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Agronomy Support

Agronomy Update – 20 June 2014

In this Edition

Get grain stores ready for harvest!
Water volume and grassland herbicide efficacy
Post-cut weed control in grass
Top tips for treating thistles
Forefront T Stewardship Forms
ASTROKerb used on oilseed rape?
Mapping patches of broad-leaved weeds

This Edition’s FAQ:
- How safe are Dow AgroSciences’ grassland products to grass?

Dates for the Diary


Get grain stores ready for harvest!

Mite and insect infestation in UK stored grain causes annual losses of 5 -10%.

Mite and insect feeding results in direct yield losses but can also have a detrimental effect on the quality of stored grain. Grain store pests can affect the nutritional value and act as a source of allergens which can lead to serious gastric problems in feeding animals. Whether intended for milling, malting or feed, infested grain runs the risk of being rejected.

Reldan® 22 is a broad spectrum acaricide and insecticide that will control all major pests of stored grain including Acarus, Lepidoglyphus and Tyrophagus, the three main mite species found in UK grain stores. Reldan 22 is the only pre-harvest grain store treatment effective on these common pests. It also controls many other common beetle, weevil and moth pests of grain.


Flour mite

Acarus or Flour mite 

Cosmopolitan food mite

Lepidoglyphus or Cosmopolitan Food Mite

Reldan 22 controls mites

Reldan 22 can be applied by knapsack. Ensure the spray operator is wearing suitable PPE, including impermeable coveralls, protective gloves and rubber boots and face protection when applying. There is no withholding period for grain subsequently stored on those premises.

Reldan 22 works by fumigation, contact and ingestion. Once treatment is dry it is safe to tip grain but fabric applications of Reldan 22 should be applied one month prior to grain filling to allow sufficient time for pests harboured in cracks and crevices to emerge and come into contact with the chemical.

Reldan 22 can only be used for a grain store intended for wheat, barley, oats, rye, and triticale storage, but is not suitable for use in those intended for oilseeds. Similarly, admixture applications can only be made to these qualifying cereals. 

For more information please download our Reldan 22 Technical Information Sheet


Water volume and grassland herbicide efficacy

Many farmers and agronomists, and particularly agricultural spraying contractors, question why Dow AgroSciences insist on such ‘high’ water volumes (minimum 300 L/ha, rising to 400 L/ha in dense grass swards and/or high weed populations) when applying DoxstarPro® and Pastor® herbicides to established grassland. Remember – we support use of Forefront® T and Thistlex® in 200 L/ha water.

Trials data and extensive commercial experience confirm that where water volumes are reduced, most often in an attempt to cover more ground in less time, the final level of control achieved on perennial weeds such as docks and thistles is inevitably reduced.  In-season levels of control can often be comparable, but control in the season following application will be lower.




Post-cut weed control in grass

Many docks are treated before first cut but if you miss the chance, all is not lost.

In some cases it can be better to treat 21 days after first cut, as all the dock plants will have fresh, even re-growth which is readily receptive to spraying. The only thing to remember is to leave at least another three weeks before the next cut of silage is taken to allow full translocation of the active ingredients in to the weed roots.  Similar is true after hay, and for mixed populations of other perennials such as thistles and nettles.


Top tips for treating thistles

The combination of clopyralid and triclopyr in Thistlex maximises activity giving excellent lasting control of creeping and spear thistle. Paying close attention to application can also help achieve long term control.

  • Use once per year at 1.0 L/ha in a water volume of 200 L/ha.
  • Use higher water volumes up to 400 L/ha where thistle numbers are higher and/or the sward is dense.
  • Apply between 1st March and 31st October.
  • Do not tank mix with phenoxy herbicides e.g. MCPA, 2,4-D or dicamba as this can affect movement into the roots.
  • Use on grazing grassland or silage, hay or haylage ground.
  • Take stock out during spraying then return no sooner than 7 days later.
  • Once sprayed, wait a minimum of 3 weeks prior to cutting to maximise translocation into the thistle roots.
  • Target actively growing plants in the rosette stage and up to 200mm across or high. If larger than this consider topping and spraying the regrowth 2-3 weeks later
  • Avoid treating weeds suffering from waterlogging, drought stress or cold stress.
  • Thistlex is LERAP B, meaning a 5 metre area must be left unsprayed next to a flowing or static waterbody (unless a LERAP assessment permits less), or 1 metre unsprayed near dry ditches


creeping thistlesCreeping Thistle (Cirsium arvense)

A perennial that grows from seed, or from root sections in the soil. Once established, the root mass can be greater than the plant above ground.

Thistle_spearSpear Thistle (Cirsium vulgare)

A biennial that grows from seed.In the first year often goes unnoticed.  In the second year the plant can grow to over a metre in diameter before flowering.

Forefront T (cattle and sheep grazing only) and Pastor also control thistles. GrazonPro can be used to control thistles with a knapsack.


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 1 NH.

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 oilseed rape?

If you have used ASTROKerb® please ensure oilseed rape straw is chopped and incorporated and not baled and carted off.


Mapping patches of broad-leaved weeds

Poppies_wheatDo you have patches of broad-leaved weeds that you think are resistant to herbicides? ADAS are interested in broad-leaved weeds such as poppy, fat-hen, chickweed and mayweed. If you have suspicious patches then please contact Sarah.cook@adas.co.uk or Lynn.tatnell@adas.co.uk who may be able to help you with testing.

Do make a note about these patches for herbicides next year as changing strategy away from SUs, to triazolopyrimidine mixture products such as Spitfire® and other actives may be of help. 


This edition’s FAQ:

How safe are Dow AgroSciences’ grassland products to grass?

Dow AgroSciences’ grassland products do not check grass growth and farmers can be confident their use will help maximise yield and quality.

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 2th-3rd The Livestock Event, Birmingham
July 30th NSA Sheep Event, Malvern
Sept 10th Tillage Live 2014, Down Ampney, Glos.
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
DoxstarPRO contains fluroxypyr and triclopyr
Forefront T contains aminopyralid and triclopyr
GrazonPRO contains clopyralid and triclopyr
Pastor contains clopyralid, fluroxypyr and triclopyr
Reldan 22 contains chlorpyrifos-methyl
Spitfire contains florasulam and fluroxypyr
Thistlex contains clopyralid and triclopyr

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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 Midge

Saddle Gall midge adult

Orange Wheat Blossom Midge

Orange 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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