Grassland Agronomy Update – April 2016


April 2016

Welcome to the Grassland Agronomy Update from Dow AgroSciences.

These technical notes offer seasonal commentary for those interested in improving grassland productivity and use on dairy, beef, sheep and equestrian enterprises.

Claim 2 BASIS points by subscribing to this email update.  To subscribe please send your details to, with the title GRASSLAND AGRONOMY UPDATE.


  • Encourage spraying for docks before first cut silage
  • Less product choice for grassland weed control
  • Catch buttercups and dandelions before flowering
  • Updated Dow Grassland App
  • Forefront T stewardship
  • Loss of Dursban WG for Frit fly and Leatherjacket control
  • Meet Brent Gibbon
  • Grazing & Cutting Intervals – What’s the difference?
  • FAQs
  • Dow AgroSciences’ Show Calendar

Encourage spraying for docks before first cut silage

Docks in silage groundDocks are now emerging and beginning to grow well. They have good root systems after a relatively mild winter which means that they will quickly  out compete the grass as temperatures increase.

Nights of hard frost can slow dock growth. However, as it is now past the Spring Equinox and days are longer than the nights, these will only set them back temporarily.

There are plenty of established docks in fields. Trigger points for timing:

  • Should be 20cm wide or dinner-plate sized  to take up the optimum amount of herbicide.
  • Should be signs of active growth
  • There is at least three weeks before cutting for silage

The best way to tackle docks in silage crops is to spray with a modern translocated herbicide like DoxstarPro®, which enters the plant and travels right down to the roots. It takes three to four weeks to do this.

Applications of 2 litres/ha in 300 to 400 litres of water will get rid of the weeds well ahead of first cut, giving the grass chance to re-colonise the space left by the dead weeds.

More milk from forage

Getting rid of broad-leaved perennial weeds will increase grass silage yields and improve its quality, allowing cows to produce more milk from forage, and less from expensive bought-in concentrates, which is helpful in times of low milk prices.

Research shows that a 10% population of docks in a sward results in 10% loss of grass growth, reducing the amount left to cut or graze.

Where docks are present, weed control is a small cost relative to the gain in extra grass and silage produced.

Spray before or after fertiliser

Spraying grassland with herbicide either a week before or a week after a nitrogen fertiliser application can boost its effectiveness.

This is because translocated products travel to the growing points inside the weed. If the weeds are growing more quickly following a dose of fertiliser, the herbicide effect will be enhanced.

Less product choice for grassland

Increasingly strict EU and national regulations are reducing the choice of herbicides available to use on grassland.

Products with grassland approvals revoked so they can no longer be bought for this use are:

Foundation Marshall XL Prompt Swift
Grassland Herbicide Mircam Plus Relay P Transfer
HiLoad Mircam Mircam Ultra Saxon Trinity
Impede Pastural Plus

Further revocations are likely as 2,4-D and MCPA begin their path through re-registration during the next two years.

Approvals based on active ingredients triclopyr and aminopyralid are sustainable and greater use of products such as DoxstarPro®, PastorPro®, Thistlex® and Forefront® T is anticipated, as the market values the high long term levels of controls and their excellent grass safety.

Spray dandelions and buttercups before they flower

Spray buttercups when they are green and actively growing for best control

Dandelions and buttercups always emerge early and should be sprayed BEFORE flowering – when there is sufficient green leaf to take in the herbicide – so timing can be tight.  April / early May is an ideal month for targeting dandelions and buttercups.

This is more likely a problem on grassland that is grazed and nutrient deficient. Such grassland may compose of less competitive grass species and so these weeds can quickly dominate a sward.

Target an application before the main flowering phase starts.

The best solution for a wide spectrum of weeds, including dandelions and buttercups is Forefront T at 2 litres/ha in 200-300 litres of water.

Remember Forefront T offers exceptional broad-leaved weed control, but can only be used on grazing ground grazed by cattle or sheep.

Updated Dow Grassland App

Grassland App Weed IDThe Dow AgroSciences Grassland App is available to download from the App Store, Google Play or the Microsoft Store right now and can help agronomists to:

  • Calculate productivity loss from grassland weeds
  • Find out how to control more than 70 different grassland weeds
  • Obtain more information on the Dow AgroSciences product range
  • Digitally manage Forefront T stewardship

Further features are imminent:

  • Sprayer calibration tool
  • Tank dose calculator
  • Searchable FAQs
  • Create a spray record

To download the APP use these links:


Forefront T stewardship

Grassland App - ForefrontT Stewardship

The Dow AgroSciences Grassland App has been configured to manage the need for Forefront T stewardship.

Agronomists currently use the Forefront T stewardship pad or CropWalker/Gatekeeper spray recommendations to convey to the operator the requisite guidance on use.

Forefront T stewardship is necessary to ensure the end user understands the implication of use with respect to manure management, and that it must not be used on grass used to make silage or hay/haylage.

The APP makes this process very easy. There are no paper records to get lost, it is immediate, the farmer does not need to sign his/her name, and consolidation and reporting is automatic.

The APP is configured for use for Apple, Android and Windows devices.

Where you want to make a recommendation for Forefront T, use the Forefront T Stewardship feature in the APP.

If you have any difficulty or want some support, contact your local Dow AgroSciences representative

Loss of Dursban® WG for Frit fly and Leatherjacket control

Chlorpyrifos can no longer be used against Frit Fly or for Leatherjacket control in new grass swards or on established grassland.

Following a European Union review, new human health-based safety levels were agreed in 2015 for chlorpyriphos. Risk assessments carried out by the HSE and endorsed by the Expert Committee of pesticides (ECP), have indicated that almost all uses of this pesticide exceeded these newly agreed levels. Exposure when correctly used was considered, the risk was assessed and, if not considered unacceptable, the pesticide could be registered for sale.

Under the new rules, any level of exposure to a substance that is deemed as hazardous is considered unacceptable.

With effect from 1 April 2016, there is only one permitted use of chlorpyriphos, which is a protected brassica seedling drench treatment, applied via automated gantry sprayers.

What does this mean for Frit fly and Leatherjacket control?

Frit fly damageThere is now no pesticide option for controlling these pests, which are a particular nuisance in new sown leys.

Options to manage a high risk situations might include:

  • Increase grass seed rate to 45 to 50kg / ha
  • Move to spring re-seeding (especially Frit fly)
  • Use a catch crop ahead of an autumn re-seed
  • Fallow the field so that Frit fly larvae will starve – estimate 2 months. (less effective with Leatherjackets)
  • Use cultivations to bring leatherjackets to surface
  • Rejuvenate swards by over seeding rather than carrying out a full reseed

Meet Brent Gibbon


Brent Gibbon took up a new role at Dow AgroSciences on 1 September last year, becoming the Grassland Agronomy Manager for the West of England (from the Scottish Borders to Cornwall) and Wales.

Brent studied Agricultural Zoology at the University of Leeds followed by a postgraduate diploma in Crop Protection at Harper Adams. After a spell with Bayer, he joined Dow AgroSciences in 2002 as Regional Business Manager, based in Shrewsbury.

He is also a member of the company’s grassland products marketing team, providing feedback on the weeds and pests causing the most problems for farmers out in the fields.

“My philosophy is that grass is a crop – just like wheat or barley, and anything that detracts from achieving its full potential yield has to be dealt with,” says Brent.

“Our grassland herbicides are tried and tested over many years and do a very good job when applied correctly. While farmgate prices remain so challenging, my aim to help farmers make the most of our products, so they can grow and feed as much grass as possible, and reduce their costs of production.”

Brent can be contacted on mob: 07779 802199 or email:

You can also follow him on twitter @BrentGibbon for his latest advice and comment as the season progresses.

Grazing and Cutting intervals – what’s the difference?

One of the most common questions asked on the Dow AgroSciences’ Hotline (Tel: 0800 689 8899) is what is the difference between ‘Grazing Interval’ and ‘Cutting Interval’?

Grazing Interval is the time the animals must stay out of a field after spraying herbicide for safety reasons – usually seven days for our products, but can be longer for others. The length of time is specified on the product label.

Amendments to products labels relating to ragwort will appear shortly:

The following phrase must appear in the ‘DIRECTIONS FOR USE’:

‘Where ragwort is present users should consult the Code of Practice on How to Prevent the Spread of Ragwort.  Ragwort plants sprayed with this herbicide are more palatable and contain higher levels of toxins.  Animals should be excluded from treated areas until any ragwort has completely recovered or died and there is no visible sign of the dead weed.  Do not include treated ragwort in hay or silage crops.’

Cutting Interval is the recommended minimum time left between spraying and cutting the grass for silage, haylage or hay – usually at least 21 days, but preferably 28 days. This gives the product time to translocate right around the plant and to reach deep into the roots, giving a more thorough kill.


Q: Why does the amount of grass affect the water volume required for spraying herbicides?

A: Achieving good spray coverage of weed leaves in dense permanent pasture is much more difficult than spraying silage aftermath or a field that has been grazed hard by livestock.

The current recommendation is that the thicker the sward, the higher the water volume needs to be – from 400 litres/ha down to 200 litres/ha.

Dow AgroSciences has commissioned some on-farm trials into the effect of lowering water volumes when spraying dock and thistle infestations. Initial results will be promoted later this spring but indicators are that performance can be maintained with a reduction in water volume if air inclusion nozzles are used. There is a limit below which water volumes must not be reduced and this is driven by human health concerns. Please see our Topic Sheet 21 for more guidance.

Q: Can Dow products be used under solar farms?

A: Yes, Forefront® T could be used for blanket spraying or GrazonPro® for application though a knapsack.

Dow AgroSciences’ Show Dates

Grassland Show 2105The technical team from Dow AgroSciences will be out and about at shows and events this summer, talking to farmers and agronomists and answering questions on how to tackle weed problems in their fields.

Catch the team at:

Month Dates Show Location
May 11th, 12th, 13th Balmoral Show Balmoral Park, Lisburn, Co. Antrim
May 12th FTMTA Grassland & Muck Gurteen College, Roscrea, Co. Tipperary
May 18th ScotGrass SRUC Dairy Research Unit, Acrehead Farm, Crichton Royal, Dumfries
May 20th NBA Beef Expo The Agricultural Business Centre, Bakewell
June 1st NSA Scotsheep Blythbank, West Linton, Peebleshire
June 7th NSA South Sheep Pythouse Farm, Salisbury
June 9th Royal Welsh Grassland Event Rhug Estate, Corwen
July 6th, 7th Livestock Event Birmingham NEC


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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Problem Solution Dose Rate Water Volume Grazing Interval
Docks and Chickweed 2.0 L/ha or 1.0 + 1.0 L/ha 300-400 L/ha 7 days
Docks, Thistles, Nettles, Buttercups, Dandelions and Ragwort 2.0 L/ha 200-300 L/ha 7 days
Thistles 1.0 L/ha 200-400 L/ha 7 days
Docks, Thistles and Nettles 4.0 L/ha or 2.0 + 2.0 L/ha 300-400 L/ha 7 days
Leatherjackets and Frit Fly 1.0 Kg/ha 200-300 L/ha 14 days
Knapsack/spot treatment: Docks, Thistles, Nettles, Brambles, Gorse and Broom 60 mls 10 Litres 7 days

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Getting rid of broad-leaved perennial weeds like docks will increase grass silage yields and improve its quality, allowing cows to produce more milk from forage, and less from expensive bought-in concentrates, which is helpful in times of lowered milk prices. “Research shows that a 10% population of docks in a sward results in 10% loss […]

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Grassland News Archive
Are Dow AgroSciences grassland herbicides clover safe?
No, clover will be killed or severely checked by applications of Dow AgroSciences’ grassland herbicides.  However you can stitch clover back in after six weeks of applying PastorPro, Thistlex, DoxstarPro or GrazonPro. When using Forefront T, clover can be reintroduced four months after application.
Can any of the Grassland products; DoxstarPro, Forefront T, PastorPro, Thistlex or GrazonPro be tank mixed with MCPA or 2,4-D?
This approach is not recommended and is not supported by Dow AgroSciences. Quick 'burn down' of top growth with phenoxy herbicides can hinder movement of the translocated active ingredients in DoxstarPro, Forefront T, PastorPro, Thistlex and GrazonPro to the roots, leading to poor levels of weed control.
Can DoxstarPro, Forefront T, PastorPro, Thistlex or GrazonPro be used on new leys (<12 months old)?
No. Grassland should be at least 12 months old for all of the above products.  
Can I apply PastorPro through a Knapsack?
No. There is no approval for hand-held application of PastorPro. Consider using  GrazonPro for hand-held applications.
Will PastorPro control thistles?
Yes. Apply at 4.0 L/ha.
Can I use GrazonPro on my lawn?
No. GrazonPro is a professional product recommended for use only as an agricultural herbicide.
How rainfast is GrazonPro?
If GrazonPro is applied to a dry leaf it will be rainfast in 2 hours.
What rate of GrazonPro should be applied through a knapsack?
60 ml of GrazonPro in 10 litres water.
What is the grazing interval for GrazonPro?
Seven days. Ideally allow 28  days if cutting the field for silage or hay. The seven day exclusion period may need to be extended if poisonous weeds are present.
Will GrazonPro control chickweed?
No, but DoxstarPro, Forefront T and PastorPro all give excellent control when applied under the correct conditions.
What is the best Dow grassland product for cow parsley control?
GrazonPro offers good control of cow parsley when used at the rosette stage. It is for spot treatment only. Forefront T and PastorPro can be applied through tractor mounted hydraulic sprayers. Forefront T offers moderate control of cow parsley. Forefront T use is limited to grass grazed by cattle and sheep only.  Although not as effective at Forefront T, PastorPro offers some control of cow parsley and can be used on field including those for silage and hay.
What is the cutting interval after spraying weeds in grassland?
After application of our products leave a minimum of 21 days, ideally 28 days  before cutting to allow maximum translocation of the active ingredients down to the roots of weeds.
What is the grazing/cutting interval after application of PastorPro?
Seven days for grazing and ideally 28 days if grass is being cut. The seven day exclusion period may need to be extended if poisonous weeds are present.
What is the knapsack rate for DoxstarPro, Forefront T, PastorPro and Thistlex?
These products are not recommended for application through a knapsack. GrazonPro at 60 ml in 10 litres of water is the best product for spot treatment.
What is the stock exclusion period for hens?
The same as for livestock: seven days and until foliage of any poisonous weeds such as ragwort has died and become unpalatable.  
What is the stock exclusion period for horses for Doxstar Pro, GrazonPro, PastorPro and Thistlex?
The same as for livestock: 7 days and until foliage of any poisonous weeds such as ragwort has died and become unpalatable.
What products do Dow AgroSciences recommend to control brambles in grassland?
Brambles should be sprayed between June and August, when plants are actively growing, but before plants begin to senesce in the autumn. It is essential that all foliage is thoroughly wetted or incomplete kill may result. The maximum concentration must not exceed 60ml of GrazonPro per 10 litres of water.   Blaster Pro can be used to control brambles in amenity grass.
What water volumes do I need to control docks in established grassland with Doxstar Pro?
Whenever DoxstarPro is used in established grassland the rate of water should always be 300-400 L/ha.
Will any Dow AgroSciences product control ragwort in horse paddocks?
No Dow AgroSciences product is recommended for control of ragwort in horse paddocks. The best method of control is to dig them up. 2,4-D can be used as an overall spray.
Will DoxstarPro, Forefront T or PastorPro control large flowering docks?
No. They must be topped and allowed to regrow. Treatments should then be made under good growing conditions to actively growing plants when they reach the rosette stage.
Will Thistlex control dandelions?
Yes, but it is not an 'on label' weed. Consider topping dandelions and then applying Thistlex 2 - 3 weeks later at the rosette stage of the weed.