Measures to combat fungicide resistance in cereal pathogens

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The management of fungicide resistance in wheat and barley pathogens is the focus of two new publications.

Developed as part of the Fungicide Futures initiative, the publications provide concise information on the best practice use for fungicides, including non-chemical control, treatment frequency, timing, dose, mixtures, alternation, multi-sites and programmes.

Robust fungicide programmes have helped to support high yields in both wheat and barley. But it is essential that programmes are designed around a solid anti-resistance strategy.

When fungicides are applied, susceptible fungal strains are usually controlled very effectively. However, any resistant strains present (through mutation or natural variation) are more likely to survive and reproduce. This process of ‘selection’ makes each subsequent generation more difficult to control. In the absence of any fitness costs, resistant strains may come to dominate the population, causing disease control to fail.

In wheat, septoria tritici is currently of greatest concern, with significant shifts in sensitivity to strobilurins and azoles in UK populations. Isolates with mutations that confer reduced sensitivity to succinate dehydrogenase inhibitors (SDHIs) are also present across the UK, with increasing frequency each year. For barley, ramularia is currently of greatest concern, with significant shifts in sensitivity to strobilurins, azoles and SDHIs in UK populations.

Paul Gosling, who manages fungicide performance work at AHDB, said: “It is essential to use comprehensive anti-resistance strategies to slow resistance development and preserve the efficacy of both existing and new chemistry. These Fungicide Futures publications provide clear information on what and, importantly, what not to do when designing fungicide programmes.”

Anti-resistance strategies should:

Exploit all practical, non-chemical control methods to reduce disease risk and slow epidemic development

Limit the time over which the pathogen population is exposed to the fungicide

Use effective mixtures and alternate fungicides with different modes of action

Use the minimum dose required to effectively control target pathogens

The two publications can be downloaded from ahdb.org.uk/knowledge-library/fungicide-futures

To order printed copies, please call 0845 245 0009 or email cereals@hallmarkconsumer.co.uk. The hard copy version comes as an A4 document that folds out to an A0 poster.

 

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