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Agronomy Support

Agronomy Update – 10 September 2014

In this Edition

Which pre-emergence for grassweeds in winter wheat?
Complete the programme to control weeds in grassland.
Reduce winter N losses from FYM, biosolids or digestate.

This Edition’s FAQs:  
Does Dow AgroSciences have anything for Cabbage Stem Flea Beetle in rape?
What do you think about Centurion Max in Oilseed Rape grassweed programmes?
Can I use Galera this autumn?

Dates for the diary

Which pre-emergence for grassweeds in winter wheat?

Drilling cereals Mundford Norfolk2 - 9-11-12Farmers recognise the integration of cultural and chemical programmes is vital to keep the menace of grassweeds in wheat in check.

At least 97% control of blackgrass is required to prevent populations increasing. Ryegrass too is becoming more difficult to control chemically and sterile brome can compete and grow very quickly, so here too a pre-emergence as part of the integrated programme can help achieve higher levels of control and avoid increasing weed burden.


Blackgrass Ryegrass Sterile Brome*
1st choice  240g/ha flufenacet applied pre-emergence
e.g. Liberator 0.6 L/ha, Crystal 4.0 L/ha. Additional actives may be stacked.
Prosulfocarb e.g. Defy 4.0-5.0 L/ha
+/-Stomp Aqua 1.75 L/ha
Flufenacet + PDM
e.g. Crystal 4.0 L/ha
Alternative choice See above PDM e.g. Stomp Aqua 3.5 L/ha
or Flufenacet based e.g. Crystal 4.0 L/ha
or Liberator 0.6 L/ha or Vigon 1.0 L/ha
e.g. Stomp Aqua 2.6 L/ha

*2000g PDM required overall in the brome programme
PDM & Stomp Aqua can be interchanged for PicoPro

Follow up post-emergence with UNITE® (blackgrass and early bromes) and Broadway® Star (bromes, ryegrass) at the 1-3 leaf stage of the grassweed when actively growing.

Take some tips on beating blackgrass.

Complete the programme to control weeds in grassland.

Sequences of DoxstarPRO® or Pastor® are supported for dock control by Dow AgroSciences.

If you have used half-rate DoxstarPRO (1.0 L/ha) or Pastor (2.0 L/ha) earlier this year, do remember to top-up with the remaining half dose to give the best chance of good weed control. Treating docks 2-3 weeks post-cut is ideal as docks will have fresh, even re-growth which is readily receptive to spraying.  Docks are best treated at the rosette stage.

Treatment is best made when docks are actively growing (but for Pastor must be completed by 31st Ocober).  Apply with a water volume of 300 L/ha. If weed numbers are high or if the sward is dense, increase to 400 L/ha.

Reduce winter N losses from FYM, biosolids or digestate.

Many farmers apply FYM, biosolids or digestate to stubbles in the autumn. These are valuable sources of nitrogen but is liable to loss over the winter.  Crops on light sandy/leachy soils are most at risk of loss.

N-Lock™ can help maintain this nitrogen over winter.  Applying N-Lock just before muck application will inhibit conversion of ammonium to nitrate. When applied when soil temperatures are declining ( and below 15°C), N-Lock will reduce nitrogen lossses from nitrification by 50% through the late autumn and winter months.

Incorporate manure and N-Lock within 10 days of N-Lock application. N-Lock may be mixed with glyphosate.

This edition’s FAQs:

Does Dow AgroSciences have anything for Cabbage Stem Flea Beetle in rape?

We are very aware this autumn, without neo-nic seed treatments, growers and agronomists are very concerned about crop damage but on this occasion, Dow AgroSciences are not able to provide a pest solution.

What do you think about Centurion Max in Oilseed Rape grassweed programmes?

Applications of Centurion Max should be made in October followed, at least 14 days later, by Kerb® Flo 500 or ASTROKerb® in November. This approach maximises the opportunity to achieve the best blackgrass control and minimises the possibility of negative crop effects. Independent trials established in autumn 2013 proved how effective a programme of Centurion Max followed by Kerb Flo 500 or ASTROKerb can be in controlling high levels of blackgrass in oilseed rape crops.

Can I use Galera this autumn?

Galera® (MAPP 11961) can be used this autumn. All farm stocks need to be used by final approval date 30th September 2015.  (Please note, Dow AgroSciences will cease selling Galera, MAPP 11961, on 30th September 2014. It can be sold by distribution until 31st January 2015).

Next year, Dow AgroSciences will be selling re-registered Galera (MAPP 16413) which can only be used from 1st March  and will have no autumn approval.

Dates for the diary

 If you have questions or queries relating to any of our products or would like to speak to one of us face to face, come and visit us at your local event.

Nov 19th AgriScot, Ingliston
Nov 19th-20th Croptec, Peterborough


For more regular updates on agronomic issues, find us on Twitter and Facebook!

If you require any further information please contact our technical Hotline on 0800 689 8899 or your local Dow AgroSciences representative.

More information can be found at uk.dowagro.com

Use plant protection products safely. Always read the label and product information before use. For further information including warning phrases and symbols refer to label.

® Trademark of the Dow Chemical Company (“Dow”) or an affiliated company of Dow. All other brand names are trademarks of other manufacturers for which proprietary rights may exist.

ASTROKerb contains aminopyralid and propyzamide
Broadway Star contains pyroxsulam and florasulam
DoxstarPRO contains fluroxypyr and triclopyr
Galera contains clopyralid and picloram
Kerb Flo 500 contains propyzamide
Pastor contains clopyralid, fluroxypyr and triclopyr
UNITE contains pyroxsulam and flupyrsulfuron-methyl-sodium
N-Lock is a novel micro-encapsulated form of nitrapyrin

Dow AgroSciences Limited, Latchmore Court, Brand Street, Hitchin, Hertfordshire, SG5 1NH.Tel: +44 (0) 1462 457272. Technical Hotline: 0800 689 8899 | UKHotline@dow.com | uk.dowagro.com


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Grassweed Emergence Monitor


Plan Your Blackgrass/Grassweed Management

Effective weed control depends on understanding specific opportunities in each crop in the rotation. Combating grassweeds requires a mix of approaches, and cultural control techniques should always be used in combination with a robust herbicide programme.

A crucial step to achieving successful control of headache grassweeds in winter wheat is to monitor when grassweeds emerge, so that post-emergence treatments can be applied when weeds are small and actively growing. Over the last three years, Dow AgroSciences’ Grassweed Emergence Monitor (GEM), in conjunction with ADAS, has been a useful tool for showing how quickly blackgrass, sterile brome and ryegrass grow away in the autumn.

This autumn we are focusing on blackgrass in winter wheat. Sites will be placed in two key blackgrass areas of the UK – Cambridgeshire and Oxfordshire, where they will be monitored every two weeks.

GEM includes:

  • Blackgrass sown 500 seeds/m2 and a “natural” unsown blackgrass population
  • Two planned drilling dates – late September and late October

It is important to remember that germination of grassweeds will also be subject to local factors and the information provided by GEM should supplement but not replace field monitoring.

If you would like to receive the latest GEM report directly to your inbox or would like to find out more about this service, please contact our Technical Hotline on 0800 689 8899, your local Dow AgroSciences representative or E-mail – ukhotline@dow.com.

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Report 1 – 8th October 2014

This week’s report:

To date, only the early drilling dates have been completed at both sites, and initial results are presented. As reported in the press, September has been a very warm and dry month. Soil temperatures at 30cm at the time of drilling (22nd Cambridgeshire and 27th Oxfordshire) were approximately 15°C. Maximum air temperatures remained at 17-20°C in the two weeks after drilling and have dropped down to 15°C in the last couple of days. Although little rain fell in September (~9mm at both sites) the heavy clay soils have moisture present. No emergence has occurred in Oxfordshire but there has been 5% emergence in Cambridgeshire. The blackgrass is at 1 leaf.

           08.10.14 Oxfordshire early drilled

All sown grassweeds are drilled at 500/m2. No herbicide treatment applied.

Current Advice for Grassweed Control in Winter Wheat:

This year blackgrass is predicted to have moderate dormancy, compared to the low dormancy seen in 2013. In practical terms this means that where moisture is not a limiting factor, germination from seed shed this season will neither be very rapid or very slow. Monitor crops closely as optimum time for blackgrass treatment is 1-3 leaves.

The drier than average September, coupled with high blackgrass populations, means that stale seedbeds may not have been overly effective. A robust and comprehensive herbicide programme is needed. A pre-emergence herbicide should be applied as soon as possible after drilling; this should then be followed post emergence by a combination of residual and contact herbicides. Aim to complete the programme in the autumn on as small a target weed as possible. Where conditions have been dry, consider delaying drilling.

Conditions are good for activity of UNITE® on blackgrass, which in common with all ALS-inhibitor graminicides works best when grassweeds are actively growing.

Where no pre-em has been applied due to dry soils, apply 240 ai g/ha flufenacet with UNITE + adjuvant.

Where a pre-em was applied but has not been totally effective due to dry soil conditions, add a ROBUST dose of residual partner + UNITE + adjuvant. Choose partner on basis of knowledge of the field / blackgrass population.

Don’t forget many broad-leaved weeds and other grassweeds will be controlled by UNITE which will alleviate many tank-mixing and sequencing issues. Mixes of UNITE + adjuvant + residual partner + BYDV insecticide are supported.

For further information on grassweed control in winter wheat see Topic Sheet 19 (Blackgrass) and Topic Sheet 20 (Brome & other grassweeds).

Use UNITE where blackgrass is the driver-weed.

Use Broadway®  Star where ryegrass, wild oats and bromes are the driver-weeds.

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Leatherjacket Report – Autumn Update 30th September 2014

crows and rooksRecent reports of adult crane-flies in Central England and Northern Ireland mean growers need to be alert for damage. Earlier this spring the SRUC reported numbers in the soil at the highest recorded levels in 39 years.

Adult crane-flies lay eggs July-September particularly on grassland or in “grassy” stubbles. Hatched leatherjackets are vulnerable to desiccation especially when young, however the rainfall forecast next week may aid their survival. Growers should be alert for any damage particularly on newly established cereals and grass leys.

Leatherjacket Damage Thresholds

 >0.3-0.5 million/ha (30-50/m2) Damage likely in new ley or cereal
 >0.5-0.6 million/ha (50-60/m2) Autumn population in grassland likely to cause damage in following cereals.
 >1 million/ha (100/m2) Population in permanent grass where treatment likely to give economic benefit.
 >2 million/ha (200/m2) Population in permanent grass likely to show visible damage if untreated.


crows and rooks

Crows and rooks feeding on larvae

leatherjacket larvae

Leatherjacket larvae


Fields with a history of leatherjacket damage should be monitored for large numbers of rooks and crows feeding on the larvae. Risk assessments and testing for the presence of leatherjacket larvae will provide a good indication of fields that are most likely to need treatment.

For cereals applications may be made from post-drilling.

Find out more about controlling leatherjackets in grassland and cereals.

If treatment is justified use Equity® at 1.5 L/ha applied in 200 to 1000 litres of water/ha.

If using Dursban® WG at the recommended rate is 1.0 Kg/ha applied in 200 to 1000 litres of water/ha.

Be aware control will be reduced if soil temperatures are below 5°C or soils are dry as the larvae will move deeper into the soil profile.

Use low drift nozzles and extend buffer zones to preserve Dursban WG and Equity use.

For conventional boom sprayer:

  • Use LERAP – low drift – three star nozzles
  • AND adopt a 20 metre no-spray buffer zone (1 metre for dry water bodies)

Say No to Drift




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Kerb Weather Data

Soil Moisture Deficit - Top 10 - 3rd October 20142nd Report – week ending 17th October 2014 


Welcome rain has caused moisture deficits to drop across the country and blackgrass to grow, however soil temperatures at 11°C – 14°C are still too warm for outstanding results to be achieved with Kerb® Flo 500  for blackgrass control.

Propyzamide, the active ingredient in KerbFlo 500, in common with other residual herbicides breaks down quickly in warm soils. If you treat now, it is likely the speed of breakdown will lead to insufficient concentration of propyzamide in the rooting zone of the blackgrass, inevitably leading to poorer levels of control.

For optimal blackgrass control Dow AgroSciences recommend Kerb Flo 500 applications are made when soil temperatures have got down to 10°C and falling, and there is sufficient soil moisture in the soil for plant uptake. Both these criteria are rarely met before November.

This advice has been proven in extensive trials over many variable autumns. Similar advice would apply to ASTROKerb®

More Kerb Weather Data will be supplied as the season progresses.

Check out application conditions for your local postcode

life cycle logo with strap line

Click on the My Farm LifeCycle to check out forecast conditions for optimizing Kerb Flo 500 and ASTROKerb applications on farm. Simply enter your postcode in the banner and click GO to view the results.



If I wait, won’t the blackgrass roots be too big/too deep for outstanding control?

Propyzamide, the active ingredient for blackgrass in Kerb Flo 500 and ASTROKerb, works mainly by root uptake in the top 5 cms of soil. As long as the oilseed rape has been established using min-till techniques, the majority of the blackgrass will be shallow rooted and even when it develops a more extensive root system, is still likely to have sufficient roots in the Kerb activity zone for uptake.

With high populations of blackgrass the use of programmes to give control is increasingly vital. Adding a “fop or dim” with good blackgrass activity as a sequence e.g. Centurion Max, or where supported in tank-mix e.g. Laser, nearly always improves control and is frequently better than carbetamide/propyzamide programmes.

Independent trials established in autumn 2013 have proved how effective a programme of Centurion Max, followed by Kerb Flo 500 or ASTROKerb, can be in controlling high levels of blackgrass in oilseed rape crops. Applications of Centurion Max should be made in October followed by Kerb Flo 500, or ASTROKerb, in November (N.B. There should be a 14 day gap BEFORE or AFTER application of Centurion Max).

Download Topic Sheet 16 “Advice for Blackgrass Control in Oilseed Rape” for further advice.


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