Time out for T0 fungicides?

Warm weather gave cereal crops a boost recently, before more seasonal conditions returned. Many early dressings of nitrogen have gone on and thoughts are now turning to early fungicides.

The amount of barley and, especially, wheat that receives T0 fungicides has risen in recent years. In fact, it’s estimated that about 70% of winter wheat receives a T0. But why is so much crop being treated? Although many make an application in response to disease pressure, a recent survey of growers and agronomists by AHDB found that a relatively high number also use a T0 spray as insurance against a weather-delayed T1.

With newer, more resistant wheat varieties, however, this threat is much reduced, because disease progression is slower. In fact, good disease resistance provides a good opportunity to either switch chemistry or eliminate the T0 spray altogether. Where a T0 is skipped, not only can costs be saved but the selection pressure on azoles (often the go-to chemistry at this timing) can also be reduced

AHDB’s initiative with FRAG-UK and key fungicide manufacturers – Fungicide Futures – has identified the key considerations at the T0 timing:

  • Given the disease pressure and varietal resistance, is a T0 needed?
  • Consider alternative chemistry to any azoles planned for T1 to protect azole efficacy
  • Consider a multi-site for septoria control (with due consideration of maximum application numbers and dose)

Further guidance on fungicide resistance management is available at Fungicide Futures and FRAG-UK

ahdb.org.uk/knowledge-library/fungicide-futures

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Paul Gosling

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