Cereal growers need to be on guard against new races of mildew and brown rust which attacked previously resistant wheat varieties last season, the Home Grown Cereals Authority has warned.

Results from last year’s DEFRA/HGCA-funded Cereal Pathogen Survey identified a new race of mildew that attacks Robigus and a new race of brown rust which attacks a number of varieties including Claire, Istabraq and Alchemy.

Glasshouse investigations found that the new strain of brown rust could potentially affect Glasgow, Xi19 and Richmond.

In addition, over 200 samples of mildew from wheat were analysed and nearly half of these had been from the previously resistant variety Robigus, reported NIAB’s Rosemary Bayles.

She suggested that growers need to watch the variety this year and be prepared to tailor their fungicide treatments to mildew control if it is necessary.

“This new race of mildew has so far only been seen in a few HGCA Recommended List trials but indications suggest that the current RL rating of 8 for Robigus might not reflect the true susceptibility of the variety,” commented HGCA’s Graham Jellis.

Yellow rust was also more widespread last year, although high summer temperatures prevented a serious epidemic, Dr Bayles added. Strains capable of attacking Robigus and Consort represented 85% of all isolates collected compared to 41% the previous year.

Full results of the survey will be published on the HGCA website, www.hgca.com