preclude the use of two applications of a product containing the same ACCase inhibiting active substance, a sequence of two different ACCase inhibitors would be possible. A sequence of a ‘fop’ followed by a ‘dim’ or a sequence of two different ‘fops’ would be allowed. Resistant grass weeds are not yet a problem in pea crops. It would also be useful to maintain tri-allate although there is some evidence of a low level of resistance (S Moss, Rothamsted Research, pers. comm.).

3. Prospects for alternatives for any foreseen major gaps in herbicide availability 3.1. Alternatives A ‘Gap Analysis’ (Table 3) shows the critical herbicide gap * * *, where there are, or soon will be no control measures at all. There is urgent need for new broad-spectrum pre-emergence herbicides to be made available for vining peas in 2008.

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Mutual Recognition of products containing Annex 1 active substances registered for the same crop/use combination elsewhere in the same climatic zone but not in the UK, is a useful route to gain approvals for vining pea pesticides. There are two pre-emergence herbicides registered for vining peas in France that are potential alternatives to those lost from the UK in the 91/414 review, and residues data are available for both:

a. aclonifen + pendimethalin. Aclonifen is on List 3B, rapporteur Germany and Mutual Recognition will be used to request authorisation in the UK.

b. imazamox/pendimethalin. Imazamox is a new active substance on Annex 1. The

formulated product has been submitted for UK registration.

The actives aclonifen and imazamox are not registered in the UK for any crop use. Pendimethalin is on Annex 1 and will be re-registered for UK peas. No alternative to the tank-mix of cyanazine + MCPB/MCPA used for the prevention of toxic volunteer potato berry formation has been found. However, HDC are funding a project FV 282, to evaluate MCPB/MCPA + adjuvants in 2006. Off–label Approvals http://www.pesticides.gov.uk/applicant_guide.asp?id=1226 based on recognition of on-label approvals in other (current Northern zone) member states are possible for UK minor crops of areas less than 50,000 ha such as vining peas now after a decline. The use of the pesticide on the crop must have an on-label approval in the Member State in which the use is approved. There must be an extant on-label approval for the use of the same product on another edible crop in the UK. This route will be used increasingly. However, the UK regulatory system does not permit recognition of off-label approvals in other member states although this would be helpful for minor crops. 3.2. Impact of the proposed regulation and revision of 91/414EEC See general comments in Executive Summary.

• Mutual Recognition of products containing Annex 1 active substances (excluding candidates for substitution) are registered for the crop/use combination elsewhere in the proposed Central zone but not in the UK, will continue to be helpful for vining peas.

Key to the Gap Analysis Tables: * * gap no immediate problem but future situation vulnerable






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Table 3. Gap Analysis (Vining Peas): Herbicides Weeds/weed species

Application timing

Gap Status







pre-em / residual

* * * Opogard & Batallion (terbutryn/terbuthylazine; Reflex T (fomesafen/terbutryn);

Terbutryn, fomesafen not supported in the EC Review Essential Use until 31 Dec 2007 Terbutryn/terbuthylazine and fomesafen/terbutryn, are the most widely used pre-emergence residual herbicides. They control a wide weed spectrum including species which cause contaminant problems in the processing factory: mayweeds, poppy, and toxic black-nightshade. fomesafen/terbutryn also controls volunteer oilseed rape.

Flexible –tine weeding inadequate for a processed crop

none yet Registered for vining peas France: aclonifen + pendimethalin; or imazamox/ pendimethalin

Yes Residues data available for both

Blois (trifluralin/linuron), Skirmish (isoxaben/terbuthylazine)

Other pre-emergence alternatives: isoxaben/terbuthylazine and linuron/trifluralin may remain but they are less effective. Trifluralin may fail Annex 1 and/or UK registration, so might terbuthylazine. Pendimethalin Annex 1 SOLA will remain but needs a partner could be tank-mixed + Blois, Skirmish or Centium.

Cleavers pre-em / residual

* * Centium (clomazone) clomazone used for cleavers control. Controls a limited range of other broad-leaved weeds. Needs a partner. .

Annual BLW post-em * * Fortrol (cyanazine) + Pulsar (bentazone/MCPB)

The most widely used post-em herbicides are tank-mixes of cyanazine plus Pulsar (bentazone/MCPB), or cyanazine + MCPB/MCPA. Cyanazine will be lost 31 December 2007 and Pulsar will not be manufactured. Bentazone is on Annex 1 important knesses: knotgrass, speedwells, annual meadow-grass, and control of large fat-hen is poor. Useful for mayweed and cleavers control.; MCPB, MCPB/MCPA are supported in the EC Review (List 1). These have limited weed spectra if used alone.

wea

prevention of volunteer potato berry formation

post-em contact / translocated

* * * cyanazine + MCPB/MCPA

A tank-mix of Fortrol (cyanazine) plus MCPB/MCPA is the only effective means of prevention - several alternatives have been tested in the past. No control volunteer potato berries after 31 Dec 2007 when cyanazine goes

Removal by hand high cost, incomplete control risk

none yet none R & D 2006 MCPB/ MCPA + adjuvants ? .

201

Annual Grasses and annual meadow-grass

pre-em / residual

* * tri-allate granular soil acting granules, applied pre- or post drilling and incorporate, but pre-emergence of the crop for wild oats, blackgrass and annual meadow-grass. (Not for volunteer cereals). Important resistance strategy for grass weeds but rarely used and difficult to obtain in the past.


Pest control Vining Peas

Bean seed fly (Delia platura) Bean seed fly larvae feed on pea seed, usually on late sown crops. Impact: yield loss – severe plant loss, sometimes whole fields affected. Control: A seed treatment is needed. Good control was achieved in trials with thiamethoxam but this active is not approved in the UK yet. Field thrips (Thrips angusticeps) The tiny black "thunderflies" feed within the enclosed leaves of the growing point just as the seedlings are emerging from the soil. Damaged leaves are pale, distorted and thickened. Impact: severe in a few situations. Control: nothing approved. Seed treatment and foliar sprays are needed. Recent work has indicated that good control of thrips can be achieved with lambda-cyhalothrin. Pea weevil (Sitona lineatus) Early sown crops in a dry spring can be more severely affected by pea weevil. The adults feed on the leaves leaving semi-circular notches around the leaf margins. Larvae from eggs, laid by weevils during the feeding period, feed below ground on the root nodules. Impact: occasionally crops are retarded by a heavy weevil attack, but damage is usually outgrown. Control: treatment is usually unnecessary. Pyrethroids offer control. Cultural control: Avoid cloddy seedbeds. Pea aphid (Acyrthosiphon pisum) The large green aphids produce colonies in the growing points of peas causing flower loss and poor pod development. Aphid can also transmit viruses including pea enation mosaic virus. Impact: severe loss of yield if uncontrolled. Control: Several approved insecticides, including pirimicarb, are available for control of pea aphid. There are no reports of insecticide resistant strains in the UK. Threshold for spray application is when aphids can be found on 15% of the plants as they begin to flower. A pea aphid population model (PAM) is available to aid decisions on treatment timing. Cultural control: Ladybird and hoverfly larvae predate aphids and these insects may keep down low infestations, however hoverfly pupae can contaminate vined peas. Research work is in progress to exploit naturally occurring aphid parasites and fungal pathogens to exert biological control and an infestation prediction model (PAM) is available from Horticultural Development Council. Pea moth (Cydia nigricana) Peas producing flowers from mid June onwards are susceptible to attack. Impact: the caterpillar that feeds on peas inside the pod and spoils quality. Control: with pyrethroids applied to control the caterpillar as it leaves the egg and moves to the young developing pod. Monitoring is carried out using a pheromone-based pea moth trap. Cultural control: Areas where field peas are grown are likely to be a reservoir of moths. Pea midge (Contarinia pisi) Pea midge is a serious pest of vining peas, particularly in localised areas. The adults lay eggs close to the developing flower bud and the larvae then feed at the base of the flowers causing them to become sterile. Impact: midge damage can cause yield loss in some seasons. Control: some pyrethroids reduce egg laying. In high-risk areas a monitoring system using pheromone traps can be used.

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Cultural control: Peas varieties with an extended flowering period can compensate for some loss of flowers and pods and should be grown in areas where midge is known to be a problem. Silver Y moth (Autographa gamma) The caterpillars of the silver Y moth feed on the foliage and pods of vining peas. Impact: is on quality. The caterpillars can contaminate the vined peas and can lead to rejection of produce by the processor. They can be a severe problem in canned peas. Control: Monitoring of silver Y moth is carried out. Crop treatment is warranted when more than 50 moths have been caught in a trap by the time that the crop has set the first pods. Pyrethroid insecticides currently approved for pea moth control give good control of Silver Y caterpillars. Cultural control: none Pea cyst nematode (Heterodera göttingiana) Pea cyst nematode is not widespread. Symptoms are a poorly developed root system, there are very few nodules present and many tiny cream to brown coloured lemon-shaped cysts can be found embedded in the root surface. Impact: yield loss. The damage occurs in patches, and infested areas usually die prematurely. Control: no nematicides are now approved for use in peas. Cultural control: A rotation of one of the host crops in five years will help to prevent the establishment of the nematode. Once present, the cysts may remain viable for twenty years or more. Slugs and snails (eg. Deroceras, Milax and Cernuella spp.) Slug feeding can result in poor seedling establishment on wet or heavy soils with high organic matter. Later, slugs can feed higher in the foliage and can contaminate vined peas. Snails migrate into the crop from vegetation surrounding the crop and feed on the foliage and are a major contaminant in vined peas in some areas. Impact: inclusion of slugs or snails in the product can lead to rejection of produce by the processor. Control: with metaldehyde pellets if needed early in the crop growth stages. It is difficult to control slugs immediately prior to vining and late application could lead to contamination of the vined produce with pellets. Cultural control: Soils containing high levels of organic debris including straw are most likely to harbour slugs. Avoid growing peas in close rotation with oilseed rape. A rotavated strip around the edge of the crop can discourage the migration of molluscs from the surrounding vegetation. Insecticides for vining peas Insecticides approved for 2006 and usage in peas (and broad and dwarf French beans) in 2003, are shown in Table 4. Vining peas receive 1 insecticide spray, on average, usually for aphid. Retailers will not permit the use of organophosphate insecticides on vining pea crops and by 2002 they were no longer used. The use of other insecticides, in particular lambda-cyhalothrin/pirimicarb, has increased. The use of pirimicarb for aphid control, particularly in vining peas, was the principal insecticide active substance used in 2003. The use of lambda-cyhalothrin continues to increase mainly for the control of pea moth. Aphids were the most important pests cited in the CSL survey for 2003, accounting for 69% of the total treated area; pea moth comprised a further 11%, with combinations of aphids and caterpillars 11%, thrips 3% and pea and bean weevil 2%. Molluscicide metaldehyde was used on 28% of the pea and bean area, mainly on vining peas.

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In 2005, triazamate was withdrawn by the manufacturer but the grower use-up period is until 4 January 2007. Bifenthrin, another pyrethroid, was approved for aphid control in vining peas Table 4. Insecticides and molluscicides approved for vining peas 2006; Review status; Aim re-registration UK vining peas; Pest; Activity; Usage of pesticides on 46,211ha in peas and beans grown in Great Britain, 2003 (spray hectares) (Source CSL Pesticide Usage survey, 2003) Insecticides and molluscicides for vining peas 2006

Review status Aim re-registration UK vining

peas


Insecticides Alpha-cypermethrin Annex 1 - pea moth pea weevil aphid contact and ingested pyrethroid Bifenthrin List 3A √ aphid Cypermethrin Annex 1 pea moth pea weevil aphid contact and stomach acting

pyrethroid 1,995

Deltamethrin Annex 1 √ pea moth pea weevil aphid pea midge

contact pyrethroid 2,086

Deltamethrin/pirimicarb Annex 1/ Annex 1 aphid contact pyrethroid /carbamate 334 Fatty acids List 4 thrips aphid soap concentrate Lambda-cyhalothrin Annex 1 √ pea moth pea weevil aphid pea

midge contact and ingested pyrethroid 26,796

Lambda-cyhalothrin/pirimicarb

Annex 1/ Annex 1 √ / √ pea moth pea weevil aphid pea midge

contact and ingested pyrethroid/carbamate

12,598

Nicotine unsupported? List 4 thrips aphid non-persistent contact alkaloid Pirimicarb Annex 1 √ aphid contact and fumigant carbamate 32,052 Rotenone List 4 thrips aphid natural contact insecticide of low

persistence.

Triazamate# use by 4 January 2007

withdrawn x aphid carbamoyl triazole 57

Zeta-cypermethrin List 3A √ pea moth pea weevil contact and stomach acting pyrethroid

Molluscicides Metaldehyde List 3A ? √ slugs & snails molluscicide bait 12,652

# no longer marketed pany request confidentiality; √ yes; Red text no longer approved; - Com

1. The likely impacts of the 91/414/EEC review process on insecticide and molluscicide availability for UK vining peas

1.1. Losses There were no important insecticide losses in the 91/414/EEC review process. Triazamate was withdrawn by the approval holder. 1.2. Impact So far, the 91/414/EEC review process has had no impact on insecticide availability for UK peas. Triazamate was rarely used in peas - there are alternatives.. Organophosphates were lost as a result of the UK OP Review, but several are still approved for vining peas in France. Retailers had a greater impact - the use of organophosphate insecticides is not permitted on UK vining pea crops and by 2002 they were no longer used.

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1.3. Future losses? Support for nicotine in the Review may be inadequate, but use is negligible in conventionally grown crops. The most important insecticides achieved Annex 1 inclusion (Table 4) but we do not yet know whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. There is no decision yet on the molluscicide metaldehyde (List 3A) in the review. At re-registration stage data may be required for each crop use of metaldehyde – if this is the case, the vining pea market may be considered too small and this use will be lost. 2. Specific insecticide/molluscicide or insecticide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

A limited range of insecticides is available for vining peas, more are needed for resistance strategy. Pea aphid resistance to pyrethroids or pirimicarb has not been found yet, but active substances with different modes of action are needed. At the time of writing no neonicotinoid is approved. It would be desirable to maintain the following: Pyrethroids particularly lambda-cyhalothrin Pirimicarb and pirimicarb/lambda-cyhalothrin It would be desirable to maintain a UK approval for metaldehyde (List 3A) molluscicide bait. Metaldehyde was applied to 27% of the pea (and bean) crop area in the 2003 survey. Slugs and snails in the harvested produce can cause crops to be rejected by the processor. 3. Prospects for alternatives for any foreseen major gaps in insecticide availability Insecticides with alternative modes of action are important for resistance strategies. 3.1. Alternatives A ‘Gap Analysis’ (Table 5) shows the critical insecticide gap * * *, where there are, or soon will be no control measures at all. The gaps identified were not a result of insecticides lost in the Review. a. Bean seed fly (Delia platura): there is no approved seed treatment. Good control was achieved in trials with thiamethoxam seed treatment, but this active is not approved in the UK yet. Thiamethoxam (new on Annex1) is to be registered in N Europe. b. Field thrips (Thrips angusticeps): nothing is approved. Seed and foliar treatments are needed. Good control was achieved in trials with thiamethoxam seed treatment, but this active is not

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approved in the UK yet. Recent work has indicated that good control of thrips can be achieved with lambda-cyhalothrin foliar sprays. c. Pea aphid (Acyrthosiphon pisum): a limited range of products is available although no resistance in pea aphid has been found yet. Aphicides with different modes of action are approved in other crops (e.g. thiacloprid), but development is needed in vining peas. Slugs and snails: metaldehyde molluscicide bait pellet is the only means of control. Slugs and snails can cause crops to be rejected by the processor but there is also a risk of crop contamination with the pellets if they are applied late. An alternative solution is needed but there are no prospects yet. A methiocarb spray might be more effective but it is not approved in the UK. Methiocarb will be re-registered for peas in Northern Europe. 3.2. Impact of the proposed regulation and revision of 91/414EEC

See comments in the Executive Summary.

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Table 5. Gap Analysis (vining peas): Insecticides and molluscicides

Pest (Latin name)

Application timing





Residues data?

Bean seed fly (Delia platura)

Seed treatment *** None approved Good control in trials with thiamethoxam but not approved in UK

none Approval of thiomethoxam needed

- yes

Pea aphid (Acyrthosiphon pisum)

foliar ** pirimicarb Limited range of products although no resistance in pea aphid yet

none Actives available but development needed

- Limited data

Field thrips (Thrips angusticeps)

Seed treatment & foliar

*** None approved

Good control in trials with thiamethoxam seed treatment but not approved in UK; Foliar lambda-cyhalothrin?

none Approval of thiomethoxam needed

- yes

Slugs and snails Bait pellets ** metaldehyde molluscicide bait: pellet, an alternative is needed.

rotavated strip on field margin

- - -

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Disease control in Vining Peas

Damping-off diseases Peas sown early in cold and wet conditions are prone to pre-emergence diseases such as Pythium ultimum. Pythium affects the developing root and shoot. Impact: Crop loss if seedlings may fail to emerge, or collapse shortly after emergence. Control: Seed treatments containing thiram protect the seed and seedlings from infection. Foot rot/Root rot (Fusarium solani f. sp. pisi, Phoma medicaginis var. pinodella/Aphanomyces euteiches) Affected plants appear in patches or along sections of rows. Plants are stunted, pale and the lower foliage may dry up. The root system may be brown and poorly developed and the base of the stem discoloured. Fusarium causes a brick-red discolouration in the vascular tissue. Infection by Phoma results in a blackening of the stem base, later plants collapse or break-off at soil-level. Aphanomyces root rot is encouraged by wet soils. Impact: yield loss - infected plants often die before pods have developed. Control: No fungicides are approved for the control of these soil-borne diseases, however, Phoma medicaginis can be seed-borne and seed treatments containing thiabendazole or fludioxonil will give some control. Cultural control: A strict rotation of is necessary to prevent the build up of these diseases in the soil. Peas and beans should be treated as one and the same crop and a break of at least four years should elapse between crops. Soil compaction should be avoided. A predictive soil test has been developed to avoid planting peas in high-risk fields. No varieties are resistant to these diseases. Leaf and pod spot (Ascochyta pisi, Mycosphaerella pinodes, Phoma medicaginis var pinodella) The 'Ascochyta complex' of three closely related fungi, are seed-borne, but M. pinodes and P. medicaginis can also survive in the soil for several years. The most common leaf and pod spotting is caused by M. pinodes. In wet weather, many small dark-brown or purple spots develop. Impact: yield loss - plants may be defoliated and patches die prematurely if infection is severe. Control: The fungi are seed-borne and if tested seed is found to be infected then seed treatments containing thiabendazole or fludioxonil should be used. To prevent leaf and pod spot developing in wet seasons, fungicides can be applied as soon as the first spots are seen on the foliage. In order to reduce pod infection, a spray should be applied as soon as the first pod is visible following a disease risk assessment. Azoxystrobin can control of leaf and pod spot, and also some control of grey mould (Botrytis cinerea) and Mycosphaerella blight. Cultural control: Use healthy seed and avoid excessive overhead irrigation during the pod-setting period. Crops that produce a drier microclimate are less likely to become infected. Peas should not be grown more frequently than once in five years on the same land. Foot rot/Root rot (Fusarium solani f. sp. pisi, Phoma medicaginis var pinodella/Aphanomyces euteiches) Affected plants appear in patches or along sections of rows. Plants are stunted, pale and the lower foliage may dry up. The root system may be brown and poorly developed and the base of the stem discoloured. Fusarium causes a brick-red discolouration in the vascular tissue. Infection by Phoma results in a blackening of the stem base, later plants collapse or break-off at soil-level. Aphanomyces root rot is encouraged by wet soils. Impact: yield loss - infected plants often die before pods have developed. Control: No fungicides are approved for the control of these soil-borne diseases, however, Phoma medicaginis can be seed-borne and seed treatments containing thiabendazole or fludioxonil will give some control.

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Cultural control: A strict rotation of is necessary to prevent the build up of these diseases in the soil. Peas and beans should be treated as one and the same crop and a break of at least four years should elapse between crops. Soil compaction should be avoided. A predictive soil test has been developed to avoid planting peas in high-risk fields. No varieties are resistant to these diseases. Downy mildew (Peronospora viciae) The fungus is soil-borne and commonly infects seedlings before emergence. Some early maturing varieties are very susceptible to mildew and these should be avoided in high-risk fields. Impact: plant loss. If secondary infection spreads to the pods, quality is reduced. Control: There are no effective means of control once the disease has become established (HDC project FV 215, 2001). The situation remains unchanged since the project was undertaken. Seed treatment with cymoxanil and metalaxyl M is effective in preventing the initial seedling infection thereby reducing the amount of air-borne inoculum that causes the secondary infection. However strains of the disease are already resistant to metalaxyl M. Botrytis pod rot (Botrytis cinerea) Botrytis pod rot (grey mould) is the most common problem in wet weather. Flower petal sticks to the developing pods or lodges on the stems in the leaf axils. Botrytis then infects the pod. Impact: brown peas reduce quality loss. Control: with fungicide spray azoxystrobin. (Vinclozolin and iprodione SOLA are not acceptable to processors). Sclerotinia (Sclerotinia sclerotiorum) The disease can affect a very wide range of crops. It causes a white mould of the stems and pods in dense crops with lush foliage. It spreads rapidly in warm humid conditions. The stems become covered with dense white mycelium and then collapse. The infection can progress to the pods. Impact: in severe cases complete crop loss. Control: with a preventative fungicide spray azoxystrobin. (Vinclozolin and iprodione SOLA are not acceptable to processors). Cultural control: a rotation, which allows at least three years between host crops, will prevent a build-up of the fungus in the soil. Sclerotia remain viable in the soil for several years, Powdery mildew (Erysiphe pisi) Pea leaves and stems become covered with a white 'dusty' film and pods may become severely infected. Occurs under hot dry conditions during the day, and high humidity at night. Impact: quality is spoilt both by the surface pod infection and the failure of such pods to fill adequately reduces yield. Control: no fungicides approved in peas, although azoxystrobin may reduce the risk of infection in late sown crops. Metconazole is approved but there are no data on powdery mildew control Cultural control: a few varieties are completely resistant to powdery mildew. Pea enation mosaic virus (PEMV) Pea aphids transmit this virus. Infected plants can appear in patches. Leaves may be crinkled and the top of the plants becomes yellow and mottled and pods may be distorted. Impact: yield loss. Control: Control of aphid infestation will prevent the virus becoming established. Cultural control: Some newer varieties are resistant to PEMV. Pea bacterial blight (Pseudomonas syringae pv. pisi) Although it is rarely a problem, this seed-borne blight can cause yield and quality loss. Control: There is no means of controlling pea blight with fungicides.

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Fungicides for vining peas Vining peas received, on average, one fungicide spray in 2003 (Table 6). Some processors and retailers discourage the use of foliar fungicide sprays. The CSL pesticide usage survey, 2003 showed that azoxystrobin was applied to 27% of the area of peas and beans grown. Vinclozolin was the next most popular fungicide. The majority of applications were made for control of Botrytis, a wet weather disease. Azoxystrobin, the principal fungicide used on peas & beans, was encountered for the first time in 2003 and accounted for 64% of all fungicide usage. Azoxystrobin had, to some extent, replaced vinclozolin, previously the principal fungicide used. Both active substances were used predominantly on vining peas for Botrytis control. Chlorothalonil in formulation with metalaxyl is no longer approved. Metconazole was approved for vining peas in 2005 for control of leaf and pod spot. Table 6. Fungicides for vining peas, 2006; Review status; Aim re-registration UK vining peas; Usage of pesticides on peas & beans 46,211ha grown in Great Britain, 2003 (spray hectares). (Source: CSL Pesticide Usage survey, 2003) Fungicides for vining peas, 2006

Review status Aim re-registered for

UK vining peas

Disease Activity Usage on peas & beans, 2003

(spray ha) Azoxystrobin New Annex 1 √ Leaf & pod spot (Botrytis) systemic translaminar and

protectant strobilurin 12,507

Iprodione SOLA Annex 1 - Botrytis Sclerotinia Stemphyylium protectant dicarboximide with some eradicant activity

563

Metconazole Annex 1 - Leaf & pod spot (Botrytis) conazole

Vinclozolin List 1 - Leaf & pod spot (Botrytis) protectant dicarboximide 3,591

- Company request confidentiality; √ yes

Seed treatments In 2003, a large area of peas was sown with seed treated with cymoxanil/fludioxonil/metalaxyl-M Table 7. Seed treatments fungicides approved for vining peas 2006; Review status; Aim re-registered for UK vining peas; Disease; Activity; Usage of pesticides on peas & beans 46,211ha grown in Great Britain, 2003 (spray hectares). (Source: CSL Pesticide Usage survey, 2003) Seed treatments fungicides approved for vining peas 2006

Review status Aim re-registered for UK vining

peas

Disease Activity Usage on peas & beans, 2003

(spray ha)

Cymoxanil/metalaxyl M/fludioxonil



acylanilines / phenylamide/cyanopyrrole

35,008

fosetyl aluminium SOLA Annex 1 (crops not decided)

downy mildew Systemic phosphonic acid

thiram Annex 1 √ damping-off protectant dithiocarbamate 3,209

Thiram/thiabendazole Annex 1/Annex 1 √ / √ damping-off Ascochyta protectant dithiocarbamate/ benzimidazole (MBC)

√ yes

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1. The likely impacts of the 91/414/EEC review process on fungicide availability for UK vining peas

1.1. Losses There were no fungicide losses in the 91/414/EEC review process. 1.2. Impact So far, there has been no impact on fungicide availability for UK vining peas. Retailers and processors had a greater impact - the use of foliar fungicide sprays, particularly vinclozolin is discouraged in peas. In wet seasons they are necessary because Botrytis affects quality. 1.3. Future losses? Important active substances are on Annex 1 (Table 6). At the time of writing, no decision has been reached on inclusion of vinclozolin (List 1). There has been no agreement so far between Member States. The Commission proposal is that vinclozolin should be included on Annex 1 for use in some other crops but not for peas. Decisions have not been made yet (June 2006). Views of the crop sectors were sought by PSD. If vinclozolin does not achieve Annex 1 listing for use in vining peas other alternatives are available. Cymoxanil (List 3B) seed treatment (Table 7) is particularly important and a decision on Annex 1 inclusion has not been made yet, or for fludioxynil (List 3A). Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. There is a SOLA for iprodione (Annex 1, on list 1 originally) in vining peas (Table 6). Residues data for some older SOLAs may not satisfy modern EC standards – a PSD study of data in archives, covering List 1 actives) suggests that new data may be required to set MRLs to support some minor crops/uses. List 2 (fosetyl-aluminium) seed treatment (Table 7) and some list 3 actives will be studied later. The impact will be on cost to the grower through HDC/PGRO levy to maintain these uses. 2. Specific fungicides or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Seed Treatments: It would be desirable to maintain all the seed treatments. Cymoxanil/metalaxyl-M/ fludioxonil is widely used, cymoxanil (List 3B) is particularly important for control of downy mildew because some strains are already resistant to metalaxyl. Downy mildew cannot be controlled with available foliar applied fungicides. Fosetyl-aluminium (List 2) as an alternative for downy mildew control Thiram/thiabendazole (both on Annex 1) is useful for Ascochyta control in some seasons.

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Thiram is the only approved fungicide for application in the UK. It is cheap and used only to prevent damping off disease Foliar sprays: There is a very limited range of fungicides available for vining peas. To avoid resistance to diseases it would therefore desirable to maintain: Azoxystrobin (Annex 1) for control of Botrytis, leaf & pod spot and Sclerotinia. Metconazole (List 2) for control of Botrytis, leaf & pod spot, but it is less effective than azoxystrobin. Iprodione (Annex 1) SOLA for Botrytis and Sclerotinia. However, iprodione resistance has recently been found in dwarf French beans (A Biddle pers.comm.). 3. Prospects for alternatives for any foreseen major gaps in fungicide availability

There is a very limited range of fungicides available for vining peas. New fungicides with different modes of action are needed, particularly with curative activity. 3.1. Alternatives Gaps identified for peas and beans were not a result of fungicides lost in the EC Review. A ‘Gap Analysis’ (Table 8) shows the critical fungicide gaps * * *, where there are, or soon will be no control measures at all: a. Downy mildew (Peronospora viciae): there are no means of control with foliar applied fungicides (see HDC Project FV 215). Actives are available in UK for other crops, but development work and residues data are needed for vining peas. b. Powdery mildew (Erysiphe pisi): Metconazole is now approved for vining peas for control of leaf & pod spot and it may be effective on powdery mildew but efficacy trials are needed (residues data not needed). c. Sclerotinia (Sclerotinia sclerotiorum): Iprodione SOLA is the only approved fungicide for this disease. Actives are available in UK but efficacy work needed. Foliar spray cyprodinil/fludioxynil is approved in France (product name Switch in US and France), multi-active ingredients anilinopyrimidine/phenylpyrrole. Cyprodonil (List 2) would be a better alternative for Sclerotinia and Botrytis control. It will be re-registered for peas in N Europe. It may be available in the UK 2007? US IR 4 project data suggests it also controls powdery mildew. d. Botrytis (Botrytis cinerea): fungicides have an on-label recommendation, but only offer a reduction in disease. Off–label Approvals based on recognition of on-label approvals in member states in the same climatic zone are possible for UK minor crops of areas less than 50,000 ha and could apply to vining peas now, after a decline. There must be an extant on-label approval for the use of the same product on another edible crop in the UK. Mutual Recognition can also be used. There is a wider fungicide choice in France for vining peas and these routes could be used increasingly. The UK regulatory system does not permit recognition of off-label approvals in other member states although this would be helpful for minor crops.

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Table 8. Gap Analysis (vining peas): Fungicides Disease (Latin name)

Application timing


Comments Solution non-chemical Solution chemical UK


Residues data?

Damping-off (Pythium spp.)

seed treatment * * thiram Only thiram approved in UK none Possible alternatives required if thiram lost

none


seed treatment * * Seed treatment cymoxanil

Only cymoxanil available and disease already resistant to metalaxyl

resistant varieties very few vining pea varieties with tolerance

No other actives developed

none none


foliar * * * none No approved fungicides See above Actives available in UK but development work needed

None in peas

Botrytis (Botrytis cinerea)

foliar * * iprodione Only iprodione approved, others offer reduced control

none Actives available in UK but efficacy work needed

Cyprodinil in France

needed

Sclerotinia (Sclerotinia sclerotiorum)

Foliar

* * iprodione Only iprodione approved. none Actives available in UK but efficacy work needed

Cyprodinil in France

needed

Powdery mildew (Erysiphe pisi)

Foliar * * * none Metconazole approved in vining peas but no data on Erisyphe pisi control

Only few Resistant varieties

Metconazole but no data available. Trials needed

none Not required

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REFERENCES The PGRO website lists information sheets for growers: http://www.pgro.org Horticultural Development Council Projects http://www.hdc.org.uk can be accessed by members of

HDC: FV 215 (2001) Peas: Downy mildew control. FV243 (2002) Vining peas: Use of mechanical weeding techniques. Appendix: weeding equipment. FV282 (new 2006) Vining peas: Control of volunteer potatoes. FV 287 (new 2006) Survey of approvals in other EU countries across all crops of interest to HDC. ASSURED PRODUCE - The NFU/Retailer partnership http://www.assuredproduce.co.ukDEPARTMENT FOR ENVIRONMENT, FOOD AND RURAL AFFAIRS (Defra) (2006) Basic

Horticultural Statistics for the United Kingdom. Calendar and Crop Years 1995/96 – 2005/06. Defra publications, London, UK.

GARTHWAITE D G, THOMAS M R, DAWSON A, STODDART H & ANDERSON H (2004) Outdoor Vegetable Crops In Great Britain 2003. Pesticide Usage Survey Report 195. Central Science Laboratory, Sand Hutton, York URL http://www.csl.gov.uk

GRUNDY A, KNOTT C, LUTMAN PJW et al. (2003) The Impact of Herbicides on Weed Abundance and Biodiversity in Horticulture. Defra project HH3403sx.

KNOTT CM (1997) Achieving Quality in Legume crops with Agrochemicals. In: Crop Protection and Food Quality – meeting consumer needs. British Crop Protection Council, University of Kent, Canterbury, UK.

LAWSON HM (1983) Competition between annual weeds and vining peas grown at a range of population densities: effects on the crop. Weed Research 23, 27-38.


Appendix: common weed names are according to Dony et al. (1986); Latin names according to Stace (1997) DONY JG, JURY SL & PERRING FH (1986) English Names of Wild Flowers, 2nd edition. The


Cambridge, UK.

ACKNOWLEDGEMENTS

The help and contributions from the following organisations are gratefully acknowledged: Processors and Growers Research Organisation, National Farmers Union (NFU), Christian Salvesen Processors, United Agricultural Products - Europe (UAP), European Crop Protection Association (ECPA) and Crop Protection Companies.

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Appendix. Weed Susceptibility to pre-emergence herbicides for Vining Peas. Key: S = susceptible; MS = Moderately Susceptible; R = Resistant; MR = Moderately Resistant. Blue text loss after 31 Dec 2007

Common name Latin name

terbutryn/ terbuthylazine

fomesafen/ terbutryn

terbuthylazine/ isoxaben 1 L/ha

trifluralin/ linuron

3.75 L/ha

pendimethalin 1.5-2 L/ha

Bindweed black Fallopia convolvulus S S MS MS MS Bugloss Anchusa arvensis S Charlock Sinapis arvensis S S S S/MS MS Chickweed, common Stellaria media S S S S S Chickweed, mouse-eared Cerastium fontanum S R R Cleavers Galium aparine R Corn marigold Chrysanthemum segetum Corn spurrey Spergula arvensis S MS Crane's-bill, cut-leaved Geranium dissectum MS Deadnettle, henbit Lamium amplexicaule S MS MS Dead-nettle, red Lamium purpureum S S S Dock, broad-leaved Rumex obtusifolius S S Fat-hen Chenopodium album S S S R S Fool's parsley Aethusa cynapium R S S Forget-me-not, field Myosotis arvensis S R R Fumitory, common Fumaria officinalis S S MS Gallant -soldier Galinsoga parviflora S R Groundsel Senecio vulgaris S S S Hemp-nettle, common Galeopsis tetrahit S MS S MS S Knotgrass Polygonum aviculare S S MS S MS Mayweed, scented Matricaria recutita S S S MS Mayweed, scentless Tripleurospermum inodorum S S S Nettle, small Urtica urens S S MS MS Nightshade black Solanum nigrum ? S Orache, common Atriplex patula S MS MS Pansy, field Viola arvensis S S S Parsley piert Aphanes arvensis Pennycress, field Thlaspi arvense S Persicaria, pale Persicaria lapathifolia S S Pimpernel, scarlet Anagalis arvensis S MS Pineappleweed Matricaria discoidea Poppy, common Papaver rhoeas S S S MS Redshank Persicaria maculosa S S S S S Shepherd's-purse Capsella bursa-pastoris S S MS R Sow-thistle, smooth Sonchus oleraceus S S MS S Speedwell, common, field Veronica persica S S S Speedwell, ivy-leaved Veronica hederifolia R MS Sun spurge Euphorbia helioscopia MR R R Thistle, creeping Cirsium arvense R R S S/MS MS Wild radish Raphanus raphanistrum S S S Annual meadow grass Poa annua S MS S R Blackgrass Alopecurus myosuroides R Brome, barren Anisantha sterilis R R Wild-oat Avena fatua R Vol OSR Brassica napus R S MR MS Vol Potatoes Solanum tuberosum * small seedling stage

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Appendix (continued). Weed Susceptibility to post-emergence herbicides for Vining Peas Key: S = susceptible; MS = Moderately Susceptible; R = Resistant; MR = Moderately Resistant. Blue text loss after 31 Dec 2007

Common name Latin name

terbuthylazine /isoxaben0.75L/ha

bentazone 1.65 kg/ha

MCPB cyanazine 2.0 L/ha

bentazone/MCPB + cyanazine

4.0 + 0.4 L/ha

Bindweed black Fallopia convolvulus MS MS S* S S Bugloss Anchusa arvensis S Charlock Sinapis arvensis S S S S S Chickweed, common Stellaria media MS S R S S Chickweed, mouse-eared Cerastium fontanum Cleavers Galium aparine S R R MS Corn marigold Chrysanthemum segetum S Corn spurrey Spergula arvensis S Crane's-bill, cut-leaved Geranium dissectum S MR Deadnettle, henbit Lamium amplexicaule MS S Dead-nettle, red Lamium purpureum MS R S S Dock, broad-leaved Rumex obtusifolius S Fat-hen Chenopodium album MR MS S S S Fool's parsley Aethusa cynapium S R S MS Forget-me-not, field Myosotis arvensis S S S Fumitory, common Fumaria officinalis S MS S S S Gallant -soldier Galinsoga parviflora Groundsel Senecio vulgaris MS R S S Hemp-nettle, common Galeopsis tetrahit S MR S* S MS Knotgrass Polygonum aviculare R MR S S MR Mayweed, scented Matricaria recutita MR S R S S Mayweed, scentless Tripleurospermum inodorum MR S R S S Nettle, small Urtica urens S S S S Nightshade black Solanum nigrum S R S MS Orache, common Atriplex patula MS MR S S Pansy, field Viola arvensis S R S* S S Parsley piert Aphanes arvensis MR S Pennycress, field Thlaspi arvense S Persicaria, pale Persicaria lapathifolia S S S Pimpernel, scarlet Anagalis arvensis S R S Pineappleweed Matricaria discoidea S S S Poppy, common Papaver rhoeas S MS S S Redshank Persicaria maculosa S S* S S Shepherd's-purse Capsella bursa-pastoris S S S S Sow-thistle, smooth Sonchus oleraceus MS S* MS Speedwell, common, field Veronica persica S MS R S S Speedwell, ivy-leaved Veronica hederifolia MR S S Sun spurge Euphorbia helioscopia Thistle, creeping Cirsium arvense suppr S Wild radish Raphanus raphanistrum S S Annual meadow-grass Poa annua S R R S R Blackgrass Alopecurus myosuroides R R R MS R Brome, barren Anisantha sterilis R R MS R Wild-oat Avena fatua R R R Vol OSR Brassica napus S MS S Vol Potatoes Solanum tuberosum

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Horticultural BRASSICAS

The brassica crops studied in this project occupy the larger areas: Brussels sprouts, cabbage, calabrese/broccoli and cauliflower. Swedes, turnips and baby-leaf brassicas are not included. Most recommendations for the crop are based on information from research funded by growers through the Horticultural Development Council (HDC) statutory Levy and/or LINK projects with Defra. The HDC R & D budget for outdoor vegetables is £4.75m per annum.

Background Crop area and use The total area (provisional) of vegetable crops has declined considerably, by nearly 50% or more since the late 1970s, partly because of increased efficiency of UK growing and marketing, but also because of competition from imports. Retailers now source a wide range of produce from all over the world, all year round. The total area of leaf, head and flower-head brassicas has also declined by about 29% from 44,284 ha in 1995 to 31,471 ha in 2005. The area (provisional) of leaf brassicas grown in 2005/06 were cauliflower 9,925 ha, calabrese 8,721 ha, cabbage (spring, summer, autumn and winter) 8,767 ha and Brussels sprouts 4,058 ha (Basic Horticultural Statistics for the UK, 2006). Cabbages can be divided into six types, depending on leaf structure, density, colour and time of maturity. These brassica crops are grown throughout the country but the main growing areas are East Midlands, South West, North West and Scotland. The frost-free climate in the South West enables early production. Most brassicas are grown http://www.assuredproduce.co.uk according to Assured Produce protocols. Retailers also have their own restricted lists of pesticides for crops and these differ between individual retailers. Markets for horticultural crops demand uniformity in size, quality, maturity and continuity of supply. Any pest, disease or weed that cause blemishes or malformation of produce, uneven or delayed maturity, or a wide size range distribution is unacceptable. Rotation Cabbage, cauliflower, Brussels sprouts, calabrese and sprouting broccoli are grown on a range of soil types, the most suitable are moisture retentive, alkaline, mineral soils. Production of cauliflower and cabbages is all year round. Crop rotation can be used to assist with crop health in conjunction with other practices. Most of the major pathogens cause spots or blemishes on the cabbage leaves/head rendering it unmarketable. These diseases are prevalent in the main production areas in most seasons. The spread of oilseed rape growing, especially spring sown and the proliferation of rape volunteers on set-aside land have aided disease spread (example, ringspot was traditionally a disease only seen in the wetter western areas of the UK). Club root is a problem in some brassica production areas particularly on naturally acid soils. Production in these areas is based on a wider rotation of four to five years between brassica crops together with a well-planned liming policy. However, continuous production can be sustained without detriment to crop quality or to the environment. Brassicas are frequently a constituent of mainly arable rotations, which may include winter wheat, sugar beet, potatoes and pulses, crops of the same family (oilseed rape) are best avoided. Oilseed

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rape volunteers can be persistent and difficult to control in brassicas. Volunteer potatoes, are a serious problem because herbicides can only offer suppression. Profitability The values of marketed crops in 2005 were approximately £47.7, £58.1, £54.1 and £30.7 million respectively – total £191.3 million. Gross Margins/ha predicted (Nix, 2005) for 2006 for cauliflower are £1175; Brussels sprouts £2400, cabbage £1665 and outputs are £3500; £4200 and £5365 respectively. These vary considerably between seasons. High standards of pest, disease and weed control are the target. The cost of harvesting and marketing can amount to at least 80% of the total cost of production, half of which may be the labour for cutting. Production systems Production of cauliflower and cabbages is all year round and clear perforated plastic film is used for their early production and for early calabrese. Where produce of small size is required: Brussels sprouts for processing, baby cauliflower and calabrese for small spear production are precision drilled in the field at high density on narrow rows, and the crop canopy closes early. Most brassica crops are grown on wide rows from transplants. The majority of the transplanted crop is grown from glasshouse raised modular transplants or small peat blocks. Bare root transplants are used less frequently. Transplanting is a major aid in crop scheduling. The modular trays provide a system that facilitates the application of a cabbage root fly insecticide treatment that uses less active ingredient per hectare than field applications.

Weed control in Brassicas Horticultural brassicas are grown in arable rotations and inherit the weeds of previous arable crops and the crop volunteers. Where brassicas are intensively grown there may be a build-up of weeds tolerant to brassica herbicides, for example shepherd’s purse and field pennycress (Appendix 1). Weeds that emerge in large numbers in autumn: annual meadow-grass, common chickweed and mayweeds are the main problems in brassicas that are transplanted or drilled from July to September. Impact: the main effect is on crop uniformity and quality. Weeds can also delay maturity. Individual weed species can affect quality: seeds from shepherd’s purse, cleavers and charlock can contaminate heads of cauliflower and calabrese; volunteer potato plants and black nightshade must not be included in harvested cauliflower, cabbage and calabrese. Tall species, such as fat-hen interfere with mechanical harvesting of Brussels sprouts; small nettle in calabrese and cauliflower is unpleasant for hand pickers. There is very little information on the impact of individual weeds on yields and plant habit and competitive effect differs widely between brassica types. The tables, based on a literature search are adapted from Defra project HH3403SX, 2003 and show the effects of weeds on quality and harvesting (Table 1) and yield (Table 2) for some brassicas. Chickweed has a low competitive effect (index 0.2 in winter wheat) compared with many species but in spring cabbage (also sown in autumn) it can reduce yields by up to 68%. The critical period defines the time when weeds need to be absent from the crop to ensure optimum yields. Some crops have a very long critical period whilst others do not exhibit one at all (Roberts, 1976) and the latter arises when any weed emergence after a single weeding to avoid irretrievable yield loss, has no impact on quality or yields. The critical period for weed removal for optimum yield in brassica crops will depend on the type of crop, the planting system (drilled vs. transplanted, row spacings etc.) and the date of

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sowing, so ‘standardised’ conclusions for ‘Brassicas’ are not possible (Defra project HH3403SX by Grundy et al.,, 2003). Data from Turner et al., (1999) indicated that weeds need to be removed 3-8 weeks after transplanting for optimum yield. Table 1. Impact of weeds on crop quality and harvesting Crop Quality Harvesting & other operations Brussels sprouts Size, disease Machine slower work rate, higher cost and

harvest losses; interfere with manual harvest (nettles, thistles)

cauliflower, Contaminants seeds & berries,


cabbages (4) Size & weight (4) large internode distance cabbage


calabrese Contaminants seeds (4) Size & weight


Numbers in parentheses see reference; Many comments from crop specialists

Table 2. Impact of weeds on yield on brassicas Crop Yield reduction Species mainly responsible cabbage, summer drilled

(1) 47-100% weeds 50-540 pl/m2

(3) 25-100% weeds 100 pl/m2 (2) USA study 52-76% fat-hen 1.2 pl/m2; 71-92% fat-hen 3.6 pl/m2

(2) fat-hen

spring cabbage transplanted

(4) 33%, 26%, 68% marketable yield (5) 20%

(4) over-wintered chickweed dominated weed flora in spring and shaded crop, Annual meadow-grass, speedwell, shepherds-purse little effect (5) annual meadow-grass

Numbers in parentheses see references

Control: Weeds are killed just prior to cultivation and planting with a non-selective herbicide such as glyphosate. In most brassica crops weed control is achieved with a pre- or post-planting application of a residual herbicide. This may be followed by applications of foliar-acting herbicides, which may also have some residual action, to emerged problem weeds and sometimes cultivations are used as well. It is important to avoid damage to brassicas and some post-emergence materials are less safe on calabrese and cauliflower which have less well-developed leaf wax. Particular problems arise when the prevalent weeds are botanically related to the crop, e.g. where Cruciferae occur in Brassica crops. Trifluralin, soil-incorporated pre-sowing/planting is the most widely used herbicide for brassicas. It is cheap, and effective on Polygonums, fat-hen and annual meadow-grass and other grasses, but it does not control cruciferous species including shepherd’s purse and charlock, or mayweeds and groundsel (Appendix). Trifluralin is often used in combination with inter-row hoeing. Pendimethalin can only be applied before transplanting and the action of the transplanter moves treated soil away from the row so some weeds within the row are not controlled. It must not be used for drilled crops. Metazachlor is widely used pre-emergence or after the 3 true-leaf stage of the drilled crop or to well established transplanted crops. Propachlor is another alternative, also widely used, but it fails to control Polygonum species or fat-hen. Chlorthal-dimethyl is expensive and can be used on sands,

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alone or in formulation with propachlor to extend the weed spectrum. Tebutam, which was not supported in the EC review, and has therefore been lost, was used pre-emergence of drilled crops or on hardened-off transplants but before weed emergence. It is sometimes necessary to use foliar contact-acting or translocated herbicides. Clopyralid is useful for control of mayweed, creeping thistle and volunteer potato suppression and is applied alone or in tank-mix. Pyridate (marketed by a different company in 2006) is sometimes used for cleavers control. Cyanazine has a SOLA for calabrese, cabbage and cauliflower and is important for control of charlock; sodium monochloroacetate, is effective on Polygonums, small nettle and field penny cress. Non-chemical control: Mechanical weeding is not possible where crops are grown under cover. Use of inter-row mechanical weed control is widely practised in transplanted crops. Drilled crops cannot be inter-row cultivated until the 5 true-leaf stage because they suffer damage if they are buried under soil. Efficacy of mechanical cultivation is poor in wet conditions because weeds re-root. A range of mechanical weeders is available: flexible tine, brush or finger weeders etc. New designs effect better control of seedling weeds within the cropping row - soil is lightly thrown around the base of the stem thus "smothering" seedling weeds. The cost of weeding once with a steerage hoe is £35 - 41/ha; or once with a brush weeder £63 /ha. However, several passes are needed because there are further weed flushes after each soil disturbance. There is an environmental impact on ground nesting birds, the cost of mechanical weeding is high.

A trial funded by the Horticultural Development Council (HDC Project FV 266/Defra LINK) for mechanical removal of weeds within the row using a vision guidance system in Brassicas began in 2005. Herbicides for leaf brassicas Herbicides approved for 2006 and herbicide usage in 2003, are shown in Table 3. The weed species controlled are given in Appendix 1. Neither cyanazine nor sodium monochloroacetate was supported in the 91/414 EEC review but they have derogations for use in brassicas until 31 December 2007. There was little use of sodium monochloroacetate in 2003. CSL surveys show that over the last 25 years the herbicide treated area for brassicas has more than doubled, possibly because programmes are used with herbicides controlling complementary weed spectra. From 1999 to 2003 the use of glyphosate has increased by 65%. Brassicas receive on average two herbicide sprays. Trifluralin has been the most popular herbicide for many years. In 2003, trifluralin was the most widely used herbicide on 60% of the leaf brassica area; metazachlor on 46%, propachlor on 35%.of the crop i.e a programme of trifluralin applied pre-sowing and incorporated, followed by metazachlor or propachlor after transplants are established and pre-weed-emergence. Chlorthal-dimethyl is only used on 1- 2% of brassicas because of the high cost. There is very little use of graminicides in leaf brassicas. Table 3. Herbicides approved for leaf, head and flower head brassicas 2006; Review status; Aim re-registration for some but not all leaf brassicas UK; Activity; Usage area sprayed with herbicides leaf brassicas (32,424 ha grown) in Great Britain in 2003 (source CSL Pesticide Usage survey, 2003)

soil erosion and

Herbicides approved for brassicas 2006 Review status Aim re-registration Activity Usage, 2003

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for some brassicas UK

(spray ha)

Total Herbicides Diquat/paraquat Annex 1/ Annex 1 √ / √ bipyrilidium 818 Glufosinate-ammonium List 2 Not decided (√ N) phosphinic acid Glyphosate Annex 1 √ phosphonic acid 8,132 Paraquat Annex 1 √ bipyrilidium 471Grass weeds Cycloxydim List 3A - oxime 50 Tepraloxydim cauliflower & cabbage only New Annex 1 - oxime .Broad-leaved weeds and grasses Carbetamide Cabbage only List 3A √ Residual carbamate Chlorpropham Annex 1 x Residual carbamate 8 Chlorthal-dimethyl List 3A √ residual benzoic acid 639 Chlorthal-dimethyl/ propachlor List 3A/3B √ / √ :residual benzoic acid/chloroacetanilide Clomazone SOLA List 3A x (√ OSR) isoxazolidinone . Clopyralid Annex 1 - translocated piclonic. 1,337 Cyanazine expires 31/12/07 SOLAs except Brussels sprouts

Not supported 1,055

Metazachlor List 3A - anilide 15,506 Pendimethalin Annex 1 - dinitroaniline 1,431 Propachlor List 3B √ chloroacetanilide 11,974 Pyridate* B sprouts & cabbage only, use by 1 January 2007

Annex 1 √ pyridazine

Sodium monochloroacetate expires 31/12/07 SOLA broccoli & cauliflower

Not supported . Trifluralin List 2 - dinitroaniline 19,723 - Company request confidentiality; √ yes; (√ N) aim re-register in N Europe; * Pyridate marketed by Belchim in future 1. The likely impacts of the 91/414/EEC review process on herbicide availability for UK leaf brassicas 1.1. Losses The following herbicides were not supported in the 91/414/EEC review: tebutam, sodium monochloroacetate, cyanazine. Of these the most important was cyanazine. The ‘Essential Uses’ of post-emergence sodium monochloroacetate, cyanazine for brassicas expire 31 December 2007. Pre-transplanting and/or pre-weed-emergence residual herbicides are used in leaf brassicas but their efficacy is dependent upon adequate soil moisture and susceptibility of weed species. Post-emergence herbicides are needed to remove weeds escaping control with pre-emergence herbicides. Cyanazine and sodium monochloroacetate are applied post-emergence. Sodium monochloroacetate is effective on Polygonums, small nettle and field pennycress. Cyanazine with residual as well as contact activity is particularly useful in controlling brassica-related weed species such as charlock. Cyanazine has a SOLA for calabrese, cabbage and cauliflower. A submission for a SOLA for Brussels sprouts was intended, but not made after lack of support was known. Cyanazine is important for control of charlock. The area of leaf brassicas sprayed with cyanazine was only just over 1,000 ha in 2003 (Table 3) and suggests that charlock is not a widespread problem yet. Sodium monochloroacetate is not widely used. Both tend to be used as ‘fire engine’ treatments. Charlock is predominantly spring germinating, Lutman classed charlock as a very competitive weed species. The average estimated decline rate in disturbed soil is c. 37 % (Lutman & Freeman, 2002) but charlock produces fewer but larger seeds than most common weed species,

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There is potential for a build up where rotations are close or if rape is grown in the same rotation. Farmers are also encouraged to manage cereals for biodiversity and charlock is highly desirable as a food source for insects and birds in wheat. 1.2. Impact Loss of cyanazine

• The impact of weeds on brassica yields depends on the population and competitive effect of the species concerned and the effect differs widely between brassica types. There is very little information on this but some data suggest yield loss could be up to 100% (Table 2).

• The impact from weed competition will be on uniformity of size of produce and maturity;

the weed seeds (particularly charlock) will affect quality by contaminating heads of cauliflower and calabrese, and some crops may be rejected (Table 1).

• Weeds also interfere with harvesting: Tall species, such as fat-hen interfere with mechanical

harvesting of Brussels sprouts; small nettle in calabrese and cauliflower is unpleasant for hand pickers.

• Hoeing is an alternative. The cost of weeding once with a steerage hoe is £35 – 41 /ha and

several passes are needed because there are further weed flushes after each soil disturbance. The cost of mechanical weeding is therefore high. There is an environmental impact on ground nesting birds soil erosion.

• Growers HDC levy has been spent on SOLAs and residue trials for an unsupported active.

• A significant proportion of growers levy through HDC has been spent on trials to identify

alternatives. Since 2002, the overall cost of these projects for horticultural crops so far is £4.714 million and of this £2.7 million is for vegetables (C Harvey, Chairman, HDC, pers.comm.). Where/if alternative herbicides are identified, and no residues data are available further HDC funds will be needed for residues studies and SOLAs. HDC estimate that since it began, the Specific Off-Label Approval programme has cost growers £3.5 million for approximately 960 SOLAs.

After 2007 the control of charlock will be difficult because it is not controlled by other herbicides approved for brassicas (Appendix). Other herbicides may be developed for control of charlock – see section 3, but none are available yet.. 1.3 Future Losses It is difficult to predict the likely impact of the review process on pesticide availability for the UK brassica industry because the decision on Annex 1 inclusion for some of the remaining active substances (Table 3) has not been made. The important herbicides for brassicas are trifluralin (List 2), metazachlor (List 3A), propachlor (List 3B) and clomazone (List 3A). or whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. Metazachlor has been found in groundwater above the 0.1 µg/L drinking water limit, (but so have other pesticides), and carbetamide was problematic in surface water in one catchment area in 2004/2005.

and

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The future of trifluralin is under consideration for non-inclusion in Annex 1. If it is included, regulatory authorities in some current northern zone Member States might not permit re-registration. In 2003, trifluralin was the most widely used herbicide on 60% of the leaf brassica area. Trifluralin, introduced in 1967, is cheap c. £5/ha and is the basic starting point for weed control for leaf (and root) brassicas. Herbicide costs are not normally an issue for horticultural crops except for those grown on a large-scale with lower gross margins (e.g. cauliflower). It is soil-incorporated pre-planting and weeds within the crop row are controlled, whereas the passage of the transplanter disturbs the residual herbicides applied to the soil surface pre-transplanting and efficacy within the row is reduced. It is useful for early plantings in wet conditions where efficacy of tractor-hoeing is poor because weeds re-root. Trifluralin provides good control of the following weeds which are a widespread problem on soils where brassicas are grown: black-bindweed, knotgrass, pale persicaria, redshank and fat-hen and grass weeds, mainly annual meadow-grass. It also has important gaps in the weed spectrum: cruciferous species including shepherd’s purse and charlock; corn marigold, mayweeds and groundsel (Appendix). Trifluralin is effective on herbicide-resistant black-grass, although this is not a current problem in horticultural brassicas, it could be in future, especially where it is grown in an arable rotation with winter wheat on heavier soils.

• If trifluralin is lost, leaf brassicas will still be grown but the impact would be on increased cost of weed control c. £17/ha. Control of weeds within the row would also be reduced. and there could be an impact on quality and harvestability.

2. Specific herbicide and herbicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

A range of herbicides is needed for leaf, head and flowerhead brassicas to cover the weed spectrum. It would be desirable to maintain: Glyphosate, non-selective herbicide pre-cropping. Trifluralin, applied pre-planting and incorporated. Propachlor, metazachlor, clomazone are also important for residual weed control. Clopyralid post-emergence is particularly important for thistle and mayweed control and for brassicas grown on highly organic soil types Pendimethalin not widely used because soil disturbance at planting reduces efficacy within the row, but it is effective on Polygonums and fat-hen and will be very important if trifluralin goes. However the cost of weed control in brassicas would increase by c. £17/ha. Carbetamex (cabbage only) is rarely used but this may change if trifluralin goes and/or grass weed resistance increases. There is little use of graminicides in leaf brassicas, but options of tepraloxydim and cycloxydim will be needed for control of grass weeds or volunteer cereals. Tepraloxydim gives some control of annual meadow-grass.

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224

(Napropamide is not much used because it is expensive and the weed spectrum is limited.) 3. Prospects for alternatives for any foreseen major gaps in herbicide availability

3.1. Alternatives A ‘Gap Analysis’ (Table 4) shows the critical herbicide gap * * *, where there are, or soon will be no control measures at all. There are new active substances that may be available in a few years time (Gap Analysis Table 4). As a result of the loss of herbicide actives, growers through HDC levy, funded trials beginning in 2004 in 12 vegetables including transplanted cauliflower, to screen new herbicides to find alternatives (HDC Projects FV 256, 2004; 2005 and 2006). The aim is to try to fill gaps left by loss of actives in the 91/414/EEC Review (HDC Gap Analysis http://www.hdc.org.uk). No herbicide tested so far would be safe in drilled brassicas (or oilseed rape) because nothing was safe to drilled swedes. Promising herbicides are further evaluated in transplanted cauliflower and Savoy cabbage, in 2005-2006 (HDC Project FV 270) with target weed charlock and ‘volunteer’ oilseed rape that will not be controlled after cyanazine is lost.

a. Oxadiargyl (on Annex 1) pre-planting was very safe to cauliflower and killed charlock, ‘volunteer’oilseed rape and all other species including Polygonums, but chickweed was not controlled and it was less effective on fat-hen than trifluralin. It has not been developed in brassica crops in Europe.

The following are all supported in List 3 of the 91/414 Review:

b. Prosulfocarb List 3A in tank-mix with pendimethalin pre-transplanting improved control of charlock and oilseed rape. It is registered for use in UK cereals but there are no residues data for brassicas from N Europe.

c. Post-weed-emergence bifenox List 3A (which has a SOLA for oilseed rape) controlled

charlock but was disappointing on other species and appeared safe to transplants.

d. Post-weed-emergence oxyfluorfen List 3B controlled all weeds and suppressed volunteer potatoes but the EC formulation and dose rates used were too damaging. It is used pre-transplanting in Spain.

All these herbicides would require generation of residues data. Other (confidential) herbicides are included in the 2006 trial. Other herbicides may be promising for brassicas. These actives are not ‘new’ although the isomers are:

e. Dimethenamid-p is ‘new’ on Annex 1. A formulation of dimethenamid-p/metazachlor (a herbicide (product Springbok) with new approval for UK oilseed rape) post-transplanting and pre-weed-emergence.

f. Dimethachlor (List 3B) appeared promising on transplanted brassicas in FV 256 Project,

and is approved for broad-leaved weed control in Germany for oilseed rape, if included in Annex 1 it will be re-registered in N Europe and possibly the UK.

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g. s-metolachlor ‘new’ on Annex 1, is a sugar beet and maize herbicide in other N EU

member states, used pre-transplanting (FV 256, 2006) also appeared to have potential. Off–label Approvals http://www.pesticides.gov.uk/applicant_guide.asp?id=1226 based on recognition of on-label approvals in other EU Member States in the same climatic zone are possible for UK minor crops of areas less than 50,000 ha and the area of leaf brassicas (individual and total) are now in this category. The use of the pesticide on the crop must have an on-label approval in the Member State in which the use is approved. There must be an extant on-label approval for the use of the same product on another edible crop in the UK. This route will be used increasingly. The UK regulatory system does not permit recognition of off-label approvals in other member states although this would be helpful for minor crops. In the US the IR-4 Program co-operates with the crop protection industry to provide new pest control solutions for US growers of specialty crops. Funding for the IR-4 Program comes from a variety of sources. Two major USDA agencies, CSREES and ARS, provide the bulk of the funding as appropriated annually by the US Congress and amounted to $13,409,100 in 2004 (Holm et al., 2005). Globally there appears to be very little herbicide development compared with the period 1990-1999. Analysis by Phillips McDougall, shows that for fruit and vegetables, no new herbicide active substances had been introduced over the period 2000-2004, and none were in R & D (Phillips McDougall, ECPA conference, November 2005). There are a few for wheat but broad-leaved herbicides for wheat are usually damaging to broad-leaved crops. Unlike insecticides and fungicides that can be used in a wide crop range, herbicides are crop specific in terms of crop safety and one that is safe to one broad-leaved crop is unlikely to be safe in another. Herbicides for oilseed rape could be useful in brassica crops, but there is little development in oilseed rape because it is competitive and has a lower requirement for weed control. This may change as the area increases unless Herbicide-Tolerant rape is grown. Introduction of Genetically Modified Herbicide-Tolerant crops seems unlikely in the near future in the UK because of concerns about seed longevity and consumer opposition. The more persistent herbicides appear difficult to register in Europe. In horticulture this will mean more applications with different products to control the whole weed spectrum A new HDC Project FV 287, by CSL, aims to survey Approvals in other EU countries across all horticultural crops. In the future, a limited range, and loss of broad-spectrum herbicides may result in change in weed spectra. Development of herbicide resistance is a possibility where weeds set seeds in late-harvested crops. There are approvals for use of pendimethalin in many crops (56) including winter wheat and a few resistant broad-leaved weed species have been identified at a few sites in the UK. A long-term Defra project screened six actives, including pendimethalin, for evidence of creeping resistance in fat-hen (Defra project HH3401SFV, 2006) the data suggest that creeping resistance is unlikely, given normal herbicide programmes, but not impossible. 3.2. Impact of the proposed regulation and revision of 91/414EEC Comments in the Executive summary apply to brassica crops.

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• Mutual Recognition could be helpful if products containing Annex 1 active substances (excluding candidates for substitution) are registered for the brassica crop/use combination elsewhere in the proposed Central zone but not in the UK. Brassicas are grown in several EU Member States.

Key to Gap Analysis Tables: * * gap no immediate problem but future situation vulnerable


Solution non-chemical - is this effective/reliable? yes/no




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Table 4. Gap Analysis Leaf Brassicas Herbicides

Weeds/weed species

Application timing Gap Status





R & D? Residues

data?


pre-plant soil incorporated/ residual

trifluralin trifluralin future uncertain. not used to control resistant grass weeds

oxadiargyl Annex 1 S Europe pre-plant residual

Yes None

carbetamide can only be used in spring cabbage 3-4 l, in late autumn & winter (grass weeds). carbetamide (pre- & post) and propyzamide can only be used in brassica seed crops (grass weeds).

Charlock pre-plant residual * * * No means of control prosulfocarb List 3A in the EC Review

Charlock post-em from 2TL / contact (& residual)

* * * none Fortrol (cyanazine) SOLA: unsupported in the EC Review - Essential Use in brassicas expires 31 Dec 2007. Used for all varieties of both drilled and transplanted cabbage. Cyanazine not widely used but is effective in controlling relatively large weeds (up to 100mm high for some species), whilst having a high degree of crop safety. It has a wide weed spectrum - good control of species often a problem in brassicas: polygonums, charlock, shepherds purse and small nettle.

Inter-row hoeing does not control weeds within the row, weeds re-grow

bifenox SOLA submit on-label for oilseed rape to supported in the EC Review (List 3A)


Yes none

Volunteer oilseed rape

pre-plant residual * * Pendimethalin gives some control Inter-row hoeing


Yes none

annual BLW Post-em * * Croptex Steel (sodium monochloracetate): unsupported in the EC Review - brassicas expires 31 Dec 2007. Used on about 14% of brassica crops (drilled and transplanted). Wide weed spectrum and is effective in controlling some relatively large weeds (but not large nettle), and provides no control of fat hen. Short harvest interval 21d.

Compositae & volunteer potato suppression

post-em from 2TL, translocated

* * clopyralid clopyralid full approval. Limited weed spectrum important for control of mayweeds, creeping thistle, sow thistle and suppression of volunteer potatoes.

Volunteer potato * * * none In trials oxyfluorfen post-em causes severe damage to potatoes, but safety margin of EC formulation in cabbage and cauliflower insufficient at 1.0 L/ha

Inter-row hoeing

oxyfluorfen post-em supported in the EC Review (List 3B S EU)

? Poland

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Pest control in Leaf Brassicas

Attention is drawn to the importance of predators and parasitoids in Assured Produce Protocols – for example, the cabbage root fly is attacked by a wasp parasitoid and several beetle species (Assured Produce - The NFU/Retailer partnership http://www.assuredproduce.co.uk). Rates of parasitism vary from crop to crop and are reduced usually when non-specific insecticides are used in brassicas or elsewhere in the rotation. Cabbage root fly (Delia radicum) The cabbage root fly is probably the most serious pest of brassica crops in the UK. Larvae, which feed on the roots, can cause plant death. There are two or three generations of cabbage root fly each year starting from fly emergence and egg laying in late April - early May and continuing, with some overlapping into September. For autumn-planted brassicas maturing in the spring, treatment is usually unnecessary. With leafy brassica crops, once the plants are established, the crop can tolerate some damage to the roots without any measurable loss in yield. Impact: yield reduction, plant loss affects quality i.e. uniformity of size of produce and maturity. The pest occasionally attacks the growing point of the plant when soil conditions are dry and the tunnels caused by larvae affect quality and have resulted in crop rejection of calabrese and Brussels sprout . Control: There were only two approved active substances - carbosulfan and chlorpyrifos for cabbage root fly control on leafy brassicas after approval for use of chlorfenvinphos expired. There is now an approval for Brussels sprout, cabbage and caulilower: spinosad SOLA applied as a pre-planting drench or 3 days post-planting spray. It can be applied prior to 1 April (chlorpyrifos must not be used to treat blocks/modules which will be planted out before 1 April). Growers are advised to alternate with different MoA products and not to reduce doses. Preventive measures, preferably with chlorpyrifos seed treatment are essential for the peak of the first generation, for both direct drilled or transplanted crops. This can be followed by spinosad. Occasionally a follow-up granule treatment of chlorpyrifos is necessary at planting or as a band along the row within 2 days of planting but this is rarely used now, instead sprays currently approved for other brassica pests (Table 5), are applied, however, these should only be used in areas of low cabbage root fly activity. Forecasting/monitoring: A chemical attractant trap is available that selectively traps adult flies and thus a combination of this trap and HRI computer prediction model, will give a reliable monitoring system. Aphids Aphids invade April to July and build up of aphids from July to October. Studies of populations show a regular "crash" occurs, normally late July - early August, where natural mortality occurs. Two species are of importance: Mealy grey aphid (Brevicoryne brassicae) Is a widespread pest of Brassicas. Impact: checks the growth of young plants, some plant death, particularly in dry conditions. Quality is spoilt where leaves curl up, and where produce is contaminated with aphid colonies. Chemical control: susceptible to early treatment with pyrethroid, carbamate and new pymetrozine insecticides. Triazamate was the most effective but has been withdrawn and is no longer approved except in sprouts where it can only be used until 31 December 2006). Other aphicides are not as effective as triazamate on mealy grey aphid. Peach potato aphid (Myzus persicae)

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The pest is becoming more important, particularly in warmer, drier seasons. It is an important vector of many plant viruses. Winged forms migrate from winter sites to summer hosts in May and June reaching peaks similar to those of the mealy grey aphid. Impact: rarely causes significant damage but marketable quality is reduced if numbers are high. Control: The current approvals are with pyrethroids, pirimicarb, pymetrozine, imidacloprid and triazamate (no longer approved except sprouts only until 31 December 2006) and a new SOLA for thiacloprid (a chloronicotinyl neonicotinoid) with O-TEQ oil (Biscaya). Three insecticide resistance mechanisms now exist in the UK Myzus persicae populations:

• Esterase-based resistance to organophosphates and some carbamates • Kdr knock-down resistance to pyrethroids • New - modified acetyl-cholinesterase (MACE) conferring resistance to (pirimicarb)

carbamates (and triazamate) So far no current resistance mechanisms exist with regard to nicotine; neonicotinoids imidacloprid, thiacloprid new SOLA (or clothianidin not approved for brassicas); or pymetrozine. Use of these three approved actives should be made where there has been a previous history of resistance or where resistance populations are suspected. Use of neonicotinoids is likely to be limited to two applications per crop and this includes seed treatment. Imidacloprid seed treatment can be phytotoxic – it affects germination of certain Brussels sprout varieties (including a popular early one). It is important: to alternate the use of different actives to enable the best chance of control; and not to reduce dose rates. Forecasting/monitoring: HDC provides forecasts of the timing and size of aphid migrations nation-wide Continuous monitoring by Rothamsted Research and forecasting helps to facilitate optimal insecticide usage and hence reduce costs, limit selection for insecticide resistance and produce environmental benefits. Rothamsted Research detected a significant outbreak of MACE insecticide resistance in the peach potato aphid during autumn 2003 (HDC project FV 238, 2004). Cultural control: Most aphid infestations develop from colonies that overwinter on old brassica crops and autumn sown oil seed rape. Insect predators (ladybirds, hoverflies and parasitic wasps) can reduce aphid populations. Cabbage caterpillars Caterpillars of many species attack brassicas. The damage caused depends upon the species responsible. The larvae of some species, when nearly mature, are difficult to kill with insecticides and cause considerable spoilage, others, may not justify treatment. The diamond back moth (Plutella xylostella), is becoming a common pest, is not controlled by pyrethroids, and can have several generations in a season. Impact: reduced quality by some species, particularly diamond back moth. Monitoring: with pheromone traps to assess moth thresholds, Control: pyrethroids as soon as young caterpillars found, other insecticides shown in Table 5. Bacillus thuringiensis, diflubenzuron are less damaging to beneficial predators and so is a new insecticide indoxacarb (pending UK approval). Cutworms Cutworms are the caterpillars of turnip moth (Agrotis segetum) and other moth species. Attacks are more severe in hot dry weather. The caterpillars hatch in June and July, feed on the foliage for at least a week, before descending to feed on the underground parts of the host plant. Forecasting and monitoring: warnings based on trap catches sometimes combined with a weather model to define 'high risk' periods, when the caterpillars are small and can be controlled by rainfall/irrigation or chemical treatment. Pheromone traps can be used to monitor moth numbers. Control: with any pyrethroid but timing is critical. Chlorpyrifos is also approved. Routine treatment is not required. Non-chemical control: with irrigation.

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Pollen beetle Adults, dispersing from oilseed rape, can damage brassicas in summer. Impact: mainly on quality by contamination of produce. Forecasting and monitoring: forecasts predict the onset of migration of pollen beetles (service to HDC members) alerts growers to start field monitoring with yellow sticky traps. Control: If beetles are found damaging the crop or are likely to contaminate harvested produce, apply insecticide - pyrethoids have a subsequent repellent effect. Cabbage stem weevil (Ceutorhynchus quadridens) Attacks all brassica crops, particularly direct-drilled Brussels sprouts. The larvae feed in stems and petioles of plants that may subsequently wilt. Treatments applied for cabbage root fly give incidental control Slugs Slugs damage brassica seedlings and established plants on medium to heavy-textured soils in wet seasons. Impact: seedling death, yield loss, uneven size grade. Contaminant affects quality. Control: monitor with traps. Apply molluscicide if trap catches and weather pattern indicate a period of high risk. More slugs are usually found at field margins. A system for forecasting slug damage has been developed for Brussels sprouts. Treatments with molluscicides are unlikely to be effective until slug activity increases in the late summer, usually as soil moisture increases. A band of molluscicide around the field boundary (within the crop or on surrounding bare soil) will deter slug movement into the crop (HDC project FV 225). Minor pests Chemical treatment for these pests is only justified if they are present in crops or where there is a history of infestation on the farm. The following are also pests of oilseed rape: Cabbage stem flea beetle (Psylliodes chrysocephala) The build up of this pest on oilseed rape may lead to more serious attacks on vegetable brassicas. Even comparatively light attacks can reduce yield. Control with a pyrethroid. Brassica cyst nematode (Heterodera cruciferae) Cabbage leaf miners (Phytomyza rufipes & Scaptomyza aplicalis) Beet cyst nematode (Heterodera schachtii) Avoid frequent cropping with alternative host crops if the nematode is present Cabbage seed weevil In recent years large numbers of adult cabbage seed weevils have infested brassica crops in some localities in mid-summer. Weevils can damage the mature crop by feeding on the outer leaves. Quality is reduced where weevils contaminate produce. Control is with a pyrethroid (as for caterpillars). Cabbage whitefly (Aleyrodes proletella) is occasionally found. Flea beetles (Phyllotreta spp.) In direct-drilled crops, under warm dry conditions, seedlings may be killed but damage is rare, but the problem is increasing. In trials (HDC Project FV 222, 2002) showed seed treatments imidacloprid was effective but tefluthrin and fipronil were less effective none gave more than 60-70% control; single sprays Lambda-cyhalothrin, cypermethrin, deltamethrin and spinosad suppressed flea beetle population only 2 days but seedling survival was increased Control with deltamethrin two spray programme if severe damage. Trap cropping (with summer turnip/Chinese cabbage) and spraying the trap crop was effective. Leatherjackets (Tipula spp.) Leatherjackets are only likely to be of importance in fields cropped after grass. Control with organophosphorus insecticide pre-planting only if risk is high.

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Insecticides and molluscicides for leaf brassicas Insecticides approved for 2006 and usage in 2003, are shown in Table 5. Table 5. Insecticides and molluscicides approved for 2006; Aim re-registration for some but not all leaf brassicas UK; Pest; Activity; Usage of insecticides and molluscicides on 32,424ha leaf brassicas grown in Great Britain, 2003 (spray hectares) (source CSL Pesticide Usage survey, 2003) Insecticides & molluscicides approved for 2006

Approval status

Aim re-registration for some brassicas

UK


(spray ha)

Biological control agents Other biological control agents caterpillar

159

Insecticides Alpha-cypermethrin Annex 1 - aphid flea beetle caterpillar contact and ingested pyrethroid 5,773 Bifenthrin List 3A √ aphid whitefly caterpillar contact and residual pyrethroid. 7,528 Carbosulfan List 2 √ early aphid, flea beetle cabbage

root fly systemic carbamate

Chlorpyrifos EC & WG formulations. Module and plant drench ; only.on B sprout

Annex 1 - aphid cabbage root fly whitefly caterpillar,

contact and ingested organo-phosphate. broad spectrum

4,935

Cypermethrin Annex 1 aphid caterpillar whitefly contact and ingested pyrethroid 8,821 Cyfluthrin Annex 1 √ caterpillar non systemic pyrethroid Deltamethrin Annex 1 √ aphid flea beetle caterpillar contact and ingested pyrethroid 7,186 Deltamethrin/pirimicarb Annex 1/

Annex 1 √ / √ aphid caterpillar pyrethroid /carbamate 12,939

Diflubenzuron List 3A caterpillar contact and stomach acting Dimethoate only SOLA for cabbage

List 2 - aphid systemic organophosphate 2,944

Lambda-cyhalothrin Annex 1 √ aphid including Myzus persicae caterpillar whitefly

contact and ingested . broad spectrum.pyrethroid

34,178

Lambda-cyhalothrin/ pirimicarb

Annex 1/ Annex 1

√ / √ aphid including Myzus persicaewhitefly caterpillar

systemic, contact and stomach activity pyrethroid /carbamate

6,381

Nicotine unsupported? List 4C aphid caterpillar contact alkaloid 6,736 Pirimicarb Annex 1 √ aphid contact, fumigant and translaminar

myzus persicae resistance reported in some areas.carbamate

30,880

Pymetrozine all SOLAs

New Annex 1 √ aphid novel azomethine systemic aphicide which prevents aphid feeding. controls OP and carbamate resistant myzus persicae.

7,218

Spinosad (not broccoli)

New Annex 1

- cabbage root fly (SOLA) diamond back & cabbage moth, moth, cabbage white & small white butterfly

from naturally occurring soil fungi

Thiacloprid SOLA New Annex 1 √ aphid chloronicotinyl Triazamate# Brussels sprouts only until 4 January 2007

withdrawn aphid including Myzus Persicae carbamoyl triazole 12,589

Molluscicides & repellents Metaldehyde List 3A ? √ slugs snails 9,877

Methiocarb List 2 not decided (√ N)

slugs snails carbamate 2,034

Thiodicarb Brusse non-inclusion ls sprouts only

√ slugs snails carbamate

Note: alpha-cypermethrin, cypermethrin bifenthrin deltamethrin chlorpyrifos will only control non-resistant strains to OP & pyrethroid of whitefly and only give some control; # no longer marketed; - Company request confidentiality; √ yes; (√ N) aim re-register in N Europe The control of MACE resistant peach potato aphids Myzus persicae is an important issue for brassica growers. Aphids were the main reason given for insecticide application, accounting for 42% of all specified applications. Caterpillars comprised a further 20%, caterpillars of the diamond

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back moth accounted for 6% with Myzus persicae comprising a further 3%. Two formulations comprised over 40% of all insecticide applications: lambda-cyhalothrin (23%) and pirimicarb (21%), with two applications of each being used on half of the area of brassicas grown. Triazamate was used almost exclusively on brassica crops, where use increased dramatically since 1999, but it has been withdrawn by the approval holder and will not be supported in the 91/414/ EEC review. It is no longer marketed and can only be used in Brussels sprouts, until 4 January 2007. Since 2003, cyfluthrin and spinosad have been approved. New approvals for 2006 included a SOLA for thiacloprid (a chloronicotinyl neonicotinoid) with O-TEQ oil (Biscaya).. Thiodicarb was not included on Annex 1 (decision July 2006). Bacillus thuringiensis and diflubenzuron are not widely used because of cost and efficacy problems Seed treatments for leaf brassicas Most seed treatments are applied before importation. In 2003 the principal seed treatment formulation applied in the UK to brassicas was thiram, accounting for 32% of the treated seed area, with carbendazim/chlorpyrifos/iprodione/thiram comprising a further 16%. Imidacloprid was applied to 9% of the brassica area sown. Metalaxyl and carbendazim/chlorpyrifos/iprodione/thiram are no longer approved. Table 6. Seed treatments approved for 2006; Review status; Aim re-registration brassicas UK; Disease or Pest; Activity; Usage of seed treatments on 32,424 ha leaf brassicas grown in Great Britain, 2003 (spray hectares) (source CSL Pesticide Usage Survey 2003) Seed treatments approved for 2006 Review status Aim re-

registration brassicas UK

Disease or Pest Activity Usage 2003

(sown ha)Fungicide/insecticide seed treatments Carbendazim/chlorpyrifos/iprodione/thiram no longer approved

628

Fungicide seed treatments Iprodione Annex 1 - seed borne Alternaria sp dicarboximide 424 Metalaxyl no longer approved Non-inclusion

Annex 1 seedling downy mildew 457

Thiram not broccoli Annex 1 √ cabbage cauliflower

seedling damping off diseases dithiocarbamate 1,239

Insecticide seed treatments Chlorpyrifos imported only List 1 - cabbage root fly. Contact insecticide. contact and ingested

organo-phosphate .

Imidacloprid SOLA List 3A x (√ sugar beet) early aphid control (Myzus persicae). Systemic insecticide

neonicotinoid 218

- Company request confidentiality; √ yes; (√ N) aim re-register in N Europe 1. The likely impacts of the 91/414/EEC review process on insecticide and molluscicide availability for UK brassicas

1.1 Losses In the past the larvae of cabbage root flies were controlled by seed-treatments, drenches, sprays and granular formulations of mainly organophosphorus insecticides. As a result of the UK review of

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anticholinesterase compounds (organophosphates and carbamates) chlorfenvinphos was revoked in 2002. The grower use up period was until 31 December 2003. The usage of organophosphates had already declined in some crops as a result of restrictions imposed by retailers, but it remained important particularly for control of cabbage root fly in brassica leaf and root crops. Chlorfenvinphos was still approved in other EU member states, but it was not supported in the 91/414/EEC review. There were ‘Essential Use’ derogations for chlorfenvinphos until 31 December 2007 for a wide range of crops in other EU Member States (Denmark, Germany, Ireland, France, The Netherlands and Spain). No ‘Essential Uses’ could be requested in the UK and thus there was less time to find effective control measures. Carbofuran is also no longer approved in the UK. Triazamate, a carbamoyl triazole, was the most effective insecticide for control of cabbage aphid. It was approved for other crops as well but was used almost exclusively on brassicas (on 12,589 ha in 2003), and use increased dramatically since 1999. Triazamate was withdrawn by the approval holder and will not be supported in the 91/414 EEC review. It is no longer marketed and can only be used, in Brussels sprouts, until 4 January 2007. Thiodicarb failed Annex 1 inclusion (decision July 2006). There is no decision yet on alternative molluscicides metaldehyde (List 3B) or methiocarb (List 2). 1.2. Impact Loss of chlorfenvinphos The cabbage root fly (Delia radicum) is probably the most serious pest of brassica crops in the UK. There are two or three generations of cabbage root fly each year starting from fly emergence and egg laying in late April - early May and continuing, with some overlapping into September. For autumn-planted brassicas maturing in the spring, treatment is usually unnecessary. Some means of control have now been found. Chlorpyrifos and spinosad control cabbage root fly in most seasons: chlorpyrifos as a seed/module treatment; spinosad has new (February 2006) SOLA for cabbage root fly control in Brussels sprouts, cabbage and cauliflower (SOLA submitted for calabrese) as a module drench pre-transplanting or as a foliar spray 3 days after transplanting. Spinosad can be applied before the 1 April (unlike chlorpyrifos). Sometimes a subsequent treatment with chlorpyrifos granules is necessary. Chlorpyrifos soil treatment is restricted by some retailers and processors (although the seed treatment on imported seed is acceptable) and is rarely used by growers now.Control of the third generation is difficult and occurs more frequently in warm autumns. Control of aerial attacks is also difficult. Whether these control measures are adequate, remains to be seen. The problem has not been solved completely and new insecticides are needed, particularly for root brassicas (not studied here).

• Cabbage root fly larvae, which feed on brassica roots, can cause plant death in leaf brassicas, affecting uniformity of size of produce and maturity. Although once plants are established, leaf brassicas can tolerate some damage to the roots without any measurable loss in yield. The damage from cabbage root fly does not usually affect quality of leaf brassicas for human consumption (unlike swedes and turnips). However the pest attacks the aerial parts of the plant when soil conditions are dry and the tunnels caused by larvae affect quality mainly in calabrese and Brussels sprout buttons, resulting in crop rejection.

• Without adequate insecticidal control, it is estimated that about 24% of the plants in brassica

crops would be lost or rendered unmarketable by the cabbage root fly – the financial loss is £44 million. This does not include root brassicas, where the situation is a lot worse.

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Loss of triazamate

• Mealy grey aphid (Brevicoryne brassicae), a widespread pest of Brassicas, checks the growth of young plants, causing some plant death, particularly in dry conditions. Quality is spoilt where leaves curl up, and where produce is contaminated with aphid colonies. It was considered by brassica advisors to be the best systemic aphicide and it was possible therefore to allow aphid infestations to build up and allow predation, before triazamate was applied. Insecticide applications could be reduced.

• Other aphicides are not as effective as triazamate on mealy grey aphid. Early treatment is

now considered necessary with other aphicides: pyrethroids, carbamate and new pymetrozine.

A significant proportion of growers levy through HDC has been spent on trials to identify alternatives for pest control in brassicas (see 3). 1.3. Future losses? It is difficult to predict the likely impact of the review process on pesticide availability for the UK brassica industry. Most insecticides are included on Annex 1 (Table 5) but we do not yet know whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage (as occurred for carrots) and this may have an impact on efficacy. There could also be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. Crop Protection Companies may not support all on-label approvals for Annex 1 listed active substances, especially on some of the minor brassica crops. The greatest threat lies with the more minor uses either on the specialist brassicas or for more minor targets on this host. More SOLAs will therefore be needed. There are some SOLAs for insecticides for brassicas (Table 5). Residues data for some older SOLAs may not satisfy modern EC standards – a PSD study of data in archives, covering List 1 actives) suggests that new data may be required to set MRLs to support some minor crops/uses. List 2 (dimethoate) and some list 3 actives will be studied later. The impact will be on cost to the grower through HDC levy to maintain these uses. 2. Specific insecticides, molluscicides or insecticide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Insecticides with alternative modes of action are important for resistance strategies and it is also important that new ones are developed for this important pest. It would be desirable to maintain the following: It is very important that active substances for cabbage root fly control on leafy brassica crops remain: chlorpyrifos and the new spinosad (carbosulfan is approved but is less effective). Spinosad has new (February 2006) SOLA to extend use to control of cabbage root fly in Brussels sprouts, cabbage and cauliflower (SOLA submitted for calabrese) as a module drench pre-transplanting or as a foliar spray 3 days after transplanting.

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Aphids: The control of MACE resistant peach potato aphids Myzus persicae is an important issue for brassica growers. Three insecticide resistance mechanisms exist in UK Myzus persicae populations:

• Esterase-based resistance to organophosphates and some carbamates • Kdr knock-down resistance to pyrethroids • New - modified acetyl-cholinesterase (MACE) conferring resistance to (pirimicarb)

carbamates (and triazamate) So far no current resistance mechanisms exist with regard to nicotine; neonicotinoids imidacloprid, thiacloprid new SOLA (or clothianidin not approved for brassicas); or pymetrozine. To avoid resistance, the use of neonicotinoids is likely to be limited to 2 applications/crop this includes imidacloprid seed treatments. Therefore the range of insecticides with different modes of action needs to be maintained. All the current options are needed for aphid control: imidacloprid seed treatment; pyrethroids (lambda-cyhalothrin, deltamethrin etc.); pirimicarb alone or in formulation with a pyrethroid; pymetrozine; new thiacloprid, and nicotine. So are dimethoate (List 2) (cabbage only) and chlorpyrifos although retailers and processors discourage their use (except chlorpyrifos seed treatment). Rotenone is not widely used but may be useful as another tool for aphid resistance management. Caterpillars: pyrethroids are widely used for control and they are cheap. Approval is being sought for a new active with a different mode of action, indoxacarb (new on Annex 1, registered in France, Belgium etc. for brassicas) for caterpillar control in brassicas and although it is more expensive it controls caterpillars of the diamond back moth (a problem in 2006) and is more benign to beneficial insects. It will be important to maintain both. Slugs: Slug damage is extremely costly for UK horticulture. In addition to the costs of molluscicide applications, there are costs associated with damage and contamination of produce by live slugs or molluscicide pellets. At the moment there are no commercially available products that give better control of slugs than molluscicide pellets. Metaldehyde is preferred in brassica crops and it preserves populations of ground beetles that are beneficial for control of other pests. Metaldehyde should be maintained, and possibly methiocarb. Nematicides are not used in leaf brassica crops. 3. Prospects for alternatives for any foreseen major gaps in insecticide availability

New insecticides with different modes of action are needed for resistance strategies. 3.1. Alternatives A ‘Gap Analysis’ (Table 7) shows the critical insecticide gap * * *, where there are, or soon will be no control measures at all. a. Cabbage root fly (Delia radicum): Several HDC projects (in swedes and turnips) evaluated alternatives including a range of film-coated seed, baits and deterrents (garlic, seaweed etc.) but none were effective (FV 223, 2002). From 2003 projects in leaf (and root) brassicas FV 242, 242a glasshouse, 242b field, and research is ongoing. Seed treatments, drenches and granular treatments

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with a number of potential alternative insecticides were tested. A number of soil insecticides with the potential to be used as drench or seed treatments for control of cabbage root fly on leafy brassicas were identified, although long term control for the 3rd generation has proved difficult. As a result there are new SOLAs for spinosad module drench. Spinosad seed treatment was effective in trials but is not yet approved. b. Peach-potato aphid (Myzus persicae): HDC Project FV 250 (2003-2006) evaluation of insecticides including new ones on clones of MACE resistant Myzus persicae was carried out at Warwick HRI Wellesbourne. Treatments were applied before after the mid-season aphid crash. In 2005, both cabbage and peach-potato aphid were present initially and the most effective treatments were imidacloprid seed treatment or an experimental imidacloprid drench. Pymetrozine, lamda-cyhalothrin/pirimicarb, and a coded product all applied with appropriate wetters reduced aphid numbers considerably. The following foliar sprays performed well and now have SOLAs for Brassicas: pymetrozine (an azomethine insecticide); a new formulation of thiacloprid (a chloronicotinyl neonicotinoid) with O-TEQ oil (Biscaya), a quick knock down and persistent insecticide The oil improves retention on waxy-leaved crops. It is approved (single application) for pollen beetle control in oilseed rape. The trial continues and will include new insecticides. Not tested in the 2005 screen - flonicamid a pyridine carboxamide (nicotinamide) has a different action site from neonicotinoids, UK registrations for winter wheat, potatoes, apples, pears for control of aphid and thrips. It is a ‘Reduced Risk/OP Alternative’ in the US. c. Caterpillars: New indoxacarb (Steward) an oxadiazine, approval for caterpillar control in brassicas sought for the UK through Mutual Recognition (registered for fruit and brassicas in Belgium and the Netherlands). It is benign to beneficials but kills all caterpillars including those of diamond back moth (not controlled by pyrethroids) and silver Y moth. The MHI is one day. However it costs around £12/ha (lambda-cyhalothrin £3/ha). Rynoxapyr (DPX-E2Y 45), another new active (new chemistry anthranilimide) from DuPont for brassicas could be more effective on caterpillars than indoxacarb, also for lettuce and potatoes. Registration to be sought in Ireland and UK possibly in 2008. It is classed in the US as ‘Reduced Risk/OP Alternative’ It will be formulated with an insecticide from Syngenta. d. Cabbage root fly, aphid and other pests: New broad spectrum active (new chemistry) but not available until 2010. It is classed in the US as ‘Reduced Risk/OP Alternative’. Applied as a drench or foliar spray. Several other new insecticides are in development in the US IR 4 project. e. Slugs: New more effective measures are needed for slug control. A new methiocarb spray has been identified for use in some crops - it is registered in some other Member States, but is not available in the UK. In the UK there are several new insecticides active substances for cereals, sugar beet and potatoes and some will be suitable for brassicas. However cabbage root fly is a more crop specific pest. The area of oilseed rape has increased dramatically in recent years and there could be further expansion - the risk of pests (pollen beetle, cabbage stem flea beetle) spreading from neighbouring rape crops to brassicas will increase. Insecticides developed for some oilseed rape pests will be useful for horticultural brassicas but there may be resistance issues (pollen beetle in France). Off–label Approvals based on recognition of on-label approvals in other (current Northern zone) member states are possible for UK minor crops and this will be useful for leaf brassicas, which are grown in other EU member states in the same climatic zone. This route could be used increasingly.

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Table 7. Gap Analysis (Brassicas): Insecticides

Pest

Application timing

Gap Status


Comments Solution non-

chemical


Solution chemical another

MS

Solution chemical other


Cabbage root fly

seed treatment * * chlorpyrifos

Chlorfenvinphos revoked as a result of Defra/PSD review of pesticides with antcholinesterase activity HDC FV 217 project showed chlorpyrifos effective but pressure low.

-

Pre-planting drench

* * spinosad (Tracer) SOLA #

- New chemistry UK reg 2010?

None yet

Post-planting * * chlorpyrifos carbosulfan at drilling or post-transplanting

Carbosulfan no protected use - FV 242c new insecticides for fly continues 2005-2006

3days Post-planting spray

* * spinosad (Tracer) SOLA

Alternate with different MoA products, do not reduce doses

-

Cabbage aphid

* * * several but less effective than triazamate on cabbage aphid

Triazamate withdrawn from EC Review, no longer sold only Brussels sprout approval remains use up by 4 Jan 2007 Dimethoate unacceptable to several retailers.

- R & D HDC FV 250

Peach potato aphid

* * * pyrethroids, pirimicarb, pymetrozine (an azomethine), imidacloprid, thiacloprid new SOLA

Resistant populations except to neonicotinoids but use likely to be limited to 2 applications per crop including seed treatment. New MoA needed for resistance strategy

- flonicamid (nicotinamide different from neonicotinoid)

New chemistry UK reg 2010?

R & D, residues data will be needed

Spinosad (Tracer) SOLA # for Brussels sprout, cabbage and caulilower, submission for calabrese)

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Disease control in Leaf Brassicas

Varieties: None of the current commercially important cabbage varieties have resistance to all the five major diseases, (ringspot, Alternaria, light leaf spot, white blister and club root). Varieties differ in their susceptibility to powdery mildew. None of the current commercially important cauliflower varieties have resistance to all the four major diseases (cauliflower mosaic virus, turnip mosaic virus, downy mildew and club root). Club root (Plasmodiophora brassica) Club root is a persistent, infectious, soil-borne fungus that affects all Brassica vegetables and cruciferous weeds shepherd’s purse and charlock. It causes swelling of the roots, which subsequently rot; plants are stunted and may die. Occurs where soil pH is low. Lime application in the rotation to maintain a soil pH 7.0-7.3 gives good control. Impact: crop loss. Control: No agrochemicals available. Black rot (Xanthamonas campestris) This bacterial disease of cauliflower, developing rapidly in wet weather, but is sometimes found on cabbage and Brussels sprouts. Field infections are usually seed-borne or spread during propagation but the pathogen survives on crop debris and is spread by rain splash. Major seed lots are batch tested. If seed lots are infected, hot water treatment is the only approved method of control but seed vigour may be affected Impact: significant plant loss especially in late autumn. Control: copper oxychloride bactericide, azoxystrobin. Cultural control: Plough in crop residues. Use a 3-year rotation. Damping off and wirestem (Pythium spp. and Rhizoctonia solani) These fungi attack the roots and stems of young seedlings. Rhizoctonia in the field affects the stem base causing the stem to break later but there are no control measures. Impact: seedling loss at propagation stage or plant loss in the field. Control: Pythium at propagation stage in the glasshouse with thiram seed treatment, propamocarb hydrochloride, toclofos-methyl (organophosphate), etridiazole, chlorothalonil, protectant fungicides, systemic fosetyl-aluminium. Downy mildew (Peronospora parasitica) Predominantly a problem during propagation but in wet seasons it can be severe in field crops. Impact: plant death if infection is severe. In cauliflower and, to some extent, broccoli/calabrese systemic infection causes a severe curd discoloration. Occasionally seen in stored Dutch white cabbage penetrating into inner leaves. Control: fosetyl-aluminium or metalaxyl M routine treatment in propagation. Fungicides from differing chemical groups should be used alternately to avoid development of resistant strains. Other fungicides approved chlorothalonil/metalaxyl M, chlorothalonil/metalaxyl, propamocarb hydrochloride. Cultural control: with resistant varieties.

Canker (Leptosphaeria maculans syn. Phoma lingam) Canker is seed- and soil-borne from infected debris. The pathogen causes blackleg in seedlings, leaf-spotting and stem canker in field crops together with a damaging storage rot in cabbage. Impact: plant loss, marketable quality is reduced.

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Control: thiram seed treatment, other fungicide sprays no approved use in field but the triazoles and strobilurins are likely to be effective. Fungicide use in store is limited to iprodione for (Botrytis) and resistance risk is high. Cultural control: a minimum of 4-year rotation. Do not grow outdoor plant beds adjacent to infected sites. Dark leaf-spot (Alternaria brassicae and A. brassicicola) This is a common leaf-spot problem in brassicas. Usually seed- and air-borne, these fungi are also soil-borne following the incorporation of infected crop residues. All brassica crops, including oilseed rape and cruciferous weeds are potential sources of the disease. Alternaria in vegetable brassica crops normally coincides with the harvest of the oilseed rape crop in July. Impact: Of greatest significance on Brussels sprouts due to button infection and in cauliflower/calabrese where curd infection occurs. Control: with seed treatments, in propagation and field with fungicide sprays – chlorothalonil, azoxystrobin, tebuconazole, difenoconazole, boscalid/pyraclostrobin. Iprodione will give some control of Alternaria. Cultural control: If possible, isolate brassica crops from each other, particularly oilseed rape. Plough in crop residues as soon as possible Ring spot (Mycosphaerella brassicicola) This disease is both seed-borne and soil-borne through plant debris in the soil. Infection is favoured by humid warm weather. Impact: reduced quality. Control: azoxystrobin propagation, eradicant sprays tebuconazole, difenoconazole, boscalid/pyraclostrobin achieves better control than with protectants chlorothalonil alone. Cultural control: wider rotations. White blister (Albugo candida) White blister occurs widely in the major brassica-growing areas. The fungus survives in the soil or on plant debris. On cauliflower curds it causes individual flower buds to swell, grow above their neighbours and turn white. Impact: marketable quality is reduced. Control: with fungicide sprays azoxystrobin, boscalid/pyraclostrobin, mancozeb/metalaxyl-M. Cultural control: plant beds should be in a dry open position. Bacterial soft rot (Erwinia carotovora and Pseudomonas spp.) Affects flower head brassicas in winter. Soft internal tissues of the stem disintegrate and rot and in winter cauliflower the curd shows brown discolour patches may occur on the curds. The biggest problem from bacterial soft rot is the invasion through damage during cutting and packing. Not widespread but severe where it occurs. Impact: quality loss if infection and decay cause floret discolouration. Cultural control: avoid damage during cutting and packing. Cool and store at low temperature. Spear rot (Pseudomonas maculicola) Affects flower head brassicas and is seed or soil-borne. Not widespread but severe in some areas. Impact: quality loss if small dark brown spots appear on the surface of the curd. Control: copper oxychloride bactericide gives limited control Cultural control: Adequate rotation. Strict hygiene is needed, especially for modules under glass. Powdery mildew (Erysiphe cruciferarum) Powdery mildew spreads from affected brassica crops by wind-borne spores. Infection is more likely to occur in dry, hot summers. It is not a problem in cauliflower and calabrese/broccoli.

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Impact: marketable quality is reduced. Control: a fungicide spray (tebuconazole) is only necessary on the more susceptible varieties in high-risk years. Cultural control: irrigation may help. Light leaf spot (Pyrenopeziza brassicae) Incidence of this disease is increasing, particularly in Scotland where there resistance to tebuconazole is reported in oilseed rape. It is soil-borne from infected debris and is also spread by rain splash and wind from neighbouring infected leaf brassica crops, particularly oilseed rape. Development is favoured by cold wet conditions. Impact: marketable quality is reduced. Control: fungicide sprays tebuconazole or difenoconazole. It is not usually a problem in flower head brassicas but difenoconazole is approved for this use. Cultural control: plough-in crop residues. Use a minimum of 4-year rotation. Root rot (Phytophthora megasperma) This disease is soil-borne, attacking roots and stems causing root rot, is occasionally seen on heavier or poorly drained soils. Impact: Yield loss. Control: None available. Cultural control: Avoid wet heavy, poorly structured soils. Grey mould (Botrytis cinerea) The grey growth or soft brown rot on leaves is usually associated with damage or the retention of dead and decaying lower leaves. Botrytis is spread by wet weather and high humidity. It is not a problem in flower head brassicas. Impact: quality reduced. Cultural control: Avoid lush soft growth from excess nitrogen. Chemical control: fungicide sprays iprodione, chlorothalonil. Minor diseases White rot (Sclerotinia sclerotiorum): An occasional problem in field-grown brassicas, more important in seed crops. Control is with azoxystrobin, boscalid/pyraclostrobin. It is too early to tell if Coniothyrium minitans (Contans) is effective commercially. White leaf-spot (Pseudocercosporella capsellae): An occasional leaf-spot pathogen. Control with difenoconazole. Virus diseases Turnip Mosaic (TuMV) virus is probably the worst virus causing severe stunting. Cauliflower Mosaic virus (CaMV) is more common causing stunting and leaf distortion. The mealy cabbage aphid and the peach potato aphid spread both viruses. Aphicides will not prevent introduction of virus but will restrict subsequent spread.Beet Western Yellows Virus (BWYV) commonly affects brassica crops. Recent work at Warwick HRI suggests that it may be implicated in tipburn in processing storage cabbage. Control: aphicides, in outdoor plant beds or early in direct-drilled crops. Cultural control: Isolate outdoor beds from other growing brassica. Plough-in brassica crop residues immediately. Storage disorders There are several identified storage disorders/diseases, of these the following are treated prior to storage with fungicides to prevent loss of quality and reduce waste.

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Grey mould (Botrytis cinerea): other fungi such as Alternaria, Mycosphaerella and Phytophthora, may cause lesions, which could lead to secondary invasion by Botrytis. Control: Pre-storage drench or dip with iprodione. Dark leaf spot (Alternaria brassicicola) Control: Pre-storage drench or dip with iprodione. Phytophthora rot (Phytophthora megasperma): is a soil-borne pathogen Control: Pre-storage drench or dip with metalaxyl-M. Other storage diseases can be reduced by controlling field infections. Pepper spot (Black speck or spotted necrosis) there are tolerant varieties. Fungicides for leaf brassicas Table 8. Fungicides approved for leaf, head and flower head brassicas 2006; Review status; Aim re-registration some but not necessarily all, leaf brassicas UK; Activity; area sprayed with fungicide leaf brassicas (32,424 ha grown) in Great Britain in 2003 (source CSL Pesticide Usage survey, 2003) Fungicides approved 2006 Review status Aim re-

registration UK brasssicas

Disease Activity Usage 2003

spray ha# Azoxystrobin New Annex 1 √ Alternaria, Xanthomonas field &

propagation, ring spot, white blister systemic translaminar and protectant strobilurin

5,387

Boscalid/pyraclostrobin not broccoli

New pending/ Annex 1

- Dark leaf spot, ringspot, and white blister

Anilide /strobilurin 5,973

Chlorothalonil Annex 1 √ Alternaria sp., grey mould, Botrytis sp., downy mildew propagation & field, ring spot, white blister

protectant chlorophenyl. 7,099

Chlorothalonil/metalaxyl not cabbage, use until 28 Dec 2006

Non-inclusion metalaxyl

Alternaria sp., white blister, downy mildew.

protectant chlorophenyl /systemic phenylamide

1,897

Chlorothalonil/metalaxyl-M not cabbage;

Annex 1 √ / √ white blister & downy mildew protectant chlorophenyl/ systemic phenylamide

3,989

Copper oxychloride SOLAs List 3A Field spear rot and Xanthomonas propagation Xanthomonas

bactericide 1,614

##Copper oxychloride/ metalaxyl SOLAs use until 28 Dec 2006

Non-inclusion metalaxyl

Xanthomonas, downy mildew bactericide/ systemic phenylamide

Difenoconazole List 3B √ Alternaria sp.& ringspot propagation & field

diphenyl-ethertriazole protectant and curative

15,513

Etridiazole cabbage & cauliflower only

List 3B Damping off, footrot, phytophthora Soil incorp/drench

protectant thiadiazole

Fosetyl-aluminium all SOLAs Annex 1 x (other crops not decided)

Damping off, downy mildew. Propagation area/drench

systemic phosphonic acid

Iprodione Annex 1 - Alternaria sp. propagation not B sprout & field, Grey mould Botrytis cinerea in storage cabbage.

protectant dicarboximide with some eradicant activity

453

Mancozeb/metalaxyl-M SOLA cabbage only

Annex1/Annex 1

- / √ white blister dithiocarbamate protectant/ systemic phenylamide

4,282

Maneb not cabbage Annex 1 - Downy mildew dithiocarbamate protectant

Metalaxyl-M SOLA cabbage Annex 1 √ Phytophthora in storage cabbage. Post-harvest

systemic phenylamide .

Propamocarb hydrochloride List 2 not decided (√ N)

Pre-plant drench or soil incorp propagation for damping off, downy mildew, Phytophthora

protectant.

Tebuconazole cabbage & Brussels sprouts; SOLA broccoli & cauliflower

List 3B not decided Alternaria spp, ring spot, light leaf spot, powdery mildew.

systemic conazole. 9,854

Toclofos-methyl List 2 √ damping off and wirestem Drench/soil incorp pre-plant

protectant organo-phosphate.

###Triadimenol cabbage & Brussels sprouts only

List 3A x Alternaria spp, light leaf spot, ring spot, powdery mildew

Systemic conazole 1,291

- Company request confidentiality; √ yes; (√ N) aim re-register in N Europe #Azoxystrobin for black rot outdoor and protected seedlings Brussels sprouts, cabbage, nothing cauliflower or broccoli Copper oxychloride bactericide SOLA Brussels sprouts, cabbage, cauliflower or broccoli protected seedlings only ##`Ridomil Plus` (copper oxychloride/metalaxyl) SOLA for use on Broccoli, Brussels Sprout, Cabbage, Calabrese and Cauliflower. The product is no longer commercially available, and stocks are very limited. ### Bayfidan (triadimenol) no longer marketed. Cupric ammonium carbonate (Croptex Fungex) drench approved for seedlings of all edible crops damping off; Potassium hydrogen carbonate approved for powdery mildew

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Fungicides approved for 2006 and fungicide usage in 2003, are shown in Table 8. Approvals are for leaf, head and flower head brassicas i.e. broccoli, calabrese, Brussels sprouts, cabbage and cauliflower (kale & collards not included) products may be used on broccoli provided they have a current label recommendation for use on calabrese or vice versa. Fungicide usage on brassicas decreased by 11% between 1999 and 2003 but had increased by 42% since 1991. The use of difenconazole, first recorded in 1999, accounted for over a third of the area treated with the principal five fungicide active substances. While the use of chlorothalonil had continued to increase from 1991 to 1999, it was replaced by tebuconazole as the principal active substance in 1999. Difenoconazole and tebuconazole were the two main fungicides used on brassicas, together accounting for 44% of the fungicide treated area. Most of the principal fungicides were applied at between half and full recommended rate with the majority, 45%, being used for general disease control. Ringspot (Mycosphaerella brassicicola) and dark leaf spot (Alternaria brassicicola) together accounted for 31% of all applications, with white blister (Albugo candida) comprising a further 9%. 1. The likely impacts of the 91/414/EEC review process on fungicide availability for UK leaf brassicas

1.1. Losses Quintozene (products Terraclor or Quintozene WP), a protectant soil-applied chlorophenyl fungicide was widely used by Plant Propagators. It was on List 1 of the 91/414 Review of existing actives but it was not supported and was revoked in 2002. No ‘Essential Use’ requests were granted. 1.2. Impact

• Effective control of disease in the early stage of plant production is critical as this eliminates one of the primary sources of inoculum for subsequent epidemic development in the field. Vegetable transplant producers have to rely on a narrow range of fungicides. Fungicides with alternative modes of action are an important for anti-resistance strategies.

• Toclofos-methyl (Basilex), approved for damping off and wirestem in brassicas remains and

is now the commercial standard.

• A project funded by growers through HDC levy (FV 235 see section 3.) was undertaken to evaluate alternatives and further work may be needed for SOLAs and to generate residues data. A significant proportion of growers levy through HDC has been spent on trials to identify alternatives.

1.3. Future Losses It is difficult to predict the likely impact of the review process on pesticide availability for the UK brassica industry. Some fungicides are included on Annex 1 (Table 8) but there are still decisions to be made on several including the most widely used: difenoconazole (List 3B) and tebuconazole (List 3B). We do not yet know whether active substances on Annex 1 will be re-registered in the

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UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could also be losses of approved products and on-label uses as manufacturers rationalise their product portfolios. Crop Protection Companies may not support all on-label approvals for Annex 1 listed active substances, especially for the specialist brassicas or for more minor targets. More SOLAs will therefore be needed. There are some SOLAs for fungicides for brassicas (Table 8). Residues data for some older SOLAs may not satisfy modern EC standards – a PSD study of data in archives, covering List 1 actives) suggests that new data may be required to set MRLs to support some minor crops/uses. List 2 and some list 3 actives will be studied later. The impact will be on cost to the grower through HDC levy to maintain these uses. 2. Specific fungicides or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Fungicides with alternative modes of action are important for resistance strategies. In horticultural brassicas, there is restricted fungicide selection on specific targets and it is very important for resistance management that as many active substances as possible are retained. By alternating different products not only is the risk of decreased sensitivity reduced, but this also reduces the risk of MRL exceedance of individual active substances by relying on a selection of different products. Were the industry to rely on single active substances for the control of specific pathogens, it could lead to increased fungicide use. It would be desirable to maintain the following: Toclofos-methyl now on Annex 1, an organophosphorus fungicide approved for damping off and wirestem in brassicas is now the commercial standard. Hand-held application must not be used (for operator safety). Tolclofos-methyl is only used occasionally, but is important in high risk situations Fosetyl-Aluminium is important for downy mildew control in propagation. Propamocarb hydrochloride is occasionally used in propagation for control of damping-off (Pythium spp.). Strobilurins, triazoles, chlorothalonil are all important important for a range of foliar diseases and needed for an resistance strategy: Triazoles are important for control of powdery mildew and leaf spotting pathogens. Strobilurins similarly for anti-resistance management but also for wider spectrum of activity against pathogens like Sclerotinia and possibly Phoma. Oomycete fungicides (metalaxyl-M) essential for effective control of damping-off (Pythium spp.), downy mildew, white blister and Phytophthora rots in the field and in store. In stored cabbage metalaxyl-M for Phytopthora and iprodione for Botrytis control are the only approved fungicides. Copper oxychloride is needed for reduction of bacterial diseases (calabrese spear rot and Xanthomonas)

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244

3. Prospects for alternatives for any foreseen major gaps in fungicide availability New fungicides with different modes of action are needed for resistance management. Fungicides with curative activity would be useful.. In the UK there are several new fungicide active substances for cereals (e.g. fluoxastrobin), oilseed rape (prothioconazole) and potatoes (e.g. fluopicolide). Actives for potato blight are a source of useful fungicides for downy mildew and other brassica diseases. New fluopicolide/propamocarb hydrochloride is unique in that it controls potato blight at all stages of the lifecycle. In France, procymidone (List 1) and thiophanate-methyl (on Annex 1) both old actives, are approved for use in brassicas for foliar diseases in addition to some approved in the UK, but they are not likely to be more useful and the future of procymidone is doubtful. The area of oilseed rape has increased dramatically in recent years and there could be further expansion - the risk of disease transfer, particularly light leaf-spot and dark leaf-spot and carry over is considerably increased as a result. However, fungicides developed for some oilseed rape diseases will be useful for horticultural brassicas, but residue studies will be needed. There are new potential solutions for the following: a. Clubroot (Plasmodiophora brassicae): clubroot continues to be a significant problem and a project funded by HDC/Defra, FV 259 demonstrated effective control with fluazinam and efficacy/residues trials are in progress fluazinam (Shirlan) is on List 3A of the Review. This could be useful for both propagators and growers where problem fields are known to occur. However a SOLA not allowed by the company until fluazinam is on Annex 1 listed. Other possible alternatives: cyazofamid (Ranman) new on Annex 1, cyazofamid potential for brassicas (US IR4 project); (Nebijin) flusulfamide company Mitsui Chemical potential for managing clubroot in brassicas (USA IR4 project). b. Propagation Fungicides at propagation (protected and outdoors) stage are needed as well as seed treatments. Better disease control at this stage would potentially reduce fungicide inputs later in the season closer to harvest, thereby minimising the risk of residues in the harvested produce. Fungicides (10-12) were selected for evaluation against each of 4 key target pathogens on cauliflower transplants in an HDC project FV 235, 2004. c. Damping-off (Pythium spp.): A pathogen of increased importance in module raised brassica seedlings. Fungicide resistance is of potential significance and requirement for range of mode of action products. The standard product, metalaxyl M, was highly effective in reducing infection with the introduced Pythium sp.. However, other isolates may be resistant. Propamocarb was totally ineffective in controlling or even suppressing the pathogen. Cyazofamid, mancozeb/zoxamide, dimethomorph/mancozeb, and fluazinam are worth further evaluation (HDC Project FV 235, 2004) and they could potentially be used as part of an integrated programme. d. Dark leaf-spot (Alternaria brassicae and Alternaria brassicicola) Ringspot (Mycosphaerella brassicicola): Dark leaf-spot is a common problem, ring spot is a very severe leaf disease of

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brassicas especially in intensive brassica production areas. Occurs in propagation (azoxystrobin SOLAs) and in the field. Currently well controlled with triazoles, particularly in tank-mixes with protectants azoxystrobin or chlorothalonil; boscalid/pyraclostrobin. New fluoxystrobin/tebuconazole to be registered for brassicas. e. Wirestem (Rhizoctonia solani): Potentially a problem during propagation though the move to modular systems for propagation significantly reduced the disease risk. Recent evidence suggests that most infections arise from soil-borne inoculum in the field post-planting. Current control is with tolclofos-methyl (propagation) the most effective fungicide in HDC Project FV 235; copper oxychloride SOLA (field). New alternative fungicides: flutolanil and pencycuron (registered for potato tubers). Efficacy and residue studies are in progress. Triflumizole (USA) also has potential. Effective bio-control products may be useful. f. Light leaf-spot (Pyrenopeziza brassicae) Is a very common leaf disease of brassicas and association with proximity of oilseed rape demonstrated. Resistance to tebuconazole in Scotland has been recorded. Fusilazole is approved for control of light leaf-spot in oilseed rape, and an application has been made for a SOLA for light leaf-spot in brassicas although this is another triazole. However, flusilazole is on List 1 of the 91/414 Review, a decision has not yet been made on Annex 1 inclusion but the Commission proposed that it is only included for a few crops (cereals, maize, sugar beet and oilseed rape). An alternative mode of action is needed. g. Grey mould (Botrytis cinerea) Carbendazim is no longer approved for stored cabbage, only iprodione remains for Botrytis control. An alternative to use in combination with or as an alternative to iprodione for resistance management is needed. New possible alternatives are: pyrimethanil, fenhexamid, mepanipyrim, cyprodinil/fludioxynil and tolylfluanid. h. White blister (Albugo candida): Reliance on metalaxyl based products, but protectants azoxystrobin, boscalid/pyraclostrobin are effective. New fluoxastrobin/ tebuconazole (approval later this year?) will be useful but only 2 strobilurin sprays permitted under FRAG guidelines i. Downy mildew (Peronospora parasitica): In the field growers are dependent on chlorothalonil, chlorothalonil/metalaxyl-M, copper oxychloride/metalaxyl. New fluoxastrobin/tebuconazole (approval later this year?). Fluopicolide (Infinito) - no approval for brassicas imminent. No new actives available for: Fungicidal seed treatments are needed – only thiram and iprodione are approved in the UK. Spear rot (Pseudomonas maculicola): An important bacterial pathogen of calabrese/broccoli. Bactericide copper oxychloride limited efficacy, no other approval. No other means of control. Black rot (Xanthamonas campestris) was not studied in FV 235. Current control measures at propagation stage with Copper oxychloride appear inadequate (HDC Gap Analysis). There is now a SOLA for azoxystrobin for outdoor seedlings, but only for cabbage and Brussels sprouts protected seedlings. Control of seed-borne bacterial pathogens is very difficult and ideally improved methods for elimination of seed infection are required – at propagation stage rapid spread can occur prior to field planting. Black rot also causes significant losses in late autumn. Current control is variable. New treatments are needed for the propagation stage and in the field.

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Powdery mildew (Erysiphe cruciferarum): Potential for resistance development, reliant on tebuconazole. Potassium hydrogen carbonate offers some control. It is supported in the Review - commodity List 4 but it needs to be re-registered in the UK before it can be marketed. Canker (Leptosphaeria maculans syn. Phoma lingam): causes blackleg in seedlings, leaf-spotting and stem canker symptoms in field crops together with a damaging storage rot in cabbage. Fungicide use in store limited to iprodione for Botrytis and resistance risk is high. Phytophthora rots (Phytophthora megasperma, P. porri): in stored Dutch white cabbage where considerable financial loss can occur if crops unprotected. Fungicide use in store restricted (metalaxyl-M only) and resistance risk is high because of treatments in the growing crop. The lack of any baseline monitoring of key horticultural pathogens means we are unable to predict any shifts in pathogen sensitivity cannot be predicted – and this could lead to unnecessary fungicide application in the future as growers increase frequency of sprays and dose rate in an attempt to achieve control. A regular structured monitoring programme, especially on key pathogens, would help to prevent this. There are a number of pathogens that currently do not present a problem to UK brassica crops but, with increased trade and the practice of raising seed crops in different parts of the world, the industry will continue to be exposed to new threats. As new pathogens appear it is necessary to validate existing approved fungicides for efficacy. Monitoring for resistance in pest populations and grass weeds has had priority. Global fungicide development overall does not appear to have decreased so far and for the vegetable sector has even increased (Phillips McDougall, ECPA conference, November 2005).

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Table 9. Gap Analysis (Brassicas): Fungicides

Common name disease Pathogen

(Latin name)

Application timing

Gap Status





Solution chemical elsewhere


Clubroot (Plasmodiophora brassicae)

Early. pre- or post-planting

* * * none Persistent soil-borne chytrid fungus. Very infectious and damaging

increased pH only partially effective

fluazinam List 3A Review SOLA not until Annex 1 listed cyazofamid (Ranman) new on Annex 1

Flusulfamide brassicas USA IR4 project # cyazofamid brassicas USA IR4 project

Yes efficacy/ residues In progress fluazinam

Canker (Leptosphaeria maculans syn. Phoma lingam)

Seed and/or seedlings

* * thiram? iprodione tebuconazole? difenoconazole? azoxystrobin? pyraclostrobin/ boscalid?

A seed- and soil-borne pathogen that causes blackleg in seedlings, leaf-spotting and stem canker symptoms in field crops together with a damaging storage rot in cabbage. Limited fungicide use in store (iprodione only) and resistance risk high

crop rotation - - No?

Black rot (Xanthamonas campestris)

propagation * * copper oxychloride SOLA

Effective control heavily reliant on provision of disease-free seed . Brussels sprouts, Cabbage, Broccoli, Cauliflower protected seedlins only

non-chemical seed treatment? crop rotation

azoxystrobin SOLA

Protected Brussels sprouts, Cabbage, Outdoor Brussels sprouts, Cabbage,

Black rot (Xanthamonas campestris)

Post-planting * * copper oxychloride SOLA azoxystrobin SOLA

Black rot causes significant losses in late autumn and Roscoff cauliflower; savoy, savoy/white cross cabbage. Control variable.

none

Powdery mildew (Erysiphe cruciferarum)

Field * * tebuconazole (potassium hydrogen carbonate)

disease significant, especially on Brussels sprouts where it can affect button quality either through direct lesions or through pepper spotting (a hypersensitive reaction). Triadimenol no longer marketed. Potential for resistance development. Potassium hydrogen carbonate offers some control but difficult application in Brussels sprouts

resistant cultivars

none ? No

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Downy mildew (Peronospora parasitica)

Propagation & field

* * chlorothalonil fosetyl-Al propamocarb-hcl chlorothalonil/metalaxyl-M

Predominantly a problem during propagation though can be severe in susceptible field crops in wet seasons. In the field dependent on chlorothalonil, chlorothalonil/metalaxyl-M, (metalaxyl non-inclusion lost after Dec 2006)

None crop rotation (limited value)

fluoxastrobin/tebuconazole approval later this year for brassicas fluopicolide no approval for brassicas imminent;

Light Leaf-spot (Pyrenopeziza brassicae)

Field * * tebuconazole difenoconazole

Resistance to tebuconazole in Scotland. A very common leaf disease of brassicas and association with proximity of Oilseed rape demonstrated. A significant problem in Brussels sprouts due to button blemish.

none

fluzilazole? but another triazole future doubtful boscalid alone?

? Residues data being generated for fluzilazole SOLA

White blister (Albugo candida)

Field * * chlorothalonil/ metalaxyl-M azoxystrobin boscalid /pyraclostrobin

An increasingly common oomycete disease of brassicas. Main problem on Brussels sprouts due to infection on buttons. Reliance on metalaxyl based products, but protectants azoxystrobin, boscalid/pyraclostrobin are effective (metalaxyl non-inclusion lost after Dec 2006)

none fluoxastrobin/ tebuconazole may be useful but only 2 strobilurin sprays permitted under FRAG guidelines

? ?

Spear rot (Pseudomonas maculicola)

Field * * * Copper oxychloride

An important bacterial pathogen of Calabrese/Broccoli. Bactericide limited efficacy, no other approval

none - ? No?

Phytophthora rots (P. megasperma, P. porri)

Store * * * metalaxyl-M

Of great significance in stored Dutch white cabbage where considerable financial loss can occur if crops unprotected. Fungicide use in store restricted to metalaxyl-M only and resistance risk high

good hygiene (in store) only partially effective

? No

Wirestem (Rhizoctonia solani)

Propagation & Field

* * tolclofos-methyl (propagation) copper oxychloride (field)

Potentially a problem during propagation though the move to modular systems for propagation significantly reduced the disease risk. Recent evidence in Defra funded studies to suggest that most infections arise in the field post-planting.

good hygiene propagation crop rotation of limited efficacy and largely untested

flutolanil Pencycuron

triflumizole (USA)

Yes (efficacy/residues)

# (Nebijin) flusulfamide, company Mitsui Chemical - potential for managing clubroot in brassicas

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REFERENCES Horticultural Development Council Project Reports can be accessed http://www.hdc.org.uk by

members of HDC: HDC Gap Analysis http://www.hdc.org.ukFV 222 (2002) Brassicas: Biology and control of Brassica Flea Beetles by integrating trap crops

with insecticide use. FV 223 (2002) Brassica crops: Evaluation of non-organophosphorus insecticides for controlling the

cabbage root fly. FV 225/HortLINK (Hort 219) CSA 5465 (2003) Integrated control of slugs in horticulture. FV 235 (2004) Vegetable Propagation: evaluation of novel fungicides for disease control in brassica

transplants. FV 238 (2004) Dissemination and exploitation of aphid monitoring data. The raw data on aphids

(including several that are pests of non horticultural crops) were also made available via the internet (www.rothamsted.bbsrc.ac.uk/insect-survey).

FV 242 (2003) Brassica crops: Evaluation of non-organophosphorus insecticides for controlling the cabbage root fly.

FV 242a (2004) Brassica crops: Evaluation of insecticides for controlling the cabbage root fly. FV 242b (2005) Brassica crops: Evaluation of non-organophosphorus insecticides for controlling

the cabbage root fly. FV 242c (2005-2006) Brassica crops: Evaluation of non-organophosphorus insecticides for

controlling the cabbage root fly. FV 250 (2003-2006) Aphid control in lettuce and brassicas. No report available yet. Articles in

HDC News March 2005, April 2006. FV 256 (2004) & FV 256a (2005-2006) Vegetables: Solutions to the loss of active ingredients for

weed control in vegetable crops FV 259 HDC Project (2004-2007) Brassicas: development and validation of detection tests for

clubroot. FV 281 (2006) The development of methods to control volunteer potatoes in a range of vegetable

crops. New project. FV 266/ HortLINK (2004 – 2006) Mechanical weeding for sustainable and organic salad and

brassica production. FV 281 (new 2006) The development of methods to control volunteer potatoes in a range of

vegetable crops. FV 287 (new 2006) CSL Survey of Approvals in other EU countries across all crops of interest to

HDC. New project. Other refrences: ASSURED PRODUCE - The NFU/Retailer partnership. http://www.assuredproduce.co.uk(5)BROWN A (1966) Herbicides in brassica crops. Experimental Horticulture 16, 102-111. DEPARTMENT FOR ENVIRONMENT, FOOD AND RURAL AFFAIRS (Defra) (2006) basic

horticultural statistics for the UK, calendar and crop years 1994/95 – 2004/05. Defra publications, London, UK.

GARTHWAITE D G, THOMAS M R, DAWSON A, STODDART H & ANDERSON H (2004) Outdoor Vegetable Crops In Great Britain 2003. Pesticide Usage Survey Report 195. Central Science Laboratory, Sand Hutton, York, UK http://www.csl.gov.uk

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GRUNDY A, KNOTT C, LUTMAN PJW et al. (2003) The Impact of Herbicides on Weed Abundance and Biodiversity in Horticulture. Defra project HH3403sx.

(3)LAWSON HM (1971) Weed competition in transplanted spring cabbage. Acta Horticulturae (Wageningen) 2 (23), 254-267

(4)LAWSON HM (1972) Weed competition in transplanted spring cabbage. Weed Research 12, 254-267.

LUTMAN PJW (2001) Current weed control and its impact. In: The impact of herbicides on weed abundance and biodiversity: A report for the UK Pesticide Safety Directorate PN0940 (eds EJP Marshall, V Brown, ND Boatman, PJW Lutman & G Squire). pp 134. IACR Long Ashton Research Station, UK

LUTMAN PJW & STEVE FREEMAN S (2002) Population dynamics of arable weeds:seed production and seed persistence IACR –Rothamsted, Harpenden p26-27

(2)MILLER AB & HOPEN HJ (1991) Critical weed-control period in seeded cabbage Brassica oleracea var Capita. Weed Technology 5, (4), 852-857.

(1)ROBERTS HA, BOND W & HEWSON RT (1976) Weed competition in drilled summer cabbage. Annals of Applied Biology 84 (1), 91-95

ROBERTS HA (1976) Weed competition in vegetable crops. Annals of Applied Biology 83 (2), 321-324

TURNER RJ, LENNARTSSON MEK, BOND W, GRUNDY AC & WHITEHOUSE D (1999) Organic weed control – getting it right in time. Proceedings 1999 Brighton Conference – Weeds, 969-974.



Cambridge, UK.

ACKNOWLEDGEMENTS

The help and contributions from staff from the following organisations are gratefully acknowledged: especially Dr Martin McPherson, Stockbridge Technology Centre; Andy Richardson, Allium and Brassica Centre; Brassica Growers Association (BGA); Horticulture Development Council (HDC), BBSRC Rothamsted Research, National Farmers Union (NFU), Christian Salvesen Processors, United Agricultural Products - Europe (UAP), European Crop Protection Association (ECPA) and Crop Protection Companies.

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Appendix. Weed Susceptibility to main herbicides for Brassicas. Key: S = susceptible; MS = Moderately Susceptible; R = Resistant; MR = Moderately Resistant; blue text not supported. trifluralin clomazone pedimethalin propachlor metazachlor metazachlor clopyralid cyanazine Common name Latin name pre-plant pre-weed em pre-plant pre-weed em pre-weed em post-weed em post weed-em post weed-em 2.3 L/ha 0.25 L/ha 3.3 L/ha 9.0 L/ha 1.5 L/ha 2.5 L/ha 0.5 L/ha 0.5 L/ha Bindweed black Fallopia convolvulus S MR R MS S Bugloss Anchusa arvensis S Charlock Sinapis arvensis R R R MR S Chickweed, common Stellaria media S S S S S 4 TL S Cleavers Galium aparine R S S MR R Corn marigold Chrysanthemum segetum R S S 2 TL S Corn spurrey Spergula arvensis MS S Crane's-bill, cut-leaved Geranium dissectum MR Cot MR Deadnettle, henbit Lamium amplexicaule S S MS S Dead-nettle, red Lamium purpureum MS S S S S 2 TL S Dock, broad-leaved Rumex obtusifolius Fat-hen Chenopodium album S MS S MR S Fool's parsley Aethusa cynapium R S S Forget-me-not, field Myosotis arvensis S S 2 TL S Fumitory, common Fumaria officinalis MS R MS R R S Gallant -soldier Galinsoga parviflora S Groundsel Senecio vulgaris R S R S S 2 TL S S Hemp-nettle, common Galeopsis tetrahit S S S S Knotgrass Polygonum aviculare S MR S R R S Mayweed, scented Matricaria recutita R R MS S S 4 TL S S Mayweed, scentless Tripleurospermum inodorum R R MS S S 4 TL S S Nettle, small Urtica urens MS MR S S S Nightshade black Solanum nigrum R MS S Orache, common Atriplex patula MS R S MR S Pansy, field Viola arvensis S S S R S Parsley piert Aphanes arvensis S S MR Pennycress, field Thlaspi arvense R R R Persicaria, pale Persicaria lapathifolia S MS MR S Pimpernel, scarlet Anagalis arvensis S S S Pineappleweed Matricaria discoidea R R MS S S S S Poppy, common Papaver rhoeas MS R S MS S Redshank Persicaria maculosa S S R MR S Shepherd's-purse Capsella bursa-pastoris R S MS S S S Sow-thistle, smooth Sonchus oleraceus R MS S MS S Speedwell, common, field Veronica persica S S S S S 2 TL 2 L S Speedwell, ivy-leaved Veronica hederifolia S S S S 2 TL S Sun spurge Euphorbia helioscopia MS R Thistle, creeping Cirsium arvense R R S Wild radish Raphanus raphanistrum R S R S Annual meadow grass Poa annua S MS S S S 2 L S Blackgrass Alopecurus myosuroides S S S S 2 L MS Brome, barren Anisantha sterilis MS Wild-oat Avena fatua MS R R Vol OSR Brassica napus R R MS R R R R Vol Potatoes Solanum tuberosum MS


CARROTS Most recommendations for carrot production are based on information from research funded by growers through the Horticultural Development Council (HDC) statutory Levy and/or LINK projects with Defra. The HDC R & D budget for outdoor vegetables £4.75m per annum.

Background

Crop area and use The area (provisional) of carrots grown in the UK in 2005 was 9,512 ha (Basic Horticultural Statistics for the UK, Defra, 2006). The value of the marketed crop in 2005 was approximately £166.9 million. The carrot area has declined since 1995 when 13,115 ha were grown. Carrots are grown mainly for fresh market, with outgrades or defective roots used for stockfeed, some are for quick-freezing or canning, or for ready prepared packs/meals. Carrots are grown in many areas but mainly in Eastern England, the East Midlands and Scotland. Most carrots are grown according to protocols http://www.assuredproduce.co.uk by Assured Produce. Retailers also have their own restricted lists of pesticides for crops and these differ between individual retailers. Rotations Carrots are frequently grown on rented land and are usually part of an arable rotation, which may include winter wheat, sugar beet, potatoes, and peas. Rotations with a four or five year break avoid build-up of difficult weed species and pests and diseases. Volunteer crops, particularly potatoes, are a serious problem in vegetable rotations and if they are not controlled, act as a reservoir of disease infection for potato crops. In carrots effective suppression of potato volunteers is achieved with a tank-mix of metoxuron + linuron, but metoxuron cannot be used after 2007. Weed beet is becoming widespread, but is controlled by carrot herbicides. Where horticultural crops are grown in a rotation that includes several cereal crops they also inherit cereal weeds. Weeds also appear to have increased as a result of reducing herbicide doses to minimise costs of growing cereals (Lutman, 2001). If weeds escape control with low herbicide doses in cereals, weed seeds can return to infest other crops in the rotation. Profitability Horticultural crops are high-value compared with winter wheat where average output was £535/ha for 2006 (Nix, 2005). High standards of pest, disease and weed control are therefore the aim. Yields of carrots are very variable – the average for maincrop carrots is 55 t/ha. The price predicted for 2006 (Nix, 2005) is £120 /tonne. Carrot maincrop value is £6,600/ha and the Gross Margin £1800/ha.

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Growing systems Carrots are grown on sandy soils so that roots can develop without restriction and be well shaped. Mechanical stone separation is often needed. A few crops are grown on organic soils. Soil blowing can occur on both soil types and where this is likely barley is sown between rows as a shelter crop and removed later with a graminicide. The production system depends on the market outlet, time of harvest and harvester used. All carrots are drilled with pneumatic precision drills. Crops are sown on wide rows 350 mm where top-lifting harvesters are used up till late October; baby carrots for processing are drilled at high populations often with twin or triple line coulters on a four-row bed system and are share-lifted from the end of August onwards. Early fresh market carrots are seeded at low density in late autumn or winter and the beds are covered in clear film plastic or non-woven fleece. Main season and late crops are drilled from February to May for harvest from August and into the following year when they may be protected in the field, by covering with deep straw or black polythene.

Weed control Carrots In most horticultural crops the policy is zero tolerance of weeds, and quality and harvesting efficiency are the major concerns (Knott, 2002). Carrots are much higher value than winter wheat and a high standard of weed control is needed. Carrots are grown on light soils and sands and weed species commonly encountered in spring sown crops on these soil types include: chickweed, fat-hen, fumitory, fool’s parsley, groundsel, knotgrass, mayweeds, wild mignonette, white campion, field pansy and speedwells. Species closely related to carrots (hemlock and wild carrot) are difficult to control. The incidence of fumitory is increasing probably because it is tolerant of most sulfonylureas used in cereals. Weeds are hosts to some carrot diseases: shepherd’s purse is a host to Sclerotinia (Sclerotinia sclerotiorum); perennial fleshy rooted species of weeds (thistle, bindweed) and sugar beet are hosts to a fungal disease of carrots violet root rot (Helicobasidium purpureum), and some to Pythium violae. Carrots are slow to emerge and at early growth stages they are poor competitors with weeds. Yield loss is dependent on weed species/crop combination and height differential. Tall weed species, which shade the carrot crop, e.g. fat-hen, have a greater effect than short low-growing species. Volunteer potatoes are particularly competitive. Some studies on weed competition in horticultural crops were done in the early 1970s but there is very little information on the effect of individual weed species and economic thresholds in comparison with the plethora of data for winter wheat. There is little information on critical periods (the time when weeds need to be absent from the crop to ensure optimum yields) for weed control in carrots possibly from 3 to 6 weeks after emergence (Defra Project HH3403SX by Grundy et al., 2003). Carrots are rather sensitive to some herbicides particularly at early growth stages, so low doses are used early during the critical period for competition.

Impact: Weeds can affect quality in terms of size grade and uniformity of crop - particularly important for baby carrots for quick-freezing or canning and for fresh market (a standard usually specified by the retailer). There is a risk of crop rejection if black nightshade is found in bunching carrots. Failure to meet specifications results in crop rejection or no sales. Yield loss is dependent on the numbers and species of weeds. Up to 100% yield loss can occur (Tei et al., 1999) – output (maincrop) for 2006 suggested is £6,600/ha (Nix, 2005).

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The impact of weeds on harvesting depends on the method. In hand-harvested carrots for bunching, nettles and thistles deter pickers. In all machine-harvested crops weeds reduce work rate, cause harvest losses and increase costs. In carrots woody, tough stemmed species e.g. fat-hen, and knotgrass slow down and clog up carrot lifters. Tall species such as fat-hen and mayweeds are a nuisance where top-lifting harvesters are employed. Control: Non-selective herbicides glyphosate and diquat/paraquat, are used to kill overwintered weeds pre-cultivation, on stale seedbeds, or pre-emergence of the crop. Glyphosate use is low in comparison with some crops. Stale seedbed techniques can be adopted for later drillings (depending on soil type and weather) to reduce weed problems. Repeat low dose programmes of herbicides are used in carrots. No single herbicide controls the whole weed spectrum encountered and several other herbicides have been developed to solve specific weed problems (Appendix). Repeat low dose programmes of pre- and post-emergence herbicides and tank-mixes are used and there are at least three herbicide applications per crop. Linuron has been used in carrots for annual meadow-grass and broad-leaved weeds for many years. Pre-emergence pendimethalin use is increasing but it needs a partner. Recently clomazone was approved and is useful for cleavers and fool’s parsley control (but it will damage barley cover). Isoxaben is occasionally used for control of mayweeds. Carrot growers rely on post-emergence herbicides for weeds escaping control pre-emergence: metoxuron for mayweeds or to suppress potatoes (on 8% of the carrot area in 2003), prometryn (for fumitory, small nettle, speedwell, Amaranthus spp.. and fat-hen). Pentanochlor and chlorpropham/ pentanochlor are essential for controlling difficult weeds such as cleavers and knotgrass. Pentanochlor can be used early, at crop cotyledon stage. Metribuzin also controls a wide weed spectrum: fool’s parsley, wild mignonette, groundsel, mayweeds, and fumitory but knotgrass, cleavers and black-nightshade are resistant. It has a SOLA but there is a risk of damage on light soils so it is used post-emergence at a low dose. Several post-emergence graminicides are approved for the control of annual and perennial grasses, and cereal volunteers; the most popular are propaquizafop and tepraloxydim, perhaps with the expectation of some annual meadow-grass control. Graminicides, are also used for destruction of barley cover in fields susceptible to wind erosion. Non-chemical control: Opportunities to suppress weeds by increasing seed rates, manipulation of row widths, time of sowing or planting and choice of variety may be available for cereals, but not usually for conventionally-grown horticultural crops. This is because the growing system adopted is to achieve the required size of produce, to suit precision drills for expensive seed and specialist harvesting equipment (or hand pickers). The time of harvest and continuity of supply is also vital and the varieties selected are dictated by the market, i.e. the retailer, processor and ultimately the consumer. Although mechanical weed control is possible in carrots grown in wide rows, weeds within the row are not controlled, and it is not an option for baby carrots grown at high densities on a close-row bed system. The cost of weeding once with a steerage hoe is c. £35/ha; or once with a brush weeder £63 /ha. Flame weeding, mechanical hoe, tine and brush weeders, hand weeding are all used in organic carrots (Turner et al., 2001). Inter-row weeding takes place as early as possible often followed by a bed weeder (a platform for people to lie prone and weed, attached to the back of the tractor). Hand weeding is usually required once or twice during the season and inter-row weeding as dictated by

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weed severity. An example http://www.agr.unipg.it/ewrsveg (Tei et al., 1999) of strategy for organic carrot production is:

• Stale seedbed; Sown on single rows 0.5 m width • Pre-emergence flaming (50 to 80 kg gas ha-1) • Carrots 2-3 true leaves brush weeding • 5 to 8 passes intra-row mechanical control (hoeing, rotary cultivation, finger weeding) • Hand weeding on ‘weed beds’ 100-500 hours ha-1

In most horticultural crops the costs of alternative weed control methods are much higher than for weed control with herbicides. Hand labour has now become expensive and on conventional farms hand labour is used for weeding only as a rescue operation, for example removing volunteer potatoes. Hand labour is also scarce – growers are dependent on workers from abroad. Herbicides for carrots Herbicides approved for 2006 and herbicide usage in 2003, are shown in Table 1. The weed species controlled are given in the Appendix. Table1. Herbicides approved for carrots 2006; Review status; Aim re-registration carrots UK; Activity; Usage of herbicides on 13,502 ha carrot, parsnip and celery area grown in Great Britain, 2003 (spray hectares) (Source: CSL Pesticide Usage Survey, 2003) Herbicides Approved for carrots 2006

Review status Aim re-registration carrots UK

Activity Usage carrots etc, 2003 spray ha

Growth regulators Maleic hydrazide SOLA Annex 1 √ potatoes pyridazinone 170 Total herbicide Glufosinate-ammonium List 2 ? (√ N) translocated phosphinic acid Glyphosate Annex 1 √ translocated phosphonic acid 3,206 Paraquat pre-drilling/pre-emergence Annex 1 √ contact, bipyridilium 63

Diquat/paraquat Annex 1 √ contact, bipyridilium 874

Grass weeds Cycloxydim# List 3A - translocated post-emergence oxime 25

Fluazifop-P-butyl# List 3A √ phenoxypropionic acid 260 Propaquizafop# List 3A √ phenoxyalkanoic acid foliar acting 5,685

Tepraloxydim# New Annex 1 - systemic post emergence 913Grass and broad-leaved weeds Chlorpropham Annex 1 x residual carbamate Chlorpropham/pentanochlor unsupported contact and residual 1,767 Clomazone List 3A √ residual (pre-emergence) 1,654

Isoxaben SOLA List 3B - soil acting amide herbicide (for use on temporarily protected crops)

Linuron Annex 1 √ contact and residual urea herbicide 24,477

Metoxuron unsupported contact and residual urea herbicide 14,389 Metribuzin SOLA List 2 x (√ N) contact and residual triazinone herbicide 1,899 Pendimethalin Annex 1 - residual dinitroaniline herbicide 8,597

Pentanochlor unsupported contact anilide herbicide 3,854 Prometryn unsupported contact and residual triazine herbicide 3,755 Trifluralin List 2 - soil incorporated dinitroaniline herbicide 726

Active substances in blue text cannot be used after 31 December 2007; trifluralin future doubtful ; # ACCase HRAC group A; - Company request confidentiality; √ yes; x no; (√ N) re-registration N Europe

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Maleic hydrazide growth regulator is banned or restricted by most retailers and it is rarely used now. In 2003, maleic hydrazide (SOLA) was applied in autumn to a small area, less than one percent of carrots. According to the CSL Survey, in 2003 linuron was applied in almost all carrots: both pre-emergence in tank-mix with pendimethalin and post-emergence with other herbicides - most crops receiving two applications on average. Metoxuron was needed to suppress potatoes infesting 8% of the carrot area in 2003. Overall metoxuron was applied to 71% of the area, average number of applications at 0.3 of the label dose. Metribuzin was only used on a small area in 2003, but usage is likely to increase as growers gain more experience on safe dose rates and timings. For 2006 there are no new herbicide approvals for carrots. The SOLA for ioxynil, a contact-acting herbicide safe to barley cover and used to control broad-leaved weeds (e.g. fool’s parsley) that emerge before carrots, has gone. Metoxuron, pentanochlor alone and in formulation and prometryn (all in blue text) will be lost after 2007. The future of trifluralin and Annex 1 listing is doubtful but it is not widely used in carrots. Linuron is on the Annex 1 positive list but when it is re-registered in the UK the maximum dose-rate per annum will be limited to 950 g a.i. /ha. This will mean that growers will have to revise their weed control strategy. The use of linuron is ‘restricted’ by some retailers. There is some limited evidence that resistant grass weeds from cereals are being carried over into vegetable crops but resistant black-grass is unlikely to occur in spring-sown carrots on light soils. To manage resistance, PSD will apply restrictions to the use of existing herbicides where there is a high resistance risk, including ACCase inhibitors ‘fop’ and ‘dim’ graminicides. In 2003, 49% of the carrot area grown was sprayed once with a fop or dim; 7.2% was treated twice (probably some to destroy barley cover, followed by an application of tepraloxydim to control annual meadow-grass). Some growers in the latter category on organic soils may be affected by the restrictions where annual meadow-grass is a problem but post-emergence metribuzin is effective (see Appendix). While the label restriction would preclude the use of two applications of a product containing the same ACCase inhibiting active substance it would not preclude a sequence of two different ACCase inhibitors. Thus a sequence of a ‘fop’ followed by a ‘dim’ or a sequence of two different ‘fops’ would be possible. Alternatively growers could use a product containing an alternative mode of action such as pendimethalin, which controls black-grass at 2000 g a.i. /ha. 1. The likely impacts of the 91/414/EEC review process on herbicide availability for UK carrots

1.1. Losses Herbicide losses/restricted doses for carrots resulting from the 91/414/EEC Review are: Metoxuron, prometryn and pentanochlor were not supported in the EC Review. The derogations for the ‘Essential Use’ of expire December 2007 and control of some weed species will then be difficult. Metoxuron, an old broad-spectrum herbicide used on 14,389 ha of parsnips and carrots in 2003, is the second most widely used herbicide after linuron. It has a derogation for ‘Essential Use’ in carrots (and parsnips) until 31 December 2007. Metoxuron applied post-emergence provides good suppression of volunteer potatoes. It controls a wide range of weeds including mayweeds and is the

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basis of most post-emergence programmes and it is often used in tank-mix with linuron. Active substances (pentanochlor and prometryn) currently used in programmes with metoxuron are themselves subject to essential use derogation. Prometryn has both contact and residual action and is the only herbicide effective on fumitory and small nettle. Prometryn also controls speedwells, sow-thistle and Amaranthus spp.. In dry seasons prometryn controls waxy-leaved weeds such as fat-hen, when other herbicides are less effective. Pentanochlor (used with metoxuron) in carrots provides the only post-emergence option for control of knotgrass and also is the only herbicide approved at the crop cotyledon stage. Pentanochlor is particularly effective against cleavers and redshank in addition to various polygonum species Linuron applied usually pre- and post-emergence is the most widely used herbicide in carrots, parsnips and celery (24,477 ha in the 2003 CSL Pesticide Usage Survey). Linuron is on Annex 1 but when it is re-registered in the UK the maximum dose-rate per year will be limited to 950 g a.i. /ha. Currently the approved dose rates are 1100 g a.i. /ha pre-emergence and 1100 g a.i. /ha post-emergence – a total of 2200 g a.i. /ha per crop. This means that growers will have to revise their weed control strategy (HDC project FV 236b). Linuron is used pre-emergence in tank-mix with pendimethalin and post-emergence of the crop either alone or in tank-mix with other actives, mainly metoxuron. If aclonifen became available a tank-mix of pendimethalin + aclonifen could be used pre-emergence, saving linuron for post-emergence use. Linuron will be submitted for UK re-registration in November 2006. Aclonifen is unlikely to be available until after 2008. No single herbicide controls the whole weed spectrum encountered in carrots and programmes with low doses of different herbicides are used. Although mechanical weed control is possible in carrots grown in wide rows, weeds within the row are not controlled and it is not an option for baby carrots grown at high populations on a close-row bed system. 1.2. Impacts

• Weeds affect quality in terms of size grade and uniformity of crop particularly important for baby carrots (for quick-freezing or canning) and for fresh market (a standard usually specified by the retailer). Failure to meet specifications results in crop rejection or no sales. There is also a risk of crop rejection if weeds, especially nightshade, is found in bunching carrots.

• The impact of weeds on harvesting depends on the method. In hand-harvested carrots for

bunching, nettles and thistles deter pickers. In all machine-harvested crops weeds reduce work rate, cause harvest losses and increase costs. Tall species such as fat-hen and mayweeds are a nuisance where top-lifting harvesters are employed. In carrots tough stemmed species e.g. fat-hen, and knotgrass slow down and clog up carrot lifters.

• Yield loss is dependent on the numbers and species of weeds. Up to 100% yield loss can

occur – output (maincrop carrots) for 2006 suggested £6,600/ha (Nix, 2005).

• There may be one or two possible alternative herbicides (see below) for some weed species, but no replacement of metoxuron for volunteer potato suppression has been found (HDC project FV 236b). There are moves to avoid potatoes in the rotation but this is seldom possible because carrot land is often rented – both crops are grown on very light soils. If no herbicidal control was available (needed for 8% of the crop in the 2003 survey), and if the crop was not harvestable, then losses could amount to more than £10 million per annum. Alternatively, far more costly methods for control of volunteer potatoes, will be used for low

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populations of volunteers: hand-pulling or dabbing glyphosate on each potato plant with hand-held applicators. Selective application of glyphosate with a ‘weed wiper’ when there is a suitable height differential between crop and volunteers will be used for severe infestations.

• There will also be an impact on the potato crop. Volunteer potatoes uncontrolled in carrots

can be a reservoir of potato blight infection - this is causing concern to potato growers (M Storey, BPC, pers. comm.). A joint project HDC/BPC is being funded to assess selective application of glyphosate using a vision guidance system (HDC project FV 281).

• A significant proportion of growers levy through HDC has been spent on trials to identify

alternatives. Since 2002, the overall cost of these projects for horticultural crops so far is £4.714 million and of this £2.7 million is for vegetables (C Harvey, Chairman, HDC, pers.comm.). Where/if alternative herbicides are identified, and no residues data are available further HDC funds will be needed for residues studies and SOLAs.

1.3. Future losses? Some key herbicides have already been lost. We do not yet know whether other important herbicides metribuzin (List 2) or clomazone (List 3A) will achieve Annex 1 inclusion or whether active substances on Annex 1 will be re-registered in the UK or N Europe. The future of trifluralin and Annex 1 listing is doubtful but it is not widely used in carrots. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. At product re-registration stage there will be dose-rate restrictions for metribuzin (because of water issues) and the maximum permitted will be 525 g a.i./ha pre-emergence, 350 g a.i./ha post-emergence. This may have an impact on potato crops, but not on carrots where there is a SOLA. In carrots doses of even 175 g a.i./ha pre-emergence can cause damage (HDC Project FV 236b, 2005) and no more than 350 g a.i./ha are used post-emergence. There are some SOLAs for herbicides for carrots (Table 1). Residues data for some older SOLAs may not satisfy modern EC standards – a PSD study of data in archives, covering List 1 actives) suggests that new data may be required to set MRLs to support some minor crops/uses. List 2 and some list 3 actives will be studied later. The impact will be on cost to the grower through HDC levy to maintain these uses. HDC estimate that since it began, the Specific Off-Label Approval programme has cost growers £3.5 million for approximately 960 SOLAs. 2. Specific herbicide and herbicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Carrot growers have lost three key herbicides and in future the dose rate of linuron will be restricted. A range of herbicides is required for carrots to cover the weed spectrum. Therefore all remaining ones must be maintained and fast access to alternatives used in other Northern EU member states (e.g. aclonifen registered for carrots in Denmark) is needed. It would be desirable to maintain remaining options: Glyphosate non-selective herbicide used pre-cropping.

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Linuron (Annex 1) forms the basis for pre- and post-emergence weed control in carrots, but when dose-rates per annum are reduced to 950 g a.i./ha it is likely to be used post-emergence. Pendimethalin (Annex 1) will then be essential pre-emergence to be used in tank-mix with clomazone (List 3A). Isoxaben (List 3B) is used where mayweeds are a severe problem. Tepraloxydim (New Annex 1), propaquizafop, cycloxydim, fluazifop-p-butyl (all List 3A) ‘fop’ and ‘dim’ graminicides important, for both grass weed and barley cover crop control to be used according to the PSD proposed label restrictions for grass weed resistance management. A sequence of a ‘fop’ followed by a ‘dim’ or a sequence of two different ‘fops’ would be possible. Metribuzin (List 2) is important for post-emergence weed control. 3. Prospects for alternatives for any foreseen major gaps in herbicide availability

3.1. Alternatives Alternative herbicides have been found for carrots (aclonifen, possibly diflufenican) but they may not be available before the ‘Essential Uses’ expire - in the case of aclonifen because of the slow process of the 91/414 review. They may fill some gaps but an alternative for potato suppression (currently with metoxuron) has not been found. A ‘Gap Analysis’ (Table 2) shows the critical herbicide gap * * *, where there are, or soon will be no control measures at all. In 2004 a system funded by growers through HDC levy (HDC project FV 256) was begun (see brassica chapter), carrots were included. Further work in carrots (HDC project FV 236b) was begun in 2005 to evaluate potential alternative herbicides (aclonifen, diflufenican, etc.) for efficacy and crop safety, and are in their second year in 2006. In these trials no treatment gave potato suppression and an alternative to metoxuron has not been found. A few post-emergence treatments (alternatives to prometryn) for control of fumitory were effective in 2006.

a. Aclonifen* pre-emergence in tank-mix with pendimethalin looked promising.. So the Off-LIn France, aclonifen has been evaluated and residues data submitted but holdups in the French regulatory process have delayed registration of aclonifen for carrots. Aclonifen + linuron tank-mixes were evaluated post-emergence in 2006 trials and this timing is authorised in Denmark for carrots. Aclonifen from Bayer CropScience), a diphenyl ether, is not a new active - it is on List 3B of the EC Review and therefore may not achieve Annex 1 listing until 2008. It is not registered for any UK crop but the aim is to register on-label for sunflower. The manufacturer has a commitment to UK registration for some vegetable crops through Mutual Recognition. The timing depends on the evaluation of the DAR dossier for Annex 1 by the Rapporteur (Germany), but here there is also a delay. Residues data for carrots are available from N Europe.

b. Post-emergence treatments will also be needed and the most effective were a tank-mix of diflufenican + linuron, pendimethalin + linuron and metribuzin (SOLA). There are no residues data available for diflufenican in carrots and metabolism studies would be needed.

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c. Prosulfocarb was less suitable for carrots because it has a limited weed spectrum and leaves mayweeds and groundsel. It is not safe to the crop pre-emergence, and caused some crop effects post-emergence. Efficacy of prosulfocarb on fumitory was poor.

* Aclonifen has no extant on-label approval for the use of the same product on another edible crop in the UK at present so the Off-Label route for crops of less than 50,000 ha (described for Brassicas) is not available. Other EU member states were consulted by the Technical Group on Minor Uses (North) http://www.pesticides.gov.uk/fg_minor_uses.asp?id=283 in a project to identify possible weed control options for carrots. Other Member States were also losing actives and had requested ‘Essential Uses’: metoxuron in Belgium, France, Ireland, Luxembourg and the Netherlands; prometryn in Greece, Ireland and France. Only the UK had ‘Essential Use’ for pentanochlor. Additional Essential Use derogations were for the use of prometryn in carrot and parsnip in the following accession member states: Latvia, Czech Republic, Lithuania, Estonia and Cyprus. Aclonifen, registered for use in carrots in Denmark was selected for an evaluation project. In the US the IR-4 project (see Executive Summary) registered s-metolachlor, a maize herbicide, for a number of crops including carrots. It is not new chemistry but had not been evaluated in the UK for vegetables and it was included in the HDC vegetable herbicide screen FV 256 in 2006. In the future, a limited range, and loss of broad-spectrum herbicides may result in change in weed spectra. Development of herbicide resistance is a possibility in carrots where weeds set seeds in late-harvested crops. There are approvals for use of pendimethalin in many crops (56) including winter wheat and a few resistant broad-leaved weed species have been identified at a few sites in the UK. A long-term Defra project screened six actives, including pendimethalin, widely used in horticulture for evidence of creeping resistance in fat-hen (Defra project HH3401SFV, 2006) the data suggest that creeping resistance is unlikely, given normal herbicide programmes, but not impossible. 3.2. Impact of the proposed regulation and revision of 91/414EEC See general comments in Executive Summary.

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Table 2. Gap Analysis (Carrots): Herbicides

Weeds/weed species

Application timing







pre-em / residual

* * * Pendimethalin (Annex 1) + linuron (Annex 1)

Linuron dose rate restricted to 950 g a.i./ha/pa when re-registered may restrict to post-emergence. Pendimethalin poor control groundsel, mayweeds

aclonifen + pendimethalin aclonifen Denmark

Yes Residues data available carrots France, Denmark


post-em

Volunteer potato foliage suppression

post-em * * * metoxuron + linuron

No control volunteer potato after 31 Dec 2007 when metoxuron is lost. Potential reservoir of potato blight. No alternative found

Hand-pulling

Glyphosate hand held applicators spot treatment but losses from neighbouring crop plants

none Glyphosate application visual guidance system trials began 2006.

Fumitory post-em * * metribuzin Little information on other potential alternatives when prometryn goes 31 Dec 2007

More trials needed

Knotgrass post-em * * * pentanochlor Poor control post-emergence, reliant on pendimethalin only if trifluralin goes.

Diflufenican + linuron?

R & D but no residues data


* * gap no immediate problem but future situation vulnerable






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Pest control in Carrots

Nematodes cyst (Heterodera), root-knot (Meloidogyne), stubby-root (Paratrichodorus and Trichodorus), root-lesion (Pratylenchus) and needle (Longidorus) Stubby-root and needle nematodes are the species most likely to damage carrots in the UK. Carrot cyst nematodes and root-knot nematodes are more localised problems. Root-lesion nematodes are recognised pathogens of carrot in Europe but their importance in the UK remains unclear. Free-living soil nematodes are widely distributed in sandy soils and can cause severe economic damage to carrot crops through direct injury to the seedling taproot, causing fanging and/or root knots or lesions. Fanging may result from a variety of factors, diseases such as Pythium or Rhizoctonia or physical factors such as soil compaction can also be responsible, thus nematicides might be an unnecessary expense. Impact: quality and yield reduction. Control: is with a nematicide (see below) applied at drilling. In a recent survey (HDC FV 278) the status of nematode control on farms was investigated. Non-chemical control: Fields infested with nematodes are usually well known and can be avoided. Pre-drilling cultivations (in 2004) resulted in a dramatic overall reduction in nematode numbers (HDC FV 249, 2005) Root-lesion nematode numbers overall were reduced by fallow year cultivations, but stubby-root nematodes were not affected. Carrot Fly (Psila rosae) Carrot Fly is a serious pest of carrots and is widely distributed throughout the carrot-growing area. Damage occurs particularly in late-lifted crops. Impact: quality is reduced where larvae tunnel into the carrot root and crops are rejected. Control: Carrot fly forecasting and monitoring: The HDC-funded carrot fly activity forecast is available by subscription to all levy payers and can give useful guidance on regional root fly activity. Field traps are an effective way of monitoring local activity and are more appropriate to individual circumstances. Both systems combined with local knowledge can be applied usefully to assist in the correct use of carrot fly control measures The most effective currently approved insecticides for carrot fly control were tefluthrin seed treatment and foliar sprays with lambda-cyhalothrin SOLA (with 6 applications of 150 ml/ha permitted) and these formed the basis of carrot fly control after the ban on chlorfenvinphos. Decis (deltamethrin) has a SOLA for 3 applications, maximum total dose 100 ml/ha but deltamethrin (and nicotine) are less effective (Finch et al., 1998) than lambda-cyhalothrin. However, a new SOLA restricted lambda-cyhalothrin to 4 applications at maximum individual doses 100 ml/ha. Another SOLA was issued in August, 2006, for 4 applications total dose 450 ml/ha but the maximum individual dose was 150 ml/ha and this may have improved the situation. It is important to achieve good control of first generation carrot fly because this lessens the second-generation attack and minimises summer damage. To achieve this, crops can be harvested before the larvae penetrate the roots. Alternatively, tefluthrin seed treatment can be used for crops drilled from mid-March and harvested before mid-August. Earlier use of tefluthrin seed treatment is not justified because the insecticide persistence would be inadequate to cover the first generation risk period. Where crops are drilled before mid-March, a timely pyrethroid insecticide treatment may be necessary if harvest is proposed beyond mid-August. On second early crops a spray treatment for first generation control timed to coincide with adult carrot fly activity may be required, Chemical control of second generation: forecast and trapping should identify the correct timing for the first treatment of the second generation. A full programme of treatments is only required for

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crops grown in high-pressure carrot fly areas. In all other circumstances a reduced programme of treatments should be used. In some seasons, the second generation may extend beyond early October, or even a third generation may appear. Non-chemical control: there should be a minimum of 5-year rotation. Attack will be reduced: where sites near over-wintered crops or last years crop are avoided, and if early and late crops (including other umbellifers) are separated. Headlands can remain uncropped as these attract the most pests. Crop covers can be used to exclude the pest but this is costly. Willow Carrot Aphids (Cavariella aegopodii) The willow carrot aphid is a major pest of umbelliferous crops. Impact: Yield loss can be particularly serious in early sown (April/May) carrots. It can transmit serious virus diseases, including Parsnip Yellow Fleck Virus (see disease section). Aphid monitoring: Aphid monitoring by CSL for willow carrot aphid is being used (HDC project FV 228b). Exploitation of the aphid monitoring data from suction traps around the UK,has been developed by Rothamsted (HDC Project FV 238, 2004). The information was used to promote the system for the 2006 season. Water traps are set up in growers’ crops and regional predictions of the first flight of the willow-carrot aphid based on environmental data from the major carrot growing regions are used. Control: these early-flyers migrate from winter hosts to the new season's crops from early May to mid June. Other aphid species commonly infest carrots and, if they are forming active and damaging colonies, treatments will need to be applied. The application at drilling of aldicarb approved for nematode control provided early protection against aphid attacks but the derogation for ‘Essential Use’ expires 31 December 2007. Where aldicarb is no longer used, the risk of aphid colonisation increases significantly, and extra vigilance is required so foliar aphicides can be applied as soon as aphid colonies are noted. Pirimicarb is more effective than pyrethroids, which only provide partial control. Cutworm Cutworms are the larval stage of the adult turnip moth. Attacks are common every year but larval survival and economic damage is mostly confined to light soils and dry seasons. Impact: the most serious effect is on the loss of quality caused when cutworm larvae burrow into maturing carrots. Cutworm larvae may sometimes reduce plant stand and yield on late-drilled crops in dry conditions. Control: chlorpyrifos use expires September 2006, but cypermethrin, deltamethrin, lambda-cyhalothrin, lambda-cyhalothrin/pirimicarb achieve control if application is timed correctly. Monitoring systems for turnip moth activity are well developed and spray warnings based on models related to larval development show the correct spray date when sensitive crops should be treated. A new real time risk assessment service (HDC Project FV 274, 2005) has been developed. Non-chemical: irrigated crops rarely require treatment. Silver Y Moth (Autographa gamma) Severe infestations of the Silver Y Moth caterpillars are a problem in some seasons, although they can be controlled with pyrethroid sprays. Insecticides for carrots Insecticides approved for 2006 and usage in 2003, are shown in Table 3. There is more insecticide use for carrots than other vegetable crops: 90% of the crop was treated with 4 applications comprising 4 active substances in 2003. Molluscicides are seldom used in carrots. Organophosphates have been one of the most important insecticide groups used over the last decade and were the main group used between 1991 and 1995. However, their use began to decline as a

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result of restrictions on use of organophosphates imposed by retailers. In 2002, chlorfenvinphos used for carrot fly control, was revoked in the UK as a result of the anticholinesterase review. The use of aldicarb, on 51% of the area grown, was stated as for control of nematodes (Longidorus and Trichodorus spp.) in carrots and parsnips, but it also controls early aphid infestations (CSL Pesticide Usage Survey, 2003) In 2005 33,856 ha of carrots alone were treated with lambda-cyhalothrin - an average of four applications, being used on 63% of the total area grown (M Thomas, CSL, pers. comm.). Pirimicarb was used on almost half of the area grown with two applications being used on average. Carrot fly accounted for 52% of the insecticide treated area in 2003. All uses of insecticides for both carrot fly and willow carrot aphids accounted for 77% of the total insecticide treated area. Carrot fly was the principal reason for control, accounting for 52% of the insecticide treated area. Table 3. Insecticides, nematicides and molluscicides approved for carrots 2006; Review status; Aim re-registration carrots UK; Pest; Activity; Usage on 13,502 ha carrot, parsnip and celery area grown in Great Britain, 2003 (spray hectares) (Source CSL Pesticide Usage Survey, 2003) Insecticides, nematicides, molluscicides approved for carrots, January 2006

Approval status

Aim re-registration carrots UK

Pest Activity Usage carrots etc, 2003 spray

haInsecticides Carbosulfan granule incorporated (New)

List 2 √ carrot fly nematodes

systemic carbamate insecticide for control of soil pests

Chlorpyrifos Annex 1 - cutworms contact and ingested organophosphorus insecticide and acaricide

8

Cypermethrin (SOLA) Annex 1 x cutworms contact, stomach acting pyrethroid insecticide 3,529 Deltamethrin (SOLA) Annex 1 x(√other

crops) insect pests contact and residual acting pyrethroid insecticide 4,203

Lambda-cyhalothrin # Annex 1 √ carrot fly SOLA, cutworm, insect pests

quick acting contact and ingested pyrethroid insecticide

43,976

Lambda-cyhalothrin/pirimicarb Annex 1 √ / √ Cutworms, aphid quick acting, contact and ingested pyrethroid insecticide

118

Nicotine unsupported? List 4C ?√ aphids, caterpillars & insect pests

general purpose, non-persistent, contact alkaloid insecticide

123

Pirimicarb Annex 1 √ aphids carbamate insecticide 12,185

Nematicide Aldicarb Non

inclusion nematodes,

aphids soil applied, systemic, carbamate insecticide & nematicide

6,700

Oxamyl (SOLA New) Annex 1 √ potatoes etc. nematodes and insect pests

Soil applied, systemic oxime carbamate nematicide and insecticide

Molluscicides & repellents Metaldehyde List 3A x slugs & snails molluscicide bait 1

Methiocarb List 2 x slugs & snails carbamate 9

Aldicarb final use date 31 December 2007; mpany request confidentiality; √ yes; x no; (√ N) re-registration N Europe; # SOLA August 2006 lambda-cyhalothrin use on carrot fly reduced to 4 applications, maximum single dose 150ml/ha, total dose 450ml/ha. In 2005 aldicarb failed to achieve Annex 1 listing in the EC Pesticide Review, and was revoked but there is a derogation for ‘Essential Use’ in carrots and parsnips and growers can use it until 31 December 2007. In 2005 a less persistent nematicide oxamyl, a soil applied, systemic oxime carbamate, achieved Annex 1 listing, there is now a SOLA for use in carrots. There is careful stewardship of both actives by the companies concerned. Carbosulfan also controls free-living nematodes. Chlorpyrifos, has been revoked for use in carrots and it can only be used until 30 September 2006.

Chlorpyrifos use expires 30 September 2006; - Co

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Seed treatments Tefluthrin was the most widely used insecticide, applied to 35% of the area sown. Fungicide formulations were the principal seed treatments used on carrots, with cymoxanil/fludioxonil/ metalaxyl-M accounting for 65% of the total area sown. Table 4. Seed treatments approved for carrots 2006; Review status; Aim re-registration carrots UK; Pest; Activity; Usage on 13,502 ha carrot, parsnip and celery area grown in Great Britain, 2003 (spray hectares) (Source: CSL Pesticide Usage Survey, 2003) Seed treatments and molluscicides approved for carrots, 2006

Review status

Aim re-registration carrots UK

Activity Usage carrots etc, 2003 spray ha

Fungicide seed treatments Cymoxanil/fludioxonil/metalaxyl-M (SOLA) Annex 1 √ / √ / √ acylanilines/cyanopyrrole/ phenylamide 7,961 Metalaxyl/thiabendazole until 28 December 2006

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phenylamide/benzimidazole 1,107 Thiram Annex 1 √ dithiocarbamate 725 Insecticide seed treatments Tefluthrin (SOLA) List 3B (√ other

crops) soil-acting pyrethroid 4,324

Metalaxyl, metalaxyl M alone, iprodione, thiabendazole / thiram no longer approved; - Company request confidentiality; √ yes; x no 1. The likely impacts of the 91/414/EEC review process on insecticide and nematicide availability for UK carrots

1.1. Losses (i) Aldicarb is a systemic carbamate, soil applied at drilling. In 2005 it failed to achieve Annex 1 listing in the 91/414EEC Review, and was revoked. There is a derogation for ‘Essential Use’ in carrots until 31 December 2007. The EU MRL is set at 0.1 mg/kg. Free-living soil nematodes are widely distributed in sandy soils and can cause severe economic damage to carrot crops through direct injury to the seedling taproot, causing fanging and/or root knots or lesions. The use of aldicarb, on 51% of the area grown, was stated as for control of nematodes (Longidorus and Trichodorus spp.) in carrots and parsnips, but it also controls early aphid infestations. In 2005 the nematicide oxamyl, a soil applied, systemic oxime carbamate, achieved Annex 1 listing, and there is now a SOLA for use in carrots. Oxamyl is not as persistent and is perceived as less effective on nematodes in carrots than aldicarb and incidental control of aphid is reduced. There is careful stewardship of both actives by the companies concerned. Aldicarb is banned by most retailers, and the use of oxamyl is also restricted. (ii) As a result of the UK review of anticholinesterase compounds (organophosphates and carbamates) chlorfenvinphos was revoked in 2002. It was used for control of Carrot fly (Psila rosae). Chlorfenvinphos was still approved in other EU member states. Later, chlorfenvinphos was not supported in the 91/414/EEC review. There were ‘Essential Uses’ derogations until 31 December 2007 for a wide range of crops in other EU Member States (Denmark, Germany, Ireland, France, The Netherlands and Spain). No ‘Essential Uses’ could be requested in the UK and thus less time to find effective control measures.

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In the UK, up until now, carrot fly control appears to have been adequate with tefluthrin seed treatment followed by several applications of lambda-cyhalothrin and there were few if any crops rejected in 2005. The lambda-cyhalothrin SOLA for carrot fly control permitted 6 applications at 150ml/ha dose rate. Some growers are finding that the 3rd generation, although less serious, is becoming a problem in warmer autumns and that 10 weeks cover is needed. Deltamethrin also has an Approval for carrot fly control but it is much less effective than lambda-cyhalothrin (Finch et al., 1998). Nicotine is also less effective than lambda-cyhalothrin. Following re-registration in November 2005 after Annex 1 inclusion of lambda-cyhalothrin, the label dose was for 100 ml/ha (harmonisation across EU). However, in February 2006 a new SOLA was issued for lambda-cyhalothrin with restrictions to 4 applications at individual doses 100 ml/ha. Some data suggest that control will be reduced to 82% at this dose rate. A new SOLA (August, 2006) now allows 4 applications, 150ml maximum dose, total 450ml. It remains to be seen whether carrot fly can be controlled adequately in future. (iii) Chlorpyrifos The use of organophosphates had already declined as a result of restrictions imposed by retailers. Growers had also indicated that chlorpyrifos was not needed. Following the environmental review of chlorpyrifos, use in carrots for cutworm has been revoked in September 2005, with a use-up period until 30 September 2006. Pyrethroids control cutworm but the timing, based on monitoring and spray warnings, is critical. All approved pyrethroids are effective and efficacy comparisons have not been made. Irrigated crops rarely require treatment but in drought years irrigation may be restricted. 1.2. Impact Loss of aldicarb

• Nematodes affect quality and reduce yields. Fanging* affects approximately 7.5% of the UK carrot crop, which is estimated currently to be in the region of 900,000 tonnes. If a farm gate value of £70 per tonne is assumed, then the cost to the industry of fanging is estimated at £4.7 million.

• Fields infested with nematodes are usually well known and can be avoided. Pre-drilling

cultivations (in 2004) resulted in a dramatic overall reduction in nematode numbers (HDC FV 249, 2005) Root-lesion nematode numbers overall were reduced by fallow year cultivations, but stubby-root nematodes were not affected.

• Oxamyl is not as persistent and incidental control of aphid is reduced. When aldicarb is no

longer used, the risk of aphid colonisation will increases significantly, and extra vigilance is required so foliar aphicides can be applied as soon as aphid colonies are noted.

*Fanging may also result from a variety of factors, diseases such as Pythium or Rhizoctonia, or physical factors such as soil compaction, so a nematicide might be an unnecessary expense. Aldicarb costs £66 - £132/ha depending on dose rate. Much of this use is prophylactic rather than based on accurate risk assessments, and this approach is contrary to the requirements of Assured Produce schemes. A review and investigation of factors influencing crop damage by plant-parasitic nematodes in carrots and parsnips (HDC Project FV 232, 2002) suggested that the use of aldicarb is not always efficient or even beneficial and that excessive use may result in enhanced microbial degradation of aldicarb in some fields and reduced nematicide efficacy. Experiments on the efficacy of aldicarb also suggested that it was very variable with between 11 and 73% of nematodes

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controlled. The project also sought to identify the damaging species, and establish thresholds for their control. Loss of chlorfenvinphos

• Carrot quality is reduced where larvae tunnel into the carrot root and crops are rejected (maincrop value is £6,600/ha). Carrot Fly is a serious pest of carrots and is widely distributed throughout the carrot-growing area. Damage occurs particularly in late-lifted crops.

A significant proportion of growers levy through HDC has been spent on trials to identify alternative insecticides as well as herbicides. 1.3. Future losses? The most important insecticides achieved Annex 1 inclusion (Table 3) but we do not yet know whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage (as for lambda-cyhalothrin) and this may have an impact on efficacy. Losses of some on-label uses are likely, particularly for carrots and other minor crops and more SOLAs will be needed – funded by HDC. There are some SOLAs for insecticides and a nematicide for carrots (Table 3). Residues data for some older SOLAs may not satisfy modern EC standards – a PSD study of data in archives, covering List 1 actives) suggests that new data may be required to set MRLs to support some minor crops/uses but those for carrots (Table 3) appear acceptable. Nicotine (List 4C) has so far been supported in the review, although it may be that the package is insufficient. The view of the industry was sought in late May 2006 on the importance of nicotine and if support were withdrawn, would there be a need for an ‘Essential Use’ derogation? The CSL Pesticide Usage Survey indicates minor usage. There is a possibility to extend the use of nicotine as an ‘Essential Use’ derogation if there is a very clear need for it to be available in the short term. A case has been made to PSD (D Richardson) and Essential Uses will be sought. 2. Specific insecticides and nematicides or insecticide and nematicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Insecticides with alternative modes of action are important for resistance strategies. It would be desirable to maintain the following: Soil applied: oxamyl (Annex 1) SOLA is important for free living nematodes now that aldicarb has been revoked. After the loss of chlorfenvinphos carrot growers have relied on the following for carrot fly control: Seed treatment: tefluthrin (List 3B) (SOLA) and Foliar sprays of lambda-cyhalothrin (Annex 1) at 150 ml/ha for carrot fly control. So far this programme has given good control but it remains to be seen whether the (August 2006) SOLA restriction to only four applications, 150 ml maximum dose rate and total dose 450ml/ha will be adequate. Pyrethroids are essential for cutworm now that chlorpyrifos can no longer be used. All pyrethroids are effective if correctly timed and no comparative studies have been done. Carbosulfan (List 2)

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currently very little used but could be important for early carrot fly control if pyrethroid resistance develops or if seed treatment products go. Pirimicarb, now on Annex 1, registration for carrots needs to be maintained for aphid control to prevent the spread of virus. Nicotine is also useful. Rotenone is not currently used, but could be important if resistance develops. 3. Prospects for alternatives for any foreseen major gaps in insecticide and nematicide availability

New insecticides with alternative modes of action are important for resistance strategies. 3.1. Alternatives A ‘Gap Analysis’ (Table 5) shows the critical insecticide and nematicide gap * * *, where there are, or soon will be no control measures at all. Nematodes: The need for new nematicides or alternative methods of control is highlighted. Oxamyl will be used. Garlic granules have recently been approved for control of nematodes, but growers have yet to assess efficacy in commercial situations. In France 1,3-dichlorpropene is used in carrots but application is difficult and costly. Ethoprophos is to be re-registered possibly for carrots in North (current) EU, and UK potatoes. A new nematicide is being evaluated for carrots in 2006. Carrot fly (Psila rosae): Cyromazine (IR 4 project, used on NL ornamentals), thiacloprid seed treatment, bifenthrin, tau-fluvalinate, flonicamid (probably only aphid) and spinosad may have potential. Because of anticipated problems with carrot fly a trial funded by HDC at Warwick HRI Wellesbournebegan in 2006, to screen new insecticide alternatives. An insecticide with new chemistry looks promising in the USA, but it may not be registered in the UK/EU until 2010. Willow Carrot Aphids (Cavariella aegopodii): The willow carrot aphid is a major pest of carrots and it is the vector for transmission of Parsnip Yellow Fleck Virus. Parsnip yellow fleck virus (PYFV) causes quality and yield loss and is a perennial problem for the carrot growing industry. Infected plants wither and centre leaves rapidly turn brown/black and brown areas within the carrot crown then develop. Outbreaks have been severe in recent years and can lead to losses of up to 20% in some crops and in 1998, were estimated at a total of around nearly £5 million. Yield loss from aphid can be particularly serious in early sown carrots. In trials aphicides commonly used in carrot crops pirimicarb, lambda-cyhalothrin and two new neonicotinoid products were all very effective against winged willow-carrot aphids. The persistence of the most effective products, a neonicotinoid (product Biscaya - a new formulation of thiacloprid spray with O-TEQ oil approved on potatoes) and pirimicarb/lambda-cyhalothrin is enough to provide good long-term protection against aphids. Off–label Approvals based on recognition of on-label approvals in other (current Northern zone) member states are possible for UK minor crops such as carrots. This route could be useful for insecticides for control in the event of other EU member states finding an answer. Carrot fly is a problem in other MS - some had derogations for ‘Essential Use’ of chlorfenvinphos.

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Table 5. Gap Analysis (Crop): Insecticides & Nematicides Pest

Application timing






Carrot fly seed treatment foliar spray

* * tefluthrin seed treatment lambda-cyhalothrin rotenone

Both tefluthrin (seed treatment) and Lambda-cyhalothrin needed. Relying on one insecticide group used extensively. SOLA Lambda-cyhalothrin now restricted to 4 applications, max dose 150ml/ha, total 450ml/ha. Deltamethrin available for general control. Alternative modes of action needed.

Improved site selection

- - -

Nematodes (Free living and cyst)

application at drilling

* * aldicarb until end 2007 carbosulfan oxamyl garlic granules

Aldicarb has been banned by most major retailers and hence growers are moving towards production without nematicide, or are adopting oxamyl instead. Garlic granules have recently gained approval but efficacy has not been commercially determined.

Bio fumigant green manures

- - -

Aphid foliar spray * * pirimicarb The reduced use of aldicarb has meant prompt application of pirimicarb is necessary to prevent virus spread. Virus is a growing problem as more frequent aphid infestations are occuring - due to less aldicarb use? The pyrethroid insecticides give partial aphid control only.

- - - -

Cutworm and Silver Y Moth

foliar spray * * deltamethrin cypermethrin lambda-cyhalothrin

Control is easily achieved with the combination of site trapping, irrigation management and timely pyrethroid applications. Severe infestations of Silver Y Moth can cause problems.

Irrigation - - -

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Disease control in Carrots

Seedling diseases Damping-off (various pathogens) Pythium spp. are probably the most important cause of seedling damping-off in carrot though Rhizoctonia, Fusarium & Alternaria spp. may also be a problem. Alternaria spp can be carried on seed. Commercial seed lots are routinely treated with fungicide to control these pathogens. Some soil borne diseases can also be suppressed by fungicide seed treatments. Control: fungicidal seed treatments cymoxanil/fludioxonil/metalaxyl-M and thiram (Table 4) are relatively cheap and effective. Metalaxyl/thiabendazole can only be used until 28 December 2006. Root diseases Cavity spot Cavity spot, caused by Pythium spp. (P. violae and P. sulcatum), is a major problem in many carrot-growing areas. The incidence of cavity spot is thought to increase in lower pH soils, on land recently manured, in wet growing seasons or in over-mature crops. Impact: on quality - crops with a high incidence of severely blemished roots can be rejected. Control: risk of significant damage is reduced by early application of a soil-applied fungicide metalaxyl-M. However, there are suggestions that enhanced degradation is occurring in some situations (HDC Gap analysis http//:www.hdc.org.uk) and HDC and Defra are funding R & D as an urgent priority to find alternatives and to improve management (HDC project FV 5g). Novel approaches are also being assessed- biofumigants (composts), mustard cover crops, potassium phosphite (HDC project FV 273). Research on PCR-assays of soil for detection and quantification of the Pythium spp. associated with cavity spot are on-going at Warwick HRI. Non-chemical: use a less susceptible cultivar particularly for late-lifted crops and high-risk sites. Crown rot Crown rot is a sporadic disease problem of unknown etiology. Itersonilia may be implicated though as yet unproven and there is also the possibility of virus interaction. Crown rot causes darkening and breakdown of internal tissues from the crown of the mature root are seen in autumn following foliage dieback. The problem is more likely to occur in cooler and wetter growing areas. There appear to be no differences in susceptibility between varieties. Impact: reduction of quality and marketable yield. Control: foliar spray with fenpropimorph or iprodione/thiophanate-methyl. Non-chemical: minimise the risk by avoiding excessive foliage development by timely nitrogen and irrigation applications. Violet Root Rot (Helicobasidium purpureum); Crater rot (Rhizoctonia carotae); Common scab (Streptomyces scabies); Liquorice rot (Mycocentrospora acerina) and Fusarium species can cause economic damage but there are no recommendations for control with fungicides. Foliar diseases Alternaria (Alternaria dauci/A. radicina) Alternaria blight is of increasing importance to UK carrots and there is increasing reliance of fungicide application for control. Alternaria radicinum may invade roots during storage causing dark lesions on root shoulders. The largest yield reductions occur when the disease develops rapidly early (in August).

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Impact: Alternaria blight can reduce plant populations, damage foliage and weakened foliage creates harvesting difficulties with top-lifting machines. It can cause large reductions in the yield of marketable roots, up to 31 t/ha depending on season and variety. The extent of yield loss is not fully understood, and probably depends to a large extent on the time of appearance of the disease. A 5% yield loss could cost UK growers in the region of £2.25 million. Control: Seed treatments containing thiabendazole control the seed-borne phase but the metalaxyl/thiabendazole cannot be used after December 2006 (metalaxyl revoked). Recommendations were to use azoxystrobin as a protectant to start the sequence, and alternate azoxystrobin and eradicant tebuconazole (HDC project FV 234, 2003). Iprodione/thiophanate-methyl gives good control of Alternaria, and could be included in sequences, particularly when applied after a high-risk period for the disease. However there is now a new approval for azoxystrobin/difenconazole also to be used in accordance with FRAC resistance management advice: do not use consecutive applications of strobilurins and alternate with fungicides from a different chemical group. A forecasting system to predict Alternaria risk can reduce spray frequency and is available on the HDC website. Non-chemical control: Many varieties exhibit improved Alternaria tolerance and should be used in high-risk situations. Good field hygiene and crop separation limits the spread of Alternaria between crops. Wider rotations and management of nitrogen and irrigation to avoid excessive foliage development will reduce risk. Powdery mildew (Erysiphe heraclei) Powdery mildew develops as a grey mycelium on the upper leaf surface. It occurs in dry, hot weather. Impact: on quality where it spoils the appearance of foliage of bunching carrots. Yield may be reduced following an early severe attack. Control: Foliar applications with fungicides (azoxystrobin, new azoxystrobin/difenconazole, boscalid/pyraclostrobin, fenpropimorph, tebuconazole) at the first sign of mildew attack when lesions can be clearly identified. Repeat treatments may be necessary on late crops. Use in accordance with FRAC resistance management advice. Non-chemical control: Avoidance of moisture stress will reduce the crop susceptibility to mildew. There are some tolerant varieties. Sclerotinia (Sclerotinia sclerotiorum) Sclerotinia attacks carrot foliage and may progress into the crown of the root to cause a root rot. Canopy closure, weather conditions, the presence of fruiting bodies and senescing leaves on the ground are important factors. Impact: Sclerotinia is one of the most economically important diseases in carrot and yield losses appear to be increasing as a result of poor control. The financial losses are serious, and it has been estimated that the disease causes annual crop losses to UK growers in excess of £5 million. Failure to control the disease can result in crop losses of 15% on average, corresponding to losses of at least £18 million per annum. Significant losses in marketable yield are likely to arise when root disease incidence is 10%. Fungicide sprays have the potential to reduce these losses by at least 20-25%, an annual saving of approximately £4 million, less chemical plus application costs. Control: boscalid/pyraclostrobin now has on-label approval for Sclerotinia control in carrots. In trials it improved foliar disease control and increased yield of marketable roots by at least 20% (HDC Project FV 260). Pyraclastrobin, a strobilurin, should be used in accordance with FRAC resistance management advice. A forecasting system, based on crop growth stage and environmental key risk factors, is being developed by SAC to predict the optimum spray timing (HDC project FV 260). Coniothyrium minitans (Contans WG), a fungus, is the first biofungicide to be registered in the UK, in 2005. It is applied before cropping, and this may be difficult to plan where crops are grown on rented land. Efficacy needs to be validated long term in commercial fields.

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Non-chemical control: Crops which have very vigorous foliage are the most susceptible to attack. Avoiding the conditions that lead to excessive foliage growth and choice of varieties with erect foliage will limit the incidence of the disease. Avoid growing carrot crops close to fields of oilseed rape to minimise infection from externally generated spores. Spores can be blown at least 200 m from neighbouring oilseed rape. Other diseases Carrot Motley Dwarf Virus and the required helper virus Anthriscus Yellows Virus, AYV), are spread by willow-carrot aphid. Infected plants are stunted with yellow crinkled and mottled foliage and roots fail to develop normally in localised areas. Parsnip Yellow Fleck Virus spread by aphid vector usually throughout the field. Infected plants wither and centre leaves rapidly turn brown/black and brown areas within the carrot crown then develop. Impact: on quality and yield. Parsnip yellow fleck virus (PYFV) is a perennial problem for the carrot growing industry. Outbreaks have been severe in recent years and can lead to losses of up to 20% in some crops and in 1998, were estimated at a total of around nearly £5 million. Control of the aphid vector will limit the spread of virus within and between crops. With the loss of organophosphate insecticides and reduced use of aldicarb, aphids are more commonly colonising in crops and therefore routine field inspections and prompt treatment are essential. A management strategy for was developed in a HortLINK project (Defra/HDC, HL 0149/FV 228a, 2004). Cool storage diseases Fungal and bacterial rots can develop on stored roots particularly those that have been damaged during harvesting operations or have been badly handled. These can be minimised by careful lifting and handling together with the maintenance of the correct storage environment. Only roots that are free of disease symptoms should be cool stored. ‘New’ diseases Xanthomonas carotae a seed-borne bacterial pathogen a new disease in UK carrots reported for the first time in October 2005 (M McPherson, pers comm.). Favoured by warm, wet weather - not considered to be a major threat to UK production given current climate. A root rot on cold-stored carrots caused by Acrothecium carotae and reported to cause severe losses in the Netherlands and Scandinavia, is the subject of research to develop a molecular diagnostic tool for detection and prediction of risk pre-storage. Fusarium avenaceum a dry brown rot, reported from the Netherlands, infections from crop debris, straw cover and contaminated crates. Root rot caused by Phytophthera spp. has been reported in the UK in recent years. It causes a banding rot in carrots – control with Metalaxyl-M SOLA Cercospora leaf blight found in East Anglia in 2004 and may be confused with Alternaria, but it affects young leaves. It is a seed-borne disease also occurring on crop residues. Cercospora causes premature leaf senescence. Impact: not known yet. Control: in trials controlled with azoxystrobin and azoxystrobin/difenconazole. Other pathogens continue to be a potential threat, including fungi such as Sclerotium rolfsii and Phymatotrichopsis omnivore.

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Fungicides for carrots Fungicides approved for 2006 and usage in 2003, are shown in Table 6. Carrots receive, on average, 3 fungicide sprays mainly for general disease control, but leaf blight (Alternaria dauci), powdery mildew, and cavity spot (Pythium spp.) are the most important diseases. The most recent CSL survey 2003 showed that most fungicides were applied at or near the full label rate, with most crops receiving two applications, of tebuconazole and azoxystrobin. Boscalid/pyraclostrobin (Signum), approved for use in carrots in 2006 for control of Sclerotinia and Alternaria, and azoxystrobin/difenoconazole (Amistar Top) new approval for Alternaria and powdery mildew, are the only new fungicides approved for carrots since 2002. The latter may also give some suppression of Sclerotinia and leaf-spot pathogens such as Cercospora. Table 6. Fungicides approved for carrots 2006; Review status; Aim re-registration UK carrots; Disease; Activity; Usage of fungicides on carrots, parsnips, celery, crop area 10,148 ha grown in Great Britain, 2003 (spray hectares) (Source: CSL Pesticide Usage Survey, 2003) Fungicides Approved for carrots 2006

Approval status Aim re-registration UK carrots

Disease Activity Usage on carrots etc.

2003 (spray ha)

Fungicides

Azoxystrobin New Annex 1 √ Alternaria powdery mildew

systemic translaminar and protectant fungicide

13,566

Azoxystrobin/difenoconazole New Annex 1/List 3B √ / √ Alternaria powdery mildew

systemic translaminar and protectant fungicide/ systemic conazole

Boscalid/pyraclostrobin New

New pending/Annex 1

- Alternaria sclerotinia powdery mildew

protectant and systemic fungicide

Fenpropimorph SOLA List 3A x(-) Powdery mildew Alternaria / crown rot

contact & systemic morpholine fungicide

7,200

Iprodione/thiophanate-methyl SOLA Annex 1/ Annex 1 x(- / -) Alternaria / crown rot systemic and protectant fungicide 4,899

Metalaxyl-M Annex 1 √ Cavity spot systemic, phenylamide fungicide 7,063

Tebuconazole List 3B not decided Alternaria dauci systemic conazole fungicide 17,925

Biofungicide

Coniothyrium minitans New Annex 1 √ Sclerotinia biofungus soil-incorporated before cropping, attacks resting bodies

- Company request confidentiality; √ yes; 1. The likely impacts of the 91/414/EEC review process on fungicide availability for UK carrots

Carrot fungicides were supported in the 91/414/EEC review because there were uses in several other crops. So far no active substances have been lost through failure to achieve Annex 1 listing. Future losses? There has been no decision on Annex 1 inclusion for tebuconazole (List 3B), difenoconazole (List 3B) or fenpropimorph (List 3A) (Table 6) and it is not yet known whether active substances on Annex 1 will be re-registered in the UK or N Europe. Dose rates and number of applications and timings may be reduced at re-registration stage and this may have an impact on efficacy. There could be losses of on-label uses as manufacturers rationalise their product portfolios. Losses of some uses are likely particularly for carrots and other minor crops and more SOLAs will be needed.

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There are SOLAs for fungicides for carrots (Table 6). Residues data for some older SOLAs may not satisfy modern EC standards – a PSD study of data in archives, covering List 1 actives) suggests that new data may be required to set MRLs to support some minor crops/uses but data for iprodione/thiophanate-methyl appear acceptable. List 2 and some list 3 actives will be studied later. Any impact will be on cost to the grower through HDC levy to maintain these uses. 2. Specific fungicides or fungicide groups it would be desirable to maintain from the agronomic perspective to avoid major difficulties

Carrots are restricted in fungicide selection on specific targets for resistance management and it is very important that as many active substances as possible are retained for this crop. New fungicides with different modes of action are needed, particularly those with curative activity. Alternating different products not only reduces the risk of decreased sensitivity of the pathogen, but also reduces the risk of MRL exceedance of individual active substances by relying on a selection of different products. Were the industry to rely on single active substances for the control of specific pathogens, it could lead to increased fungicide use and ultimately risk MRL exceedance. It would be desirable to maintain the following: Seed treatment cymoxanil/fludioxonil/metalaxyl M Cavity spot in carrots is still a problem - possibly expectations are too high, and enhanced degradation/extended infection period is suspected. However, metalaxyl M, the only approved means of control, is needed until a more effective alternative is found. An effective range of foliar fungicides is required for leaf blights (Alternaria spp.), powdery mildew and Sclerotinia and other pathogens affecting the growing crop. A mixture of products from different mode of action groups for efficacy range and anti-resistance strategies is needed. Ideally one or more triazole products, morpholines & strobilurins need to be maintained: Strobilurins for Sclerotinia control Triazole tebuconazole (List 3B), fenpropimorph (List 3A), for resistance management of strobilurins, Azoxystrobin/difenoconazole (Annex 1/List 3B) important for powdery mildew and Alternaria, and Thiophanate-methyl/iprodione both Annex 1 another chemical group for resistance management. Coniothyrium minitans (Contans WG) (New Annex 1), a fungus, was the first biofungicide to be registered in the UK in 2005. It is applied before cropping, and this may be difficult to plan where crops are grown on rented land. It will take several seasons to determine long-term efficacy relative to fungicide application. 3. Prospects for alternatives for any foreseen major gaps in fungicide availability New fungicides with different modes of action are needed, particularly with curative activity. The large fungicide market will not deter development. Global fungicide development overall does not

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appear to have decreased so far and for the vegetable sector has even increased (Phillips McDougall, ECPA conference November 2005). Fungicides for potato blight control and for use in vines are potential sources of active substances for carrots. 3.1. Alternatives A ‘Gap Analysis’ (Table 7) shows the critical fungicide gap * * *, where there are, or soon will be no control measures at all. The gaps were not as a a result of the 91/414 Review. a. Sclerotinia: Fluazinam, a pyridinamine fungicide for potato blight control, was effective in brassica trials, is relatively cheap but is not being progressed. A new foliar spray from Syngenta, cyprodinil/fludioxynil (an anilinopyrimidine/phenylpyrrole) is approved in France and the US (product name Switch in France and US). It is being developed for Sclerotinia control may be available for other crops in the UK 2006? US IR 4 project data suggests it controls Alternaria, rots, powdery mildew. In the IR4 project it is registered for carrots. Cyprodinil (Annex 1) to be re-registered for carrots in other EU Member States in the same climatic zone. b. Cercospora leaf blight: new disease. It is a seed-borne disease also occurring on crop residues. Cercospora causes premature leaf senescence. In trials conducted by ADAS azoxystrobin/ difenoconazole, azoxystrobin were effective. c. Cavity spot: Alternatives to soil-applied fungicide metalaxyl-M are needed. There are suggestions that enhanced degradation is occurring in some situations (HDC Gap analysis www.hdc.org.uk). HDC is funding R & D to find alternatives as an urgent priority (FV 5g). Cyazofamid (Ranman Twinpak) from Belchim, a cyanoimidazolesulfonamide protectant, a mitochondrial transport inhibitor, is approved in the UK for control of blight in potatoes. In the US it is pending registration in carrots and other crops (IR4 Project) in California for control of late blight, downy mildew and club root. It might control cavity spot. d. Powdery mildew (Erysiphe heraclei): An effective range of different mode of action products is available but there are some concerns for the future if fenpropimorph is lost because there is a high risk of resistance to strobilurins. New 2006 approval for azoxystrobin/difenoconazole (Company aims to register difenoconazole List 3B for UK carrots after Annex 1 inclusion.) Currently there are no approved fungicides for control of Violet root rot and no new solutions, although the efficacy of some of the more recent fungicides such as azoxystrobin and pyraclostrobin/boscalid is unknown. Off–label Approvals based on recognition of on-label approvals in other (current Northern zone) member states are possible for UK carrots and this route could be useful for fungicides. Whilst not specifically a gap in the armoury, the lack of any baseline monitoring of key horticultural pathogens is a significant gap, because it means we are unable to predict any shifts in pathogen sensitivity – and this could certainly lead to unnecessary fungicide application in the future as growers increase frequency of application and dose rate in an attempt to achieve control. A regular structured monitoring programme, especially on key pathogens, would largely prevent this.

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Table 7. Gap Analysis (Carrots): Fungicides Disease (Latin name)

Application timing





Cavity spot (Pythium spp.)

Early post-drilling

* * Metalaxyl-M The most important disease in UK carrots and reliance on a single active substance for control. Resistance risk moderate-high though no confirmed reports of problems to date. Varietal tolerance important. Cyazofamid is pending registration in carrots and other crops in the US (IR4 Project) in California for control of (late blight, downy mildew and club root)

Varietal tolerance & crop rotation. Not effective in all cases Calcium sulphate?

None found to date Cyazofamid for UK potato blight, in US carrots

None?

Powdery mildew(Erysiphe heraclei)

Foliage * * azoxystrobin, fenpropimorph, tebuconazole

Occurs in dry seasons. Alternation with different mode of action products possible at present (morpholines, strobilurins & triazoles). Potential for loss of morpholines in 2008 & high resistance risk with strobilurins could be a problem in future.

Varietal resistance. Partially effective but not in all cases

An effective range of different mode of action products available…but some concerns for future

Possibly (Data not available)

White rot (Sclerotinia sclerotiorum)

Foliage * * boscalid/ pyraclostrobin, Contans (Coniothyrium minitans)

Fungicides with other MoA needed. Too early to determine if Contans will reduce sclerotial inoculum in soil to acceptable level…relative to impact of ascospore infection from outside source. Varieties with erect foliage assist control

Calcium cyanamide? Contans Possibly…

fluazinam Syngenta, Shirlan approved for potato blight

cyprodinil/ fludioxynil

R & D done Residues data

Violet root rot (Helicobasidium purpureum)

Foliage * * * None A disease of sporadic, but increasing, importance in intensive rotations with susceptible crops

None none available

Black root rot (Thielaviopsis basicola)

Post-harvest * * * None A disease of some significance in pre-washed bagged carrots. Previous fungicide control with carbendazim replaced with cultural/water disinfection approach

Better management, disinfection of wash-water.

carbendazim (earlier approval withdrawn)

? None (no data available)

Common scab (Streptomyces scabiei)

? * * * None A bacterial disease caused by soil-borne Streptomyces species. Modern molecular methods revealing new information and broad range of species/sub-species involved in disease complex.

Site, crop rotation, irrigation, pH control

none available ? none

Liquorice rot (Mycocentrospora acerina)

? Post-harvest

* * * None, may be suppressed by other

An occasional problem in the field and post-harvest. Rarely warrants specific control measures at the present time

No none available carbendazim

? No (no data available)

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fungicides applied for other targets

azoxystrobin? boscalid/pyraclostrobin?

Crater rot (Rhizoctonia carotae)

? (Post-harvest)

* * * None, though azoxystrobin likely to assist in suppression of the pathogen in the field

An occasional problem, usually though not exclusively in stored carrots

No none available azoxystrobin?

? No (no data available)

Cercospora Leaf blight (Cercospora carotae)

Foliage * * * None, though other foliar applied fungicides likely to provide some control

A recently reported foliar pathogen of carrot in the UK, can be confused with Alternaria. Some fungicides applied for Alternaria e.g. azoxystrobin, azoxystrobin/difenconazole provide some control in trials.

No azoxystrobin/ difenconazole azoxystrobin tebuconazole etc .

? R & D Residues data available

Root rot (Acrothecium carotae)

* * * None A new disease of carrot not currently reported from UK but reported from Scandinavia, Netherlands& Canada. Primarily affected crops in cold stores rather than in field storage.

No not known ? Yes

Bacterial blight (Xanthomonas carotae)

Seed? * * Copper ammonium carbonate Croptex Fungex for any crop

A new disease in UK carrots found for the first time in Autumn 2005 (McPherson, pers comm.). Not considered to be a major threat to UK production given current prevailing climate. Favoured by warm wet weather.

Possibly. Clean seed Crop rotation

none available

? Not at this stage

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REFERENCES Horticultural Development Council Projects can be accessed http://www.hdc.org.uk by members

of HDC: HDC Gap Analysis http://www.hdc.org.ukDefra & HDC Project FV 5g (on-going) To improve management of cavity spot. FV 228a,b/HortLINK HL 0149 (Current). Parsnip Yellow Fleck virus in carrots: extending

understanding of virus and vectors to support the development of a disease management strategy

FV 232 (2002) Carrots and parsnips: investigations of the problems with plant-parasitic nematodes in support of an IPM strategy

FV 234 (2003) Carrots: the management of Alternaria blight on carrots. FV 236b (2005) Carrots: To investigate safe and effective new herbicides, for weed control in

Carrots and Parsnips to replace those lost through the EC Review, 2005. FV 238 Dissemination and exploitation of aphid monitoring data FV 249 (2005) Carrot: a cost-benefit study in the control of free-living nematodes, soil diseases and

volunteer potatoes by comparing specific management systems before and during cropping FV 256 (2004) & FV 256b (2005) Vegetables: Solutions to the loss of active ingredients for weed

control in vegetable crops FV 260 (2005-2007) Carrots: forecasting and integrated control of Sclerotinia disease. HortLINK/HDC FV 228a (2004) Parsnip Yellow Fleck Virus: development of a disease

management strategy. FV 273 (2005) Biofumigants FV 274 (2005) Cutworm development and survival: a risk assessment and early warning

programme for growers. FV 281 (new 2006) The development of methods to control volunteer potatoes in a range of

vegetable crops. FV 278 (2005) Carrot: Survey of major growers to promote sustainable methods of nematode

control and investigate factors limiting their uptake. FV 287 (new 2006) Survey of approvals in other EU countries across all crops of interest to HDC. Other references: ASSURED PRODUCE - The NFU/Retailer partnership http://www.assuredproduce.co.ukDEPARTMENT FOR ENVIRONMENT, FOOD AND RURAL AFFAIRS (Defra) (2006) Basic

Horticultural Statistics for the United Kingdom, Calendar and Crop Years 1994/95 – 2004/05. Defra publications, London, UK.

DEPARTMENT FOR ENVIRONMENT, FOOD AND RURAL AFFAIRS (Defra) (2006) Project HH3401SFV: To determine the effect of strategies of herbicide use on sensitivity of weed populations

FINCH S, COLLIER RH & JUKES A (1998) "What a difference a spray makes". In: The Grower, July 23 1998, p20.

GARTHWAITE D G, THOMAS M R, DAWSON A, STODDART H & ANDERSON H (2004) Outdoor Vegetable Crops In Great Britain 2003. Pesticide Usage Survey Report 195. Central Science Laboratory, Sand Hutton, York, UK. http://www.csl.gov.uk


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GRUNDY A, KNOTT C, LUTMAN PJW et al. (2003) The Impact of Herbicides on Weed Abundance and Biodiversity in Horticulture. Defra project HH3403SX.

HEAP I (2006) International survey of herbicide-resistant weeds. hhtp://www.weedscience.org accessed April 2006

HOLM RE, BARON JJ & KUNKEL DL (2005) The IR-4 Program and its cooperation with the crop protection industry to provide new pest control solutions to U.S. speciality crop growers. In: Proceedings 2005 BCPC International Congress – Crop Science & Technology, Glasgow, UK, 31-42.

KNOTT C M (2002) Weed control in other arable and field vegetable crops. In: Weed Management Handbook (ed RE Naylor), 9th edition, British Crop Protection Council. Blackwell Science, Oxford, UK.


TEI F, BAUMANN DT, BLEEKER PO et al. (1999) Weeds and weed management in carrots – a review. In: The 11th European Weed Research Society Symposium 1999, Basel, Switzerland. http://www.agr.unipg.it/ewrsveg.

TURNER RJ, LENNARTSSON MJ, HESKETH M, GRUNDY AC & WHITEHOUSE D (2001) Weed control in organically grown- carrots. Proceedings of the BCPC Conference – Weeds 2001, 291-296.



Cambridge, UK.

ACKNOWLEDGEMENTS

The help and contributions from staff from the following organisations are gratefully acknowledged: in particular Dr Martin McPherson, Stockbridge Technology Centre; British Carrot Growers Association (BCGA); Plant Systems; Horticulture Development Council (HDC); Vegetable Consultancy Services (VCS); Fresh Produce Consultancy Ltd.; BBSRC Rothamsted Research; National Farmers Union (NFU); Christian Salvesen Processors; United Agricultural Products - Europe (UAP); European Crop Protection Association (ECPA) and Crop Protection Companies.

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Appendix. Weed Susceptibility to carrot herbicides. Data from product labels UK and other countries, and other information – please treat with caution. Key: S = Susceptible; MS = Moderately Susceptible; R = Resistant; MR = Moderately Resistant; Dose rates L/ha or kg/ha; cot cotyledon stage; blue text loss after 31 Dec 2007; green text approved Denmark not the UK

linuron liinuron metribuzin clomazone pendimethalin pendimethalin aclonifen pendimethalin+aclonifen metoxuron prometryne pentanochlor Common name Latin name Pre 2.2L/ha Post 1.1L/ha Post 0.5kg/ha Pre 0.25L/ha Pre 5L/ha Pre 1.5 –2 L/ha Pre 2-2.5L/ha pre 2 + 2L/ha Post 5.5L/ha pre/post 2.3kg/ha Post 5.6L/ha Bindweed, black Fallopia convolvulus S S S MR S MS MS S S (Spre) S Bugloss Anchusa arvensis S MR S Charlock Sinapis arvensis S S S R MS S S S (MSpre) Chickweed, common Stellaria media S S S S S S S S S S S Cleavers Galium aparine MR R R S S R MS MS S R ? Corn marigold Chrysanthemum segetum S R MS S S S Corn spurrey Spergula arvensis S S S S S Dead-nettle, henbit Lamium amplexicaule S S S Dead-nettle, red Lamium purpureum S MR S S S MS MS S S S Dock, broad-leaved Rumex obtusifolius Fat-hen Chenopodium album S S S MS S S S S S S S Fool's parsley Aethusa cynapium S MS R R Forget-me-not, field Myosotis arvensis S S S S S S Fumitory, common Fumaria officinalis R R S R MS R R MS S MS Gallant -soldier Galinsoga parviflora S S Groundsel Senecio vulgaris S MR S S R R R MS MS(Spre) Hemp-nettle, common Galeopsis tetrahit S S S S MS S S Knotgrass Polygonum aviculare MS MR MS MR S R (Spre) Mayweed, scented Matricaria recutita S R S R MS MS MS S S (Spre) MS Mayweed, scentless Tripleurospermum inodorum S R S R MS MS MS S S (Spre) MS Nettle, small Urtica urens S S S MR S S S Nightshade, black Solanum nigrum S MR S S MS R MS S S Orache, common Atriplex patula S S S S S Pansy, field Viola arvensis S S MS R S MS R MS S S Parsley piert Aphanes arvensis S S Pennycress, field Thlaspi arvense S S S Persicaria, pale Persicaria lapathifolia S S S MS S S Pimpernel, scarlet Anagalis arvensis S S S S MS(Spre) S Pineappleweed Matricaria discoidea S R R MS MS MS S S MS Poppy, common Papaver rhoeas S S R S S S S Redshank Persicaria maculosa S S S S S MS MS S S S S Shepherd's-purse Capsella bursa-pastoris S S S S S S S S S S Sow-thistle, smooth Sonchus oleraceus S S MS MS S R MS MS (Spre) S Speedwell, common, field Veronica persica S S S S S MS S R S S Speedwell, ivy-leaved Veronica hederifolia S S S R S S Thistle, creeping Cirsium arvense R R R R R R R R Wild radish Raphanus raphanistrum S S S S MS S S Mspre Annual meadow-grass Poa annua MS MR S MS S S MS S (Spre) S Blackgrass Alopecurus myosuroides MS S R S Wild-oat Avena fatua R R R Vol OSR Brassica napus S R MS S S MS Vol potatoes Solanum tuberosum suppression

Documents

SUMMARY - Health and Safety Executive · A Agronomic impact of Directive 91/414/EEC D rew ssociates CONTENTS Pages Executive Summary (C Knott) i Summaries of crops (C Knott, M Ogilvy)