before considering the other limited

alternatives. Try not to spray until

absolutely necessary to avoid

driving further resistance.

Once emerged oilseed rape can be

quite tolerant of CSFB grazing.

It has been suggested that thresholds for damage are when:

• 25% of leaf area is lost at the 1-2 leaf stage

increasing to

• 50% of leaf area lost at the 3-4 leaf stage.

As a group pyrethroids are prone to ‘lock-up’ if applied in

hard water. This means that the effective active ingredient

available for control is reduced - sometimes by as much as

50%. Trials have shown that adding a water conditioner to

the spray water before mixing the insecticide reduces the

in-tank lock-up of the active ingredient The amount of active

ingredient arriving at the site of activity is significantly

increased in the critical period after application.

Promoting early and vigorous

growth of the oilseed rape plants

will be key to enable them to cope

with adult CSFB grazing. ProCam

trials have identified certain foliar

nutrition/growth stimulant products

including Universal Bio, phosphites

and zinc ammonium acetate that

produced significant increases in

oilseed rape root and shoot growth

over conventionally fertilised plants.

As well as CSFB attention will have to be paid to aphids i.e.

Myzus persicae the Peach Potato aphid - the main vector for

the spread of Turnip Yellow Virus (TuYV). Most M. persicae

are resistant to pyrethoids and pirimicarb. Control will rely on

pymetrozine e.g. Plenum and other options e.g. thiacloprid

- Biscaya. Currently M. persicae numbers caught in traps

are low but may rise steeply if temperatures remain high in

September. Your ProCam agronomist will have the latest

information on the optimum timing and product selection to

suppress CSFB and TuYV and promote crop growth.

A major threat to oilseed rape establishment this autumn will

again be Cabbage Stem Flea Beetle (CSFB). The lack of any

neonicotnoid seed treatments means crops will be even more

vulnerable to early adult beetle grazing. Some areas have

had adequate rains to encourage rapid crop germination

and growth but many parts remain dry and crops are slow to

emerge. There are signs, as September starts, that adult CSFB

are emerging from their summer rest period and evidence

of shotholing is being found on early emerged plants. Close

monitoring is needed at this time as this is the stage at which

the crop is most vulnerable.

The beetles can feed on and

destroy the growing point and in

high infestations can kill seedlings

even before they emerge. Once

the cotyledons are through, the

crop is usually more tolerant

of attack. Resistance to the

pyrethroid group of insecticides has been identified within

the CSFB population although the level of the resistance

varies within field populations across the UK. However,

pyrethroids should still be the first starting point for control

New SeaSoN PoiNterSFine weather in August has allowed good progress with harvest and cultivations but the attention is already shifting to weed and pest control in new season crops.

Technical UpdateSEPT ’16

Conventional

Universal Bio

Procam Agriculture Tel: 01763 261592 Fax. 01763 262504Fieldcare South Tel: 01777 839000 Fax. 01777 839111

The dormancy of blackgrass seed shed from this year’s

plants has often been used to give guidance on the most

effective cultivation strategy and the likely benefit of ‘stale

seedbeds’ in reducing blackgrass seed burden prior to

drilling. To date there has been no confirmation of the

2016 dormancy levels. However, temperatures through late

June and early July when blackgrass seed was maturing

were at or slightly above the long term average.

This would suggest dormancy levels may be at least on

a par with last year’s moderate level or even possibly a

little less dormant.

However, the value of any stale seedbed in reducing

blackgrass numbers will be most dependent on the quality

of the ‘seedbed’ - fine and firm to ensure good seed/

soil contact - and the presence of moisture to get the

shed blackgrass seed to grow. Delaying drilling, ideally

into or past mid-October will also allow time for a lot of

blackgrass seed to ‘flush’.

N.B. the dormancy factor only applies to seed shed this

year. Old seed in the soil from previous years will have no

dormancy restrictions and should germinate quickly in

favourable conditions.

The majority of blackgrass seed will germinate in the top

5 cm of soil. This was confirmed in a simple but effective

ProCam trial. A set number of blackgrass seeds collected

from the same population source was planted in pots

at varying depths and the emergence monitored at 14

day intervals. The table below confirms that the majority

of seed in undisturbed ground will germinate from the

surface and the top 5cm of soil.

A shallow cultivation strategy may avoid bringing up

seed from deeper in the soil profile and adding to the

blackgrass burden. However, this will only work if soil

structure is in good order. Any restriction to water

movement through the topsoil will limit the effectiveness

of herbicides and be more conducive to the blackgrass.

So cultivation and drilling strategies need to be adapted

to individual field requirements following soil examination.

Key action points for grass weed control this autumn:

Before drilliNg

• Spray off any emerged blackgrass – in fine,

consolidated, moist ‘stale seedbeds’. There will be

some good opportunities this year, but patience will

be required for optimum benefit. Seed from previous

seasons will germinate quickly after cultivation

- if adequate moisture is available.

• Be flexible in selecting cultivation/drilling strategies.

Be prepared to modify operations to field

requirements.

at drilliNg

• Don’t drill too early! Drilling later allows more time

to remove grass weeds before drilling BUT even more

importantly residual herbicides will work better if

applied to cooler, wetter soils - more likely to be found

in early to mid October than September!

• Attention to seedbed quality is essential. For maximum

residual herbicide effect seedbeds need to be fine and

firm - No Clods! If another cultivation pass is needed

do it!

• Aim to establish a competitive crop. Check Thousand

Grain Weights and adjust seed rates accordingly.

• Drill the worst blackgrass fields last to get the optimum

benefit from a ‘stale seedbed’.

HerBicide StrategieS

• Use a robust pre-emergence residual herbicide

’stack’ and/or sequence ideally with 4-5 different active

ingredients. Trials have shown that increasing the

number of elements from different herbicide groups

in a ‘stack’ improves overall control. Equally important

it minimises the risk of developing resistance within the

grass weed population.

• Apply residual herbicides pre-weed emergence

and within 48 hours of drilling. This becomes more

important with later drilling into moist soils when rapid

grass weed germination and growth can be expected.

graSS weedSControl StrAtegy

2016

The ProCam orb and ‘Agronomy that Delivers’ are trademarks of ProCam Europe Ltd. ProCam Agriculture, Saxon Way, Melbourn, Royston, Hertfordshire SG8 6DN Fieldcare South, Agronomy House, Gamston Airfield, Gamston, Retford, Notts DN22 0QL

www.procam.co.uk

% Blackgrass Emergence

25-Nov

09-Dec

23-Dec

06-Jan

20-Jan

03-Feb

17-Feb

0cm 29 31 38 41 54 54 54

0-5cm 5 7 9 10 11 11 11

5-10cm 1 3 4 4 5 5 5

10-15cm 0 0 1 1 1 1 1

15-20cm 0 0 0 0 0 0 0