Response of various cultivars of cucumber to different isolates of Pseudoperonospora cubensis (Berk et Curt.) Rostow under artificial epiphytotic conditions

This research was conducted at the Department of Plant Pathology, University of Agriculture Peshawar during the 2011 growing season of the crop to determine the response of various cultivars of cucumber to different isolates of the downy mildew fungus Pseudoperonspora cubensis under artificial epiphytotic conditions. Five cucumber cultivars (Desi, Long Green, F1 hybrid, Dollar and Khyber) were tested for their response to infection by four different isolates of Pseudoperonospora cubensis. Significant differences (p<0.05) were found among the treated and control plants. F1 Hybrid and Dollar F1 were found to have the least disease severity. Among the isolates, isolate 4 caused the highest disease severity. In control plants, the disease severity was less. The interaction of cultivars and isolates was also significant in disease severity after thirty and forty days of inoculation.