Readjust management for backward wheat crops in 2024, growers urged

According to Mr King, as well as finding ways to bolster their delayed growth, and managing them with inputs cost-effectively tailored to their yield potential, backward crops are also more vulnerable to attacks from yellow rust.

“Ordinarily, Septoria tritici is the main disease that’s top-of-mind in winter wheat,” says Mr King. “While this will clearly still need protecting against, there’s less time for it to build up over winter in late-drilled crops. Conversely, backward crops are at heightened risk from yellow rust, due to their smaller leaf area. Left untreated, yellow rust can cut yield by as much as half – which is particularly unwelcome if yield potential is already lower due to backward growth.”

Harsh frosts needed

Although yellow rust infection can be reduced by frosts, Mr King says harsher frosts are needed than often realised – for example, continuous minus 5–6^oC temperatures for five days. Yellow rust can also rear up again quickly in favourable conditions, he says, going through its life cycle in just 10–12 days, so early prevention is crucial.

“To stay on the front foot against yellow rust, consider a suitable triazole fungicide at the March T0 spray timing as crops come out of winter. Then, for the pivotal T1 timing in April, make sure the fungicide used has a track record of strong yellow rust activity, and isn’t only focused on septoria. Check the independent AHDB fungicide dose response curves for information; you’ll see Solatenol, the SDHI fungicide in Elatus Era, has given outstanding yellow rust control and yields in a yellow rust situation across multiple years.

“Elatus Era also provides long-lasting protection against Septoria tritici and is cost-effective, which are also important properties for a foliar T1 fungicide – the aim of which is to begin protecting the top three yield-building leaves. Together, these leaves contribute about 75% of final winter wheat yield. If yield potential has been diminished at all by late planting or delayed growth, ensuring as much of that 75% yield contribution is retained as possible becomes even more important.”

Prevention better than cure

With all wheat crops, Mr King urges regular inspection through winter and into spring for early signs of yellow rust and other diseases, and to take into account variety resistance. “There are plenty of varieties with low resistance ratings against yellow rust,” he adds, “and prevention is better than cure.”

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