Barley growers facing crisis as fungicide resistance grows

The sudden and dramatic breakdown in the ability of two key fungicide groups to control the important barley disease ramularia highlights the importance of using an integrated management approach to crop protection.

SRUC crop pathologist Dr Neil Havis told the Agronomy 2018 conference that both the SDHI and the azole groups had given poor control of ramularia in 2017 – leaving only chlorothalonil as an effective control measure against the disease.

However, he warned that, with chlorothalonil currently on the EU list of products likely to be phased out, barley growers could soon find themselves in a vulnerable position.

Head of the college’s crops and soils systems, Professor Fiona Burnett, stressed the need for the use of best practice to 0 Prof Fiona B urnett urged growers to vary treatment reduce the build-up of disease races resistant to fungicides.

She said that by limiting the number of times a specific active ingredient was used – and using it in combination with other products with a different mode of control – the lifetime of sprays could be enhanced.

She also advocated the use of varietal resistances and other practices such as sowing date to draw up tailored spray programmes which minimised the likelihood of product effectiveness breaking down. But she added that it was crucial that the whole industry was on board as this was the only way to ensure the efficacy of the available products was maintained.

Reporting that while there was a high risk of the breakdown of both SDHI’S and azole groups’ ability to control Scotland’s key wheat disease, septoria, she said the good news was that there were no further signs of this happening last year: “While a new active ingredient being developed for controlling septoria offers the prospect of some light at the end of the tunnel, we need to eke out the effectiveness of current control measures for two or three years yet – and then make sure we use the new chemistry sensibly.”

Burnett also said that the use of elicitors and biostimulants – which acted like vaccines to prime the plant’s own defences before a disease attack – was also helping in the fight against disease resistance.