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
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.
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.
This slow growth has also delayed T1 applications, which are around seven to 14 days later than usual, and means that this year we are likely to see both T1 and T2 applications applied during May.
When rain arrives, disease risk may increase suddenly, as stressed crops grow away quickly, so growers should keep monitoring. Any Nitrogen that was applied to dry ground will now be taken up and this provides an opportunity to make any final crop nutrition applications, including trace elements as required.
Crops that were backwards in April may bounce back quickly after rainfall and with warmer weather during May, rapid growth spurts are likely. This increases the potential for lodging, so appropriate plant growth regulators (PGRs) should be applied at the right time. Growers may need to apply PGRs as a standalone application if timings do not coincide with fungicides.
Looking forward to T2 (flag leaf fully-emerged) applications later in the month, the risk of Septoria and mildew may rise depending on the weather, and especially if the interval between T1 and T2 applications is stretched beyond three weeks, or a less robust fungicide was applied at T1.
With wheat prices remaining high (as at the end of April) and crops showing good potential, there is a good incentive to provide robust protection to the flag leaf as the main driver of yield.
Some diseases such as Septoria have a long latent period, and may not be visible on the leaf even though it is present in the plant. Knowing whether disease is present or not can establish whether you face a protectant or curative scenario. Updates to Bayer’s National Snapshot Project, which reports on Septoria and Yellow Rust incidence on farms across the UK using our new Rapid Disease Detection technology could give growers some local insight into disease risk.
For all-round disease control, 1 - 1.5 L/ha of Ascra will be effective against Septoria, Yellow Rust, Eye spot, Fusarium head blight, and other key diseases. In lower-risk scenarios, where crops were drilled in November or later, and have good Septoria resistance ratings (7 or higher), 1 - 1.25 L/ha of Aviator 235Xpro is an alternative option.
The Xpro formulation of both Ascra and Aviator offers benefits beyond disease control. It delivers improved drought stress tolerance and increased crop greening, which can help to deliver yield even in a low disease year. In a dry season, these physiological benefits may be even more important to enhancing yield potential.
It’s been a very typical spring so far, with average rainfall and temperature for this time of year. The result is that crops are looking good with plenty of yield potential.
Disease levels are a mixed bag. Plenty of Septoria is being seen in the base of crops, and while yellow rust disappeared after the cold snap in February, it has re-emerged mainly in the East of England but is also being seen in southern and western areas.
By early April most crops will have received half of their required nitrogen though some areas of the UK have struggled to travel due to wet or very windy conditions. Crops will also either have already received their T0 fungicide along with a PGR, or spraying will be imminent.
As the month progresses, it’s important to address any remaining grass-weed problems with a contact herbicide if none has been applied, before weeds become too large.
Crops will shortly start to grow away quickly, reaching the typical T1 timing at GS31-32 within the month. It is important to assess the crop carefully to ensure at least ¾ of leaf 3 has fully emerged prior to spraying.
While some growers may choose to only target yellow rust at T0, a robust T1 fungicide is highly recommended to protect against Septoria and other key diseases, depending on levels of disease at application time.
Where crops are unprotected from Septoria and we receive typical showery weather in April, they may be at high risk of disease.
To get an idea of Septoria and yellow rust disease progression in your area, take a look at Bayer’s national snapshot project. Our technical managers have partnered with local farmers to track disease in commercial wheat fields across the UK and Ireland using our new Rapid Disease Detection technology.
Varieties with good Septoria resistance ratings (7 or higher) and that were drilled November or later, are likely to under less disease pressure, so growers have the option to flex the rate of Ascra down to 1 L/ha or apply Aviator at 0.8 – 1 L/ha.
Crops that did not receive a protectant fungicide for Septoria at T0 and were drilled in September/October should start with a higher rate of Ascra, between 1 – 1.2 L/ha depending on observed disease levels.
If T1 sprays have to be delayed from optimal timings, growers may face a curative scenario for Septoria. In which case a higher 1.5 L/ha rate of Ascra will help to ensure good control, plus ongoing protection.
In addition to Septoria, Ascra will also target yellow rust and reduce the incidence of eye spot in susceptible crops, while both Aviator and Ascra will play a part in reducing Fusarium head blight within the programme.
After a relatively cold February, soils are warming and drying as we move into March, and with that, field-operations can re-start.
Getting fertiliser onto crops and contact herbicides will be a priority task in the early part of the month.
While most crops will benefit from 150 kg/ha of nitrogen, growers should take soil or leaf-tissue samples to identify other crop nutrition requirements and address any deficiencies as soon as possible. Pant growth regulators will need to be applied towards the end of the month to encourage and maintain tillering.
Contact herbicides will be required to remove any remaining grass-weeds, and target later-germinating broad-leaved weeds. It’s important to complete herbicide programmes so growers should assess the species present to help choose the most appropriate products.
Where fields have a mixed-population of grass-weeds and broad-leaved weeds, Pacifica Plus provide good control of a wide range of species, including black-grass, sterile brome, chickweed, cleavers, fumitory, mayweed, and many others. Atlantis OD is the better choice if black-grass is the main target weed.
Over the past two seasons, Bayer’s weed screens have shown that Monolith provides better control of certain brome species, including rye-, soft-, and meadow-brome. The different brome species are difficult to identify at this time of year, so refer to field history to assess which species are likely to be present.
Some growers are seeing a significant number of barley volunteers in wheat crops after last season’s difficult year where many barley crops were difficult to combine. Monolith is the best approach here and will prevent competition to the growing wheat crop.
Crops should be regularly monitored for disease, with a view to applying a T0 when the crop reaches GS30 (first node visible) which is usually around the end of March.
Despite the cold weather in February, there are continuing reports of yellow rust present in a number of varieties, including Skyfall, KWS Extase and Gleam. The changing yellow rust environment with new races makes it difficult to know whether adult plat resistance will develop in time to protect yield. It may be prudent to take action now to control yellow rust, even on varieties where you would expect good resistance. An application of 100 g/ha of a tebuconazole product will help to keep any yellow rust at bay until T1. Remember that if a strobilurun is used at T0, it must only be applied alongside another fungicide with a different mode of action.
Other diseases to consider include Septoria and mildew. Septoria is frequently being seen in crops after winter, and a multisite may be required to hold back disease before T1. With the loss of chlorothalonil, folpet is a good alternative. If there are high levels of mildew seen in the crop, an application of Torch (Spiroxamine) could be considered, but otherwise any tebuconazole applied to treat yellow rust will also control mildew.
The focus for most winter wheat crops during February will be monitoring disease levels and completing herbicide programmes, to protect yields through to harvest.
By the end of 2020 around 90% of the planned winter wheat crop had been drilled, and most crops have grown away well and have continued to tiller during milder spells in January. There is still some drilling to do after sugar beet, mainly in the East, but the overall picture for winter cereals is looking much better than it did in February 2020.
The mostly mild winter weather means it is quite easy to find disease on certain varieties, particularly Yellow Rust in Skyfall and KWS Zyatt, and Septoria lesions are being seen on more susceptible varieties. However, the low temperatures in late January will hopefully have provided a check to Yellow Rust and it will pose less of a threat going into early spring.
Growers should focus on monitoring crops, getting an overview of what disease challenges may lie ahead, and which fields may require action in the spring.
Weed control is a mixed-bag across the UK following a challenging autumn where rain delayed some activities. Growers will need to assess their own situation field by field, to review what actions need to be taken.
Some growers were able to get pre-emergence herbicides onto crops in good time, and were able to apply follow-up applications of contact-acting herbicides. Other crops received delayed pre-ems, or had non applied at all.
Where good weed control was achieved with residuals in the autumn, growers should ensure they complete programmes to prevent seed return for following seasons. If conditions allow for sprayers to travel in February, and temperatures remain mild enough for active weed growth, then getting contact herbicides on to crops to control grass-weeds and broad-leaved weeds should be a priority.
For the past two seasons, Bayer’s weedscreens have shown that February herbicide applications have been effective in controlling grass-weeds. As weeds start to re-grow, they more readily take up the chemistry applied to them, but are still small enough to tackle with a contact herbicide.
Where fields have a mixed population of grass- and broad-leaved weeds, Pacifica Plus provides good control, including of black-grass and a wide range of important broad-leaved weeds such as mayweed, chickweed and fumitory. From the 1st February, Pacifica Plus can be applied at 0.4l/ha, but if the field has a history of high brome population, growers should wait until 1st March when Pacifica Plus can be applied at the higher rate of 0.5l/ha to achieve better brome control.
Where the focus is mainly towards controlling black-grass, Atlantis OD can be applied at 1.2l/ha as soon as conditions allow.
When applying contact-acting herbicides it is vital that weeds are actively growing, so growers need to monitor crops and soil temperatures to determine the optimal time to spray.
Finally, to promote tillering in any backwards crops, an early applications of nitrogen could be beneficial if conditions allow.
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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.