Crops were looking well as we approached the end of March. A good spell of weather with warmish days, albeit with a few frosts, has allowed growers to crack on with field work.
A lot of ploughing has been completed, oilseed rape crops are moving quickly, while fertiliser has been applied to wheat and barley.
In most cases sprays had yet to start at the time of writing, so that will be a priority as soon as conditions allow. Watch out for any late frosts, cold dips in temperature, fluctuations that will create stress conditions for the crop, which will not help if they are going to get a herbicide as well.
The first decision on disease control programmes in wheat will be whether to use a T0 spray this season. With the cold weather this winter having knocked back disease some growers and agronomists may decide that will be able to miss it out this spring.
If you do decide to apply a T0, avoid using primary azoles, such as prothioconazole. These are best saved for the main timings and will slow resistance build up if they are not used at every timing.
The first T1 sprays in wheat will likely go on towards the end of the month, with some slipping into May. Timing is key – aim for final leaf three fully emerged. It’s fiddly and time-consuming to dissect plants, so not all will do it, but it is the best way to get timing spot on rather than relying on nodal growth stages, which can be anything from GS31-33.
Our initial Rapid Disease Detection tests on our monitor crop in Scotland has shown that so far we have the most Septoria, including on what should be a clean variety, Sundance. There’s also been some reports of yellow rust in Fife and Lothians.
Ascra Xpro (bixafen + fluopyram + prothioconazole) will be a good all-rounder for T1, covering both of those key diseases, plus mildew and eyespot. Rate can be flexible depending on disease risk and variety – anything from 1.0 L/ha to 1.5 L/ha in exceptional circumstances.
The Xpro range, which also includes Aviator (bixafen + prothioconazole) offers other benefits through its Leafshield formulation, including rainfastness in minutes, which is useful with the catchy weather we often have in Scotland.
There are also greening benefits on the label, based on trials where there have been yield benefits in the absence of disease.
Winter barley crops are looking good but can shoot through their growth stages quickly so keep an eye on them for the GS30-31 timing for T1 sprays. That’s likely to be from mid-April.
Typically base applications around 120g/ha of prothioconazole so 0.6 L/ha of Siltra Xpro (bixafen + prothioconazole). Fandango is also an option, although it’s more popular as a T2 spray.
Both are strong on all the main barley diseases, including Rhynchosporium and net blotch, and are also fully approved for use on malting barley crops.
Given oilseed rape price is reaching £400/t and that crops look to have decent potential this season, growers are likely to be prepared to invest in maximising yields.
At the beginning of April last stem extension sprays for light leaf spot control or growth regulation might be going on. If you’re using Proline (prothioconazole) be aware of the maximum total dose in the crop all season of 1.26 L/ha.
Levels of light leaf spot have been high in crops, as shown by Spotcheck results, so you do want to stop the disease from getting onto the pods and affecting yields.
Later in the month topping up light leaf spot control will also be a consideration for the flowering spray, along with Sclerotinia control. Aviator (prothioconazole + bixafen) at 0.75 L/ha is a good choice.
More growers will be on a two-spray approach this season given that oilseed rape price. If that’s your intention the first spray should be when the crop has a yellow hue or 10-15% flowering and then return three weeks later for the second spray.
If you go with a one-spray approach then the timing is closer to mid-flowering.
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As part of Bayer’s Rapid Disease Detection project in 2021, our technical managers have partnered with local farmers to track disease progression in commercial wheat fields across the UK and Ireland. Click to read weekly updates and results.