Use OSR resistance
GROWERS could do more to exploit oilseed rape variety resistance to phoma canker and light leaf spot, says PBIC Monsanto osr breeder Matthew Clarke.
Data from disease test beds at the Cambridge breeder, plus official disease resistance ratings, show some of the more resistant varieties, such as Canberra, are more resistant to canker symptoms than autumn leaf spotting would suggest.
More resistant varieties, like Cohort, Disco and Canberra, are more easily managed, spraying time is less critical and threshold disease levels are less likely to be met, he says.
By contrast, with less resistant varieties, like Royal, Courage and Shannon, spray timing is more critical and thresholds will usually be reached.
Hope for the future lies in new variety Caiman. Although not picked for recommended list trials, it offers a 9 for phoma resistance which will be used in breeding programmes, he says. *