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Pest managementin cereals and
oilseed rape– a guide
2
Contents
BYDV vectors 4
Grey field slug 6
Gout fly 7
Wheat bulb fly 8
Yellow cereal fly 9
Wireworms 10
Leatherjackets 11
Summer aphids 12
Orange wheat blossom midge 13
Peach-potato aphid 14
Cabbage aphid 14
Cabbage stem flea beetle 15
Other flea beetles 16
Wessex flea beetle
Turnip flea beetle
Large striped flea beetle
Pollen beetle 17
Cabbage seed weevil 18
Brassica pod midge 18
Other pests 19
Frit fly
Thrips
Saddle gall midge
Rape winter stem weevil
Cereal ground beetle
Cabbage stem weevil
Biological and cultural control 20
Further information 23
Autumn 2003
The impact of pests on yield and quality can bemore variable than that of many diseases.However, they do pose a serious threat to UKcrops and can reduce yield by 10% or more,sometimes much more.
With increasing concerns about theenvironment, there is a need to balance pestcontrol against encouraging other insects whichcan actually benefit the crop.
Integrated strategies seek to use cultural controloptions, encourage natural enemies and only usecrop protection methods when they are fullyjustified – usually by the use of thresholds.
Developing such strategies depends on a soundunderstanding of pests, their life cycles and theirnatural enemies.This guide brings together thelatest knowledge from research funded by Defraand HGCA.
Jon Oakley, a leading entomologist, has gatheredhere information that will be invaluable togrowers who seek to minimise pest damage,maximise the marketability of their crops andenhance the environment on their farms.
Professor Graham Jellis Director of ResearchHGCA
The Home-Grown Cereals Authority (HGCA) has provided funding forsome of the projects on which this guide is based but has not conductedthe research or written this guide. While the authors have worked onthe best information available to them, neither the HGCA nor theauthors shall in any event be liable for any loss, damage or injuryhowsoever suffered directly or indirectly in relation to the booklet orthe research on which it is based.
Reference herein to trade names and proprietary products withoutstating that they are protected does not imply they may be regarded asunprotected and thus free for general use. No endorsement of namedproducts is intended, nor is any criticism implied of other alternative, butunnamed products.
Front cover: Gout fly and
parasitoids on wild flowers
in a field margin.pest management
in cereals and oilseed rape
– a guide
3
For peststhat seed
treatmentsmay control
(eg cabbage stem flea beetle,
wireworm,wheat bulb fly)
Has risk of pest
increased?
Yes Order seed treatment
No
BE
FO
RE
SO
WIN
GF
RO
M S
OW
ING
TO
EM
ER
GE
NC
EA
FT
ER
EM
ER
GE
NC
E
Yes
No
Have thesepests causeddamage inpreviouscrops?
For peststhat
cultivationsmay control(eg green bridge
BYDV,leatherjackets,
frit fly)
Yes Plough early, or use desiccant
No
Doesprevious crop
or stubbleregrowth
increase risk?
Control of slugs
Are slugs abovethreshold?
Yes Sow deeper androll after sowing
Monitor using traps
Yes Apply molluscicide
Do slugs posea particular
threat? (eg is there ahistory of slugproblems, does
the weather favour the pest?)
Monitor forpests that
affect growingcrops
(eg pollen beetle,wheat blossommidge, gout fly)
Will pest levelsexceed
threshold?
Yes
YesConsider treatment at correct timing
NoIs there a
risk ofimminent
attack?
No
Do not use seedtreatment
No No
Effective pest control➤ Assess the risk of infestations.
➤ Minimise pest risk by cultural means.
➤ Maximise the effects of natural enemies.
➤ Only use treatments if economically justified.
General principles of pest management
No
No Yes
Are natural enemies present?
Life cycles
4
BYDVTwo different aphid species transmit barley yellowdwarf luteovirus (BYDV) to cereals and grasses inthe UK. Very low populations, which may gounnoticed, can cause economic damage.
In autumn most aphids probably come fromgrasses, especially perennial ryegrass.Virus mayalso come from other cereal crops and volunteers.
BYDV VECTORS
The asexual strain – overwinters on cereals
and grasses.Aphids are frost-susceptible, theLT50 being -0.5ºC. In colderwinters survival of this strain isrestricted to milder coastaldistricts.
The sexual strain – overwinters as eggs on bird
cherry trees.Most wild bird cherry trees arefound in northern Britainalthough they occur across the UK.
Eggs of bird cherry-oat aphidare very frost-resistant. Birdcherry trees are not infected byBYDV, so spring migrants areinitially virus-free. Aphids of the sexual strain do not transmitBYDV within winter cereal crops.
Bird cherry-oat aphidRhopalosiphum padi
The aphids are green todusky brown with rust redpatches at the rear.
Transmits: The PAV andRPV strains of BYDV.
Grain aphidSitobion avenae
The aphids may be green,red or brown with blacklegs.
Transmits: The MAV andPAV strains of BYDV.
Life cycle
The grain aphid is mainlyasexual feeding on cereals andgrasses all year round.The aphidis more frost-resistant than thebird cherry-oat aphid with aLT50 (lethal temperature for
50% of the aphids) of -8ºC.Grain aphids survive on cropsthrough most winters. Numbersincrease during mild spellswhen further BYDV spread may occur.
Economic importance
Risk factors
The grain aphid is the mainBYDV vector in eastern, mid
and northern Britain. Losses canbe up to 2.5 t/ha.
Winter crops: In mild winterssignificant spread may occur inany crops exposed tomigrations of the wingedaphids.These can continue intoNovember and infect later sowncrops.
Spring crops: After mildwinters BYDV may betransmitted to late-sown cropsby winged aphids.
Economic importance
Risk factors
The bird cherry-oat aphid is themain vector of BYDV in south-
west England and in warmautumns elsewhere.
Winter crops: Crops sownearly, particularly in a warmautumn, are most susceptible tobird cherry-oat attack.Theseconditions allow aphids to breedrapidly before frosts kill them.
Spring crops: After mildwinters BYDV may betransmitted to late-sown cropsby winged aphids.
5
BYDV VECTORS
Chemical control
Applying a seed treatment incorporatingimidacloprid (Secur) can provide about sixweeks’ protection, less at very low seedrates. It may not replace the need to spray.
In mild seasons the threat of aphidinfestation may continue through the winter.
A pyrethroid spray will kill most winglessaphids.
Chemical control is ineffective on spring-sown crops.
Action thresholdsNo satisfactory thresholds for treatmentexist.
Spray timing BYDV starts to spread within the cropwhen the second wingless aphid generationemerges. Spread, initially slow, accelerates asthe third wingless aphid generationappears. Aphid breeding is governed bytemperature, so a ‘T sum’ system ofaccumulated day degrees above 3ºC can beused to predict best spray timings.Temperature accumulation should bestarted from:▼ six weeks after sowing for imidacloprid-
treated crops▼ date of emergence for other crops▼ one week after application for pyrethroid-
treated crops.
1. Calculate ‘T sum’ by subtracting 3ºC fromthe daily mean temperature and addingthe result to the running total.
2. If ‘T sum’ is 170 (second generation couldbe starting)– consider a tank-mix insecticide if
treating the crop for another purpose.3. If ‘T sum’ is 340 (significant spread
imminent) – apply a spray treatment as a priority.
A crop should suffer little yield loss fromfresh BYDV infection after GS 31 or after aprolonged cold period. A month with meandaily temperatures below 5ºC will severelyreduce grain aphid survival.
Ground beetles and spiders may attack aphids in the autumn andwinter and parasitoids can be active in mild weather. Minimum tillageleaves more predators, but increases the risk of ‘green bridge’ transfer.
Grass banks and grassed field margins may assist predator survival,but can also harbour infective aphids. Grassed areas should beconsidered in large arable fields of 20 ha or more.
no tr
eatm
ent
too late
tank m
ix
high priority
17 Sept
24 Sept
1 Oct
8 Oct
15 Oct
22 Oct
29 Oct
5 Nov
12 Nov
19 Nov
26 Nov
MarFebJanDecNovOctSept
Dat
e o
f cro
p em
erge
nce
Month
‘Green bridge’ transmission
1. Clean stubble before preparing seedbed.2. Leave at least five weeks between ploughing and sowing the new crop.3. Consider applying a desiccant herbicide if cultivation to sowing interval is less than five weeks.4. Delay sowing by a week to reduce BYDV spread by up to half.5. Choose a moderately resistant spring barley variety (see HGCA Recommended Lists) if growing crops after mild winters or in
milder districts.
Cultural control
Warm, moist soil conditions facilitate aphid movement throughsoil.‘Green bridge’ transmission is most likely in south-westEngland, on early-sown crops and in mild, damp autumns.
Aphids can transfer directly from grass or ploughed-down grass or
weedy stubbles to new cereal crops.The aphids can feed on newcrop roots, and transmit virus directly without appearing aboveground level to provide a control opportunity. Any cereal aphidspecies present may transmit virus – often the RPV strain of BYDV.
Early emerged crops are most at risk ofBYDV infection. Decisions on whether totreat crops emerging in September mustbe made by the start of October. Thetreatment window is wider for later-emerging crops.
Use ‘T-sum’ (see above) for specificlocality.
An example of the effect of date of crop emergence on need to spray in a mild winter
Natural enemies
Both species
The grey field slug breeds year round exploiting any mild, damp periods. Mature adult slugs each lays up to 500 eggs.Typically many eggsand young slugs die from desiccation which keeps populations stable. If weather conditions are particularly favourable and mortality low,populations may increase to very high levels.
Slugs feed opportunistically on a wide range of plant material changing from male to female as they mature.They are inactive inunsuitable conditions and resume feeding in mild, damp, still weather.
6
CEREAL & OILSEED RAPE PESTS
Slugs are most damaging toseeds and seedlings. Cereals arevulnerable up to the fourth leafstage (GS 14); oilseed rape to
the four true-leaf stage (GS 1.4).After these stages slug grazingdoes not generally threatenplant survival.
All cereal and oilseed crops,particularly if grown on heavier,wetter soils and sown in loose,cloddy seedbeds, are vulnerable.
Such conditions allow access toseeds and germinating seedlingsand also favour slug survival.
Cultivation in dry conditionsleads to physical damage anddesiccation.
Cereal seed should be sown atleast 12 mm deep. For allcombinable crops soil
consolidation prevents access toseed as well as encouragingseed-to-soil contact, and rapidgermination. A Cambridge rolleris suitable.
Slug pellets are effective at the soil surface for 4–7 days, but only killactively feeding slugs. In mild, damp weather pellets only kill aproportion of sexually active mature slugs. Juveniles often escape asthey remain in the soil. Pellets have limited impact. Damage mayresume within a month or, if conditions improve, weeks of treatment.
Action thresholdsAction thresholds for cereals arebased on slug numbers caughtin refuge traps – before or aftertreatment. These can be madefrom plant pot saucers or tiles,baited with layers mash, orproprietary mats can bepurchased. Catches reflectnumbers of slugs active on thesurface, not in the soil.Trapsonly give useful informationwhen mild damp nightconditions encourage activity.
A catch of four or more slugsa trap generally justifiestreatment, provided conditionsremain favourable.
The threshold applies tocereal crops. Slightly lowernumbers are probably worthcontrolling in oilseed rape.
Trapping, and treatment if thethreshold is exceeded, isgenerally advised:▼ before sowing if the field has
a history of slug damage▼ before sowing if wet weather
delays sowing in a preparedseedbed
▼ following sowing if seedbedtilth is poor and furtherconsolidation is not possible
▼ the crop is slow to emerge orto grow to GS 1.4 and whendamage is visible.
Several predators eat slugs.Ground beetles are probably themost common in arable fields.
Life cycle
Grey field slugDeroceras reticulatum
Many slug speciesare found in arablefields. Only thegrey field slug is of economicimportance oncereals andoilseeds.
Economic importance
Risk factors
Cultural control
Chemical control
Natural enemies
There are two generations each year.
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Distinct autumn (andspring) breeding peakslead to two overlappinggenerations at any time.
Distinct spring (and autumn)breeding peaks lead to two
overlapping generations at any time.
The grey field slug is mottled grey and of medium size.
7
CEREAL PESTS
The pest is present across theUK, but only causes economicdamage from the south coast tothe midlands in wheat, barleyand triticale. Incidence appearsto be moving north. In 2002,high levels of damage were seenin early-sown crops as far northas Staffordshire and Lincolnshire.
Winter damage kills affectedtillers and any still dependent onthe mother plant.Unaffected
tillers,with a developed crownroot system can survive andcompensate for damage at lowerlevels of incidence.Where halfthe crop or more is damaged,yield losses range from 0.25tonnes/ha to total crop failure.
Shoots damaged by springgenerations lose 30% of grainyield on average. Late-sowncrops suffer losses up to half oftheir potential yield.
Crops emerged by the end ofSeptember are at greatest riskfrom the autumn generation.
Late-sown winter and springcrops are at greatest risk fromthe spring generation. Egg-layingcommences in mid-May in the
south of England, late May inthe midlands. Crops at, orbeyond, GS 37 by this timesuffer little damage.
Oats are immune, but gout flycan attack couch grass.
▼ Sow winter wheat and barleyin sheltered fields nearwoodland after lateSeptember.
▼ Sow spring crops as early aspracticable in areas wheredamage is prevalent.
Chlorpyrifos and pyrethroidinsecticides, used to control fritfly and BYDV vectorsrespectively, will give usefulcontrol of the autumngeneration where sprays areapplied before eggs hatch. In2002, treatments after earlyOctober were ineffective.
Action thresholdsLimited evidence suggests thattreatment is economic in wintercrops if eggs are found on morethan half of the plants at GS 12.
No threshold exists for spring-sown crops.
Life cycle
Gout FlyChlorops pumilionis
Larvae feeding in stems cause a ‘gouted’appearance – swollen main stem and primarytillers with leaves puckered and torn above. Inwinter crops, damage is first seen in December,but mainly in January/February. Infested spring-sown crops show damage in June and July whichprevents ear emergence from the flag leaf.
Damage tends to be highest in sheltered fieldsnear woodland.
Economic importance
Risk factors
Cultural control
Chemical control
Natural enemies
Upper surface black with yellow beneath,three black stripes on thorax.
There are two generations each year.
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Larvae feed by secretingenzymes to break downsurrounding tissues.This causesno obvious damage to shoots.As the stem extends this breakdevelops into a line of damage.
Adult flieshatchbefore
harvest.
Adults shelter inwooded areas and
hedgerows.
Eggs laid onupperside of first
unfurled leaf.
Adult flieshatch. Eggs
laid onuppermostunfurledleaf andhatch in
7–10 days.
Larvaecrawl intoleaf sheathand feed onleaf sheathbeneath
ear.
Larvaepupate in leafsheath.
Larvae feed.Larvaefeed.
Larvaepupate in
stem.
Pupation
Larvae of the parasitoid wasps,Stenomalus micans andCoelineus niger, feed inside thegout fly larvae.They can kill80% or more of gout fly larvae.Adult wasps are active slightlylater than gout flies and couldbe vulnerable to late insecticideapplications. Stenomalus micans
All cereals, except oats, can beattacked.Adults fly up to half amile from previously-attackedfields to lay eggs. They lay eggson stubbles after cultivation andprefer freshly-turned soil. Underhot, dry conditions they lay eggsbetween row crops, especially ifthe foliage is wilting.Eggs may be laid on:▼ bare soil following fallows,
set-aside, or early harvested
crops (eg vining peas) ifcultivated between mid-Julyand mid-August
▼ row crops, eg sugar beet,potatoes and onions but notbrassicas.
Frequency of attack depends onthe population of vulnerable firstwheats on the farm:▼ more than 25% – regularly▼ 10–25% – occasionally ▼ less than 10% – rarely.
Tefluthrin seed treatments areeffective with later sowings, butmay not fully protect earlier-sown crops. Drill treated seedno deeper than 40 mm.
Chlorpyrifos egg hatchsprays are applied between thestart of egg hatch in Januaryand its peak in February orMarch. Egg hatch is monitoredeach year to provideinformation on timing and theneed to add, or switch to,dimethoate for later sprays.
Dimethoate is applied whendeadhearts first appear inMarch. It should be appliedbefore larvae move off to attackother shoots in late March.
Action thresholdsEgg numbers can be estimatedfrom soil samples. Each yearADAS forecasts (availablethrough Dow*) the proportionof fields likely to exceedthreshold levels:▼ above 5 million eggs/ha –
damage inevitable, extrameasures needed
▼ 2.5–5 million eggs/ha (sowingSept–Oct) – damage likely
▼ less than 1.25 million eggs/ha(sowing Nov–Mar). Late sowncrops may suffer damage.
Plant samples may beexamined to determinenumbers of larvae presentwhen deadhearts are firstfound. Stripping off the outerleaf sheath can reveal a brownstain where larvae are feeding.A small entry hole in the leafsheaf confirms that a larva hasentered.The thresholds assumeplant populations of at least 200plants/m2:▼ 10% tillers attacked @ GS 20▼ 15% tillers attacked @ GS 21▼ 20% tillers attacked @ GS 22
onwards.
The main egg predators areground beetles and their larvae.
Small rove beetles, particularly
Aleochara bipustulata mayparasitise the pupae, and kill upto 50% of them.
Life cycle
Wheat bulb flyDelia coarctata
Wheat bulb fly larvae attack shoots of wheat,barley and rye from January to April.They boreinto plants, feed at the shoot base and eat throughthe central leaf which dies, causing the classicdeadheart symptom. Larvae lack legs and arewhite to pale yellow with a blunt tail end.
Economic importance
Risk factors
Cultural control
Chemical control
Natural enemies
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Larvae hatch and invade shoots ofwheat, rye and barley.
Larvaepupate atbase ofplants.
Eggs laid onbare soil
andbetween
row crops.
Larvae attack 3–5further shoots.
Adults feed onsaprophytic fungi on
host plants.
8
CEREAL PESTS
Yield loss depends on tillerdensity at the time of attack.Crops still at the single shootstage in February are mostvulnerable and may be totally
destroyed.Well-tillered cropsgenerally withstand up to 100larvae/m2 without economicimpact on yield.
Avoid cultivating fields destinedfor wheat in late July and earlyAugust.This reduces numbers ofeggs laid, especially if fields foroilseed rape, and other non-host crops, are worked at this time.
Early sowing reduces theimpact of wheat bulb fly, butincreases survival of larvae andnumbers on the farm the nextyear.
Overwinters as eggs.
Egg
Larva hatching
* Dow AgroSciences Technical Hotline – 0800 689 8899
Each larva damages only a singleshoot so economic impact isgenerally low. Most crops can
withstand a considerablenumber of larvae by producingcompensating tillers.
Crops at low plant populationsand early-sown crops in
sheltered fields close towoodland are at greatest risk.
▼ Establish at least 200plants/m2 in vulnerablesituations.
Pyrethroid sprays applied tocontrol BYDV vectors alsocontrol yellow cereal fly.No treatments arerecommended once larvae haveentered plants.
Action thresholdsNo action thresholds have beenestablished.
The eggs and pupae are themost vulnerable stages to
predation by ground beetles.
Life cycle
Yellow cereal flyOpomyza florum
Yellow cereal fly, like wheat bulb fly, causes‘deadheart’ as larvae enter through the top of theshoot.The yellow cereal fly larva does not leave anentry hole; wheat bulb fly larva does.The larva,yellow and with a pointed end, looks similar to fritfly, but occurs later in the winter.
Economic importance
Risk factors
Cultural control
Chemical control
Natural enemies
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Eggs hatch.
Larvae enter and feed on wheat shoots.
Eggs overwinter.
Adults spend the summer inwoodland.
Adult flies hatch.
9
CEREAL PESTS
Larvaeleave theshoots topupate in
soil.
Flies move to early-sown wheat crops in
late September.
Eggs are laid at thebase ofplants.
Eggs overwinter.
Arable and cropping and the environment – a guideassesses how any onemanagement decision affects all other decisions in anintegrated cropping system.
10
CEREAL PESTS
Wireworms have become amore serious pest since thewithdrawal of organochlorineinsecticides and the increase ofwinter cropping.They can nowaffect all winter cereal or winter
cereal/ley rotations. Heavyinfestations can cause yield lossof up to 0.6 t/ha in cereals.
Peas, linseed and flax aremore tolerant of damage thanother crops.
Crops at highest risk are sownwithin two years of ploughingout permanent pasture.However, any rotation with
predominant winter cropping,particularly with grass weeds, isat risk.
▼ Consolidate seedbeds torestrict movement.
▼ Control grass weeds.
▼ Consider including a springcrop in the rotation.
Seed treatment with tefluthrinor imidacloprid controlsmoderate attacks.
Action thresholdsPopulations can be very patchyso estimating numbers isdifficult. Examining soil cores inthe field for larger wireworms orin the laboratory for smallerones is costly and rarelyjustified.▼ Use a seed treatment if
wireworms exceed thethreshold of 750,000/ha.Some residual damage is likelyif numbers exceed 1.25 M/ha.
The main natural enemies arefungi and parasitic wasps.
Life cycle
WirewormsAgriotes lineatusAgriotes obscurus
Wireworms are the larvae of click beetles.Yellow larvae with distinct legs at the frontand two dark spots at the tail, bite into stemsat the soil surface causing a hole withtattered edges. By the time this is evident,wireworms have usually moved along rows toattack further shoots.
Economic importance
Risk factors
Cultural control
Chemical control
Natural enemies
Wireworms have a 4–5 year life cycle.
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Egg laying.
Adults active. Adults active.
Larvae feed.
Pupae
Adult click beetles cause no economic damage.They live for about a year and lay eggs in grass fields. Larvae then feed for five years beforepupating in the spring. Numbers increase over the years; highest populations occur in old permanent pastures.Wireworms feed inploughed-down turf for about six months before moving to the surface to damage the next two crops.
11
CEREAL PESTS
Yield losses can range up to totalcrop loss at the highest
infestation levels. Loss dependsmainly on September rainfall.
Attacks on all cereals andoilseeds frequently occurfollowing grass, wherepopulations build up.Adults donot fly far and infestations takesome years to develop. Larvaecontinue feeding in plougheddown turf.When it rots they
move to feed on the new crop.This leads to damage suddenlyappearing some weeks aftercrops emerge.
Dry September weather canreduce numbers considerably aseggs and young leatherjacketsare vulnerable to desiccation.
Chlorpyrifos is the onlyapproved chemical.
Action thresholds▼ Assess leatherjacket numbers,
before ploughing, byexamining soil samples orflooding plastic pipes, driveninto the ground, filled withbrine. Proprietary brine-basedtesting kits are available.
▼ Assess leatherjacket numbers,in established crops if damageis seen, by scratching soileither side of crop rows.
▼ Treat with chlorpyrifos if:•over 50 leatherjackets/m2 for
spring cereals (5 in 12 pipes)•5 leatherjackets/m of row in
spring cereals.Lower levels may causesignificant damage in springoilseed rape and linseed.
A range of viral, bacterial andprotozoan diseases attackleatherjackets. Rooks areattracted to patches ofleatherjacket damage and mayindicate infestations. Predatorysoil insects, eg ground beetles,eat eggs and young larvae.
Life cycle
LeatherjacketsTipula paludosa Tipula oleracea
Leatherjackets (grey, legless larvae of cranefly, ordaddy longlegs) feed below the soil surface makingstems at the surface appear ragged. Stems breakand keel over. Wireworms and other minor pestscause similar effects.
Economic importance
Risk factors
Chemical control
Natural enemies
Two species cause economic damage.
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Tipula paludosa
Pupae
Eggshatch.
Eggs scattered onsoil surface, mainly
in grassland.
Larvae feed in winter whenever soil temperatures at night exceed 5ºC.
Adultsemerge.
Flying adults lay eggs.
Larvae Larvae
▼ Plough early before most eggsare laid to reduce carry-over.
Cultural control
Larvaepupate
near soilsurface.
A plastic pipe driven in theground is filled with brine.
12
CEREAL PESTS
Summer aphids
Rose-grain aphidMetopolophium dirhodum
The aphids are green witha dark green strip alongthe body.
Yield losses can reach 4 t/ha,but losses of 0.25–1 t/ha aremore usual where populations
exceed threshold levels. Onlyvery severe infestations producevisible symptoms in crops.
Grain aphidSitobion avenae
The aphids may be green,red or brown.
Economic importance
Both species
All cereals are at risk.Winterbarley is less affected due to itsearlier senescence. Impact isgreater where soluble stemcarbohydrate reserves are low,
eg drought-affected crops orcrops damaged by other pestsand diseases. Dry settled weatherduring early grain fillingincreases the risk.
Risk factors
Measures, such as grass strips,proposed to increase naturalenemies of crop pests, canprovide harbourages for aphids.Wildflower strips with diverse
grass mixture are less likely toharbour pests and willencourage parasitoids andhoverflies.
Cultural control
Pyrethroids are the main choiceto control ear infestations, butare less effective on earlierinfestations on the undersidesof leaves. Pirimicarb providesmore selective control ofaphids.Additionally, it has avapour action which penetratesfurther into the crop.
Action thresholdsTreatments should only beconsidered if aphid numbers areincreasing. Spray when:▼ 50% tillers infested before
GS 61▼ 66% tillers infested from
GS 61 to two weeks beforethe end of grain filling.
Chemical control
The grain aphid spends all yearon cereals and grasses and mayoverwinter on winter cereals(see BYDV vectors). Freshmigrations infest crops from Aprilonwards.
Colonies overwintering oncrops tend to be infested byparasitoids. Grain aphidnumbers may rise initially, butthe parasitoids limit furtherpopulation increase. Outbreakstend to occur after colder
winters which reduce naturalenemies more than the morecold-hardy aphids.
Initially, grain aphids feed onleaves. During grain filling theymove up to ears and feed fromthe phloem supply to grain.
Numbers increase most rapidlyduring settled, dry weather.Theywill increase until checked bycrop senescence, unless reducedby heavy rainfall or naturalenemies.
Life cycle
The rose-grain aphidoverwinters as very frost hardyeggs on roses. It migrates tocrops in spring.
Rose-grain aphids aresusceptible to all grain aphids’natural enemies, so do notthrive in crops alreadycolonised by grain aphids.Afterhard winters when both grainaphid and natural enemies arescarce, rose-grain aphid maycause problems.
These aphids remain on theleaves and do not move up tothe ear.
Life cycle
Natural enemies
Specific to aphidsParasitic wasps, hoverflies,lacewings, ladybirds areattracted to aphid infestationsand can provide control ofpotentially damaging numbers.
Some fungal diseases are alsospecific to aphids.
Polyphagous predatorsGround beetles, soldier beetles,rove beetles, spiders may help tomop up low numbers early in theseason, thus slowingdevelopment.
13
CEREAL PESTS
Each larva reduces grain size by 30–50%. Pericarp damageallows easier water entry, oftenresulting in sprouting in the earand reduced Hagberg fallingnumber.
Damaged seeds are susceptibleto attack by pathogenic fungi,especially Fusariumgraminearum; they may fail to germinate or produce weak seedlings.
Potentially damaging larvalpopulations may be found in anyfield where wheat has beengrown over the past five years.Higher soil populations are likelywhere wheat crops have beenfrequently grown during thisperiod.
Crops growing in fields withhigh resident populations are
more vulnerable to attack whenweather conditions are marginalfor flight.
Midges can fly half a mile ormore in mild evening weather.They accumulate in the mostsheltered fields at thevulnerable growth stage andattack new crops.
Life cycle
Orange wheatblossom midgeSitodiplosis mosellana
The orange-coloured larvae feed on wheat,barley and rye grain during grain filling. Larvaeare up to 3 mm long.They lack legs, but have aprominent head capsule. Adult midges, alsoorange, and about 3 mm long, are found duringear emergence.They rest at the crop baseduring the day and fly up to the ears in theevening to lay eggs.
Economic importance
Risk factors
Chemical control
Natural enemies
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
▼ Reduce the frequency ofwheat crops in the rotation inmore sheltered fields.
▼ Grow resistant varieties,eg Welford.
Cultural control
▼ Apply chlorpyrifos to wheatcrops within a week offinding a threshold number ofmidges laying eggs on theears.
Pyrethroid sprays applied foraphid control may give somecontrol of the midge if thetiming coincides with flight, butthis control is unreliable andnot a label recommendation.
Action thresholdsThresholds refer to numbers ofmidges laying eggs in theevening.The midges can becounted at night using a torchor in early morning.They fly offas temperatures rise.
If several nights are suitableduring ear emergence, countmidges each evening and usethe average figure.▼ For feed crops –
1 midge/3 ears.▼ For milling and seed crops –
1 midge/6 ears.Consider using yellow stickytraps hung at ear height at thestart of ear emergence tomonitor activity. In crops at thethreshold levels, expect to catchabout 10 midges in each trapthrough ear emergence.
Ignore midge activity after thestart of flowering, as eggs laidafter this stage do not developproperly.
Cocoons, containing larvae, can survive for up to five years in the soil. Each year some reactivate and pupate if soil surface is moist.
Larvae feed for twoweeks, then drop to
the soil to formcocoons.
Somelarvae
pupate.
Adults fly.
The most important naturalenemies are small parasiticwasps, especially Macroglenespenetrans. During the day theysearch for and lay their eggs inmidge eggs.This does not reducecrop damage, as the parasitoidlarva does not develop until themidge larva has overwintered.
Parasitism levels can exceed
80% and give useful control. Bynot spraying below thresholdlevels, parasitoid numbers mayincrease and provide longer-term midge control.
Polyphagous predators alsokill adults and can kill larvaedropping to the ground if drysoil prevents them burrowingto safety.
Eggs laid withinflorets in suitablehost crops. Eggs
hatch in one week.
Cabbage aphidBrevicoryne brassicae
This aphid is covered by grey, waxy scales. It is found under leaves and causespuckering and yellowing. Later infestations move on to developing flowers andpods.
14
OILSEED RAPE PESTS
Life cycle
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Only very heavy aphidinfestations cause directdamage. Numbers may increaseafter serious outbreaks ofinsecticide-resistant aphids onpotatoes.
Aphids transmit the beetwestern yellow virus, whichcauses temporary reddening ofinfected plants in spring.Virusinfections have been low inrecent years.
Economic importance
Peach-potato aphidMyzus persicae
The peach-potato aphid feeds on oilseed rape, many other field and protectedcrops as well as weeds. Individuals may be green, yellow or light red. Like cabbageaphids, they are found under leaves.
Earlier-sown winter crops tendto be at greatest risk duringwarm autumns. Later-sown
spring crops tend to be atgreatest risk after mild winters.
Risk factors
Aphids that colonise crops inautumn may have survivedthrough many generations ontreated crops.This may lead tohigh levels of insecticideresistance restricting insecticidechoice.
Three forms of insecticideresistance occur:▼ Kdr resistance to pyrethroids▼ MACE resistance to pirimicarb
▼ E4 strains resistant topyrethroids, pirimicarb and OPs.
Seek expert advice onalternative insecticides ifcontrol is poor. Neonicotinoidseed treatments, such asChinook, currently control allresistant forms for severalweeks following emergence.
The parasitoid, Diaeretiellarapae normally provides goodcontrol.
Chemical control
Life cycle
Aug Sept Oct Nov Dec Jan Feb Mar Apr May June July
The cabbage aphid carriesturnip mosaic virus andcauliflower mosaic virus.Spring rape can become
severely infested after mildwinters and allow infestationson winter rape to increase todamaging levels.
Economic importance
A waxy covering protectscabbage aphid from contactinsecticides, which can limitchoice.
Pyrethroid insecticides may notcontrol cabbage aphid. Considerusing use a higher rate ofpirimicarb plus added wetter.
Chemical control Natural enemies
Cabbage aphid may cause directdamage in spring if over 13% ofwinter rape plants or over 4% of
spring rape plants are infestedbefore petal fall.
Action thresholds
Adults infest other crops. Adults infest crops and transfervirus in mild autumns.Asexual females
overwinter. Coldweather reduces
survival.Asexual females
overwinter.
Infests winter rape. Overwinters on brassica plants. Multiplies rapidly when mild andmay cause direct damage.
15
OILSEED RAPE PESTS
Large numbers of adults feedingin the autumn kill plants,occasionally causing total cropfailure.The pest originallyattacked mustard and brassica
seed crops in East Anglia. It nowcovers England and Wales and isspreading in Scotland.
Crushers may rejectcontaminated seed.
Earlier-sown crops often attractmost cabbage stem flea beetle.
Warmer autumns favour egg-laying and earlier hatch of larvae.
Delaying sowing reduces thenumbers of adults attracted andof eggs laid.
Chinook seed treatmentreduces adult feeding andnumbers of eggs laid.
A pyrethroid spray shouldcontrol feeding adults andlarvae that have not entered themain stem.Treatments persistwell through the winter.One spray usually suffices.
Action thresholdsConsider applying an earlypyrethroid spray if adults haveeaten:▼ over 25% of the leaf area at
the 1–2 true leaf growth stageor ▼ over 50% of the leaf area at
the 3–4 true leaf stage▼ the crop is growing more
slowly than it is beingdestroyed.
If no adult spray applied, applytreatments to control larvae if:▼ over 5 larvae/plant ▼ over 50% petioles damaged.
The main natural enemy is thewasp Tersilochus microgaster,which parasitises larvae inspring.All parasitoids may bevulnerable to pyrethroids.
Parasitoids remain as pupae inthe soil until the next crop, andmay be damaged by ploughing.Minimum cultivation after rapefavours parasitoid survival.
Life cycle
Cabbage stem flea beetlePsylliodes chrysocephala
Adult beetles, 3–4.5 mm long, blue-black or lightbrown in colour, are sometimes seen crawling acrossthe top of trailer loads of grain at harvest.
The adults return to crops just after emergence andchew ragged holes in cotyledons and early trueleaves. Eggs are laid. On hatching, larvae bore intopetioles and continue feeding close under thesurface.These are distinguished from larvae of otherpests by their black head and black plate at the tailend. Later, larvae move into the main stem to feedunder the growing point.
Economic importance
Risk factors
Cultural control
Chemical control
Natural enemies
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Larvae feed on mainstem behind growing
point.
Larvaepupate in
soil.
Larvae continue tohatch if mild and feed in
petioles.
Larvae continue tohatch if mild and feed
in petioles.
Adultsmove to
new crop,mate andeat leavesfor a week
or so.
Eggs laid atthe base of
plants ifmild.
Eggs hatch.
Adults emerge andfeed on foliage.
Adults‘rest’ inmoist,
shelteredplaces.
16
OILSEED RAPE PESTS
Life cycles
The life cycle of the Wessex flea beetle is not fully understood. Adults appear and cause damage in September.
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
The Wessex flea beetle is ofincreasing importance insouthern England. An initialoutbreak in Wiltshire has spreadto other areas. Crops can beseverely checked.
Turnip and striped fleabeetles are principally pests ofspring brassicas.
Crop damage has increasedfollowing the withdrawal oflindane.
Economic importance
Wessex flea beetlePsylliodes luteola
Turnip flea beetlesPhyllotreta cruciferae,Phyllotreta nigripes, etc
Large striped flea beetlePhyllotreta nemorum
Wessex flea beetle is most likelyto damage earlier sown crops,especially if slow to grow awayin September.
Later sown spring crops are
most susceptible to turnip andstriped flea beetles.Any cropsmay be at risk if growth ischecked by sunny, dry weather.
Risk factors
Cultural control
Delay sowing autumn crops andsow in a well consolidatedseedbed to improve seed-to-soilcontact and germination.
Sow spring crops as early assoil conditions and weatherallow.
Chinook seed treatment may beused on winter, but not yet onspring, crops.
Pyrethroid sprays on growingcrops only provide 3–4 daysrespite, but may help a cropsurvive until wetter weatherreturns.
Base spray decisions on samecriteria as for cabbage stem fleabeetle.
Action thresholdsNo thresholds for treatmentexist.
Chemical control
There are some wasp parasitoids.
Natural enemies
Turnip and large striped flea beetles
Hibernation Migrate to crops and feed on leaves.Lay eggs at plant base.
Larvae feed on roots.
Adults emergefrom late July.Direct feedingcan damage
crops.
Hibernation
Other flea beetles
These beetles are smaller than cabbage stem flea beetle. Adults jump away when disturbed.
Attacks crops in the autumn. Attack crops in autumn and spring. Attacks crops in spring.
17
OILSEED RAPE PESTS
Three wasp parasitoidscommonly attack the larvae:Phradis interstitialis, Phradismorionellus and Tersilochusheterocerus.
Minimum cultivation afteroilseed rape will enhance waspsurvival.
Natural enemies
Loss of pod sites from pollenbeetle damage, albeit sometimessevere, rarely reduces winteroilseed rape yields. Cropsusually compensate for earlierlosses, producing more andlarger seeds on lower racemes.
Varietal associations andrestored hybrids may lose moreyield because male fertile plantsare attacked and cross-pollination is reduced.Spring crops are much morevulnerable than winter crops.
Economic importance
Pollen beetleMeligethes aeneus
These small, shiny, black beetles may arrive from thegreen bud stage onwards.They lay their eggs in the buds.Larvae later feed mainly on pollen in the flowers. Larvaehave a head capsule and six legs.
Pigeon and frost-damagedwinter crops that remain at thegreen and yellow bud stages forlonger are susceptible.
Varietal associations, restoredhybrids and later-sown springcrops may also be at greater risk.
The use of ‘canopymanagement’ to optimisepotential pod number mayincrease susceptibility to pollenbeetle.
After all buds on winter cropshave opened beetles migrate toother egg-laying sites, causing asecond flush of migration tospring crops.
Spring crops are less able tocompensate for damage thanwinter crops and so oftenjustify treatment.
Risk factors
Cultural control
▼ Sow spring crops as early as possible.
Resistant strains of beetles haveappeared in France andSweden. Investigate controlfailures to establish the level ofresistance of the population.▼ Only use pyrethroid sprays
during green to yellow budstages if thresholds areexceeded.
Action thresholdsApply chemical controlmeasures if the thresholds areexceeded:Winter oilseed rape▼ over 15/plant at green-yellow
bud▼ over 5/plant for backward
crops▼ over 2/plant for varietal
associations.
Spring oilseed rape▼ over 3/plant at green bud.
(In Scotland 1/plant atgreen bud stage.)
Chemical control
Life cycle
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Eggs laid in buds.
Hibernation HibernationAdults migrate at over 15ºC. Feedon pollen inside buds or in openflowers on oilseed rape plants.
Larvae and then pupae.
Adult beetleshatch and feedon a variety of
plants.
Larvae feeding in flower
18
OILSEED RAPE PESTS
The parasitoids Trichomalus perfectus,Mesopalobus morys and Stenomalinagracilis generally keep numbers in check.
Natural enemies
Life cycle
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Numbers rarely exceed damaging levels on winter oilseed rape.The pest isimportant in allowing entry of brassica podmidge. It may be more important on springoilseed rape.
Economic importance
Cabbage seed weevilCeutorhynchus assimilis
This small black weevil with a curved snout lays its eggsinto developing oilseed rape pods during flowering.A brown scar indicates the egg-laying puncture, usuallycausing a kink in the pod. One white larva with a brownhead capsule develops inside the pod, eating the seeds.
Cabbage seed weevil tends to be of greaterimportance in the northern britain.
Risk factors
Risk factors
Cultural control
Delaying sowing of spring crops reducesnumbers of adults attracted and of eggslaid.
▼ Apply a pyrethroid spray approved foruse during flowering if the threshold isexceeded.This should be applied by petalfall and before too many eggs are laid.
Action thresholds▼ over 0.5/plant
in northernBritain
▼ 1/plantelsewhere.
Several wasp parasitoids, including Omphaleclypealis and Platygaster subuliformis mayattack pod midge, killing up to 75% of larvae.
Chemical control
With damage greatest on headlands andaffected pods very conspicuous, this pestcan be over-rated.
However, spring oilseed rape yields canbe severely reduced.
Economic importance
Brassica pod midgeDasineura brassicae
These small, dark orange midges appear during flowering.Theylay eggs through holes left by seed weevils in developing pods.Many small, white larvae with no obvious head occur in eachaffected pod. They cause swelling and eventually pod burst.
Sprays for seed weevil provide incidentalcontrol of pod midge by reducing egg-laying sites.
Action thresholdsNo thresholds for treatment exist.
Chemical control
Natural enemies
As the adult midge is a weak flyer, crops onheadlands are more exposed to immigrantmidges; thus largest yield losses often occurin small narrow fields.
Cultural control
▼ Block oilseed rape fields and rotate thecrop around the farm to reduce theimpact of immigrant pests.
Overwinters as adults that fly into oilseed rape crops soon after
flowers open.
The weevils lay eggs directlyinto the pod, chemically
marking pods to deter anyfurther egg-laying.
Larva developswithin the pod,eating 3–4 seedsbefore burrowing
out and dropping tothe soil to pupate.
Adult weevils hatch in August and hibernate in non-crop situations.
Life cycle
Larvae can hatch over a three-year period after rape. In June and July partial 2nd or 3rd generations attack late winter and spring rape.
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Larvae overwinter incocoons in soil.
Adults emerge. Larvae overwinter in cocoons in soil.Adults mate. Fly to oilseedrape. Lay eggs in cabbage seed weevil holes or plant damage.
Larvae feed. Pods swelland burst. Larvae dropto soil. Some develop to give 2nd and 3rd
generations of adults.
19
OTHER CEREAL AND OILSEED RAPE PESTS
Frit flyOscinella frit
ThripsLimnothrips cerealiumLimnothrips denticollis
Thrips fly to cereal crops inMay and lay eggs in the boots ofemerging ears.Yield loss mayfollow if young thrips reducesap flow by feeding on stemsand flag leaf sheaths.
Larvae also feed under theglumes and on developing graincausing black spotting, andpossibly reduced flour quality.
Control measures are notusually justified.
There are three generations offrit fly a year, all of which canoccur on ryegrass.▼ First generation flies appear
in May and lay eggs in cerealand grass stems. Larvaecausing a classic deadheartsymptom can severelydamage late-sown spring oats.
▼ Second generation fliesappear one to two monthslater and lay eggs indeveloping oat and wheatgrains. Larvae then feed onthe grain.
▼ Third generation flies hatchfrom harvested grain,sometimes causing atemporary nuisance in stores.Eggs may be laid on ryegrass,allowing larvae to transfer toany following winter cerealcrops sown within five weeksof ploughing out the old ley.
Plough early if possible orcontrol by chlorpyrifos spraysapplied pre- or early post-emergence if the risk is high.
Rape winterstem weevilCeutorhynchus picitarsis
Rape winter stem weevil adultslay eggs in the autumn. Larvaefeed in the stem base throughthe winter. Large numbers mayseverely stunt the crop. Initiallylimited to Lincolnshire andCambridgeshire, the pest has
now spread to other areas.Pyrethroid sprays applied to
control cabbage stem fleabeetle and aphid vectors areeffective against this weevil.
Saddle gallmidgeHaplodiposis marginata
Blood-red coloured larvae hatchfrom eggs and feed under theleaf sheaf causing saddle-shapedgalls. Damage restricts sap flowto the ear and can lead tolodging through stem breakage atthe point of galling. Damage ismost serious on cereal-dominatedrotations on clay soils.
Cerealground beetleZabrus tenebrioides
Cabbagestem weevilCeutorhynchus pallidactylus
Stem weevils lay their eggs inoilseed rape stems in May.Larvae in large numbers canreduce seed filling and, inextreme cases, kill plants.
Adults are difficult todistinguish from those of seedweevil. For practical purposesassess together.▼ Treat if threshold of 2 weevils
a plant of any species, isexceeded.
This pest attacks crops inEngland, from Oxfordshire andCambridgeshire southwards.Larvae burrow into soil, pullingdown and eating shoots fromOctober to May. Adult beetlesfeed on cereal ears before
harvest and on spilt grain andstubble re-growths.Damage is worst in all-cerealrotations and with minimalcultivations. A non-cereal breakcrop or early ploughing willprovide good control.
Adult midges lay rafts of redeggs on leaf surfaces in May.
20
BIOLOGICAL AND CULTURAL CONTROLMany pests have naturalenemies. Sometimes, thesepredators and parasites providesufficient control to prevent anyserious crop damage occurring.Some predators are specific toparticular pests.
Enhanced use of naturalenemies forms a part of‘Integrated Crop Management’.The deliberate introduction ofpredators is not viable in broad-acre arable crops.
Where natural enemy numbersare initially low, serious pestdamage may occur. Pesticidesmay be needed to slow down
the rate of pest increase andrestore the balance betweenpests and natural enemies.
Broad-spectrum pesticidesoften control both pest andnatural enemies removing thebenefits of natural control.Often, pesticides are appliedjust after damage or infestationsare identified. Such treatmentswill prevent beneficial pestsfrom multiplying to populationsthat will significantly reducepest numbers.
If a pesticide application isnot fully effective – due to dose,timing, application technique or
weather conditions – naturalenemy numbers and theirbeneficial effects may bereduced. In such cases, more
severe pest damage may occurdue to reduced natural enemynumbers.
Main natural enemiesPredator Larvae eat Adults eat Comment
Parasitic wasps – Hymenoptera – ParasiticaParasitoid populations depend wholly on pest numbers, rising in response to outbreaks and declining as pest numbers fall.
Endoparasites – live within and consume a single host individual.
Stenomalus micans Gout fly larvae Nectar Initially host larvae develop to full size.Then, parasitoid larvae startto feed, killing them before pupation.
Macroglenes penetrans Orange wheat Parasitoids do not prevent crop damage, but can give longer-termblossom larvae population control if 80%+ of pest larvae are parasitised.
Aphidius rhopalosiphi Grain aphids NectarAdult parasitoids are very sensitive to insecticides, so timing mustbe accurate.
Diaeretiella rapae Cabbage aphids
Ectoparasites – the larvae develop outside the host’s body and may consume several individuals.
Trichomalus perfectus Cabbage seed weevil The adult wasp inserts its egg through a hole bored into the pod by the weevil for egg laying.
Spiders – AraneaeErigone atra Webs typically trap Spiders are particularly vulnerable to pyrethroid insecticides.Lepthyphantes tenuis around 30% of aphids
flying through the cropas well as wheat blossom midge adults and small flying insects.
Hoverflies – SyrphidaeSyrphus ribesii Each larva can eat Nectar Wild flowers in field margins attract hoverflies if local pollenEpisyrphus balteatus c. 400 aphids on arable sources are scarce. Oilseed rape and other flowering crops
crops. A ratio of attract large numbers.1 larva: 30 aphids can Adult hoverflies feed on pollen.control severeinfestations.
Rove beetle
21
BIOLOGICAL AND CULTURAL CONTROL
Local management has moreinfluence on predators than onpests. Many natural enemiessurvive in the soil, whereasmany pests migrate toalternative habitats.
Parasites are favoured byminimum cultivation, althoughcrop regrowth must becontrolled to discourage pestsand diseases.
In marginal habitats, the samemanagement practices canencourage both predators andpests.A mix of diverse grassesand wild flowers shouldminimise pest carry-over.
Alternative host plants formany cereal pests, eg ryegrassor meadow grasses, should beavoided.Tussocky grass beetlebanks may not be appropriate ifbeetle pests attack cropsgrowing nearby.
Enhancing predator survival Cultivation and agronomyCultivations can influence pestcarry-over within a field:▼ Effective destruction of the
old crop, followed by a gap ofat least five weeks, reducescarry-over.
▼ Soil consolidation can hinderpest movement fromploughed down residues togerminating seeds.
Rotations influence pestnumbers available to attacksucceeding crops.
Pest attack is often mostsevere at the edge of the fieldnearest to where the same cropwas grown in the previous year.These edge effects can beminimised by growing severalfields of the same crop togetherin a block. Rotations should beplanned to maximise distancesbetween fields or blocks ofcrops over succeeding years.
Predator Larvae eat Adults eat Comment
Ground beetles – Carabidae
Present in fields all year round.
Pterostichus madidus Slugs and other Slugs and other Also eat weed seeds and plants.P. melanarius invertebrates invertebrates
Trechus quadristriatus Eggs of wheat bulb fly Eggs of wheat bulb fly Favoured by minimum cultivation and stubble re-growth.and cabbage root fly and cabbage root fly
Bembidion ustulatum Springtails and other Springtails and otherpests pests
Overwinter in field margins, flying adults forage in crops during summer.
Demetrias atriapillus Wide range of Cereal aphids and Partially control low aphid populations.Agonum dorsale invertebrates other prey in foliage Favoured by beetle banks and grass margins.
Soldier beetles – CantharidaeCantharis fusca Slugs and soil insects Aphids and other pests Adults hibernate off-crop.Rhagonycha fulva
Ladybirds – CoccinellidaeAdalia bipunctata Aphids Aphids Adults hibernate off-crop. Eggs are laid among aphids.Coccinella Larvae are voracious and can reduce aphid populations.
septempunctata
Rove beetles – StaphylinidaeTachyporus hypnorum Mildew and aphids Mildew and aphids Adults climb cereal stems at night. Hibernate in long grass inT. obtusum in cereals margins and beetle banks.
Aleochara bipustulata Pupae of wheat bulb Develop as parasites on fly pests.A. bilineata fly and cabbage root fly
22
BIOLOGICAL AND CULTURAL CONTROL
Sow a seed mixture containing grasses, egfescues and bents, and wild flowers – usequite low seed rates to reduce costs. Plantsof particular benefit for attracting hoverfliesand parasitic wasps include cow parsley,hogweed, wild celery (umbellifereae) andyarrow, scabious and knapweed(compositeae). Margins are best sown onthe east or north sides of fields to reducehedgerow shading.
▼ sow ryegrass which harbours many pests▼ sow umbellifereae, which attract many
flies, if carrots, parsnips, celery or marketbrassicas are grown.
Action Do not
Action Do not
Action Do not
Action Do not
Enhancing natural enemiesAttract hoverflies and parasitic wasps; also provide food for wild birds, butterfliesand bees.
Provide within-field hibernation sites for ground and rove beetles, spiders andnesting sites for ground-nesting birds, eg partridges and skylarks.
Enhances parasite activity on oilseed rape pests and survival of spiders.
Allow specific natural enemies, eg parasitic wasps, ladybirds, hoverflies andlacewings to build up on host pests.
Field margin strips
Plough up rigs from opposing sides tocreate a bank splitting larger fields. Sowwith tussock-forming grasses, eg cocksfoot,red fescue and timothy. Avoid sprayingadjoining crop with insecticides. Beetlebanks provide the greatest benefit in largefields where non-crop habitats are limited.
▼ use if cereal ground beetle is a problem.
Beetle banks
Use minimal cultivations, wherever possible,to enhance carry-over of natural enemiesand enhance spider survival. Ploughingreduces numbers of natural enemies whichpupate in the soil, eg parasitic wasps.Rotational ploughing is advisable whereherbicide-resistant grass weeds or cerealground beetle pose problems.
▼ use after oilseed rape if in an area proneto disease.
Minimal cultivation
Follow label requirements for missinginsecticide sprays on headlands in thesummer and follow LERAPs guidelines forbuffer zones near watercourses.Conservation headlands, with reduced broad-leaved herbicide use, enhance the benefit.
▼ reduce the buffer zone for pesticides withan A LERAPs classification (includes mostinsecticides)
▼ spray insecticides on a conservationheadland after 15 March.
LERAP* and conservation headlands
* Local Environment Risk Assessment for Pesticides
23
CEREAL PESTSFURTHER INFORMATIONHGCA guidesArable cropping and the environment – a guide, 2002
HGCA Topic Sheets Posted free to levy payers on request.
32 Minimising pesticide usage on cereals and oilseed rape
38 Dealing with wheat bulb fly
39 BYDV control based on aphid monitoring
45 Summer pest control on wheat
48 Seed treatments for pest control in winter oilseed rape
HGCA Research Reviews (cereals)*
10 The biology and control of cereal aphids
28 Orange wheat blossom midge: a literature review and survey of the1993 outbreak
33 Impact of changes in arable agriculture on the biology and control ofwheat bulb fly
HGCA Project Reports (cereals)*
47 Slug forecasting in cereals
53 Research on slug behaviour: I The role of soil water in regulating theactivity of terrestrial slugs II Cultural methods to reduce slug damagein cereals
56 Improving the forecast of BYDV high risk conditions in autumn-sowncereals
67 Control of wheat bulb fly in winter wheat: I Chemical methods IIVarietal susceptibility
87 Monitoring aphids and virus to improve forecasts of barley yellowdwarf virus
106 Orange wheat blossom midge: survey of the 1994 outbreak
110 Determination of factors affecting grain aphid movement withreference to spread of BYDV in the autumn and winter andforecasting direct damage in the summer
112 Assessing modern cultivars of winter wheat for damage by the greyfield slug
120 The epidemiology of a new leatherjacket pest (Tipula oleracea) ofwinter cereals in northern Britain
129 Key factors for modelling secondary spread of barley yellow dwarfvirus
135 Aphid and virus dynamics to improve forecasts of barley yellow dwarfvirus risk
148 Effects of polyphagous invertebrate predators on cereal pests
155 Aphid sex pheromones to enhance parasitoid efficiency
173 Integrated farming systems (a field-scale comparison of arablerotations) I Experimental work II The economic evaluation of inputdecisions
198 Evaluation of opportunities for dissemination of national pest anddisease information
205 Development and validation of decision support methodology forcontrol of barley yellow dwarf virus
206 The importance of barley yellow dwarf virus (BYDV) infection inspring barley and opportunities to manage the disease
226 Improving the efficacy of chemical control of wheat bulb fly
229 Appropriate aphicide doses for summer aphid control on wheat
HGCA Research Review (oilseeds)*
OS1 Insect pests of oilseed rape
HGCA Project Reports (oilseeds)*OS14 The status and potential of parasitoids of seed weevil and pod
midge on winter oilseed rape
OS43 Alternative seed treatments to gamma-HCH for controlling cabbagestem flea beetle on winter oilseed rape
OS54 Seed dressings to control slug damage in oilseed rape
OS57 The further development of seed treatments to control cabbagestem flea beetle and other pests on winter oilseed rape
OS60 Control of slug damage in oilseed rape by seed treatment –development and field tests
Websites
HGCA: www.hgca.com
Crop Protection Association:www.crop-protection.org.uk
Game Conservancy Trust:www.gct.org.uk
Leaf:www.leafuk.org
Maltsters’ Association of Great Britain:www.ukmalt.com (includes list of Agrochemicals accepted by the British Beer and Pub Association andBrewing Research International for use on malting barley).
Pesticides Safety Directorate:www.pesticides.gov.uk
Rothamsted Insect Survey:www.rothamsted.bbsrc.ac.uk/insect-survey/
Voluntary Initiative:www.voluntaryinitiative.org.uk
Books
The UK pesticide guide, CAB International, 2003.
Pest and Disease Handbook, D V Alford, Blackwell Science, 2000.
Biocontrol of Oilseed Rape, D V Alford, Blackwell Science, 2003.
Legislation
In Great Britain, the storage, supply, advertisement, sale and use of pesticides areregulated by The Control of Pesticides Regulations 1986 (as amended) (COPR), ThePesticides (Maximum Levels in Crops, Food and Feedingstuffs) (England and Wales)Regulations 1999 (as amended) and in Scotland by The Pesticides (Maximum Levelsin Crops, Food and Feedingstuffs) (Scotland) Regulations 2000, and commonlyreferred to as the MRL Regulations. Similar legislation exists in Northern Ireland.This legislation implements Part III of The Food and Environment Protection Act1985 (FEPA).
NOTE: *Project Reports and Research Reviews are available at cost from HGCA.
AcknowledgmentsThis guide represents a knowledge transfer project.The guidedescribes general principles developed through HGCA and/orDefra-funded research.
Written by Jon Oakley, ADAS and edited by Dr Clive Edwards,HGCA; and Geoff Dodgson, Chamberlain.
The editors acknowledge the helpful comments made by manyexperts including: John Young, BASF; Dr David Cooper, Defra;Professor Graham Jellis, HGCA; Philip Morrall, Bairds Malt andStan Sole, Crisp Malting on behalf of MAGB;Alan Bide and SteveCook, Hampshire Arable Systems; Sue Mattock, Dr DavidRichardson and Martin Roberts, Defra PSD; Julian Hasler, NFU;Dr Richard Harrington, Dr Wilf Powell and Professor IngridWilliams, Rothamsted Research; Dr Andy Evans, SAC Edinburgh;Michael Tate, Syngenta.
Design by Chamberlain.
For information on HGCA services:
Research and DevelopmentTel: 020 7520 3945E-mail: [email protected]
Crop MarketingMarket Information (MI)Tel: 020 7520 3972E-mail: [email protected]
British Cereal Exports (BCE)Tel: 020 7520 3925E-mail: [email protected]
Market DevelopmentTel: 020 7520 3901E-mail: [email protected]
PublicationsTel: 020 7520 3920Fax: 020 7520 3931E-mail: [email protected]
Website: www.hgca.com
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© HGCA 2003
