Integrated control of potato late blight (Phytophthora infestans) in Switzerland: concept and first results1

A project has been undertaken in Switzerland to reduce the number of applications of fungicides to potato by a reduction of late blight incidence and disease pressure as well as by providing reliable and precise spraying recommendations against blight. We try to achieve this aim by combining different elements: (1) to delay and to impede disease progress, it is planned to promote less susceptible potato cultivars and to reduce the number of primary foci by advising seed potato growers to protect their crops more carefully; (2) the data of about 20 weather stations are utilized to test different forecasting systems; (3) these (theoretical) indications on the appearance of the disease are complemented by extensive monitoring of real late blight occurrence in the field; (4) the late blight susceptibility of all cultivars grown in Switzerland is being assessed by special trials. From the combination of all this information, spraying recommendations will be formulated according to regions and cultivars.