Getting the most from your wheat crop means making smart decisions throughout the season to get the best control of threats to your yield from diseases, weeds and pests.
Posted 2 years ago
By the end of October, around 80% of drilling had been completed, with wheat plantings up on previous years’ average.
Where wheat is still to be drilled following maize, potatoes and/or sugar beet, it’s important to review seed rates, and increase to 400, 450, or 500 seeds per square metre depending on the soil type.
Where crops have already been drilled, the focus has turned to weed control.
Crops that were drilled in September may require a top-up with a residual herbicide. If six weeks has passed since applying Liberator at 0.6 L/ha, then a top-up at 0.3 L/ha can be applied. Alternatively, 0.5 L/ha of metribuzin in Octavian Met or Alternator Met gives increased grassweed control as well as important broadleaved weed species, including groundsel, cranesbill, and poppy.
Where grassweeds have established through a residual application, or if none was applied, 1.2 L/ha of Atlantis OD alongside a residual partner (top-up or full rate depending on previous applications) can improve control of black-grass at the 1-2 leaf stage.
Crops that will be drilled from November onwards should be through the worst of the black-grass germination period, and an application of 0.6 L/ha of Liberator with or without another herbicide partner, should be sufficient for most scenarios.
Depending on the temperatures in November, aphids may still need monitoring and an application of insecticide if the T-Sum threshold is met, to protect crops from barley yellow dwarf virus (BYDV).
Slugs are an increasing problem in cereals crops, particularly on heavier land. Slug grazing will be the main activity to watch for in September and early-October-drilled crops, while later drilled crops should be monitored for seed-hollowing. This is the last winter that growers may use metaldehyde slug pellets (up to 31 March 2022), and the full Metaldehyde Stewardship Guidelines should be followed when using this treatment. Ferric phosphate slug pellets are an alternative option.
After a generally dry September, growers will need to be patient in October and wait for a good flush of grass-weeds to spray off, before drilling. Where black-grass is particularly challenging it is worth waiting to drill until after the 15th October, when the main black-grass germination period will have passed.
Once stale seedbeds have been achieved, and seed has been drilled into fine, firm seedbeds, the priority will be to apply residual herbicides.
For the most challenging grass-weed species, namely black-grass, rye-grass, and brome, start a robust residual programme with Liberator and Proclus. Here, three modes of action work in synergy to target different parts of the weed’s plant cells, leading to highly effective control.
Aclonifen, the active in Proclus, is taken up by the emerging weed shoots, rather than the roots, and maintains good efficacy even where conditions turn dry after application, although soil moisture is still key to achieving the best performance from residual herbicides.
The addition of Proclus in a pre-emergence programme improves the weed-control performance over the use of Liberator alone, and with a long half-life of just over 100 days it can be particularly useful where weed germination is protracted, such as with perennial rye-grass.
Where crops were drilled in September, it may now be time to top up earlier-applied residuals. Applying either 0.3 L/ha of Liberator, or 0.5 L/ha of Octavian Met or Alternator Met will provide extended control of a range of grass-weeds and broad-leaved weeds.
Aphid pressure may also start becoming an issue in September-drilled crops. Monitor against thresholds using the T-sum calculator to calculate if and when to spray to protect crops from barley yellow dwarf virus (BYDV).
It has been a protracted harvest this year, and some crops will still be standing well into September. This over-running of combining operations will have a knock-on effect on autumn cultivations, with less time available for stale seedbeds prior to drilling.
Where crops are drilled in September, growers should be aware that the crop will face increased agronomic challenges, including more grass-weeds, and higher Septoria risk in the spring from greater exposure to the fungus in the autumn.
Being patient will certainly pay dividends in terms of weed control, but it is important to identify weed species present before starting cultivations.
‘Brome’ covers a number of different species which require different management techniques. The seeds of soft, rye and meadow brome may not be fully ripe after combining. They need a period of time of the soil surface before they can be encouraged to chit. Great and sterile brome, conversely, should be encouraged to chit as soon as possible after combining to prevent seed dormancy. Once you have identified the brome species present, use the appropriate approach to stale seedbeds.
Rye-grass is a growing challenge across some cereal-growing areas of the UK, including the South East and parts of East Anglia. However, black-grass is still the predominant grass-weed threat. Light cultivations one or twice before drilling, followed by a glyphosate spray, will remove a significant amount of black-grass and rye-grass during the main germination period, before drilling.
Drilling from mid-October, once the peak of black-grass germination has passed, is still optimal from a weed-control point of view, but for those looking to drill in September a robust herbicide programme is recommended.
Proclus and Liberator contain three active ingredients from different herbicide mode of action groups, which target different parts of the weed plant. Excellent results were seen last year and this combination provides the best start to a full programme.
Proclus should be used as a true pre-emergence, applied within 48 hours of drilling to a firm, level seedbed, to achieve optimum results. However, all pre-emergence herbicides will benefit from being applied as soon as possible after drilling, since after 48 hours black-grass may have chitted and residual activity will begin to decline.
Where rye-grass is a particular problem, growers have seen excellent results by starting their programme with Proclus and Liberator and a mixing partner, of either triallate or prosulfocarb.
Fields with the highest threat of grass-weed problems should be prioritised for pre-emergence applications. Try to ‘spray as you go’ rather than wait to get every field drilled before you start spraying.
This is a testing time for crops as we head towards harvest. This season’s weather has resulted in a perfect storm for disease and may leave some growers with questions about whether they employed the best approach to disease control.
T1s on the whole were applied later than normal this year and the expectation was that T2s would follow quickly behind. However, with cooler than average temperatures most T2s were stretched beyond the optimal three-week period in many cases. And while T3s have been applied, we are now seeing very high levels of Septoria.
Some growers are considering an additional fungicide as a top-up, but it is a race against time since GS71 (watery ripe stage) is the latest time of application for most products.
As crops mature during July there is still time to do some tidying up to reduce weed seed return and support improved future weed control. Wild oats have been a particular problem this year, so hand-rogue small stands of plants, along with any black-grass and brome species present can pay dividends in the long term.
If there are larger patches of grass-weeds still present, consider spraying these off. However, this must be done very soon, since weed seed will shortly become viable.
In milling wheat crops, a final top dressing of nitrogen can be applied between the end of flowering and the milky-ripe stage, to ensure optimal protein levels.
As part of pre-harvest preparation growers can take advantage of a free trial of Climate FieldView, Bayer’s digital platform that provides real-time data, captured by the combine and allows growers to analyse yield by field and crop, instantaneously. These results can help to support decisions on future operations, including rotations, seed rates, fertiliser rates and crop protection applications.
Looking ahead to post-harvest operations, growers can start planning their work-loads and particularly, stale seedbed operations for grass-weed control.
The predominantly cool and dry weather in April, with low overnight temperatures, has tempered crop development, and wheat plants have moved slowly through their growth stages. In many areas crops are beginning to look stressed from lack of water.
The unsettled weather in May means that many crops were still waiting for their T2 spray at the end of the month. They will be required in early June, as soon as possible or once crops reach GS39.
In many cases the time between T1 and T2 sprays has been extended beyond the recommended three to four weeks, however despite the wet weather, the relatively cool conditions to the end of May have held back disease pressure, with Septoria being kept below leaf 3 at the end of the month. This means that T2s will likely to be going on in a protectant scenario, where fungicides are most effective.
Temperatures are expected to return to normal in June which will increase Septoria pressure, and there are also reports of Yellow Rust coming back into crops, after disappearing during the cooler weather in April. However, Brown Rust is yet to feature.
Check Bayer’s National Snapshot Project, to see reports on Septoria and Yellow Rust incidence on farms across the UK using our new Rapid Disease Detection technology.
For all-round disease control at T2, 1 - 1.5 L/ha of Ascra will be effective against Septoria, Yellow Rust, Eye spot, and reduce Fusarium head blight, and other key diseases.
Looking ahead to T3 fungicides, which will likely be made towards the middle of June, your choice of fungicide will depend on what you want to achieve with your wheat crop.
To protect wheat quality, targeting Fusarium will be key and this means getting the timing right. . Wet conditions at flowering will increase the risk of Fusarium infection therefore apply your T3 at the first sign of anthers emerging from the middle of the ear. Proline gives the strongest protection against Fusarium and the microdochium species, while also giving a good top-up of protection against Septoria. If Brown Rust is a concern, the addition of tebuconazole or a strobilurin will provide added protection, provided two strobilurins have not already been used in previous applications.
To prolong the crop and boost yield potential, Aviator 235Xpro can provide protection against Fusarium and leaf diseases in one product, provided two SHDIs have not already been used in previous applications. Aviator offers additional benefits including crop greening which will be a significant benefit if drought becomes a problem.
Other tasks for June include final weed control, which at this stage will involve hand-rouging, spot-spraying or spraying-off larger areas where grass-weeds have not been controlled.
Growers should also monitor orange blossom midge around flowering. Use sticky traps or pheromone traps in susceptible crops, especially varieties without resistance. In milling wheat, the threshold for an insecticide spray is one midge per six ears, while in feed wheat the threshold is one midge per three ears.
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Find out more information about the key disease threats to your wheat crop. For each disease you can learn how, where and when the disease infects wheat, average yield impact, symptom recognition and our advice on appropriate control strategies.