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Agronomy Support

Agronomy Update – 30 March 2015

In this Edition

Remind me of latest timings for Galera

Save time by tank-mixing fungicides and herbicides!

Leatherjackets and spring drillings

What should you be doing now about weeds in grazing areas and silage crops?


This Edition’s FAQ:
– What is the best product for getting rid of chickweed in gappy leys?

Remind me of latest timings for Galera

Galera TimingThe latest application timing for Galera® in winter oilseed rape, flower-buds visible above the crop canopy, is linked to the physiological development stage of the crop and is not associated with the number of leaves present around the flower-buds that are forming.

Recent pigeon grazing will have left some crops stripped of their leaves; therefore assessing timings for Galera applications could be difficult. This growth stage timing is not dependent upon leaves protecting the developing flower-buds as there is no requirement for a physical barrier to protect the buds from Galera.

Dow Shield® 400 has a similar cut-off timing.

Save time by tank-mixing fungicides and herbicides!

Early season wheat fungicides are upon us with more reliance on early protection against Septoria. There are many gSprayingrass and broad-leaved weeds needing to be controlled as well before they compete with the crop. Growth regulators are an added pressure. Taking advantage of the tank-mixability of UNITE® and Broadway® Star is great for saving time.

Each spray application costs between £10/ha (farmer applied) and £14/ha (contractor applied) and saving a pass can add up to big money and avoid hassle this spring, as well as improve yield through better timeliness.

Broadway Star and UNITE are supported with chlorothalonil and this will not compromise efficacy and performance on weeds. These will also mix with many formulated fungicides such as Cherokee, Alto Elite, Tracker and Ignite +/- Bravo 500. Avoid mixing with products containing tebuconazole as these can give excessive shortening.

Do not add a PGR on top of this mix. If using a PGR stick with UNITE or Broadway Star + adjuvant + ½ rate chlormequat and nothing else.

Remember both Broadway Star and UNITE offer control of a huge range of broad-leaved weeds such as cleavers, cranesbill, poppy, speedwell, charlock, groundsel, volunteer rape, volunteer beet and many others as well as grassweeds, further cutting down on need for additional passes or products.

Always use an adjuvant with either Broadway Star or UNITE.

Remember to follow tank cleaning procedure on label when using UNITE or Broadway Star!

Leatherjackets and spring drillings

Newly sown spring cereals as well as root crops are particularly susceptible to damage from leatherjackets.

Pest numbers go in cycles and leatherjackets have been abundant over the last couple of years. However initial results from the SRUC autumn survey, suggests the risk is lower this year. Leatherjackets can be assessed by soil sampling with corers and washing out in a laboratory, or by heating soil cores and driving out the leatherjackets. An alternative method is based on driving plastic pipes into the ground and filling with brine and counting leatherjackets that float to the surface. For row crops numbers can be assessed by scratching either side of the row.

Damage thresholds for treatment:

>0.25 million/ha (25/m2)
Or 5 per 2 metres of row
Damage likely in sugar beet and other row crops.
>0.3-0.5 million/ha (30-50/m2)
Or 3-5 per metre of row
Damage likely in new ley or cereal
>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.

By May, larvae will stop feeding and pupate into adults.

What should you be doing now about weeds in grazing areas and silage crops?

  • Reflect on last year – which fields/areas will benefit most from weed control this year?
  • Walk the fields now and map where seedling docks and thistles have overwintered.
  • Decide whether these areas warrant spraying. Remember where weeds grow grass cannot grow. A 10% infestation of docks or thistles means 10% less grass.
  • Select products that translocate within the stem, leaves and roots of the target weed, giving long-lasting control. Choose a herbicide that has been specifically formulated for the target weed, e.g. Doxstar®Pro for docks and Thistlex® for thistles.
  • Book the contractor if required.  Demand for grassland spraying is increasing due to changes in the application regulations.  Select a spray date when the weeds are actively growing and 20cm high or across (docks) or 25cm high or across (thistles). In silage crops, spraying should take place three to four weeks before harvest – work back on a calendar to find the ideal date.

Grass Docks and Dairy GrazingDocks

  • Grow in soils rich in nitrogen and phosphates
  • Colonise trampled/poached grass
  • Can also appear as seedlings in arable crops after grass
  • Left untreated infestations increase in size
  • Tap roots can reach depths of 1.5m where they access moisture and nutrients
  • Flower from June onwards
  • Can produce 60,000 ripe seeds/year
  • Seeds spread on animals or in manure
  • 60% the feed value of grass
  • Tough stalks can puncture silage wrap on round bales leading to spoilage
  • Can live ten years or more
  • Crowns can fragment over time so one plant can become many.

This edition’s FAQ:

What is the best product for getting rid of chickweed in gappy leys?

DoxstarPro and Forefront® T are very good at getting rid of chickweed in established silage and grazing leys respectively – but they must be at least one year old.

A new herbicide from Dow AgroSciences is planned. Currently in the approval process with The Chemicals Regulations Directorate (CRD), the new product should be available for farmers to use in Spring 2016.


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.

Broadway Star contains pyroxsulam and florasulam
Dow Shield 400 contains clopyralid
DoxstarPro contains fluroxypyr and triclopyr

Forefront T contains aminopyralid and triclopyr
Galera contains clopyralid and picloram
Thistlex contains clopyralid and triclopyr
UNITE contains pyroxsulam and flupyrsulfuron-methyl

More information can be found at

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


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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 –

Previous Reports

Related Links

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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

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
Site Soil Total number of viable eggs (inc. hatched) Percent hatched % Tiller infested
1. Ixworth, Suffolk Mineral 16 50.0 1.6
2. Terrington St Clement, Norfolk Mineral 12 58.3 1.9
3. Littleport, Cambridgeshire Organic 9 44.4 2.5
4. Fimber, North Yorkshire Mineral 37 2.7 0.0
5. Huggate, East Yorkshire Mineral 10 10.0 0.0

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

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

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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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The whole farm approach to controlling weeds in combinable crops, using rotations, cultivation methods, sowing date, variety choice and weed knowledge alongside crop.