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.


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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.

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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 | |