60% wheat expected to infect yellow rust in UK 2010

"Worrying and dangerous" threat of yellow rust strain
 
More than half the winter wheat acreage in the ground during 2010 will be susceptible to yellow rust (What is it? ). Of those varieties, nearly 60 per cent are expected to be susceptible to the new Solstice yellow rust race which became widespread last season. NIABs [National Institute of Agricultural Botany] Rosemary Bayles said the industry had an unusual situation with such high susceptibility to yellow rust in winter wheat. "It is a worrying and potentially dangerous situation," she said.
 
The striking feature is the change in varieties resistance ratings to yellow rust, with a substantial number having disease ratings cut by 4 or 5 points [out of 10 for complete resistance]. The number of yellow rust isolates in 2009 had risen significantly, although testing for the year had not been completed. "The suggestion is that 80 per cent of isolates tested in 2009 could turn out to be virulent," said Dr Bayles. Varieties with lower ratings may be susceptible to some rust races.
 
Despite the enormous number of pathogens in existence, the main yellow rust races could be grouped into either the Robigus, Original V6, or new Solstice types. Varieties such as Solstice, Viscount, and Qplus showed resistance to earlier yellow rust types, but not to the new Solstice type.
 
"The safest option will be to grow varieties with high resistance ratings as companions to susceptible varieties. A diversification scheme will be produced to assist in spreading the risk from one variety to another, including disease control strategies and planning fungicide programmes accordingly," Bayles said.