Working with Allium & Brassica Agronomy, Walsh found levels of up to 60 per cent infection of TuYV in some winter cauliflower crops and 100 per cent in a Lincolnshire Brussels sprout trial.
Though it has few obvious symptoms in plants, the virus reduces yield in Brussels sprouts by 22-65 per cent depending on variety and by 16-36 per cent in cabbages, he added.
Walsh is assessing the efficacy of insecticides against its main vector, the aphid Myzus persicae. But he said: "There is a need for more sustainable control methods. Resistance has been detected in the wild relatives of brassicas and we are now looking for collaborators to exploit this."