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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 protection products.

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Grassland Agronomy Update – June 2015


Welcome to the first Grassland Agronomy Update from Dow AgroSciences.

These regular technical notes are a seasonal commentary to help those interested in improving grassland productivity on dairy, beef, sheep & equestrian enterprises.

You can claim 2 CPD points for subscribing to this Update.  To subscribe please send your details to, with the title GRASSLAND AGRONOMY UPDATE.


  • What should farmers be doing about weeds in grassland?
  • New weed App launched
  • New Topic Sheet – Applying herbicides to grassland
  • Fast Facts – Docks
  • Look out for leatherjackets
  • Grassland BASIS training
  • Ask the Expert
  • FAQs
    • What is the best product to use to control hogweed?
    • Why are phenoxy-based herbicides disappearing?
    • What is the best product for getting rid of chickweed in gappy leys?
  • Diary Dates


What should farmers be doing about weeds in grassland?

  1. Walking the fields and mapping where docks and thistles are now flourishing, putting on fresh growth and getting taller. Cold nights during the past few weeks have held back grass growth, but not the deeper rooting weeds. In many cases they are standing proud of the sward, making them easier to see and treat.
  2. Deciding whether these areas warrant spraying. Where weeds grow grass cannot grow and a 10% infestation of docks or thistles means 10% less grass for the animals to eat.
  3. Selecting the most appropriate products. Translocated sprays travel within the stem, leaves and roots of the target weed, giving long-lasting control. It is best to choose a herbicide that has been specifically formulated for the target weed, eg Doxstar®Pro for docks and Thistlex® for thistles.
  4. Booking the contractor – demand for grassland spraying is increasing due to changes in the application regulations, so booking early is essential so the job can be done at the right time. This is when the weeds are actively growing and 20cm high or across (docks) or 25cm high or across (thistles)
  5. In silage crops, spraying should take place three to four weeks before harvest to allow the herbicides to work right down into the roots. On most farms it may be too late now to get a pre-cut treatment in. If so, farmers should aim to spray a couple of weeks after cutting. This will allow a good flush of weeds, which will all be at a similar stage of growth and ideal for treating.

New weed App launched

Grassland APPDow AgroSciences has launched a new Grassland Weed App for use on mobile phones, tablets and iPads. It can be downloaded for free from the App Store or Google Play.  Use ‘Dow Grassland’ in search fields of the App Store and Google Play.

Quick and easy to use, the app helps livestock farmers choose the best products to spray to get rid of perennial and annual weeds, allowing them to grow more grass in their fields.

To start, producers can find out just how much productivity, in terms of stocking rates or milk and meat production, they are losing from current levels of weed infestation. This is a stark reminder of the economic justification for having clean pastures and not allowing weeds like docks, nettles and thistles to gain a foothold.

By entering the range of weeds present in the field, the app then lists which products are the best for the job, including important information on dose rates, water volumes and stock withdrawal periods.

“We have developed this app to be a useful ‘on-the-go’ tool for farmers to use when they are out in the field amongst the weeds,” says Andy Bailey, grassland agronomy specialist for Dow AgroSciences. “It clearly demonstrates the detrimental effect weeds have on output and leads them to the best herbicide solutions.”

Finding a local contractor
The app also has the facility to locate the nearest NAAC affiliated contractor to farms across the UK.

“New rules coming into force this autumn on who can apply plant protection products, and the requirement for regular sprayer testing from November 2016, is likely to make more livestock farmers seek outside help for spraying,” says Mr. Bailey. “With this app they can find a skilled contractor nearby, and one who operates according to the NAAC’s professional guidelines.”


New Topic Sheet – Applying herbicides to grassland

Top tips on spraying weed in grassland including:

  • Water volumes
  • Pressure
  • Boom height
  • Bout marking
  • Conditioners
  • Quad bike sprayer calibration

can be found in the new Topic Sheet – Application advice for grassland herbicides.

Fast Facts – Docks

Ideal size for treating

Ideal size for treating

  • Grow in soils rich in nitrogen and phosphates
  • Colonise trampled/poached ground
  • 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 for ten years or more
  • Crowns can fragment over time so one plant can become many

Look out for leatherjackets

leatherjacket larvaeLeatherjackets (crane fly larvae) are voracious feeders and can decimate grass by chomping on roots and shoots, severing the plants at or just below soil level.Female crane flies lay up to 400 eggs into grassland during the summer, which hatch into leatherjacket larvae two to three weeks later.

Infestation levels of 1 million/ha are common in established grass – leading to a potential loss of 2t grass dry matter/ha. New leys put in after a badly infested sward are particularly vulnerable to attack.

If one or two leatherjackets can be found now by scratching the top 2-3cm of soil, treatment is likely to be cost-effective.

Use this Risk Assessment Chart to confirm the level of threat and treat with Dursban® WG at 1kg/ha if required, as long as soil temperatures are above 5°C.

Treating established leys now will help protect any new reseeds planned later in the year.

 Grassland BASIS training

Demand for places on the BASIS Certificate in Crop Protection in Grassland and Forage Crops course is growing rapidly as businesses supplying crop protection products react to growing interest from livestock farmers seeking agronomic advice.

Economic drivers such as high feed costs and poor market prices are forcing dairy, beef and sheep farmers to maximise their use of grass to feed their animals, and many are looking for help to do this.

While the amount of technical information on growing, managing and utilising grass and forage crops has increased significantly over the past decade, from the likes of EBLEX, DairyCo and the British Grassland Society, there are still very few ‘experts’ on the ground to provide farmers with advice precisely tailored to their needs.

Spotting this gap in provision, BASIS, the independent organisation that promotes and encourages professional standards in the pesticide, fertiliser and allied industries, added a specialist grassland and forage crop module to their crop protection courses.

The courses are delivered through BASIS approved trainers, including SRUC and Harper Adams University. The latter has run several grassland courses and is planning more due to increasing demand.

“There are two main reasons why more people want a professional qualification in these areas,” says Louisa Dines, senior lecturer in agronomy at Harper Adams who leads the BASIS certificate in crop protection courses.

“Farmers are now asking for much more detailed advice concerning grassland agronomy including how to tackle weeds, pests and diseases. This course gives advisers all the information they need to respond.

“Secondly, legislation demands that all those who recommend and sell pesticides to end-users must hold a recognised certificate of competence – which this is.”

The full certificate requires 200 hours of commitment from the student, with 70 hours in the classroom delivered in three blocks of three days over nine months, with a further 130 hours supervised experience gained out in the field.

After this the student has to pass all four elements of an exam, which includes a multi-choice question paper, a practical identification assessment, a 3,000 to 5,000-word project and field station and panel interviews.

The syllabus includes short, medium and long term leys, permanent pasture and various crops grown for forage including maize, peas, vetches, forage brassicas and cereals grown for silage.

All aspects of agronomy are covered. For example at the end of the course, students can accurately identify grassland weeds, select and justify appropriate cultural and chemical control measures and calculate suitable herbicide dose rates to get rid of them.

“The full certificate is tough and equivalent to final year honours degree level, so it may be too advanced for some people to attend straight off,” says Ms Dines.

“We also run a grassland foundation award consisting of two blocks of two days in the classroom with 25% study outside. We have had 32 people go through this in the past two years and many have gone on, or want to go on to do the full certificate.”

Mark ShawChallenging but rewarding

Mark Shaw, regional development manager and agronomist for Mole Valley Farmers passed the full grassland and forage crops certificate last September, and says it was one of the most challenging but most rewarding aspects of his career.

“I wanted a professional qualification that was well respected by the industry and that stays with me for ever,” says Mr. Shaw.

“Most agronomists walk over the grass to get to the arable crops! But grass is our most widely grown crop and is the most important – yet only receives 7% of all inputs.

“There is incredible scope to increase the output from grass and forage crops, and I am now in a good position to help my farmers achieve this. I would recommend the course to anyone working in this sector – there is a great future in it.”

Ask the Expert – Andy BaileyAndy Bailey

Andy Bailey is Principal Biologist and Grassland Agronomy Leader for Dow AgroSciences. Passionate about all things scientific, he is on a mission to get farmers to treat grassland as a crop.

Why farmers should control weeds in their grass fields?

Grass is much cheaper to feed to livestock than bought-in straights and concentrates, and can be just as good nutritionally. So it makes economic sense to grow and feed as much grass as possible – grazed or conserved.

If farmers are to rely more on grass to produce their milk and meat, fields need to be in good condition and full of productive plant species. Damaged ground with compacted soils require appropriate remedial action and weedy pastures should be dealt with.

Where weeds grow, grass cannot grow

A 10% infestation of docks or thistles reduces grass yields by a corresponding amount and they also reduce the feed value. So it pays to eliminate perennial weeds for quantity and quality reasons.

The best way to tackle broad-leaved weeds is with a translocated herbicide specifically formulated for the target weed, such as DoxstarPro against docks and Thistlex against thistles. Where there is a range of weeds present, Pastor®Pro is good for cutting situations and Forefront T the most effective broad spectrum herbicide a farmer can buy – but only for use on land grazed by cattle or sheep.

Topping is wasted effort

Chopping down weeds with a mower or topper is not as cheap as farmers usually think – when the true cost of labour, tractor depreciation, machine wear and fuel are taken into account.

And topping can only ever be a temporary solution. It may give instant satisfaction, but in the case of docks, new shoots soon grow up from underground stems that branch off their substantial taproot.

So fields that are topped even seven times or more throughout a season will still have roots intact. However, just one application of a translocated herbicide to young weed growth will reach all parts of the plant, killing it from within, and allowing the grass to grow back in its place.

Bumper year for weeds?

Broad-leaved weeds overwintered well in the mild winter, but like the grass, stalled a bit during the cold nights in March and April. But the general mix of warm sunshine and rain since has boosted weed growth. Farmers should allow at least three weeks between treatment and cutting silage crops – so this spray window may have passed by on many farms. The next chance will be between first and second cut, when there will be an opportunity to spray the even regrowth of weeds.

The Dow AgroSciences’ team will be keeping an eye on weed growth across the UK this spring and reporting back from the field. Follow me on twitter @andybaileydow for regular updates on what they have seen.



What is the best product to use to control hogweed?

The best product is Grazon®Pro which will achieve better results than PastorPro.  Apply only one treatment per year.

Why are some phenoxy-based herbicides disappearing?

In Europe, all pesticides have to go through regular and rigorous re-registration to remain on the List of Authorised Products. The tests look at aspects such as operator exposure, suitable application techniques and potential effects on the environment.

For example, the molecule dicamba has recently been put forward for re-registration. This means that all products that contain dicamba also have to be re-registered, including those where dicamba is mixed with stalwarts like MCPA and Mecoprop.

The tests are getting tougher to pass, and the cost of putting molecules and formulations through the process more expensive, costing many thousands of pounds in money and manpower.

Some of the companies selling herbicides based on older chemistry, are deciding not to support all of them through the re-registration process, so they will not be available for use on farm anymore.

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.

Diary Dates

 The technical team from Dow AgroSciences will be out and about at many shows and events this summer.

For regular updates on agronomic issues, find us on Twitter and Facebook!

For further information please contact the technical Hotline on 0800 689 8899 / or go to

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.

DoxstarPro contains fluroxypyr and triclopyr.
Dursban WG contains chlorpyrifos.
Forefront T contains aminopyralid and triclopyr.
GrazonPro contains clopyralid and triclopyr.
PastorPro 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 email: |

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Orange Wheat Blossom Midge Pestwatch

Final Report – 10th June 2015

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

OWBM can attack wheat (winter and spring), barley, oats and rye, although significant damage in the UK has only been reported in wheat and rye.

Commonly grown susceptible varieties include Gallant, JB Diego, Revelation, Cordiale, Claire, Relay and Crusoe.

Skyfall, KWS Santiago and Leeds are resistant to OWBM as are Belipi and Mulika.

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


County Location Mean OWBM per kg soil % as cocoons % as larvae % as pupae
1 Bucks Wendover 0 0* 0* 0*
2 Cambs Boxworth 15.7 24.3 34.3 41.4
3 Herefordshire Sutton 0.1 0 0 100
4 Kent Burmarsh 0 0* 0* 0*
5 Norfolk Terrington 1.5 34.6 46.2 19.2
6 Yorkshire, East Raywell 1.4 15.8 52.6 31.6
7 Yorkshire, North Sessay 0.6 0 100 0
  Mean   2.8 14.9 46.6 38.4

*values not included in calculation of means

The third monitoring round showed a mean of 38.4% pupation. Pupation was underway at 57% of the sites selected for monitoring.

There have been a few reports of adult OWBM emerging and being caught in pheromone traps.

At 4th June typical crops had the flag leaf swollen (GS 45), whilst those that are were more backward were at late stem elongation (GS 37-39). The most forward crops were at early ear emergence (GS 51). The benchmark for typical winter wheat crops on the 6th June is GS 59 (HGCA Wheat growth guide) so all crops are behind what might be expected. There is potentially still some OWBM pupation to come so crops could still be at risk when they reach the susceptible growth stage.

Spring crops can also be at risk if they reach the susceptible stage while midges are still emerging.


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 over the next few weeks. 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.

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

Previous Reports

Report 1 – 14th May 2015

Report 2 – 29th May 2015

Final Report – 10th June 2015


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Kerb Weather Data service

The Kerb® Flo 500 and ASTROKerb® application window is now closed for this season.

Please revisit this page mid October, when the Kerb Weather Data service will start again, providing advice on when conditions are optimal for applications of Kerb Flo 500 and ASTROKerb.

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