EFFECTS OF TEMPERATURE AND DURATION OF SURFACE WETNESS ON SPORE PRODUCTION AND INFECTION OF CUCUMBERS BY DIDYMELLA-BRYONIAE

Effects of temperature on spore germination, sporulation, infection, and symptom development on stem pieces and flowers of cucumber infected with Didymella bryoniae were studied under conditions of 100% relative humidity (RH). Infection of leaves and petioles of young, intact cucumber plants was studied at various combinations of temperatures and durations of surface wetness. Processes studied at 100% RH occurred over a wide range of temperatures (20-28 C), with an optimum of 24-25 C. When temperature and duration of surface wetness were varied in combination, wetness duration was the most important factor that affected the proportion of leaves and petioles that became infected.