After weather disrupted T1 fungicide applications at GS32, ensuring no longer than 21 days elapses before applying the T2 will be critical to good disease control in winter wheat this year.

That’s the view of George Green, Association of Independent Crop Consultants (AICC) director for Scotland, who advises growers across Aberdeenshire and helps Inverurie Farm Consultancy’s Ian Dalley co-ordinate the group’s Scottish trials.

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The main wheat disease issue across his patch is always septoria, with mildew also having the potential to limit crop potential in a favourable season. Yellow rust rarely threatens, except in areas such as Fife, or very weak varieties.

George said that this year, the cold and wet start to the year had prevented mildew from developing into a significant problem, aided by prothioconazole-based T1 applications, which have good protectant activity on the disease.

The prothioconazole was partnered with fenpicoxamid in co-formulation Univoq, and combined with multisite folpet, reflecting the septoria pressure and prevalence of winter wheat varieties with weak scores, such as Lili and Skyscraper.

“Growers are used to applying a robust programme to those varieties and this year it will certainly be needed. So far, the cold has limited septoria progression up to the T1 spray, with disease sitting on older leaves.

“It’s now getting much warmer and the showers continue, and they will be splashing septoria spores up the crops. Last year was a benign disease year, but 2023 won’t be and it needs to be managed accordingly,” he noted.

The increased risk and the fact that the timing of T1 fungicides was not ideal on many farms due to the catchy weather is reflected in his T2 advice.

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With QiI-azole formulation Univoq used widely at T1, a sound anti-resistance strategy is to rotate fungicide classes through the programme and this should be considered, as well as good septoria activity.

This led George to recommend a standard T2 application of fluxapyroxad + mefentrifluconazole product Revystar, which contains an SDHI and a newer azole, which is less affected by sensitivity shifts to older molecules in septoria populations. Dose should be 1-litre/ha, increasing slightly to 1.25-litres/ha if risk requires, or the ability to cover the area quickly with the sprayer is lacking on a particular farm.

“Multisite active folpet could be included at T2 as well, but that will depend on the conditions leading up to application, which is typically around 1 June. If the weather continues there could be a case.”

George added that growers were currently looking a varieties with more robust resistance to septoria, which would allow the genetics to do a bit more of the heavy lifting against disease.

Two examples were hard Group 4 feed wheats, KWS Dawsum and Champion from DSV, which had improved septoria scores over established wheats in Scotland, plus have good resistance to mildew. “They tick a lot of boxes, but the sticking point is that neither are suitable for the grain distilling market so important here," he argued.

“Organisations, like Scottish Agronomy, had been liaising distillers to see if they will take more hard wheats, which would help with the uptake of varieties with better disease resistance. It would make things a lot simpler for farmers.”

Data pool drives independent advice

AICC runs independent replicated field trials that test and compare the performance of current and near market fungicides in key cereal crops like wheat and barley throughout England and Scotland.

This continually adds to a large pool of data that can be combined with other sources and local knowledge to help AICC members and their farmer clients make the most cost-effective decisions in any given season, whether disease pressure is high or low.

George runs the organisation’s trials work close to his base near Oldmeldrum, Aberdeenshire, focussing on barley disease control work relevant to AICC members across the UK. “This year, I’m doing work on my own farm with elicitors like laminarin, along with sulphur and multisite folpet.

“Although it is only tramline trial work and not entirely scientific, they offer an indication of what these products can offer and whether they merit more detailed investigation in replicated trials next year.”