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Agronomy Support

Arable Update – May 2018


In this Edition:

  • Arable Update Special: Weed Control in Spring Cereals
  • Residual Herbicides
  • Post-Emergence broad-leaved weed control
  • Post-Emergence grass weed control


Arable Update Special: Weed Control in Spring Cereals

Spring cereals tend to sit in two camps so far this year – those drilled before the Easter deluge and those that have either only just been drilled or are still to be drilled! Weed control may not be top of mind in these crops with the backlog of work, however, we hope that the quick guide below gives some useful food for thought.

Residual Herbicides

The use of residuals in spring cereals is increasingly popular, primarily driven by the need for grass weed control. There is a strong geographical variance, ranging from 5% of the crop treated with a residual in some areas, to 80% in others. Whatever the products used, efficacy depends upon a number of aligning factors, such as seedbed conditions, appropriate moisture levels, weed seed germination profile, product rate, etc. Results from trials, and feedback from many agronomists, show that a number of important weeds can come through a residual herbicide, such as poppy, fat hen, black bindweed and fumitory. This means that the use of a follow-up contact spray after the use of a residual is commonplace. Products containing Arylex are well suited as follow-up sprays.

Those that drilled spring cereals before Easter were unable to get back to spray and now weeds have passed growth stages where residuals are effective. The more recently sown cereals are moving so fast in the ideal growing conditions, resulting in both crop and weeds going beyond the optimum timing. This means that contact herbicides such as Arylex products will be the main weed control approach for many spring cereal crops.

Post-emergence broad-leaved weed control

Where a residual has not been used, controlling the broad-leaved weeds early is a priority. Data from 38 trials in spring barley, where no residual had been used, showed yield increases from herbicides being greatest when applied between GS12 and 25 of the crop, while applications from GS24-32 did not yield significantly higher than the untreated. Yield however is not the only component to consider as many weeds can impact on harvesting. It is also important to consider weed emergence patterns as post-emergence weed control depends on the weeds being present at the time of application.

The tools available for broad-leaved weed control in spring cereals have changed in recent years with the most significant being the loss of the Ioxynil. At the same time new herbicide introductions have given new tools with many advantages. The addition of the ArylexTM range of herbicides (PixxaroTM, ZyparTM and TrezacTM) offer a number of benefits:

  • Wide spectrum of weeds controlled including fumitory, fat hen and black bindweed
  • Reliable control in variable weather conditions
  • Tank mix compatibility
  • Wide windows of application
  • Low carry-over risk to following crops
  • Control of ALS resistant weeds including poppy and chickweed

Using the products successfully will depend on knowing the weeds present and mixing with other herbicides to fill gaps:

The ideal target size of weeds is from 4-6 leaves. Dose rates of the Arylex products should be adjusted according to weed size and should not be used as a ‘rescue treatment’ when weeds have passed certain weed sizes/growth stages. See product details for more information.

Pixxaro and Trezac often benefit from adding an adjuvant, particularly in conditions where weeds have become waxy.

*Where ALS resistant poppies are present at a high population, every percentage-point of control is critical and in these situations, Trezac is the product of choice.

Post-Emergence grass weed control

In spring barley, post emergence grass weed control is principally based around Axial (Pinoxaden) for wild oats. Applications typically take place at flag leaf emergence of the barley. Zypar, Pixxaro and Trezac are fully supported in a tank mix with Axial plus adjuvant.

In spring wheat, we now have approval for Broadway®Star (at 200g/ha), which delivers control of a wide range of broad-leaved weeds as well as activity on wild oats. The timing of application is between growth stages 23 and 32 of the spring wheat. For more information our tech sheet has details.

For more information click on the links below:




If you require any further information please contact our Technical Hotline on 0800 689 8899 or your local
Dow AgroSciences representative.

Use plant protection products safely.  Always read the label and product information before use.
Pay attention to the Risk Indication and follow the Safety Precautions on the 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.

Pixxaro contains halauxifen-methyl (Arylex active) and fluroxypyr
Trezac contains halauxifen-methyl (Arylex active) and aminopyralid
Zypar contains halauxifen-methyl (Arylex active) and florasulam
Broadway Star contains pyroxsulam and florasulam
Starane Hi-Load contains fluroxypyr

More information can be found at

Corteva AgriScience, Agriculture Division of DowDuPont, CPC2, Capital Park, Fulbourn, Cambridge, CB21 5XE.  Tel: +44 (0) 1462 457272.
Technical Hotline: 0800 689 8899 | |

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Grassland and Maize Agronomy Update – April 2018

Grassland & Maize newsletter

Welcome to the Grassland and Maize Agronomy Update from DowDuPont. With the merger of Dow AgroSciences, DuPont Crop Protection and DuPont Pioneer, this newsletter now covers maize as well as all things grassland.

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

You can claim two CPD points for subscribing to this email update.


  • Curled dock versus broad leaved dock
  • Treating docks ahead of first cut silage
  • Why multi-strain grass silage inoculants can help your grass silage fermentation
  • Timing of Ragwort control
  • Weedwiper and use of Dow AgroSciences selective herbicides
  • Weed spectrum of Leystar
  • What control you can expect when targeting flowering buttercup
  • Dandelions in grazing fields
  • Sycamore seedlings in paddocks
  • Grandfather rights – reminder
  • Labels and use on grassland
  • FAQs
  • Grassland shows calendar

Curled dock versus broad-leaved dock

Broad-leaved dock (Rumex obtusifolius) and curled dock (Rumex crispus) are problem weeds in grassland.

Broad-leaved dock has broad lower leaves with an elongated heart shape.  The leaves are usually at least half as wide as they are long.  The flowering stems are well branched.   Flowering starts in late June or July and the fruits, when fully ripe, are a reddish-brown colour and often remain in clusters on the stems.

Curled dock has narrower leaves which are usually at least three times long as wide.  The leaf margins are often wavy.  The flowering stems are much less branched that those of broad-leaved dock and tend to be carried close to the main stem.  Flowering starts in early June.

Although both species are perennials, curled dock tends to be much shorter-lived than broad-leaved dock, and can behave as an annual or biennial in some situations with plants dying after flowering.  Individual plants of broad-leaved dock can be very long-lived, especially in pastures.  Both species occur in meadows and pastures.  Both species produce large numbers of seeds (>25,000 per plant) which are very persistent in the soil.

Check product labels when selecting a dock herbicide. Some products such as Cimarron and Pinnacle only have broad-leaved docks on the label.


Broad-leaved dock                                                                      Curled dock

Advantages of treating docks ahead of first cut silage

Spraying docks with a translocated herbicide now, when they are young, healthy and actively growing, will increase grass silage yields and improve the feed quality of the resulting forage. The higher dry matter and sugar content of grass after controlling docks is also likely to improve silage fermentation and reduce the chances of making poor silage.

Docks are at the right size for spraying when they are 20 cm wide rosette or “dinner-plate sized.”

The best way to tackle docks in silage crops is to spray with Doxstar®Pro, which enters the plant and travels right down to the roots. It takes three to four weeks to do this, so farmers should work out when first cut is likely to take place, then spray at least three weeks before that date.


Why the multi-strain grass silage inoculants, Pioneer Brand 1188 and Pioneer Brand 11G22, can help your grass silage fermentation

If the weather is unfavourable during harvest then the grass crop will be wetter and will undergo a more extensive fermentation. At low dry matter contents fermentation stability may not be reached until the pH is as low as 3.8. Strains of bacteria demonstrate varying levels of tolerance across the likely range of pH values.

Dry and sunny weather before and during silage harvest will increase sugar levels. As the dry matter increases so does the osmotic pressure. Different strains of bacteria demonstrate varying ability to withstand changes in osmotic pressures.    Strains that have a higher osmotolerance should perform better in high dry matter silages. Silage inoculants with more than one strain of bacteria are more likely to be effective across a wide range of moisture contents.

Strains of Lactobacillus plantarum show poor tolerance at the higher pH levels that are associated with the early stage of the silage fermentation. Entercoccus strains are more active at higher pH levels and it is for this reason that two strains of Entercoccus are contained within Pioneer Brand 1188 and Pioneer Brand 11G22 silage inoculants. Their role is to “kick-start” the fermentation until the pH drops to 5.0 when the Lactobacillus plantarum become more active.

Inoculants reduce dry matter losses from silage even under favourable weather conditions. Extensive trials comparing the fermentation dry matter losses under difficult, medium and easy ensiling conditions show that the application of an inoculant significantly reduces dry matter losses even under easy conditions.


Benefits of using Pioneer Brand 1188 and Pioneer Brand 11G22:

  • Rapidly lowers pH and stabilises the silage with minimal use of available sugars
  • The controlled fermentation results in 20% less in-silo losses
  • Reduces ammonia nitrogen, content by an average 46%
  • Maximises lactic acid production, minimises acetic and butyric acid formation
  • Improving nutritional value of treated silage: An average advantage of 3.5 units of DMD
  • Increasing silage intakes with both cattle and sheep by 5-16%
  • Increasing the rumen microbial protein by 50% due to higher energy and protein quality in treated silage
  • Producing an extra 1.5 Kg milk/day
  • Producing an extra 4 Kg beef live – weight gain per tonne of grass ensiled

These results have been proven in independent research trials

Timing of Ragwort control

Ragwort is one of the most frequent causes of plant poisoning of livestock. It is responsible for over 90% of the complaints on injurious weeds in the United Kingdom.

Cultural control of ragwort by cutting, digging out or puling is often ineffective. Chemical control with MCPA and 2,4-D gives some control on young plants but performs poorly on late rosettes or flowering plants. The best long term control of ragwort is achieved from Forefront® T applied to actively growing rosettes.

Dow AgroSciences trials – ragwort control one year after treatment

Weedwiper and use of Dow AgroSciences selective herbicides

Weedwiper is not an approved application technique for any of our products. The only product that has an approval today via this method is glyphosate.

CRD require a full regulatory dossier for this method of application and so consequently this is something we cannot support at this time.

Weed spectrum of Leystar and its use as a new sown ley herbicide

In new grass leys the key target weeds are annual weeds such as mayweed, chickweed, fat-hen, seedling thistles etc. Leystar™ controls these seedling weeds and many more besides. Many grassland herbicides have lost their approval for new sown leys, so Leystar fills a vital gap. Leystar is applied at 1.0 L/ha to new sown leys, and can be used from when the grass has three true leaves.

    Seedling weeds controlled with Leystar at 1.0 L/ha
Black bindweed Common sorrell Field bindweed Mayweed (1 true leaf)
Black nightshade Corn chamomile Fool’s parsley Ribwort plantain
 Buttercup Corn marigold Forget-me-not Shepherd’s-purse
 Charlock (1 true leaf)  Daisy Greater plantain Spurrey
Chickweed Dandelion Groundsel Thistles (from seed) (1 true leaf)
 Cleavers (1 true leaf) Docks Hemp-nettle Wild Radish
 Cover, trefoil Fat-hen(up to 2 leaf)  Knotgrass Yarrow


What control you can expect when targeting flowering buttercup

Best control of buttercups is achieved if they are sprayed before flowering. However, the trigger for spraying a field of buttercups is often once the farmer has noticed that the field has turned a shade of buttercup yellow! Replicated Dow AgroSciences trials showed that useful control of creeping buttercup can still be obtained during flowering. However, for best overall control, pre-flowering applications of Envy™ or Forefront T both at 2.0 L/ha are preferred.




Dandelions in grazing fields

The ubiquitous dandelion is found throughout the country, in grassland where there is limited disturbance. Although dandelions are palatable to stock, they are relatively unproductive in terms of nutrition and so can reduce the overall value of pasture if allowed to establish. Envy at 2.0 L/ha is a good option for dandelion control. It’s an ideal product in horse paddocks too as there are no manure restrictions.





Sycamore seedlings in paddocks

A common query at this time of year is how to control sycamore seedlings, particularly in horse paddocks. Ingestion of sycamore seedlings containing the toxin hypoglycin A can cause the sometimes fatal condition equine atypical myopathy in horses and ponies. Although not a label recommendation, spot treatment with Grazon®Pro or a boom spray with DoxstarPro or the Pas·Tor agronomy pack will give control of sycamore seedlings. Horse owners need to be aware of grazing intervals, as may need to leave longer than 7 days if poisonous weeds are present.



Grandfather rights – reminder

This option will no longer be available from December 31st 2018. If you have farmer clients – particularly those wishing to use GrazonPro or glyphosate around the farm and that don’t have this qualification or a PA6 then do encourage them to get certified else they will lose the right to apply.

Labels and use on grassland

Make sure only herbicides that have a label recommendation for use on grassland are used on this crop. If it’s not on the label then farmers are being miss-sold, have no backup from the manufacturer if something goes wrong and it can be an illegal application putting in jeopardy cross compliance.


Q. Are sprays safe to the grass?

A. Dow AgroSciences selective herbicides only work on broad-leaved weeds and do not affect any species of grass. This means they are completely safe to use in grass fields when used correctly. However, clover will be severely damaged or destroyed.

Q. When can silage be cut if Forefront T is going to be used this spring?

A. Forefront T should NOT be used on grass destined for silage in the year of its application. It can be used in a silage field after the last cut of silage has been taken. Grass from that field can be used to make silage the following year but resulting silage and manure must stay on the farm.

Show dates

May 10th Grassland UK Bath & West Showground
May 16th Royal Welsh Grassland Carnbwll, Powys
 May 25th NBA Beef Expo Shrewsbury Livestock Auction Centre
 May 30th NSA Scot Sheep Ballantrae
July 18th NSA Sheep Event Three Counties Showground, Malvern
September 8th NSA South Sheep South of England Showground


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 DowDuPont or Pioneer.  All other brand names are trademarks of other manufacturers for which proprietary rights may exist.

DoxstarPro contains fluroxypyr and triclopyr
GrazonPro contains clopyralid and triclopyr
Envy contains fluroxypyr and florasulam
Forefront T contains aminopyralid and triclopyr
Leystar contains fluroxypyr, clopyralid and florasulam
Pas·Tor contains clopyralid, fluroxypyr and triclopyr

Corteva AgriScience, Agriculture Division of DowDuPont, CPC2, Capital Park, Fulbourn, Cambridge, CB21 5XE.  Tel: +44 (0) 1462 457272.

Technical Hotline: 0800 689 8899 email: |


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View All Topic Sheets
What are the LERAP requirements for Broadway Star/Palio?

The CRD re-approvals for Broadway Star (MAPP 18273) and Palio (MAPP 18349) removed the requirement for a buffer zone and therefore LERAP requirement for these products. It is however important to check other requirements e.g. Cross Compliance for the Basic Payment Scheme (BPS) requires no application of pesticides to land within 2 metres of the centre of a watercourse or field ditch, or to land from the edge of the watercourse or field ditch to 1 metre on the landward side of the top of the bank of a watercourse or field ditch.

What is the current situation with regard to Unite?

Unite, along with other products that contain flupyrsulfuron, are now subject to a withdrawal notice. The timelines are as follows:

Up until the 31 March 2018 Unite can be sold (sales period)

Up until the 13 December 2018 Unite can be used, stored or disposed of (use-up period)

Full details of the withdrawal notice can be found here

Please note this withdrawal does not affect Broadway Star and Palio

Why is Unite subject to a withdrawal notice?

The active substance, flupyrsulfuron, has not been approved for renewal at an EU level. Note this does not affect Palio and Broadway Star as these products do not contain flupyrsulfuron.

What are the following crop restrictions/cultivation requirements for Pixxaro EC?

After an application of Pixxaro EC at 0.5 L/ha up to BBCH 45, the following crops may be sown.
• Autumn: Beans*, Cereals, Clover*, Grass, Lucerne*, Oilseed Rape, Peas, Phacelia
• Spring: Beans, Cereals, Clover, Grass, Lucerne, Maize, Oilseed rape, Onions, Peas, Potatoes, Sugar beet, Sunflowers

*Plough prior to sowing

The Pixxaro EC label advises ploughing prior to sowing winter beans, however, Dow AgroSciences support autumn sown field beans without ploughing prior to drilling, following an application of Pixxaro EC (in spring to the previous cereal crop) with one exception: high pH soil (8 or over) in a dry summer, in these situations ploughing is then recommended prior to drilling autumn sown field beans.
We are working on adding following crops such as carrots, brassica transplants and borage as a following crop.

When is the best time to control sterile brome in winter wheat?

Sterile or barren brome germinates in the autumn and grows very quickly.

Control is best achieved in a programme with  2000g ai/ha pendimethalin followed ideally by autumn applied Broadway Star or Unite. Best control is achieved when applied before GS24 of the brome.  

Which pre-emergence herbicide should I use for ryegrass control in a Broadway Star programme?

Use 3200 g  ai / Ha of prosulfocarb.  Additional pendimethalin may help.

Can the straw from oilseed rape treated with ASTROKerb be used for animal bedding?

Oilseed rape straw from crops treated with ASTROKerb needs to remain in the field and must not be baled and used for bedding.  It may be removed from the field to be used for burning for heat or elctricity production.

Can I plant cover crops even where they are not listed as a following crop on the label?

The planting of any crop (not subject to human consumption/MRL requirements) not specifically  recommended on the label would need to be at the users risk where following crop safety has not been demonstrated.

What is the knapsack rate for DoxstarPro, Forefront T, Pas·Tor 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.