Prediction of Yield Loss due to Eyespot in Winter Wheat

SUMMARY Field plots inoculated and uninoculated with Pseudocercosporella herpotrichoides (Fron) Deighton were compared in trials over a period of nine years. Regression analysis showed that percentage yield loss due to inoculation was related to the incidence of severe eyespot lesions, but was more closely related to the amount of lodging due to eyespot. Disease incidence in spring was not a reliable indicator of the subsequent rate of disease development, or of its effect on yield, but loss in yield sufficient to justify fungicide application was not observed when less than 10 per cent of shoots showed eyespot symptoms in spring.