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Agronomy Support

Agronomy Update – 25th February 2015

In this Edition

The “three” crop rule and cereal herbicides
Grassweed solutions for late drilled winter wheat
Planning to treat ryegrass with Broadway Star?
Check oilseed rape now for weeds

This Edition’s FAQ:
What can I add to Atlantis WG for cleavers?
Why has Galera (MAPP 16413) got a 36 month following crop restriction?
What can I plant after failed oilseed rape?

The “three” crop rule and cereal herbicides

CAP reform and greening is forcing changes to rotation and future cropping. Beans and peas are attracting particular interest. Integrating what may be sudden changes of rotation with past herbicide use in preceding crops will be vital. Minimising future headaches now, will be a positive move.

For UNITE® treated winter wheat:

In autumn 2015, cereals, oilseed rape, field beans, red and white clover or grass may be sown to succeed a cereal crop treated with UNITE. Next spring 2016, there are no restrictions at all on crops.

So winter or spring field beans or peas are a following crop option with UNITE. Also remember there are no additional cultivation requirements for drilling crops like oilseed rape where direct drilling is desired.

Grassweed solutions for late drilled winter wheat

Many have drilled late as an approach to improving blackgrass control across the rotation. In addition now beet has been lifted more winter wheat has been drilled over January and February.

Late drilling usually means lower yields compared to crops in the autumn, however this year as ever there will be a real focus on minimising production costs which UNITE with its grass and broad-leaved spectrum will help meet. In either situation grassweeds are likely to be small and as soils warm, broad-leaved weeds will germinate and grow.

As well as controlling blackgrass, bromes, ryegrass and any wild oats, UNITE will also control many yield-robbing and rotational problem weeds such as cleavers, cranesbill, poppy, speedwell, charlock, groundsel, volunteer rape, volunteer beet and many others – perhaps saving a further spend on other broad-leaved weed herbicides and alleviating pressure tank mixing with fungicides later in the programme.

Top Tips for Optimal Spring Blackgrass Control with UNITE

  • Apply to as small a target weed as possible – up to GS24
  • Apply during a period of active growth – 2-3 days active growth either side of the application
  • Ensure correct application rate – don’t stretch a pack to fit a field
  • Always apply with a recommended adjuvant
  • Apply with a residual herbicide if appropriate
  • Apply to a dry leaf and at least 2 hours rain free
  • Ensure optimal application techniques are followed:
  • Use conventional Flat Fan, Variable Pressure Flat Fan or Twin Fluid nozzles
  • Apply in 130-150 l/ha using a Fine to Medium spray quality
  • Ensure boom height is correct and appropriate forward speed chosen

UNITE can be mixed with chlorothalonil e.g. Bravo 500 if you want to get the T0 on as well.

Planning to treat ryegrass with Broadway Star?

Ryegrass in winter wheatRyegrass is becoming more difficult to control. It’s a common grassweed in parts of the country such as Shropshire, Kent and Yorkshire but surprisingly enough can also be the key driver-weed in traditional “ blackgrass” areas such as Essex. Autumn germinating ryegrass is particularly competitive.

Late applications will lead to variable or poor control. Endeavour to apply Broadway® Star early at T0 when actively growing as grassweeds in advanced stages of growth at late tillering /stem extension onwards, are more difficult to control. This will remove weed competition early before canopies close-in preventing good spray coverage and mean less complicated tank mixes at T1 and T2.

Sudden changes in temperature, presence of EMR and drying soils can all affect the level of control achieved. Weed growth and stage continues to be the biggest efficacy driver. Most consistent ryegrass control occurs from earlier applications.


This weed, particularly the common form, Senecio vulgaris, is cropping up more and more in arable rotations across the UK.

Seeds germinate throughout the year and seed shed can mean more than one generation a year even though it is an annual. It can flower within about 6 weeks of emergence and its speedy growth habit can catch many out. Seeds are dispersed by wind. It prefers loamy soils or sandy soils with a pH above 6.0.

Although not on label, Galera®, Dow Shield® 400 and ASTROKerb® all control groundsel in oilseed rape. Again not on label but Broadway Star controls it up to flowering. Groundsel is on-label for UNITE up 6 etl. Spitfire® does it to 50 mm again off label at 1.0 L/ha, but you will get better control if you tank mix with CMPP, HBN or with a dicamba+ mecoprop mix. Watch that speedy growth habit!

Check oilseed rape now for weeds

Cleavers are the most aggressive broad-leaved weed competitors impacting yield and as such, significantly decrease final percentage oil content. As yield robbers, mayweeds, groundsel and thistles, follow closely behind.

All these weeds impact harvesting flexibility and carry potential admixture penalties.

  • Identify which fields will benefit from treatment with Galera
  • Applications can then be made as soon as conditions are suitable
    • Galera MAPP 11961 – Use up on farm stocks this spring. This can be applied in February
    • Galera MAPP 16413 – Application is from 1st March
  • Galera should not be applied until large variations in day/night air temperatures have passed (i.e. no frosts)
  • Applications should be made to a dry leaf
  • Galera is rainfast after a period of 6 hours drying
  • Control of cleavers is maximised when applications are made just before crop canopies close

With such obvious populations of broad-leaved weeds present in oilseed rape crops, the temptation is get out early and treat with Galera, but caution is required. To optimise performance, stable air temperatures are required of at least 6oC and rising, but preferably 8oC or higher. The warmer and more stable the conditions, the better the results are likely to be. Warm days and cold nights (high diurnal variation) are likely to give poor results, particularly against cleavers.

Another issue at this time of year can be wet leaves. Galera needs 6 hours drying time, after application to a dry leaf, for best results. A breeze to dry the plants off in the morning and a planned application during the warmest part of the day is the approach most likely to give good results. That is why having the appropriate fields identified and the required amount of Galera on farm and ready to apply is so important. With the cut off of flower buds visible above the crop canopy, the opportunities to spray can be limited.

This edition’s FAQs:

alomy cleavers in WWWhat can I add to Atlantis WG for cleavers?

Adding in 0.5l/ha Spitfire will control cleavers. This 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) e.g you can follow with more Starane XL for instance for later geminating weeds up to a maximum of 7.5 g florasulam ai/ha in total


Why has Galera (MAPP 16413) got a 36 month following crop restriction?

Regulation is causing greater restriction in what we can all do on farm; this is especially true of pesticides. When Galera was re-registered tighter regulatory requirements in relation to residues in following crops meant that the following advice appears on label:

Following application of Galera the following restrictions on planting the following crops must be observed:
Wheat, barley, oats, maize, oilseed rape: 4 months (120 days)
All other crops: 36 months (3 years)

This new restriction is not because Galera is suddenly causing new problems in these “other” crops but more to do with tighter regulatory demands. We now have to show picloram does not cause residue issues in following crops and are busy gathering data in what are called “confined rotational studies” to enable a wider choice of following crops on label such as beans and potatoes. Sufficient data is unlikely to be available before end of 2016.

For many of you with rotations based on cereals, winter or spring and oilseed rape this will not be an issue. Where it could be and cleavers are not the main target Dow Shield 400 is still an option but remember not to plant susceptible autumn-sown crops (e.g. winter beans) in the same year as treatment with Dow Shield 400 even though this seems unlikely! Dow Shield 400 does have approval on spring rape. Again in the unlikely event spring beans and peas are following rape, do not apply Dow Shield 400 any later than the end of July in the previous year.

Galera (MAPP 16413) has an EAMU approval on spring oilseed rape but beans etc. cannot be planted for 36 months as per label recommendations for winter oilseed rape.

Galera® ([old] MAPP 11961) already purchased from distribution by Jan 31st can still be used this spring. The Galera (MAPP 16413) following crop restrictions do not apply to this approval. However ploughing or thorough cultivation should be undertaken prior to planting beans peas, potatoes, carrots and other sensitive crops leguminous crops as damage could occur. Please heed warnings on label.

Fera Liaison does have a note of Galera (MAPP 16413) having following crop restrictions which should hopefully feed into the various crop recording systems for stewardship.

What can I plant after a failed winter oilseed rape crop?

We have been getting reports of rape crops having been eaten by pigeons. 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!

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.

Use plant protection products safely. Always read the label and product information before use.
Pay attention to the Risk Indication and follow the Safety Precautions on the 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
Dow Shield 400 contains clopyralid
Galera contains clopyralid and picloram
Kerb Flo 500 contains propyzamide
Spitfire contains fluroxypyr and florasulam
UNITE contains pyroxsulam and flupyrsulfuron-methyl


More information can be found at uk.dowagro.com

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

Report 9 – 17th March 2015

Last autumn in conjunction with ADAS we started monitoring blackgrass emergence at two sites in key blackgrass areas of the UK – Cambridgeshire and Oxfordshire.

Monitored plots have not received any herbicides at all and blackgrass counts are cumulative.

This week’s report:

Soil temperatures have risen at both sites to 6.5°C in Cambridgeshire and 6.9°C in Oxfordshire. Maximum air temperatures have continued to rise to an average of 10.5°C with minimum temperatures at around 2°C. The previous fortnight has been dry with slightly more rain on Oxfordshire (6mm) than Cambridgeshire (1mm). Soils have dried out rapidly and crops (and blackgrass) have started to grow.

There has been no further blackgrass emergence.


17.03.15 - Oxfordshire early drilled

17.03.15 - Oxfordshire late drilled


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

Current Advice for Grassweed Control in Winter Wheat:

With dry soils, warmer temperatures and active growth, UNITE® should now be applied before the blackgrass gets any bigger.

Fields which would benefit from UNITE® are fields with blackgrass and other grassweeds (ryegrass, bromes, wild oats) and/or broad-leaved weeds such as cleavers, cranesbill, poppy, speedwell, charlock, groundsel, volunteer rape, volunteer beet and many others. UNITE is a flexible option for reduced tillage establishment for following crops of oilseed rape. Beans are also a following crop option. UNITE controls blackgrass up to GS 24.

If you wish to include a T0 fungicide as a tank-mix these are supported, including chlorothalonil (except products containing tebuconazole) perhaps saving a pass.

UNITE is rainfast in 2 hours. Always add adjuvant.

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

For further information on grassweed control in winter wheat see Topic Sheet 3 (Blackgrass) and Topic Sheet 5 (Brome & other grassweeds)

Use UNITE where blackgrass is the driver-weed.

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

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.

Previous Reports

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Wheat Bulb fly Pestwatch

Final Report – 26th February 2015

Dow AgroSciences in conjunction with ADAS, are monitoring Wheat Bulb fly 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. 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.field

This week’s report

Hatch is progressing in the east, where we now have approximately 50% hatch and second instar larvae at all sites.  In contrast hatch in the north is still at an early stage of egg-hatch with no plant invasion this week.




Date: 23rd February 2015
SiteSoilTotal number of viable eggs (inc. hatched)Percent hatched% Tiller infested
1. Ixworth, SuffolkMineral1650.01.6
2. Terrington St Clement, NorfolkMineral1258.31.9
3. Littleport, CambridgeshireOrganic944.42.5
4. Fimber, North YorkshireMineral372.70.0
5. Huggate, East YorkshireMineral1010.00.0

What does this mean for you?

Egg-hatch sprays in the east will now have limited effect.  In contrast egg-hatch sprays in the north are still likely to be effective. Application is now being made difficult by recent rain and wet soils.

Where you are able to travel, for those fields at risk apply Dursban WG at 1.0 kg/ha in 200 to 1000 litres per hectare of water.

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.

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

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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

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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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