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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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Arable Update – May 2016

TP21869 Arable Update Newsletter header

MAY 2016


In this Edition:

Broadleaved weed control in cereals

N-Lock Nitrogen Stabiliser – the year so far

Dow Shield celebrates 40 years!

Reldan 22 for controlling mites and pests in grain stores


Broadleaved weed control in cereals

cleavers and vol OSR in wheatSo far it’s been a difficult season for finding those spray opportunities to control broadleaved weeds in winter cereals, however fear not, our broadleaved weed products, Spitfire® and Starane® XL, have long windows of application and they can cope with changeable and challenging weather conditions!

Spitfire and Starane XL are both well-established products offering weed control up to GS 45 (before boots swollen) in winter wheat and barley and up to GS 39 in spring cereals. Both products are based on florasulam and fluroxypyr, the combination of these active ingredients in a formulated product work to deliver outstanding control of cleavers and other broadleaved weeds.  Spitfire delivers a higher loading of florasulam to give a wider weed spectrum and more robust activity in cold conditions whereas Starane XL gives a lower loading of florasulam and is ideal for controlling brassica weeds such as volunteer oilseed rape and mayweeds alongside cleavers – the main weeds that come through residual programmes.

Spitfire and Starane XL are not Sulphonyl Ureas (SUs) and both have excellent following crop profiles, even from late season applications, giving peace of mind when following with sensitive crops like oilseed rape.

Finally both products have a wide range of fully supported tank mix compatibilities including growth regulators, fungicides and trace elements, meaning you can fit the product with existing crop protection programmes. For more information on Spitfire and Starane XL visit our website.

N-Lock  Nitrogen Stabiliser – the year so far

Many areas have experienced above average rainfall during March and April, and the risk of nitrates leaching or moving down the soil profile away from crop roots will have significantly increased. Growers who applied N-Lock from mid-March onwards, in winter cereals and oilseed rape, will have protected their fertiliser investment by keeping more nitrogen in the root zone for longer which will help to optimise crop yield.

This spring we have seen N-Lock™ used alongside digestate applications on winter cereals. In adopting this strategy, the N-Lock will hold some of the nitrogen in the digestate in the ammonium form for up to eight to ten weeks. One of the benefits of this  will be to help  reduce the amount of unwanted lush growth.

N-Lock works by inhibiting the bacteria that converts ammonium to nitrite, ammonium is positively charged and binds with the negatively charged soils therefore reducing the risk of leaching. Conversely nitrite and nitrate are negatively charged so are repelled by the negatively charged soil particles resulting in potential leaching.

N-Lock must be incorporated into the soil within 10 days of application to start acting on the nitrosomonas bacteria which convert ammonium to nitrite. The best ways of achieving this are by cultivation, prior to sowing a spring cereal or maize crop or incorporation by rainfall [12mm]. N-Lock has an extensive list of tank mix partners; a typical example is that it can be applied with a pre-emergence herbicide to maize. Once in the soil the N-Lock will inhibit the nitrosomonas bacteria for eight to ten weeks depending on soil temperature.

NLock in maizeMaize responds particularly well to N-Lock applications and has delivered on average a 9% yield increase in field trials conducted by Dow AgroSciences over the past two years. The crop uses most of its nitrogen during July and August; with fertiliser application usually taking place weeks before in the seed bed and when the crop is small before applications physically damage the plants. During this period nitrogen can be leached and moved away from the small maize roots limiting yield potential of the crop.

As well as maize yield increases we have seen improved cob weights and kernel size. In cereals yield increases have averaged 4.7% and there have been improved hectolitre weights and in some cases increases in grain protein .

To get the best out of N-Lock it is important to ensure efficient incorporation into the soil and measure the results that this nitrogen stabiliser product gives you.

So protect your fertiliser investment with N-Lock and optimise your yields.


Dow Shield celebrates 40 years!

Dow Shield 400 BottleCast your mind back to 1976! It was the era of the three day week and the Soweto riots in South Africa. But it would probably be remembered more for the famous UK summer drought – still the worst on record. It resulted in stand pipes in the street and plagues of ladybirds. Gardeners saw their lawns go brown; farmers watched their crops die on their feet.  And Dow Shield® (clopyralid) was registered in the UK! – over 40 years ago!

Having been available for 4 decades doesn’t mean that there have been no improvements on its journey. In that time all registration hurdles have been exceeded and four years ago Dow AgroSciences invested in and launched a new and improved double strength Dow Shield 400 formulation.  The double strength formulation is packaged in a new pack with no foil to dispose of making it easy to handle, reducing point source contamination risk and makes spraying more streamlined. Through this process it held onto and even expanded its key crop recommendations.

Having invested in Dow Shield throughout all the rigorous registration challenges over the last 40 years Dow anticipate that Dow Shield will be around for many more years to come.

Dow Shield in sugar beet

thistles and potatoes in sugar beetForty years ago sugar beet growers could use Dow Shield (clopyralid) to control thistles. Further investment saw volunteer potatoes added to the label in 1991. And growers today are still able to use this effective herbicide in sugar beet.

In 1976 beet yields in the UK were down to just 30 tonnes/hectare due to the drought. In 1976 there were 15,000 growers providing beet for 17 beet factories. Now 40 years later there are just 4 factories and 3,000 specialist growers growing 75 t/ha average yield.

The progress in yield has been outstanding; increasing by 2% each year as a consequence of new varieties and cost-effective inputs. But the theoretical potential for sugar beet yield is thought to be 150 t/ha. In parts of California they are growing 120 t/ha and even in France the average sugar beet yields is 90 t/ha. Yield is down to genetics and inputs.

Sugar beet is a very uncompetitive crop, particularly during the first eight weeks of growth when weeds with a high biomass are able to flourish and compete.

These weeds, such as volunteer potatoes and thistles, impede crop growth and shade the canopy, blocking out sunlight and having a detrimental effect on yield.

With lowering sugar beet prices, the only way of making a good margin is to grow the heaviest crop you can, whilst carefully managing some key costs. Dow AgroSciences says this means using the right herbicide early and often enough on the most competitive weeds, which are those that grow above the canopy.

Controlling thistles

Thistles are a significant nuisance in sugar beet. Just one creeping thistle stem per square metre can reduce the beet yield by 1 t/ha. One tall weed per square metre can cost 11% of yield.

Dense stands of tall sappy stems compete directly with sugar beet, and control should start when weeds are small.

Creeping thistles, spear thistles and sow-thistles are controlled by Dow Shield 400 at 0.25 l/ha plus a coformulation of desmedipham + ethofumesate + phenmedipham at 2 l/ha at rosette stage of the crop. This must be followed up by Dow Shield 400 at 0.5 l/ha 3 to 4 weeks later. No more than 0.75 l/ha of Dow Shield can be used per crop.

In addition Dow Shield 400 will control corn marigold, groundsel, pineapple weed, scented mayweed, scentless mayweed, black-bindweed, pale persicaria and redshank.

Controlling potato volunteers

Just 5 potato volunteers per square metre can result in yield loss of 16.5 t/ha of beet, as well as running the risk of being a source of potato blight and Potato Cyst Nematodes (PCN). So these large weeds need to dealt with to make a difference to yields and gross margins.

Because there is a considerable overlap between sugar beet and potato growing areas, beet will always run the risk of potato volunteers as a potential weed problem. This year there haven’t been sufficient winter frosts to reduce the viability of daughter potato tubers in the ground, so there will be even more volunteers than usual.

Dow Shield 400 is considered to be the single most important herbicide to use on volunteer potatoes. Used as a part of an integrated control programme across the rotation, in beet it has a significant impact in reducing the populations of these weeds.

  • Best control is achieved when applications begin when emerging volunteer potatoes are 5-10cms tall, and sugar beet is at cotyledon stage. A second application should be made when the volunteer potatoes are 10-20cm tall usually 7-14 days after the first application.
  • Dow Shield 400 can be used at any time during the classic sequential low dose programme at 0.25 l/ha initially with the residual metamitron plus oil spray and thereafter with other products in the programme, applied in 80 to 100 l/ha of water.

Dow Shield in maize

Maize at 5 leaf stageIn 1976, over 40 years ago, maize was an insignificant crop in the UK and AD plants on farms were unknown. With the development of maize varieties that suit UK climate and the need for another break crop, maize has increased its area to close to 200,000 hectares anticipated this year. This growth may be for one of four reasons –

  • as a consequence of the Three-Crop Rule
  • to spread the workload
  • to introduce another break crop on the farm in order to get rid of difficult to control weeds such as blackgrass
  • to add to energy production.

The majority of maize, according to the June Census 2015, is fodder maize, but there is a smaller area of maize that is grown for energy production in AD plants. Last year 19% of the total maize planted was grown for this purpose – so nearly 1 in 5 fields are destined for the AD plant now, with 4 in 5 for forage purposes.

  • Maize is a weak plant during establishment and maize seedlings can be overwhelmed by weed competition, especially by those high biomass weeds that grow quickly.
  • Weeds colonise bare open soil between the rows and take advantage of the wide rows and upright growth habit of the maize crop.
  • Early removal of weeds such as thistles, sowthistles and mayweeds is essential to achieve yield.
  • Crops are generally sprayed two or three times with a herbicide, pre and early post-emergence, to help the crop to grow through this vulnerable early stage.
  • Dow Shield 400 was granted a full label recommendation for forage maize in 2012 and is a very useful product to control high biomass, highly competitive weeds such as sow-thistle, mayweeds, groundsel and corn marigold.
  • It can be applied post-emergence to all varieties of forage maize at 0.25 l/ha from the 3 leaf stage up to the 9 true leaves of the crop. It shows very good crop safety, despite its post-em window.

When Dow Shield 400 is used in maize destined for the anaerobic digester, it takes 6 months for the chemical to breakdown and so the digestate should not be spread onto susceptible crops. If the digestate is spread onto grass, cereals, oilseed rape or maize, there are no worries.

The label text says ‘Dow Shield 400 residues in plant tissue (including digestate) which have not completely decayed may affect succeeding susceptible crops. If treated crop remains have not fully decayed by the time of planting following crops, avoid planting peas, beans, other legumes, carrots, potatoes, lettuce, glasshouse and protected crops. Winter beans and peas should not be planted in the same year as treatment. Where susceptible crops are to be planted the following spring, do not apply Dow Shield 400 later than the end of July of the previous season.’

Other herbicides, both pre-emergence and post-emergence, used in maize have following crops restrictions.  “Growers, especially those new to the crop, need to make sure they read the labels thoroughly, so they are familiar with any restrictions on following crops.”

Dow Shield in Game cover

Millet and triticale mixUntil last year Dow Shield 400 (clopyralid) had an EAMU for game cover crops, but it had a cut-off date of the end of May, which was far too early for any practical use. Most game cover crops are drilled in April or May and so will be treated for weeds in May or June. This contact herbicide now has an extended window to the end of July in the year of application, so its use will be a lot more practical for those who want to create a better game cover.

Game cover crops need careful managing, with weed control being an essential part of this management. Reducing weed pressure helps crop establishment.

Several different crop species are established each year to provide shelter and food for game birds. Dow AgroSciences have run a series of trials over two years to establish the safety of their advanced clopyralid formulation on a number of commercially available mixes and crop types used in game cover. The screens demonstrate that at 0.25 l/ha of Dow Shield 400 there was no damage on red millet, white millet, sorghum, maize, mustard, quinoa, Gold of Pleasure or borage. Buckwheat suffered minor but transient damage. However sunflowers, red clover and chicory were significantly damaged and should be avoided in any mix. When the dose rate was raised to 0.5 l/ha, white millet, sorghum, maize, Gold of Pleasure and borage were again unaffected, but at this higher dose rate red millet, mustard, quinoa and buckwheat showed minor crop damage.

Other products in the Dow AgroSciences portfolio can also be used in game cover crops including Kerb® Flo 500 (propyzamide), Starane 2 (fluroxypyr), Starane XL (fluroxypyr + florasulam) and Starane Gold (fluroxypyr + florasulam) and Thistlex® (clopyralid + triclopyr). They are widely used in arable and grass crops, so are easily transferable into game cover crop situations under their EAMU’s.

Well over 40 crops recommended for Dow Shield

Cauliflower cropVegetable, allium and nursery crop growers have suffered through loss of crop protection actives, either as more products are revoked or go through re-registration and lose crops and uses. Dow AgroSciences has been busy adding to their recommendations and supporting and encouraging Extension of Authorisation for Minor Uses (EAMU’s) for their chemistry.  One classic active ingredient, clopyralid, continues to be an important herbicide for specialist growers and each year additional crops are added or recommendations altered to make them even better.

“Dow Shield 400 has full label recommendations for 19 different crops, including swedes, turnips, mangels, bulb onions, broccoli/calabrese, cabbage, cauliflower, fodder beet, forage maize, linseed and Brussels sprouts as well as most cereals and rape and 19 EAMUs, including asparagus, garlic, shallots, chard, spinach, spinach beet, Chinese cabbage, kale, collard, outdoor leafy herbs, outdoor leeks and salad onions. Adding together its label recommendations and EAMU’s, well over 50 crops can be treated with Dow Shield 400 now and the list is always growing and evolving.

Allium growers have fewer and fewer chemicals but Dow Shield 400 has recommendations for most allium crops including bulb onions, salad onions, outdoor leeks, garlic and shallots. Dow Shield 400 should be used from 1st March and when these crops have at least 2 true leaves but before 6 weeks prior to harvest.

Cabbage, cauliflowers and broccoli can also be treated from the 2 true leaf stage up to 6 weeks before harvest and Brussels sprouts between the 2 true leaf stage up to 9 true leaves. It is 0.26 l/ha for annual weeds, for perennials it’s 0.5 l/ha in a single application or up to 0.75 l/ha total maximum dose from two applications in a programmed approach.

No peas or beans should be planted in the same year as the treatment with Dow Shield 400 however.

For any EAMU, growers should obtain a copy of the notice of approval via the Chemicals Regulation Directorate (CRD) web site, ADAS offices or NFU.

Reldan 22 for controlling mites and pests in grain stores

Grain storeReldan® 22 (chlorpyrifos–methyl) is still registered in the UK for the control of mites and pests in stored grain and on the fabric of the stores.

Mites and pests can

  • spoil quality
  • result in problems of reduced nutritional value, taint and contamination of insect fragments,
  • can be responsible for between 5% and 10% loss of yield
  • or even lead to complete crop rejection
  • give rise to mould infestations as moisture and heat in the grain heap increase.
  • act as a source of allergens leading to difficulties when feeding animals.

Control measures in stores need to start up to one month before harvest, so growers need to plan what action they are going to take in May. It is important to protect the investment already made in the crop when moving from field into store.

Various species of mites, weevils, beetles and moths are frequent problems in grain stores and grain heaps. Saw-toothed grain beetle and flour mites are the most commonly occurring pest species in grain, yet some insecticides have no effect on mites. Working by contact, ingestion and fumigant activity, the acaricide and insecticide Reldan 22 controls all major pests of stored grain. In fact it is the only pre-harvest grain store fabric treatment that controls the three main mite species – flour mite, Cosmopolitan food mite and Copra mite.

“In addition it controls a long list of other insects – Saw-toothed beetle, Rust-red grain beetle, Foreign grain beetle, Rust-red flour beetle, Confused flour beetle, Merchant grain beetle, Indian meal moth, Warehouse moth, Mediterranean flour moth, Grain weevil and Rice weevil.”

  • Reldan 22 is best used as part of an integrated management approach to treat the fabric of the store.
  • This process starts by completely emptying stores of old grain or any debris.
  • Any handling equipment such as airways, ducts, intake pits and elevators should be swept or cleaned using a high pressure airline, paying attention to cracks and crevices where pests will harbour.
  • The sweepings need to be disposed of well away from the grain store site or be burnt.
  • There are several application options for Reldan 22 –
    • by knapsack sprayer
    • or by tractor-operated spray lance.

The product is applied at 200 mls in 5 litres of water per 100 square metres when treating the fabric of the store. It should be applied up to 4 weeks before harvest. One treatment is allowed. There is no withholding period.

It can also be used on harvested grain in store as an admixture treatment. In this instance Reldan 22 is applied using a suitable applicator to grain that has been dried, cooled and cleaned. After this admixture treatment, grain should not be processed for 90 days, so this approach is most suitable for grain intended for long term storage. Just one application can be made per batch.

Reldan 22 is approved for use on grain store structures and equipment as well as on stored grain heaps of wheat, barley, oats, rye and triticale.  It is accepted by the British Beer and Pub Association (BBPA) and the Brewing Research International (BRI) for use on cereals for malting and brewing.


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.

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.

Dow Shield 400 contains clopyralid
Kerb Flo 500 contains propyzamide
N-Lock contains nitrapyrin
Reldan 22 contains chlorpyrifos-methyl
Spitfire contains fluroxypyr and florasulam
Starane 2 contains fluroxypyr
Starane XL and Starane Gold contain fluroxypyr and florasulam
Thistlex contains clopyralid and triclopyr

More information can be found at


Dow AgroSciences Limited, Latchmore Court, Brand Street, Hitchin, Hertfordshire, SG5 1NH.Tel: +44 (0) 1462 457272. Technical Hotline: 0800 689 8899 | |

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Grassland Agronomy Update – July 2016


Welcome to the 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 email update.


  • Spraying clover in grass swards
  • Tackling Heracleum
  • Who can buy sprays?
  • Dock beetle and Ramularia rubella – help or hindrance?
  • Application advice on the Grassland Weed App
  • How flowering affects spray efficacy
  • FAQs
  • Dow AgroSciences’ show dates

Spraying clover in grass swards

If weeds need controlling and clover is present then what are the options?

docks & clover

Docks and Clover

Where weed infestations are small or concentrated in particular areas, applying herbicides as a spot treatment or through a weed wiper will kill the weeds, leaving the clover relatively unscathed.

At best a weed wiper will deliver 70% of the control that an overall spray application would achieve. Currently just glyphosate has an approval for this method so it does have limitations.

Where weeds account for 20% or more of the field, there may not be enough saving in bagged nitrogen fertiliser to be worth saving the clover.
In these situations, use an effective translocated herbicide such as Doxstar®Pro, Pastor®Pro or Thistlex®, and re-introduce the clover later by over-sowing 6 weeks later. If using Forefront® T, wait for 4 months.

Oversowing – have a plan

The key is allowing the clover seed to fall on bare, moist soil so it can germinate. This can be done with a combination of tight grazing and grass harrowing or direct drilling.

On cutting ground

  • Check and correct pH, P and K in the previous autumn
  • Spray with an appropriate translocated herbicide at least three to four weeks before cutting
  • After cutting, stock with dry cows or youngstock. Do not apply N
  • Grass harrow – two to six passes to create 25% bare ground
  • Broadcast clover seed and grass harrow
  • Roll and/or stock with dry cows or youngstock for six to ten days
  • Remove stock and rest for three to four weeks, then mob stock graze and repeat until winter

On grazing ground

  • Check and correct pH, P and K in the previous autumn
  • Spray with an appropriate translocated herbicide in the autumn
  • Grass harrow dense swards previous spring and autumn
  • Graze tight March/April (for April sowing), although sowing is preferable in July
  • Grass harrow – two to six passes to create 25% bare ground
  • Broadcast clover seed and grass harrow
  • Roll and/or stock with dry cows/youngstock for six to ten days
  • Remove stock and rest for three to four weeks, then mob stock graze and repeat until clover has established

Tackling Heracleum

The number of Hotline queries on hogweeds has increased this year. But what can be done to control Apiaceae weeds?

Giant Hogweed

Giant Hogweed

Hogweeds (Heracleum) are a genus of about 60 species of biennial and perennial herbs in the carrot family Apiaceae. Many species exhibit lofty, upward-facing white flowers borne on the top of thick, bristly stems. They are close relatives of cow parsley.

Giant hogweed (Heracleum mantegazzianum) is a native of the Caucasus Mountains, growing four to five metres tall. It is now a serious invasive weed across Europe including the UK, after being introduced as a garden plant in the early nineteenth century.

Giant hogweed can cause severe photo-dermatitis if its sap gets onto human skin, causing burns when exposed to sunlight.

Common hogweed (Heracleum sphondylium) is also common in Europe and its sap can also cause rashes and skin irritation.

Classified as an invasive alien, it is an offence to cause giant hogweed to grow in the wild anywhere in the UK. It can also be subject to Anti-Social Behaviour Orders, where occupiers of giant hogweed infested ground can be required to remove the weed or face penalties.

Controlling hogweed

Giant Hogweed 5When they are small, and before they have produced a flowering spike, hogweeds can be pulled up by hand. It essential to cover arms and legs and to wear a facemask when doing this.

Cut plant debris, contaminated clothing and tools are potentially hazardous too. Wash any skin that comes into contact with the plant immediately.
If the infestation is too large, or it is too late to pull the plants up, chemical control should be considered.

Young foliage should be sprayed in May and the plants re-treated in August and September if needed. Or summer foliage can be cut back down and the regrowth sprayed. Mature plants are likely to need more than one treatment to kill them.

Dying giant hogweed is a controlled waste and if taken off-site can only be disposed of in a licensed landfill site with full documentation.
The smaller native hogweed is not classed as a controlled waste, but should still be disposed of with care to avoid human contact.

Dow herbicides?
Currently our most effective solutions are those that contain aminopyralid and can be applied via a knapsack: Synero®, Garlon® Ultra or Icade®.

Who can buy sprays?

All farmers who are spraying herbicides now need to be certified – but they don’t need certification to buy them.

Grassland StoreNew legislation, under the Plant Protection Products (Sustainable Use) Regulations that came into force at the end of 2015, now requires all sprayer operators, however old they are, who are applying professional pesticide products (PPPs), to have a Specified Certificate.

Farmers who were born before 31 December 1964 and previously sprayed under the ‘Grandfather Rights’ exemption, must take the Level 2 Award in the safe use of pesticides replacing grandfather rights, or take the existing Level 2 safe use of pesticides (PA) certificate.

If they do not want to take the tests, they must hand over the spraying to a family member or employee who has the correct qualifications, or use a spray contractor.

Buying PPPs

However, uncertified farmers can still buy most pesticides, such as DoxstarPro and Thistlex over the counter, as long as they know that the person who will be using them is certified. There is no legal obligation to show any certificates to the person selling the products.

The farmer buying the products needs to ensure the intended sprayer operator is suitably qualified, or will be working under the direct supervision of someone who is suitably qualified, perhaps because they are undergoing training.

This legislation applies to all livestock farmers and smallholders, many of whom may only occasionally use professional pesticides. Even those using products such as Grazon®Pro in a knapsack on their own farm, have to be certified.

Specified certificates, previously known as certificates of competence, are issued by City and Guilds Land Based Services. Visit the National Proficiency Tests Council at or the local agricultural college for PA2 (ground crop sprayer – mounted or trailed) and PA6 (hand-held applicator) courses.

Existing PA certificates of competence in the safe use of pesticides continue to be recognised under the new legislation.

For more information see the Changes to Legislation: A Guide for Grassland Herbicides on the Dow AgroSciences website

Dock beetles and Ramularia rubella – help or hindrance?

Dock beetles (Gastrophysa viridula) and the fungus Ramularia rubella can attack dock plants – but are they helpful when spraying?

dock beetle cropped

Dock beetle

Green dock leaf beetle is a native beetle, which is green with a metallic shimmer. Depending on the light they can look gold green, blue, purple, violet or red. Their strong legs also shimmer.

They feed mainly on any of the Rumex species, including broad-leaved dock. Their larvae can only completely develop on Rumex.

The females breed from March to October, laying more than 1,000 eggs in clusters on the underside of the dock’s leaves. The segmented larva hatches after three to six days. After three moults, the larva pupates in a burrow 2cm underground, and the new adult emerges six to nine days later.

Ramularia rubella fungal spores attach onto docks in moist conditions. Their tentacle-like hyphae enter the plant through the stomata on the underside of the leaves. Once inside the plant, they push between the plant cells and feed off the nutrients in the leaf.

Ramularian and dock beetle damage

Ramularian and dock beetle damage

Ramularia can also produce toxins, which are activated by sunlight and cause plant cell death. Dead cells create large dark spots with creamy centres on the leaves.

The fungal spores are airborne and released – spreading to other leaves on the same plant and to other docks nearby.

How does this affect spray treatments?

For best control, docks should have young, fresh, actively growing leaves when they are sprayed.

Dock leaves that have been shredded by dock beetle or are covered in purple splodges hinder uptake and translocation of herbicides.

Ramularia is more of a problem in spring, but dock beetles are more of a problem from June through to August.

If affected docks are to be treated, it is best to top the large plants and wait for two to three weeks of fresh regrowth, before spraying with a translocated herbicide such as DoxstarPro.

Application advice on the Grassland Weed App

Grassland App Weed IDThe Dow Grassland APP is available on iOS, Android and Windows platforms. It has a lot of useful support features for those involved in grassland weed control.

An intuitive easy to use APP which:

  • Enables a deep drill of all our grassland technical knowledge
  • Choose a combination of up to 3 weeds and find the best solutions for their control
  • Pick a weed size and get guidance on whether to spray or not
  • A tank dose calculator tool
  • Create a spray record
  • Manages Forefront T stewardship requirements

If you haven’t already downloaded the Dow Grassland APP you can do so with these links:
App Store / Google Play / Windows Store 

If you have already downloaded the APP, please ensure you are using the latest version.


How flowering affects spray efficacy

Spraying herbicide at different times in a plant’s life will significantly affect the result.

2. It is too late to treat buttercups when they are flowering and the field is yellow

All plants have a vegetative stage and a reproductive, or flowering stage.

All the time the plant is not producing seed heads, active growth focuses on the production of new roots and leaves.

During sexual reproduction, seed head development is triggered by mechanisms based on temperature and day length. The stems of the inflorescence buds elongate upwards to carry the developing flower above the ground.

The key aim of translocated herbicides is to travel deep down into the roots to exact a high level of control. This is best done when the plant is growing in a vegetative state.

At flowering, most of the nutrients and water are being carried up towards the flower, rather than down into the roots.

The effect of spraying perennial weeds at flowering is likely to be reduced control. Although the top growth may look like it has been killed, it’s the root control that that determines success and they may not have received sufficient herbicide to make that certain.

Dow AgroSciences advises farmers to spray perennial weeds such as docks, thistles, nettles, buttercups and ragwort BEFORE they flower for best results.

If that proves difficult, then accept that control may be 50% to 80% of what you would expect to achieve or top and spray resulting regrowth some 2 weeks later.


Q: How can I control yellow rattle in grassland?
Forefront T will give the best control, as long as the field is to be grazed with cattle or sheep, or is treated after the last cut of the year. Where fields are being cut for hay or silage use GrazonPro instead.

Q: How soon can I slot-seed grass or clover into a field after treating with Forefront T?
Grass seed can be stitched in after four weeks but for clover you will need to wait 4 months after spraying with Forefront T.

Q: Is it safe to cut for hay 14 days after spraying with Dow AgroSciences grassland products?
Yes, it is safe to cut hay. However, for best long-term weed control, Dow AgroSciences advises leaving up to 28 days before cutting the crop, to allow the active ingredients to reach right down into the roots for more effective control.

Q: As a farmer, do I need to have the Dow Grassland App to be able to receive Forefront T stewardship recommendations from my agronomist?
No, a farmer just needs to be able to receive and respond to the stewardship recommendation email. This can be done via a PC, tablet or smartphone.

Q: Will DoxstarPro have any effect on nettles?
Yes, DoxstarPro will give moderate control and a reduction in top growth, as will Thistlex. However, PastorPro or GrazonPro are better alternatives for using against nettles.

Grassland Show 2105Show Dates

The technical team from Dow AgroSciences will be out and about at many 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:

July 6th/7th Livestock Event Brimingham NEC
Nov 16th AgriScot Edinburgh



2 BASIS points (1 crop protection and 1 personal development) will be awarded to those subscribing to Dow AgroSciences’ Grassland Agronomy Update. Please include course name ‘Grassland Agronomy Update’ and ref number: CPE/51889/1617/g, on your training record. If necessary contact Robert Calladine ( to redeem points. These details are valid until 31st May 2017.

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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
Forefront T contains aminopyralid and triclopyr
Garlon Ultra contains aminopyralid and triclopyr
GrazonPro contains clopyralid and triclopyr
Icade contains aminopyralid and triclopyr
PastorPro contains clopyralid, fluroxypyr and triclopyr
Synero contains aminopyralid and fluroxypyr
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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Preparing Grain Stores for Harvest

With farm economics under pressure, growers cannot afford to risk post-harvest losses due to poor grain store hygiene.

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

Pests, in particular mites, can still breed at low temperatures of 5°C.  The mild winter will have allowed egg- laying and populations may have already become established; these can build rapidly so it is important to take preventative action.

Mite and insect feeding results in direct losses but can also have a detrimental effect on the quality of stored grain. Whether intended for milling, malting or feed, infested grain runs the risk of being rejected.

Flour mite

Mites – the commonest pest of stored grain

Good ventilation, drying and cooling are important processes in grain store management. Respiring insects and mites will generate heat and moisture and can cause localised hot spots within the grain pile which further promote breeding and may encourage the development of moulds.

Reldan™ 22 is a broad spectrum acaricide and insecticide that will control all major pests of stored grain including Flour, Cosmopolitan and Copra Mites, 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.

Ideally fabric applications of Reldan 22 should be applied 4 weeks 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 works by fumigation, contact and ingestion and can offer protection for up to 6 months against mite and insect infestation. There is no withholding period for grain subsequently stored on those premises.

Pre-Harvest Action Plan:
Grain store fabric treatment using Reldan 22 should be used as part of an integrated management approach:

  1. Ensure grain store is emptied of any old grain and debris
    o Apply the same principles to grain handling equipment
  2. Sweep or ideally use a high pressure airline grain store paying close attention to crevices
    o Don’t neglect roof space including rafters and joists, and under the ventilation flooring. Dust provides a breeding site for mites and insects
    o Ensure sweepings are disposed of well away from grain store sites or ideally, burn them
    o Wear appropriate PPE including a dust mask
  3. Apply Reldan 22 at 200ml in 5-10 Litres of water per 100 m2 ideally 4 weeks before harvest via a knapsack, motorised knapsack or tractor-operated spray lance
    o If surfaces are porous increase the water volume to 10 litres per 100m2
  4. Wear impermeable coveralls, suitable protective gloves, rubber boots and face protection and for best practice ensure good ventilation during application
  5. Post treatment and through-out grain storage check grain store regularly for insect activity using sticky and pitfall traps

Can I apply Reldan 22 to stores intended for oilseed rape?
Yes. If the store is metal bins allow 4 weeks minimum before loading with oilseed rape. If concrete, this can be reduced to 1 day but do remember ideally you want 4 weeks between treatment and filling, to allow treatment to work.

For more detailed support literature on Reldan 22, click on this link.

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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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View All Topic Sheets
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.  

What can be used to control volunteer rape in cereals?

Spitfire controls volunteer rape and can be used in wheat, barley, oats rye and triticale including those undersown with grass.  UNITE and Broadway Star also offer excellent control of volunteer rape as well as key grassweeds.

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, 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.

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.

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.