Integrated management of early and late blight in potatoes

The main region of potato production in Israel is in the northern Negev. The climate there is semi-arid with mild winters and hot, rainless summers. Potatoes are grown in two growing seasons, autumn and spring. Two foliar diseases, early blight (caused by Alternaria solani) and late blight (caused by Phytophthora infestans), threaten the crop and if not managed properly, may induce substantial yield losses. However, since late blight is potentially more destructive than early blight, more efforts are devoted to its suppression. Concepts for the integration of genotype resistance, age-related resistance and fungicide type for the suppression of both early and late blights were developed based on the epidemiology of the pathogens and in relation to their interactions with the host. The concepts were formulated in a holistic framework named "the integrated management strategy". The integrated management strategy was evaluated in 7 field experiments from 1994 to 1998; 4 of which were conducted in the autumn season and 3 in the spring season. Both early and late blights developed in all experiments at various levels of intensity. Analysis of disease progress curves revealed that in plots managed according to the integrated management concepts early blight was suppressed as good as in plots treatment with a specific fungicide against A. solani, and late blight was suppressed as good as in plots treated with specific fungicides against P. infestans. Less sprays and lower quantities of fungicidal active ingredient were applied in plots treated according to the integrated management strategy. Yield in the integrated management treatment did not differ, or was significantly higher, than yield in the other control treatments. Potato growers in the northern Negev region currently implement the concepts of the integrated management strategy.