Reduced fungicide inputs to control Phytophthora infestans in potato cultivars with high levels of polygenic resistance

Final disease ratings, apparent infection rates and areas under disease progress curves were used to calculate lower fungicide rates for potato cultivars with high levels of polygenic resistance to Phytophthora infestans. Areas under disease progress curves offered more reliable indications than final disease ratings or apparent infection rates. Control of epidemic development was achieved using 20-80% of the recommended application rates of mancozeb on plots of cvs Brodick, Cara and Torridon compared with full application rates on cv. Maris Piper.