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  1. Spraying off areas of crops affected by black-grass is a difficult call to make, but it is one that more growers are considering in the fight against this increasing problem.

    Midlands-based Hutchinsons-Cropwise agronomist Andrew Wright says concerns about the spread of black-grass further north and west across the UK, combined with disillusionment over the efficacy of products affected by herbicide resistance, means there is more acceptance of this zero-tolerance approach.

    Andrew Wright

    Assessing crops during January and February for black-grass that has survived autumn treatments is key to making an early decision that minimises the financial impact and allows more time to sow an alternative spring crop if required, he says.

    “It is a difficult decision to make and there’s no set black-grass population threshold to go by; it’s really down to individual growers.

    “Some will want to spray-off areas of crops at the first sign of any surviving black-grass, while others will persevere, especially in regions where good results can still be achieved with spring herbicides, such as parts of Derbyshire and west Nottinghamshire.”

    Where a spring herbicide is to be applied, Mr Wright favours products based on iodosulfuron-methyl-sodium and mesosulfuron-methyl.

    He acknowledges efficacy can be reduced where resistance is present, but correct application still delivers worthwhile control of black-grass and other key weed species, such as wild oats and brome.

    Spring crops account for 20-25% of the cropping in Mr Wright’s region and he urges anyone going down this route to follow a few simple steps to minimise the risk of stimulating a troublesome black-grass flush within the crop:

    •    Prepare seedbeds in the preceding autumn
    •    Spray-off with glyphosate in the spring once soil has warmed and black-grass has emerged – typically two weeks before drilling
    •    Avoid further soil disturbance before drilling
    •    Drill later in spring when soil is warm and crops can establish quickly
    •    Minimise soil disturbance at drilling – direct drill if possible
    •    Sow competitive crops at a high seed rate to outcompete black-grass e.g. spring barley, up to 400 seeds/m2.

    Mr Wright also says the importance of delayed autumn drilling combined with an effective pre-emergence strategy for effectively reducing black-grass numbers before winter has been clearly highlighted this season.

    “We’ve seen some excellent results where growers have drilled later – typically after mid-October up to the first week of November – into good seedbeds and have used an effective pre-emergence herbicide strategy that included tri-allate.

    “However, where crops have been drilled earlier than this and/or seedbeds have been more cloddy, you can find black-grass coming through in places.”

    Spring black-grass control tips

    •    Map problem areas now ready for treatment
    •    Apply post-ems early when weeds are small, but…
    •    Ensure weeds are actively growing
    •    Consider the wider spectrum of weed control available from post-ems beyond black-grass
    •    Don’t overlook any areas of poor autumn control
    •    Consider spraying-off areas of crops where surviving black-grass populations justify to prevent weeds from setting seed and multiplying further
    •    Re-drill areas with spring varieties where possible
    •    Minimise soil disturbance when drilling spring crops (5cm depth max).

  2. Farmers must be bold and take a “zero tolerance” approach to spring-emerging black-grass and populations that survived autumn control, urges Hutchinsons agronomist and Norfolk farmer Alex Wilcox.

    Although autumn control was generally very effective given favourable weather and soil conditions well into November, he warns that high dormancy means there is a continued risk of fresh black-grass emergence into the spring.

    Alex WIlcox in WInter Wheat Dec 2016

    Early treatment of small susceptible weeds is crucial, but growers must also ensure black-grass is actively growing to maximise efficacy of post-emergence chemistry, he says. This may require patience, especially when coming out of a cold spell.

    In winter wheat, Mr Wilcox favours using a full rate of an iodosulfuron-methyl-sodium + mesosulfuron-methyl-based product applied as soon as conditions are suitable. He also recommends including a water conditioning agent such as X-Change to enhance control.

    “Even where resistance to this chemistry is present in field populations, there will still be some black-grass control and there is added value from control of wild oats and a range of broad-leaved weeds.”

    Fields should be walked over winter to identify and map problem areas of black-grass ready for treatment, he advises. “There’s got to be a zero tolerance approach towards any patches of black-grass.”

    He acknowledges there is limited ability to control black-grass in oilseed rape into the spring, but insists it must be a cleaning crop to avoid stoking up future problems, which again means a no-tolerance approach.

    “If you haven’t achieved good control from propyzamide-based products then be brave and mark these areas out, spray them off and re-drill with a hybrid spring oilseed rape.”

    For those putting problem black-grass areas into spring cropping, Mr Wilcox says minimising soil disturbance at drilling is key to avoiding a flush of black-grass within the spring crop. Direct drilling can therefore produce good results.

    Where drill systems disturb more soil, he advises growers to focus on establishing a competitive crop as quickly as possible.

    “Delaying drilling until late March or early April when ground is warmer can work, but it isn’t always suitable especially if you’re disturbing more soil as it simply encourages a flush of black-grass at the same time.

    “You may be better drilling earlier at a higher seed rate when conditions are cooler and black-grass isn’t growing to ensure the crop is in the ground and ready to go as soon as it warms up.”

    Spring black-grass control tips:

    •    Map problem areas now ready for treatment
    •    Apply post-ems early when weeds are small, but…
    •    Ensure weeds are actively growing
    •    Don’t overlook any areas of poor autumn control
    •    Minimise soil disturbance when drilling spring crops (5cm depth max)
    •    Consider the wider spectrum of weed control available beyond black-grass.

  3. With spring fast approaching, what are the best options for spring sowing - will spring 2017 be comparable with that of 2016?

    The open autumn has meant that many growers have been able to delay planting their wheat and benefit from controlling early flushes of blackgrass.  However , we envisage continued growth in spring plantings compared to 2016, with some varieties of spring barley proving popular and demand now starting to outstrip supply, says David Bouch, Hutchinsons seed manager.

    David Bouch of Hutchinsons

    “There will be challenges for OSR growers where winter OSR crops have been lost. The total area lost is somewhat difficult to ascertain. Some estimates say in excess of 70,000 ha, but it is safe to say that the hectares entered have seen a significant decline, due to both lack of moisture at the time of establishment and also to flea beetle damage where crops did survive.”

    Spring barleys are the preferred option for those growers with black grass concerns, and there are many varieties that can be considered as viable options for this sector, he says.

    “Propino will undoubtedly be the most widely grown and in turn could find seed supplies tight. Of the newer varieties, there will be increased interest in both RGT Planet and also Laureate where higher yield potential, coupled with initial support from the malting industry, offers encouragement. Agronomically both varieties also offer the possibility for cleaner crops.”

     “KWS Irina offers opportunity in different markets and again demonstrates good untreated yield, coupled with very stiff straw. There will still be a place for Concerto and Odyssey which both have malting and distilling potential. Finally, in the west where feed barley and a need for straw are more pressing, then Kelim has been a consistent performer.”

    Spring drilling will increase in 2017

    “Spring wheats are very individual choices and if milling is the requirement there is little need to look further than Mulika - whilst out yielded by all the other spring varieties, it is the only variety to offer group one milling qualities. It also possesses OWBM resistance along with Belvoir. “

    “KWS Kilburn offers the greatest yield potential for growers looking to keep things simple in terms of storage, if hard wheats are already in the farm rotation.”

    Mr Bouch notes that there is the potential to see a growth in spring oilseed rape on the back of high market values for the crop at harvest 2017. “Varieties  Builder, Dodger and Doktrin can be considered as options. Hybrid has to be the choice, with the necessary vigour needed for successful establishment.”

    He believes linseed could also see some interest, as contract prices currently look more attractive than they have in recent seasons.

    “Peas and beans are likely to be in reasonably tight supply with yields from harvest 2016 being disappointing and therefore, for those growers who are looking to plant after failed OSR crops, there may be a need for early decision making to acquire varieties of choice. “

    “Beans will undoubtedly be Fuego, Fanfare and Vertigo as the standard bearers, but there will be some interest in the new variety Lynx that has the best downy mildew resistance of any variety currently available. “

    “The choice in peas - Prophet and Campus - offer both yield and quality as large blues, with Campus in particular having excellent standing ability to enhance its claims for consideration.”

    Mr Bouch warns that supplies of seed for several popular varieties are likely to run short, and advises  growers to act promptly  in order to  secure their most preferred options.


  4. A three year survey carried out by Cobb Agri in collaboration with Hutchinsons, has shown that sulphur levels in UK soils are continuing to drop to very low levels, and need addressing this spring if crops are to reach their full potential.

    Sulphur is an essential plant nutrient that is required for optimum crop yields and quality as it plays an important part in plant metabolism; sulphur is essential for the formation of plant proteins and amino acids. Recent declines in atmospheric sulphur concentrations (as a result of reduced industrial emissions) have led to sulphur deposition rates across the UK that are not enough to meet crop requirements.

    “We suspected that many of our soils were deficient and we wanted to gain a snapshot of how these levels were changing from season to season. We knew two years into the survey that we had issues with severely low levels of sulphur in our soils, and this additional third year of testing has confirmed that levels are continuing to drop,” says Andrew Goodinson, agronomist with Hutchinsons.

    “For the purposes of accuracy, we opted for grain testing as this is the most reliable method of measurement for sulphur, as tissue and soil testing can produce wildly fluctuating results.”

    “Over the three years we have tested over 500 samples and our concerns have been confirmed; sulphur levels are continuing to decrease in our soils, with no obvious geographical bias.”

    “If we take results from 2015 and 2016 specifically, and look at two separate farms that we surveyed the issue is very clear. One farm that was sampled showed an N:S ratios of 17:1 in 2015 which dropped to 12:1 in 2016, a similar story was recorded at a second site where the sulphur levels dropped from 15:1 in 2015 to 11:1 in 2016.

    Andrew Goodinson

    “These results improved as we increased the rate of SO3 applied. “

    Mr Goodinson puts down these decreasing levels to a range of climatic factors. “We know that atmospheric deposition of sulphur is less with lower sulphur dioxide emission, so there is less sulphur available to plants generally. Meanwhile, warmer temperatures last autumn have led to faster mineralisation of the nutrient, which followed by heavy rainfall resulted in the removal of sulphur as well as nitrogen, magnesium and potash from the rooting zone of crops.”

    “We have found that the standard recommendation of sulphur for winter wheat is 25-50kg/ha SO3 (RB209) is not enough to replace the low levels that we have identified in the survey,” says Jessica Smith of Cobb Agri who was closely involved in the testing.
    Sulphur is a mobile nutrient and autumn applications may move down the soil profile away from the root zone restricting the availability of this nutrient, so there can often be an issue to get the timing of application correct, spring applications are more effective, “she says.

    Mr Goodinson recommends planning ahead for sulphur applications in the spring. “Prevention is better than cure. “Sulphur must be applied to the soil at the right growth stage, we recommend applying it at the first and second pass of nitrogen. We would generally recommend the addition of 75kgs/ha of sulphur to winter wheat, and a 100kgs/ha of sulphur to oilseed rape.”

    “However it is important to recognise that for the best results, sulphur rates should be increased alongside nitrogen rates and this was another reason why a greater proportion of the results fell into the low category this year.”

    “For example in organic manures with low rates of nitrogen, the sulphur levels will most probably be adequate. However, in very hungry soils that need higher concentrations of nitrogen, the sulphur levels will need to be increased proportionately,” he says.

    “On one farm where liquid digestate was applied, the ratio was 11:8 compared to 13:8 where no digestate had been applied.”

    “It’s also worth remembering that spring crops are not as responsive to sulphur as with the shorter growing period they have less time for uptake. “

    Organic manures can supply useful amounts of sulphur, with the crop-available S supply varying according to manure type
    Liquid digestate 35m3/ha = 40kg SO3
    Poultry litter 5t/ha = 40kg SO3
    FYM 25t/ha = 60kg SO3

    Why is Sulphur important?

    • Sulphur and nitrogen deficiency can often be confused. Chlorosis (yellowing) occurs in the younger leaves first, when sulphur is deficient. When nitrogen is deficient it will be the older leaves to show initial signs. However even in the absence of visible symptoms, yields can be affected. A quick leave tissue test for Malate:Sulphur ratio can highlight any issues.

    • Baking experiments have shown that loaf volume increases significantly if the bread making wheat has been fed with the correct levels of sulphur. If the N:S ratio is higher than 16:1 bread quality and loaf volume is compromised.

    • Acrylamide is a processing contaminant that has been found in cooked food that is formed during high temperature cooking and processing of wheat. HGCA trials have shown that asparagine levels, and hence acrylamide formation, can increase if wheat is grown in sulphur deficient conditions.


  5. Avoid single species cover crops and tailor mixes to farm conditions and objectives to get the best results out of this much-hyped addition to arable rotations, say organisers of a new field-scale demonstration.

    Farmacy’s 60-acre Calcethorpe cover crop demonstration site at Glebe Farm near Louth on the Lincolnshire Wolds is evaluating a range of seed mixes and management techniques to give growers a practical insight into the reality of growing cover crops.

    The trials have already shown how selecting the right cover crop mix brings a host of benefits above and below ground and organisers expect to see clear yield benefits from improved soil structure and nutrition in the subsequent spring barley crop.

    Alice Cannon

    “You don’t have to spend a fortune on exotic mixes, but you do have to select species that will work for your situation,” says Market Rasen-based Farmacy agronomist Alice Cannon.

    “It is possible to establish an effective cover crop for £20-40/ha, which is half the cost of some mixes, and maybe lower if you’re able to home-save some seed, however there is a clear purpose to these crops and investing in the correct species is vital.”

    There are a number of reasons for sowing a cover crop (see below), but no single species or mix can achieve all of these benefits so growers must prioritise the main aims for specific field conditions, she says.

    “Once you’re clear what you want from the cover crop, select a mix that can achieve these results.”
    Cover crop benefits:

    • Improving soil health by providing food for soil fauna and flora
    • Better soil structure and natural aggregation from root and biomass growth
    • Adds fertility (nitrogen) and organic matter
    • Reduces leaching
    • Moisture retention (light soil)
    • Prevents erosion (wind and water)
    • Suppresses weeds
    • Dries soil from depth (heavy land)
    • Forage for livestock.

    Mixes show more resilience

    Miss Cannon urges growers to avoid single species cover crops and choose mixes based on at least three different options.

    “The resilience of cover crops to pests and diseases really improves when they’re used in a mix. The presence of other species ‘confuses’ pests, reduces the transfer of diseases and also spreads the risk of crop failure should a problem occur with one species.”

    This was clearly highlighted in the Calcethorpe trials this autumn where all single species plots of peas and vetch following vining peas were decimated by pea and bean weevil, whereas only minimal damage was seen in legumes sown as part of a mix. Similarly, oats suffered significantly more BYDV and crown rust where sown alone rather than in a mix.

    Mixing species also brings different attributes in terms of root growth and above-ground biomass production, Hutchinsons technical manager Dick Neale adds. Crops such as linseed and sunflower produce large fibrous root systems, while others like radish and mustard put down a larger tap root able to break compaction layers.

    “We’ve seen roots go down to at least 1m and in general I’d expect to see 50% more root growth than top growth in most crops, however this depends on the drilling date and establishment conditions.

    “Extremely dry conditions have seen some August drillings perform very poorly in 2016 while later sowings into moisture have flown out of the ground. The aim is to get a mix of roots in the ground, but the type of crop sown depends on what you want to achieve.

    “The cultivation benefits of cover crops can be significant, but you must be prepared to give them time to work, at least three years ideally.”
    Even within crops there is quite a variation in their characteristics and potential benefits, so it is worth seeking advice on the best option for your situation, Miss Cannon says.

    White mustard for example is fast to establish and produces more above-ground biomass than brown mustard, but stems have a tendency to turn “woody” post-flowering and nitrogen is less readily available to the following crop.

    White mustard may therefore be a better catch crop option where growers want a lot of biomass quickly but are prepared to wait a season for the nutritional release, whereas brown mustard may be preferred for a quick fertility boost in the following crop, she notes.

    Heavy versus light land options

    The most appropriate cover crop options vary considerably depending on soil type.

    On light, drought-prone land, such as Glebe Farm, spring moisture retention within the soil is a major draw of cover crops, Mr Neale says. Mixes should therefore include crops with dense fibrous root systems that bind soil together well and also have “flatter” top growth to cover the soil surface and retain moisture.

    Establishing cover crops 2

    The favoured mix in these trials is based on 57kg/ha spring oats, with 1kg/ha white mustard, 7kg/ha spring linseed, 38kg/ha spring beans and 33kg/ha spring peas.

    “On this land I’d expect an extra 0.5t/ha yield in the following spring barley crop from the extra moisture retention this cover crop delivers,” he notes.

    Conversely, on heavy land, especially where black-grass management is an issue, Mr Neale recommends species with deeper roots able to penetrate dense layers and dry soil from depth.

    Top growth should be more erect to allow light and air to reach the soil surface to stimulate black-grass germination and let land dry out in spring. Spring oats and linseed are particularly suited to this, he adds.

    Destruction timing is key

    Desiccation timing is critical to get the best results from cover crops and the optimum will vary for every site, Mr Neale says.
    Generally, cover crops on light land can be sprayed off with glyphosate closer to drilling than those on heavy land.

    The moisture held in the top growth and roots within the seeding zone is an asset to the new crop on drought-prone land, whereas on heavier soils earlier termination of the cover crop – typically at least six weeks before drilling - allows more time for surface layers to dry out, he explains.

    Again species mix is key in relation to the “exit” strategy. Oats or rye must be sprayed or grazed off at least five weeks ahead of a following spring cereal, regardless of soil type, because they produce negative allelopathy and will cause a delay in growth.

    If top growth is to be retained, ask whether your drill can handle it? These issues should be planned for as you do not want to delay spring sowing of cereals or yield will be lost due to a lack of tillering time.

    Growers are reminded that EFA legislation requires eligible catch crop mixes to be established by 31 August and retained until at least 1 October, while cover crops must be established by 1 October and retained until 15 January.

    Find out more

    Two more free demonstration days are due to be held at the Calcethorpe cover crop site next year.

    In February there will be an event showcasing different termination methods for cover crops, while a separate drill demonstration day in March will examine how different drills cope with drilling into cover crops.

    Contact Alice Cannon ([email protected] – 07583 692576) for more information and to register your interest in attending.

    Tips for getting the most from cover crops:

    • Be clear of the reasons for using a cover crop
    • Avoid single species mixes – minimum of three different species
    • Tailor mixes to end goal and farm characteristics
    • Exotic and expensive mixes are not always best
    • Reduce costs by home-saving seed
    • Establish cover correctly – treat it like a crop
    • Time desiccation correctly according to soil type and following crop.

  6. A cooperative of 18 mustard farmers have joined forces to embark on the UK’s biggest ever project to protect and eventually boost pollinator populations.

    The English Mustard Growers (EMG), a farm collective based in Cambridgeshire, Lincolnshire and Norfolk which supply seed to the Colman’s English Mustard brand, are working in partnership with crop production specialists, Hutchinsons, to map the availability of nectar and pollen throughout the year.

    The aim of the project is to ensure pollinators, such a honey bees, receive a steady supply of food resources, which will in turn support crop yields. The ten year project, which began in 2014, is the biggest of its kind in the UK, covering a total of 10,000 hectares of land, and is fully supported by the British Beekeepers Association. (BBKA)

    Surveying flora and fauna

    Now two years into the project the EMG have been busy growing a variety of plant species, including bulbs, shrubs, hedges and wild flowers across their farmland, to ensure pollinators have enough nectar and pollen supply before hibernation at the end of autumn.  Autumn and spring months are crucial for the survival of honey bees as this is when nectar and pollen supply is at its lowest.

    In a bid to enhance nectar and pollen supply, the farmers participating in the project have planted a total of 21,000 flowering bulbs within their hedgerows, ditches and field margins. One of the participating farms has also planted over 500 native hedge species and plans to grow over 200 shrubs a year to re-generate the surrounding woodland.  

    This comes after survey results revealed the importance of hedges and shrubs to nectar and pollen supply as well as being safe places for bees to breed and escape predators.  Over the autumn period, participating farms intend to grow over 13 hectares of flower rich margins and 3.5 hectares of pollen and nectar mix plants which will provide bees will a supply of food throughout next spring and summer.  

    The project has also importantly inspired farmers to work collectively to connect their land to create extensive wildlife corridors. To date, a total of 85 kilometres of hedgerows and just over 380 kilometres of grass margins, in which many of the new plant varieties are being grown, have been established. This is the equivalent distance of over two laps on the M25.  The longer term ambition of the project is to help protect pollinator populations and boost the broader biodiversity within the region.
    In addition to maintaining and eventually improving pollinator populations, the project will also help protect crop yields and boost British agriculture.  Michael Sly, Chairman of the English Mustard Growers explains: “One of our mustard varieties, White Mustard (Gedney), depends entirely on pollinators, such as bees, for its pollination during flowering time.  This, coupled with the significant role bees play in our wider ecosystem, makes this a particularly important area for us to support.”

    Bee on Phacealia

    Delving further into the science behind the project, each of the participating farms underwent a detailed survey in which a botanist calculated the total amount of pollen and nectar available in crops, hedgerows, woodland and field margins.  The data was then used to estimate the amount of pollen and nectar produced by different types of plant species on a month by month basis.

    Mike Hutchinson, director of Hutchinsons crop production specialists, who conducted and analysed the initial survey, and will continue to advise growers for the duration of the project said: “By mapping the availability of pollen and nectar on individual farms on a monthly basis, each farmer can identify where the availability gaps are - usually during early spring and late autumn - and can take measures to enhance supply during these times. Solutions can include changing cutting regimes on grass and flower margins or building diversity into crop production. The aspect which makes this project effective and unique is its scale and ability to monitor nectar and pollen supplies on a month-by-month basis.”

    The collaborative project is an example of how agricultural suppliers, expert advisors and farmers can work together to benefit biodiversity and secure the continuous supply of vital crops.  

    On Farm Practices to increase pollinator populations

    Many pollinating insects have become reliant on a narrow range of arable crops, notably oilseed rape and beans, for their nectar supply and it is crucial to build more diversity into this supply throughout the year, not just the main summer months through stewardship schemes and other measures – and this project is all about fine tuning and improving some of the things that are already in place.

    Mr Hutchinson acknowledges that it may be difficult and potentially quite costly to establish purpose-bought herbaceous seed early in the season, so instead suggests trying to identify and encourage naturally-occurring beneficial plants on certain uncropped areas, field margins or awkward field corners.

    “For example, ground ivy, white/ red deadnettle and dandelion are all useful species for extending insect food availability, while planting early flowering shrubby species such as goat willow and blackthorn can give longer-term benefits.”

    “Changing cutting regimes on grass and flower margins to delay flowering is another relatively easy way to extend food supply for insects, while including late-flowering species like knapweed in any mix is a useful addition for boosting end of season food” he says. “There are also a number of other wild species that flower later in the year, such as field scabious and wild carrot.”

    He adds that all of these measures are designed to be practical, achievable and fit in with the specific landscape of the farm. “We sometimes see land being taken out of food production with the noble intention of providing habitat for pollinators. However, it isn’t until one analyses the entire landscape that it becomes evident that the changes being made are not necessarily having the desired effects.”

  7. A two-spray strategy is key to tackling light leaf spot in many crops of oilseed rape this autumn, according to leading agronomy firm Hutchinsons.
    With high disease risk forecast and recent AHDB research suggesting spore infection may be occurring earlier than previously thought, the traditional approach of one autumn fungicide may prove ineffective in many situations, the firm’s northern regional technical manager Cam Murray says.
    “Light leaf spot is a real issue in this area and early control is certainly better; think of it like the protectant approach to septoria control in wheat.
    “It is vital to get control of the disease from the start. If we don’t there’s little chance of stopping infection spreading from the leaves to the stem in the spring, especially as none of the main fungicide options offer very strong curative ability. Prothioconazole is generally the strongest active on light leaf spot, but that still only offers relatively limited curative control.”

    Cam Murray Hutchinsons

    Mr Murray’s preferred approach is to apply the first fungicide spray in early autumn at the 5-6 leaf stage of the crop and follow this up with a second spray towards the end of October or early November before worsening field conditions prevent travel.

    Prochloraz and propiconazole is a relatively cost-effective mix at the earlier timing, with prothioconazole and tebuconazole preferred for the second spray, he suggests.

    Forward crops (i.e. those with 6-8 leaves by early October) may require growth regulation and in such cases consider metconazole or tebuconazole-based products, adds Hutchinsons technical development director David Ellerton. However these may not offer the level of disease control required if used alone.

    Cereal growth regulator mepiquat chloride in combination with metconazole also has clearance for autumn application in forward oilseed rape, although he says this should be applied at the 4-6 leaf stage for maximum benefit. Again, this product will require an additional fungicide in many situations.

    Mr Murray reinforces the importance of varietal resistance in tackling light leaf spot and suggests that where growers have sown a particularly disease resistant variety (e.g. rated 7 for LLS) there may be scope for a single autumn fungicide.

    “However, if you do go down this route, make sure it goes on earlier rather than later,” he notes.

    LLS with spores

    All growers are reminded that although light leaf spot has traditionally affected crops mainly in Scotland and northern England, it is frequently being found across southern England. Likewise, phoma incidence appears to be spreading further north as climatic conditions change, highlighting the need for constant vigilance and robust agronomy.

    Hutchinsons are involved with the University of Hertford and a number of breeders in projects to increase the durability of varietal disease resistance and progress will be communicated to growers via newsletters and our trial site open days next summer.

    Beware of virus-carrying aphids

    One issue growers should be aware of in future is Turnip Yellows Virus (TuYV), which is spread by the peach-potato aphid (Myzus persicae).
    A recent survey by Hutchinsons and Bayer CropScience found oilseed rape crops in Scotland on average had 32% leaf infection with TuYV, while English crops showed 63% infection.

    Aphid resistance to common insecticides such as pyrethroids and pirimicarb, together with the loss of neonicotinoid seed treatments means a change in control is needed this season, says Dr Ellerton.

    “There are no cheap and cheerful options for controlling aphids anymore and most are contact-acting, so aphids have to be present for them to work effectively.”

    Both pymetrozine and thiacloprid have approval for use in the autumn to control aphids in oilseed rape and both actives will control resistant populations, he says.

    “Hutchinsons trials have also shown the addition of an adjuvant based on orange oil considerably improved aphid control and reduced TuYV infection.”
    Dr Ellerton recommends growers track aphid activity using monitoring services such as the AHDB/ Rothamsted email alerts and regularly inspect their own crops for aphids where risk is high.

    Insecticide treatments can often be combined with the autumn fungicide, but only if the two timings coincide and neither application timing – nor resulting efficacy - is compromised.

  8. Unusually dry weather across much of southeast England resulting in some oilseed rape crops being written off has heightened the need for a much more flexible approach to agronomy this autumn.

    Kent-based Hutchinsons agronomist David Shepard says just 10-15mm of rain fell across a large area of Kent during August and September, which has hit oilseed rape hard and is creating some real challenges for agronomy.

    “Everything is quite backward due to the weather, with the best crops around the four leaf stage,” he says. “But some crops are only at the cotyledon stage and we’re still waiting to see how they will fare in the next couple weeks, before making a decision on them.”

    The difficult conditions mean it is vital to monitor crops closely over coming weeks and tailor autumn treatments to crop requirements.
    For Mr Shepard this already means a likely switch from a favoured two-spray approach to a single well-timed fungicide for phoma and light leaf spot protection.

    “At the start of the season I’d have gone for two sprays, but given the backward crops and dry weather keeping visible disease levels low, it will probably be just a single spray now, with phoma being the priority.”

    David Shepard H&S

    A large area of more resistant varieties in the ground across his region will help to reduce phoma risk, but the underlying threat remains high so he still recommends applying a fungicide when the treatment threshold of 10-20% plants infected with phoma leaf spot is reached. The Rothamsted Research phoma risk forecast can help identify when this will be reached.

    Boost Backward Oilseed Rape

    Fungicides with growth regulatory activity should not be used on backward crops (i.e. those with around three leaves by early October) and instead it is worth considering products that can help increase rooting, such as those based on penthiopyrad + picoxystrobin.
    Trials have shown excellent control of both phoma and light leaf spot from these actives, with an ability to considerably increase root mass, enabling better nutrient and water uptake without reducing crop size above ground, says Hutchinsons technical development director David Ellerton.
    He also highlights recent AHDB research suggesting light leaf spot is becoming more widespread and spores are being produced earlier in the season than previously thought. He therefore recommends growers apply a fungicide that is effective against both diseases unless variety resistance is particularly strong.

    “If light leaf spot is building earlier before symptoms are visible, it needs treating accordingly. Just because you can’t see it doesn’t mean the disease isn’t there.”

    Products based on a combination of prothioconazole and tebuconazole are also an excellent option for controlling both phoma and light leaf spot, he says.

    If no early spray has been applied for phoma, then Dr Ellerton says a routine protectant fungicide should be applied for light leaf spot in late October or early November.

    Even where a phoma spray has been applied a second application may be required, especially if the first fungicide was applied very early, he notes.
    Mr Shepard adds that foliar nutrition, such as phosphite or zinc-ammonium acetate complex could be worthwhile at the 1-2 leaf stage to give backward crops an extra boost, especially where dry soils are limiting nutrient uptake from the ground.

    Take Control of Forward Crops

    Any growers with forward crops (i.e. those with 6-8 leaves by early October) requiring growth manipulation and disease control should consider metconazole or tebuconazole-based products, Dr Ellerton adds. However these do not offer the level of disease control of earlier options if used alone.
    Cereal growth regulator mepiquat chloride in combination with metconazole also has clearance for autumn application in forward oilseed rape, although should be applied at the 4-6 leaf stage for maximum benefit. Again this product will require an additional fungicide in many situations.

    David Ellerton (3)

    Beware of virus-carrying aphids

    The other main disease to watch out for this autumn is Turnip Yellows Virus (TuYV), which is spread by the peach-potato aphid (Myzus persicae).
    A recent survey by Hutchinsons and Bayer CropScience found oilseed rape crops in England on average had 63% leaf infection with TuYV, while Scottish crops showed 32% infection.

    Aphid resistance to common insecticides such as pyrethroids and pirimicarb, together with the loss of neonicotinoid seed treatments means a change in control is needed this season, Dr Ellerton says. “There are no cheap and cheerful options for controlling aphids anymore and most are contact-acting, so aphids have to be present for them to work effectively.”

    Both pymetrozine and thiacloprid have approval for use in the autumn to control aphids in oilseed rape and both actives will control resistant populations, he says.

    “Hutchinsons trials have also shown the addition of an adjuvant based on orange oil considerably improved aphid control and reduced TuYV infection.”
    Dr Ellerton recommends growers track aphid activity using monitoring services such as the AHDB/ Rothamsted email alerts and regularly inspect their own crops for aphids where risk is high.

    Insecticide treatments can often be combined with the autumn fungicide, but only if the two timings coincide and neither application timing – nor resulting efficacy - is compromised.

  9. Wet weather this summer in many parts of the UK has led to large slug populations and means growers need to be extra vigilant in monitoring crops for damage from slugs to ensure crops are protected during early stages of growth.

    The use of metaldehyde-based slug pellets last autumn led to exceedances of the Drinking Water Directive limit of 0.1 ppb in many areas and this has highlighted the need for close adherence to industry stewardship guidelines on metaldehyde use this coming autumn, says Dr David Ellerton, Hutchinsons Technical Development Director.

    “Although the overall threat from slugs is potentially high this autumn, field monitoring and judging the risk of slug damage on a field by field basis remains critical to avoid unnecessary pellet applications, whilst still protecting crops from slug attack.”

    Ideally, bait trapping for potential slug problems in oilseed rape should commence in the previous crop and also in stubbles for cereals, he advises.

    Monitor slug levels ahead of planting

    “The thresholds for oilseed rape are four or more slugs per trap in the previous crop and one slug per trap in the previous stubble. The cereal threshold is four or more slugs per trap. However, trapping is only an effective means of monitoring slug activity when the soil surface is moist and slugs are active.”

    “Crops are most vulnerable to slug damage in the first four weeks of growth - the cut off point for monitoring cereals is the start of tillering and for oilseed rape the four leaf stage.”

    He points out that a risk assessment for slug damage, including the current and previous crops, field history, soil type, seedbed quality, weather conditions and planting date, can be used in conjunction with trapping to judge the need for chemical control.

    “Slug pellets will continue to be the most important means of controlling slugs this autumn, ideally aiming for a minimum of about 40 pellets per square metre, but other measures including seedbed cultivations with adequate consolidation, seed dressings and depth of drilling can have a significant impact.”

    There are now only two main active ingredients available for slug control - metaldehyde and ferric phosphate. For many years, metaldehyde has been the main active ingredient that farmers chose to use for slug control. Nevertheless it needs to be managed carefully to avoid problems with drinking water contamination.

    An industry led initiative coordinated by the Metaldehyde Stewardship Group (MSG) has established clear guidelines for operators to follow – the aim being to avoid this product being restricted or possibly withdrawn from use completely.

    Metaldehyde has four routes by which it can enter water:

    • Direct – e.g. inadvertently spreading pellets into watercourses
    • Point source – e.g. spills on hard surfaces which eventually get into drains
    • Surface run off from fields following heavy periods of rain
    • Water moving through the soil that carries metaldehyde with it into the field drainage system.

    Scientific studies have highlighted field drainage as the main route by which metaldehyde reaches water courses highlights Dr Ellerton. “Moisture moving down the soil profile will take metaldehyde into the drainage system and from there into ditches and streams.”

    “In order to limit water contamination, the annual maximum metaldehyde dose for the calendar year has been set at 700g of active ingredient per hectare and a maximum total dose of 210g ai/ha between 1st August and 31st December, the period when there is the greatest risk of metaldehyde peaks occurring.”

    Metaldehyde Stewardship Group (MSG) best practice application guidelines

    • Use minimum active per hectare to avoid drainage and run-off losses
    • Maximum application rate 210g metaldehyde/ha*
    • Maximum total dose from 1st August to 31st December: 210g metaldehyde/ha* for additional protection of water, suppliers/ BASIS advisors may recommend rates reduced to 160g a.s./ha or less*
    • Maximum total dose rate: 700g metaldehyde/ha/calendar year*
    • No pellets to be applied within 6 metres of a watercourse
    • Do not apply when heavy rain is forecast
    • If drains are flowing do not apply metaldehyde based slug pellets
    *from any combination of metaldehyde products

    A decision support tool to identify high risk situations for water contamination from a range of active ingredients including metaldehyde is the ‘Wate Aware’ App which has been developed by Adama and has now been amended and upgraded for autumn 2016 to include SlugAware.

    It helps growers to assess the risk of water pollution from key products based on current and future weather forecasts, soil type and water deficit at specific locations and is available to download onto Apple or Android smart phones and tablets .This helps growers to identify the potential risk of water contamination from chemical applications and should be used to help avoid peaks appearing in water from metaldehyde and a range of oilseed rape herbicides.

    Helping Water Companies

    An additional way in which Hutchinsons agronomists are helping to reduce the movement of metaldehyde to watercourses is to provide information to water companies on molluscicide application timing, enabling them to predict high risk periods for metaldehyde reaching water.

    “Those companies which abstract water from rivers into reservoirs are then able to only divert water when the risk of metaldehyde peaks are low, thereby reducing exceedances and the likelihood of restrictions on the use of metaldehyde in future, “ says Dr Ellerton.

    Dr Dave Ellerton

    “Subsequent to requests from water companies for such information, the Metaldehyde Stewardship Group (MSG) launched the ‘Get Pelletwise!’ Agronomic Update system last autumn, providing a number of water companies with weekly electronic reports from agronomists. “

    “The reports detail regional agronomic information to help them anticipate metaldehyde usage and inform water abstraction decisions. This initiative will be extended this autumn to cover some 14 water companies, an increase of some 20% on last season and will look to include over 40 counties throughout the UK.”

    “Currently the MSG and a number of water companies have set up metaldehyde pilot catchments in which high risk fields have been identified. Farmers with these fields are being requested to refrain from applying metaldehyde in order to protect water and levels in nearby water sources will be monitored to assess the impact of these measures. “

    “There have been encouraging results to date, although the success or otherwise is largely dependent on the involvement of farmers in the catchment.”
    In the meantime, he points out that more needs to be done to ensure there is no repeat of metaldehyde peaks appearing in water this autumn.

    “Clearly minimising the amount of active ingredient applied to fields will make a significant difference.  Selection of high quality pellets to reduce breakdown and minimise dust during application may also help. Yet one of the key methods would be switching to other products with different modes of action, where there is a high risk to water.”

    Alternative Product – Ferric Phosphate

    The only other viable alternative for broad acre crops now is ferric phosphate which was launched in the arable market in 2009, the first new molluscicide for 30 years, he adds.

    “Its key benefits are that it is as effective as metaldehyde, but is very specific to target only slugs and snails and so presents no threat to wildlife. It is also virtually insoluble in water and therefore may be used in situations at high risk of metaldehyde entering water; such as vulnerable water catchment areas, headland treatments adjacent to watercourses (where other pellets may not be used), and poorly drained heavy soils.”

    “It is important to remember that, unlike metaldehyde, slugs which ingest ferric phosphate do not die on the surface of the soil where they can easily be found, but will crawl underground to die. However, they will rapidly stop feeding and so the crop will quickly recover following treatment.”

    Preserving Active Ingredients

    In summary if growers adopt sustainable slug control policies of only applying high quality slug pellets where risk of slug damage is high, abiding by the MSG guidelines and switching into an alternative mode of action in situations where there is a risk of metaldehyde entering water, it should be possible to preserve the remaining molluscicide active ingredients in the market place, contends Dr Ellerton.

    “However, it is crucial that the agricultural industry joins together in adopting best practice strategies to minimise the risk of metaldehyde reaching water courses and so maintain this vital active ingredient in the battle against slugs.”