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Agronomy Support

Agronomy Update – 16 July 2014

In this Edition

Post-harvest cultural control of Bromes
Top and treat in 2-3 weeks
Forefront T stewardship forms
ASTROKerb used on oilseed rape?
Dock control sequences with DoxstarPro or Pastor
This Edition’s FAQ:   Can I treat weeds in grass in the autumn?
Dates for the diary


Post-harvest cultural control of Bromes

If bromes are becoming a problem on your farm, the first step to getting better control across the rotation is to identify the species. The Anisantha types have long awns and large drooping panicles (flowering heads), whilst the Bromus types have short awns and tighter, upright panicles.


 Sterile (or Barren) Brome
(Anisantha sterilis)

This is the most common species in the UK



Great brome
(Anisantha diandrus)
Great brome
      Meadow brome
(Bromus commutatus)
Meadow brome
 Soft brome
(Bromus hordeaceous)
Soft brome
Rye brome
(Bromus secalinus)


Accurate identification is vital as the two species types, Anisantha and Bromus do vary in their seed maturity at harvest. Their varying germination patterns can also make herbicide timings within a crop difficult, particularly so when both are present, so taking advantage of cultural control is vital.

For Anisantha species (sterile and great brome):

  • Seeds are ripe at harvest.
  • Exposure to light induces dormancy, so plough for good control.
  • If there is not a good cover of chopped straw covering seeds on the soil surface, shallow cultivate as soon as possible after harvest, to bury seeds and encourage germination.
  • Spray off seedlings with glyphosate pre-drilling.
  • Delaying drilling will significantly improve control.
  • Stale seedbeds will only be effective if soil is sufficiently moist. 

For Bromus species (meadow, rye and soft brome):

  • Seeds often under-ripe at harvest.
  • Seed burial immediately after harvest induces dormancy, so increases seed survival.
  • Leave seeds to ripen on soil surface for 1 month before cultivating.
  • Shallow cultivate after a month, then spray off emerged seedlings with glyphosate.

HGCA have produced an excellent guide on bromes, Identification and control of brome grasses.




At this time of the year brambles, Rubus fruticosa, can be 2-3 metres long and once established difficult to eradicate. Of course they provide valuable autumn berries for wild-life but if left unchecked can rapidly spread out from hedgerows into fields where they interfere with management.

Some arrive from seed but most establish where the tips of stems root. Digging-out roots, although hard work can be one method of control but as they can regenerate well below soil level this needs to be done thoroughly. Prickly stems can also make this a painful job.

Alternatively this time of year presents the opportunity to use GrazonPro® for control with a knapsack. This is best used June-August when brambles are actively growing. Wear suitable protective clothing when handing and measuring the concentrate and whilst spraying; gloves, coveralls and rubber boots are essential. Face protection (face shield) is needed when handling the concentrate.

It’s good practice to keep other people and pets out of treated areas for at least two hours until spray has dried on the leaf. Keep grazing stock (including hens!) out for 7 days after spraying.

Don’t be tempted to cut brambles back post-spraying; ideally wait for 28 days to maximize translocation down to the roots.

You may find our Knapsack weed control guide  helpful.

GrazonPro will also control broom and gorse. It also has good activity on hawthorn and sycamore and will give some control of birch and blackthorn.

For boom sprayers, although not on label Forefront® T (sheep/cattle grazing only) will offer good control of brambles; Pastor®, DoxstarPro®  and Thistlex®  also may offer some activity.

Blaster® Pro controls brambles in amenity grassland. Dow AgroSciences also sell other products for amenity areas which control brambles as well as other difficult invasive weeds such as  Japanese Knotweed.


Top and treat in 2-3 weeks

It’s now high summer and perennial grassland weeds like docks, thistles and nettles are flowering or have flowered. For these perennial weeds, rather than attempt to do a half-decent job by treating today, it’s much better to top and treat the re-growth in 2-3 weeks. This applies to both knapsack applications with GrazonPro, as well as tractor- mounted spraying including Forefront T.

Forefront T stewardship forms

 If you are a stewardship-trained agronomist able to recommend Forefront T, please return completed stewardship forms to Dow AgroSciences via your business focal point within your company or direct to Sacha Shepherd at Dow AgroSciences Ltd, Latchmore Court, Brand Street, Hitchin, Hertfordshire SG5 1NH.

Just as a reminder please ensure Forefront T is only used where the production of manure is minimised and this manure is returned to grass .i.e. cattle and sheep grazing only.


ASTROKerb used on Rape?

If you have used ASTROKerb® please ensure oilseed rape straw stays on the field and not baled and carted off.


Dock control sequences with DoxstarPro or Pastor

Sequences of DoxstarPro or Pastor are supported for dock control by Dow AgroSciences. If you have used half-rate DoxstarPro or Pastor earlier this spring, do remember to top-up with the remaining half-dose for efficacy. 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. 


This edition’s FAQ:

Can I treat weeds in grass in the autumn?

Yes. September is an ideal month for weed control in grassland.Weeds such as docks, dandelion, buttercup, and thistles have got flowering out of the way and are back into leafy growth and make an excellent target. In addition as the weeds start to prepare for winter, they are actively translocating down to the roots so the herbicide will be taken down there too.

Autumn control is an excellent opportunity for farmers to lessen the weed burden for the following spring which can help with farm workload and ease herbicide timings especially where you will be shutting up grass for silage and hay.

Forefront T can be used this autumn following a silage or hay cut this year. However no further cuts may be taken this year (cattle or sheep grazing only) and if a cut is taken in 2015 this forage must stay on the farm and any manure from stock fed this forage must stay on the farm and go back to grass.


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.

July 30th NSA Sheep Event, Malvern
Sept 10th Tillage Live 2014, Down Ampney, Gloucs
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.
BlasterPro contains clopyralid and triclopyr.
DoxstarPro contains fluroxypyr and triclopyr.
Forefront T contains aminopyralid and triclopyr.
GrazonPro contains clopyralid and triclopyr.
Pastor contains clopyralid, fluroxypyr and triclopyr.
Thistlex contains clopyralid and triclopyr.


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.co

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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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