Significant changes have been made to yellow rust resistance ratings on the HGCA’s Recommended List for winter wheat following a resurgence of the disease in crops last season, which included a new race affecting a number of high profile varieties in the UK. And the advice to growers from leading plant breeder Nickerson, who’s varieties make up over 50 per cent of those rated as ‘highly resistant’ to the disease, is to consider the revised ratings carefully and look to spread the risk with this autumn’s plantings.

According to HGCA, yellow rust ratings for several varieties have fallen by four points or more, including the popular Group 4 feed wheat Oakley, which has fallen from a medium risk of 6, down to 2, making it “as susceptible to the disease as Robigus”. Other significant changes reported by the HGCA are Solstice which has fallen from 9 to 4, Ketchum and Viscount from 8 to 4, Duxford and Marksman from 8 to 5, and new Group 1 variety Gallant which falls from 6 to 4, the same as Solstice.

Nickerson cereal pathologist, Paul Fenwick says that the company’s own disease rating trials for yellow rust tie in with those produced by the HGCA, based on 2009 data to allow for the aggressive nature of the new race that appeared, and he confirms that the new ratings are a true reflection of current varietal resistance.

“It’s reassuring to see that 9 out of the 15 varieties which the HGCA rated as highly resistant (8 and 9) to yellow rust are from the Nickerson stable, including several of the newer ones. The Nickerson pedigree suggests that our new varieties have similar resistance to the older ones such as Claire, which after 10 years on the Recommended List is still highly resistant to the disease.”

“A variety like Claire has been on the Recommended List a long time and it is still highly resistant,” points out Mr Fenwick. “It’s got a level of proven durability, as has Alchemy, and the newer ones like Invicta, Cassius and Panorama are following suit.”

Mr Fenwick warns growers that whatever the weather patterns this winter, yellow rust inoculum will be a factor next season and the new Recommended List ratings should be considered ahead of further plantings this autumn. He states:

“They used to say that you shouldn’t grow more than you can spray in a day if varieties were susceptible to yellow rust, and I think that still holds true today. Spread the risk by keeping an eye on yellow rust ratings when making variety decisions, and monitor crops carefully for the disease later in the season for the appropriate fungicide choice.”