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Agronomy Support

Agronomy Update – 27 January 2015

In this Edition

Managing Early Season Cleavers with Grassweeds

This Edition’s FAQs: 
What weather conditions are ‘best’ for applications of UNITE and Broadway Star?
What is the risk of Wheat Bulb fly this spring?
Slugs have eaten my rape! What can I plant now?
Can I still use Galera?

Dates for the diary

Managing Early Season Cleavers with Grassweeds

cleavers in WWWith the mild autumn cleavers have been germinating. Tying-in control with targeting grassweeds presents a highly cost effective opportunity to have a go at these most yield robbing weeds before they start to compete.

Consider the following scenarios:

Scenario 1 – UNITE® is best suited when…

  • Blackgrass is up to GS24
  • +/- A range of other weeds are present – brome, ryegrass, cleavers, cranesbill, etc.
  • You want to get the T0 fungicide on e.g. Bravo 500 on as well

Scenario 2 – Atlantis WG + Spitfire® are best when…

  • Blackgrass post GS24
  • A tank mix with Spitfire @ 0.5 – 0.6 L/ha delivers:
    • Complete control of cleavers
    • Wider broad-leaved weed spectrum (vs. straight florasulam/amidosulfuron)
    • Superior control (activity in cold)
    • Split dose ALS flexibility (vs. amidosulfuron)

This Edition’s FAQs

What weather conditions are ‘best’ for applications of UNITE and Broadway Star?
Broadway® Star and UNITE in common with all ALS-inhibitor graminicides, require 2-3 days of ‘active’ growth either side of the application. For this to occur, soil temperature (measured at 10 cms deep) needs to be a minimum of 6°C, ideally 8°C.  This surface soil temperature can change significantly at this time of year within a short period of time quickly rising after a period of cooler/frosty weather when milder weather returns, presenting an opportunity for active growth to occur and spraying to take place. Where it is possible to travel, farmers should be vigilant if conditions are mild and favour active growth as these are good opportunities for grassweed control with Broadway Star (bromes, ryegrass, wild oats and broad-leaved weeds) or UNITE (blackgrass and broad-leaved weeds).

What is the risk of Wheat Bulb fly this spring?
Overall the risk is low however many crops have been late drilled to help control blackgrass and these may be at risk. Check out our latest  Pestwatch report for more detail.

Help! Slugs have eaten my rape! What can I plant now?
Some are thinking ahead as to spring cropping options just in case the rape does not pull through. Options after a November-January application of Kerb® Flo 500 include April drilled spring oilseed rape at own risk. We advise ploughing but are aware of farmers who have successfully established spring rape without doing so. Following crops of beans or peas need a 10 week interval after application of Kerb Flo 500 to the previous oilseed rape.

Spring oilseed rape can be drilled if the oilseed rape crop has been treated with ASTROKerb®.  Again  own risk and just like Kerb Flo 500, we advise ploughing. Don’t drill spring beans or peas!

Can I still use Galera?
We have been receiving reports of sow thistles germinating in rape.  Galera® ([old] MAPP 11961) purchased from distribution by Jan 31st can still be used throughout 2015 up to 30th September, (in effect this spring) including January/February.

Galera oilseed rape herbicide has now been re-registered as MAPP number 16413.  In line with all other clopyralid containing products in the UK, autumn use is now withdrawn.  New label Galera (MAPP 16413) can only be used from 1st March 2015 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.

Feb5-7thFarm Tractor & Machinery Trade Association Show, Naas, ROI
Feb25thRoyal Northern Agricultural Society Spring Show, Inverurie

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
Galera contains clopyralid and picloram
Kerb Flo 500 contains propyzamide
Spitfire contains fluroxypyr and florasulam
UNITE contains pyroxsulam and flupyrsulfuron-methyl

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 are 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 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 please complete this form.  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.

Related Links

Print                               broadway-star     broadway-sunrise

Report 6 – 18th December 2014

This week’s report:

After the coldest fortnight so far, with average minimum air temperatures below 2°C and average maximum temperatures at around 8°C, soil temperatures are around 6°C in Cambridgeshire and 7°C in Oxfordshire (measured at 30 cms – see temperature advice below). It has rained to some degree every day at both sites keeping the clay soils wet and minimising opportunities for spraying.

Blackgrass emergence has ceased but plants have continued to grow. In the early drilled the largest plants are producing their third tiller and the smallest their first; in the later drilled plants are first tiller and the smallest now up to 2 leaves.

Grassweeds, in particular blackgrass will grow at a base temperature below 6°C however this growth is not active, it is slow.

18.12.14 Cambridgeshire early drilled

18.12.14 Oxfordshire early drilled

18.12.14 Oxfordshire late drilled

18.12.14 Cambridgeshire late drilled

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

Current Advice for Grassweed Control in Winter Wheat:

UNITE®, in common with all ALS-inhibitor graminicides, requires 2-3 days of “active” growth either side of the application. For this to occur, soil temperature measured at 10 cms deep need to be a minimum of 6°C ideally 8°C. This surface soil temperature can change significantly at this time of year within a short period of time quickly rising after a period of cooler / frosty weather when milder weather returns, presenting an opportunity for active growth to occur and spraying to take place. Where it is possible to travel, growers should be vigilant if conditions are mild and favour active growth as these are good opportunities for grassweed control with UNITE.

Consider including additional residual e.g. e.g. 240 g ai/ha before 31st December /120 g ai/ha after 31st December flufenacet, particularly where no pre-emergence has been applied or where it has been ineffective, or where further emergence of grassweeds is expected. For more recent drillings include a residual partner as further emergence is likely. Choose partner on basis of knowledge of the field/blackgrass population.

For optimal results:

  • On pre-tillering blackgrass apply UNITE in 130 – 150 litres of water per hectare as a FINE-MEDIUM spray with either CFF, VPFF or Defy Nozzles
  • For tillering blackgrass apply UNITE in 150 litres of water as MEDIUM spray with either CFF, VPFF or Twin fluid nozzle

Where local conditions are not ideal for application of UNITE, consider applying appropriate residual grassweed herbicides such as flufenacet, PDM or prosulfocarb sprays to ‘manage’ the grassweed populations. Follow with UNITE + adjuvant + /- residual partner when suitable conditions arise.

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.

The next edition of GEM will be when conditions improve in the New Year.

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Wheat Bulb fly Pestwatch

Report 2 – 22nd January 2015

Dow AgroSciences in conjunction with ADAS, are monitoring Wheat Bulb fly egg-hatch.

This pest tends to be a problem of the eastern counties from Essex to Yorkshire but can occasionally be a problem elsewhere. Wheat, barley and rye following fallow, potatoes, vining peas, sugar beet and onions are at most risk. Oats are not attacked. Many have delayed drilling until November to help control blackgrass.  Late drilled or backward crops where they only have one or two tillers at the time of Wheat Bulb fly egg-hatch in January/February are particularly vulnerable to damage. Crops sown after the end of March are unlikely to be attacked.

With many oilseed rape crops harvested particularly early last year, some farmers are concerned that their following cereals maybe at risk; however over many years the ADAS/HGCA survey has generally not found high numbers of Wheat Bulb fly eggs following oilseed rape.

Dimethoate sprays which were used for treatment when Wheat Bulb fly damage was seen are no longer approved so it is now even more important to identify fields which are of most risk. Treatment is now confined to preventative insecticidal seed treatments and/or treatment with chlorpyrifos (Dursban WG or Equity) at egg-hatch.

The latest HGCA Wheat Bulb fly survey indicated that only 1 field out of the 30 surveyed in eastern and northern England were above the 250 eggs/m2 economic treatment threshold for early/mid-autumn drilled crops. This is the joint lowest recorded since 1984. However, egg numbers in the north (Yorkshire) at 126/m2 were higher than in the east at 46/m2.

It’s likely that dry weather which allowed the 2014 harvest to proceed without delay, restricted the feeding ability of adult flies and this combined with low egg numbers in the previous two years has resulted in the low count.

For late November- March drillings, a lower threshold of 100 eggs/m2 is applicable. In the north of England, 53% of sites were above this level but, in the east of England, only 13% of sites were above this level.

The full survey results are available on the HGCA website www.hgca.com.

For egg-hatch monitoring, samples have been taken at the sites shown below where Wheat Bulb fly eggs were found in the autumn:

Progression of egg-hatch will be monitored over the next few weeks.

wheat bulb fly eggs


Hatch is underway in the east of the country but not yet in the north.  Values for percentage hatch in the east are probably over estimates in view of the low numbers of eggs recovered.  A greater volume of soil will be taken from these sites next week to try to increase the number of eggs extracted.

Site (19th January) Total number of viable eggs
(inc hatched)
Number of hatched eggs Percent of eggs hatched 
1. Ixworth, Suffolk 16 8 50.0
2. Terrington St Clement, Norfolk 3 1 33.3
3. Littleport, Cambridgeshire 6 0 0.0
4. Fimber, North Yorkshire 6 0 0.0
5. Huggate, East Yorkshire 9 0 0.0

It is not known precisely what initiates egg-hatch but is thought to be associated with diurnal fluctuations of more than 5oC between minimum and maximum soil temperatures.  It has been relatively mild, so probably we have yet to experience more widely the threshold difference between maximum and minimum temperatures.

What does this mean for you?

Dursban WG egg-hatch sprays are applied between the start of egg-hatch in January and its peak in February or March. These are most likely to be justified on high-risk fields, where egg numbers are known to be above 2.5 million eggs/ha. This may be in addition to any insecticidal seed treatment, if this has been used.

In the absence of egg counts for specific fields, risk assessments for treatment must be made on the basis of locality, previous cropping, drilling date, plant population, tillering and soil type. Use Risk Assessment Charts to identify fields at risk. Be prepared to apply Dursban WG at 1.0 kg/ha in 200 to 1000 litres per hectare of water at the appropriate time.

Equity® also has recommendations for Wheat Bulb fly.

An interval of 14 days must be observed between applications of Equity or Dursban WG and UNITE® or Broadway® Star, regardless of weather conditions. For Atlantis WG and similar approved formulations leave a longer interval of 4 weeks for crop safety.

For other compatibilies please refer to Equity or Dursban WG tank-mix advice. If necessary, Dursban WG

or Equity can be applied to frosty ground but should NOT be tank mixed.

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)

Visit Say No to Drift website


Previous reports

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Kerb Weather Data

Final Report – week-ending 21st November 2014


Soil temperatures across much of the country have declined and where able to travel, growers should consider making their Kerb® Flo 500 and ASTROKerb® applications.  Applications of Kerb Flo 500 or ASTROKerb must only be made after taking all necessary precautions to avoid contaminating surface waters. If heavy rain is forecast the responsible course of action would be to delay the application. The longer the period of time, between application and a severe rainfall event the less likely it is that Kerb will be lost through surface run off and drain flow

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

 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.



Do I need a dry-leaf for application? 

The propyzamide active in Kerb Flo 500 is soil acting so spraying wet weeds at run-off or light rainfall after application is not an issue. Ideally, the rainfastness of ASTROKerb is 1 hour for the aminopyralid element. Spraying on a drying leaf is OK but if rainfall falls within 1 hour and causes run-off efficacy may be reduced. All applications should be made with due regard to water stewardship, i.e. do not spray where there is a risk of run-off to adjacent watercourses. 

Can I apply Kerb Flo 500 in a frost? 

Kerb Flo 500 may be applied in frosty conditions but avoid application onto frozen ground where subsequent rainfall could result in run-off into watercourses. For ASTROKerb please ensure frost is off the target broad-leaved weed.

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

Download updated tank-mixes for Kerb Flo 500 and ASTROKerb.

smd 20.11.14


soil temp 20.11.14

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