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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 will resume again in the Autumn


Plan Your Blackgrass/Grassweed Management

A crucial step to achieving successful control of headache grassweeds in winter wheat – blackgrass, ryegrasses and sterile brome, is to monitor when grassweeds emerge, so that post-emergence treatments can be applied as soon as possible when the weeds are small and are actively growing.

To help growers and advisers understand growth of these weeds, Dow AgroSciences is funding an ADAS monitoring scheme once again this season.

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.

Related Links

      Print                                broadway-star      broadway-sunrise

GEM first began in the autumn of 2010, and already some key factors influencing emergence patterns have been recognised – the rapid emergence of sterile brome being one of them. Sterile brome is most effectively controlled in the autumn when small.

This year we are focusing on blackgrass and monitoring two sites in Cambridgeshire and Oxfordshire.

Report 9 – 14th March 2014

Dow AgroSciences’ Grassweed Emergence Monitor (GEM) in conjunction with ADAS is focusing on monitoring blackgrass emergence in two key blackgrass areas of the UK – Cambridgeshire and Oxfordshire. Winter wheat has been drilled in September and late October and includes blackgrass sown at 500 seeds/m2 and a “natural” unsown blackgrass population.

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.

This week’s report:

There has been no further emergence at either site for either drilling date.

Established blackgrass is growing. Blackgrass growth stages vary between two leaves with the largest plants approaching GS30 in the September drilled.

15.03.14 Cambridgeshire early drilled 15.03.14 Oxfordshire early drilled
15.03.14 Cambridgeshire late drilled 15.03.14 Oxfordshire late drilled

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

Current Advice for Grassweed Control in Winter Wheat:

Apply UNITE® + adjuvant ASAP. UNITE may be used up to GS 24 of the blackgrass. Consider including additional residual e.g. 120g ai/ha flufenacet particularly where no pre-em has been applied, or where further emergence of grassweeds is expected e.g. spring bromes.

For the best results with UNITE and Broadway Star, 2-3 days of active growth are required on either side of the application.

Apply UNITE at 0.27 kg/ha (1 pack treats 4 has) in 100-200 litres water/ha (Optimum 130-150 litres water/ha) as a fine – medium spray with flat-fan or twin fluid nozzles to a drying leaf. UNITE is rainfast in 2 hours.

Use UNITE where blackgrass is the driver-weed.

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



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Orange Wheat Blossom Midge

Report 2 – 29th May 2014

In support of product stewardship of Dursban® WG, Dow AgroSciences in conjunction with ADAS have monitored Orange Wheat Blossom midge (OWBM) populations. Sites in the major cereal growing regions were selected for monitoring based on historical high risk for OWBM attack.

Pest Lifecycle

For more information on the lifecycle of Wheat Blossom Midge click here.

As well as giving an indication of overall numbers another important aspect of Pestwatch is to warn when larvae are moving through their lifecycle and pupating so the arrival of adults can be anticipated for in-field monitoring. The duration of the pupal stage varies according to temperature, typically spanning a period of 2 to 4 weeks, but can be as short as 1 week.

Air temperatures above 15°C are particularly favourable for flight of newly emerged adults. Adults lay eggs on emerged ears, before flowering, in crops between GS53 and GS59. Eggs hatch in 4-10 days, depending on temperature and the larvae move to a developing grain and feed for 2-3 weeks.

Substantial loss of yield and quality can result.


After sampling of 13 potentially high risk sites for OWBM, eight were selected for re-sampling with the objective of tracking midge pupation. Results for an additional two sites in Kent are included below.

Site No County Location Mean OWBM per kg soil % as cocoons % as larvae % as pupae
1 Norfolk Terrington 2.1 48.0 32.0 20.0
2 Bucks Wendover 0 0 0 0
3 Cambs Stetchworth 1.3 26.7 73.3 0
4 Cambs Boxworth 12.3 32.0 27.9 40.1
5 Suffolk Ixworth Thorpe 1.1 0 0 100.0
8 Herefordshire Wigmore 0.5 25.0 75.0 0
9 Herefordshire Sutton 2.6 41.7 45.8 12.5
13 Yorkshire, North Ryton 1.1 5.0 60.0 35.0
14 Kent Burmarsh 0.1 0 100.0 0
15 Kent Eridge 0.2 0 100.0 0
Mean (10 sites to 22 May 2014) 2.1 17.8 51.4 20.8

Although very variable, pupation has been recorded at 63% (5 of 8) of fields selected for further monitoring and as far north as North Yorkshire.


Identify fields at high risk and consider the use of traps at the most susceptible sites. These are typically wheat fields where the pest was noted last year, especially if no treatment was carried out. Monitor closely on warm, still evenings in crops at the susceptible growth stage. Emergence of male midges can also be monitored using pheromone traps.

OWBM-susceptible varieties of winter wheat crops are at risk until the early flowering stages are reached (average GS 61 including secondary tillers across the field).

Typically crops are at the boots swollen stage (GS 45) with the most forward already beginning to flower (GS 61). Those at GS 45 could be at GS 53 within 3-8 days depending upon temperatures. A few are already flowering and no longer at risk from OWBM. In general, crops are less advanced as you move north. Although some midges have been reported, the recent wet and windy weather has not been ideal for midge migration but drier, warmer weather will be more favourable for the pest.

The economic risk is highest in crops intended for seed or milling. This is reflected in the lower threshold of one OWBM per 6 ears. The threshold for feed wheat is one midge per 3 ears.

How can I tell the difference between adult Saddle Gall midge and OWBM?

Adult Saddle Gall midge has also been reported so it will be important to distinguish these species when examining crops. Saddle Gall midges are similar in appearance to OWBM. However there are some key characteristics to help differentiation:

  • Saddle Gall midge tend to fly earlier than OWBM
  • OWBM are distinctly orange and approximately 3 mm in length
  • Saddle Gall midge are reddy-brown and slightly larger
  • Saddle Gall midge lay eggs on the leaf in a grid like pattern whereas OWBM lay their eggs on the glume or floret.
Saddle Gall MidgeSaddle Gall midge adult Orange Wheat Blossom MidgeOrange Wheat Blossom midge

Be prepared to apply Dursban WG at 0.6 kg/ha in 200 to 1000 litres/ha water if thresholds are met or exceeded. Spray between ear emergence and the start of flowering (GS51-59) to control developing larvae. If justified treatment should commence once the majority of ears have emerged. Ears not emerged at the time of treatment will not be protected.

Equity® also has recommendations for OWBM.

Precautions should be taken to minimise impact against wildlife by only applying an effective insecticide when necessary. When spraying Dursban WG or Equity:

  • Consider beneficial insects
    • All major groups of cereal insecticides pose a potential risk to beneficial insects particularly when sprayed during summer and the wheat blossom midge risk period.
    • Adopting a 12 metre no-spray buffer zone beside hedgerows or grass strips will allow an area for beneficial arthropods to survive and re-colonise the field.
  • Comply with SAY NO TO DRIFT stewardship advice
    • Use LERAP – low drift – 3 star rated nozzles
    • Adopt a 20 metre buffer zone alongside watercourses ( 1 metre dry ditches

Say No to Drift

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Kerb Weather Data

Get the full picture and weather data

To get more detailed information, starting in October,  sign up for our e-newsletter and full weather data to see whether conditions are correct for Kerb Flo 500 or ASTROKerb applications– simply sign up.

Using Kerb Flo 500 or ASTROKerb gives you the highest possible control of blackgrass and other difficult to control grassweeds, important not only for the rape crop but also reducing the weed seed burden in following cereal crops. ASTROKerb also provides excellent control of poppy and mayweed.

Follow these guidelines to get the best possible control of blackgrass in your fields from Kerb Flo 500 and ASTROKerb:

  • Performance is best where crops have been established using min-till techniques
  • Applications should be made to firm, moist soils with a fine tilth
  • Applications must be made to small blackgrass plants, before they tiller
  • Best applied when soil temperatures have got down to 10°C at 30 cm and falling and there is sufficient moisture in the soil for plant uptake. Both these conditions are rarely met before November. (Both products can be used up to January 31st). Please note the soil temperature in the postcode search is at 10 cm and will be more variable than at 30 cm
  • Increased rates should be used where blackgrass resistance has been confirmed
  • Strategic use is recommended in tank mix or sequence with graminicides. In difficult blackgrass situations adding a “fop” with good blackgrass activity nearly always improves control.

Good stewardship

Water stewardship needs to be top of mind to both safeguard the environment and to protect these valuable products from withdrawal. If you can travel, applications of Kerb Flo 500 or ASTROKerb must only be made after taking all necessary precautions to avoid contaminating surface waters. Kerb Flo 500 and ASTROKerb may be applied in frosty conditions but avoid application onto frozen ground where subsequent rainfall could result in run-off into watercourses. More information on water stewardship can be found on the Voluntary Initiative website.


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