EPIPHYTIC FUNGI ON APPLE LEAVES AND THEIR VALUE FOR CONTROL OF THE POSTHARVEST PATHOGENS BOTRYTIS-CINEREA, MONILINIA-FRUCTIGENA AND PENICILLIUM-EXPANSUM

Fungal populations were examined each month on apple leaves, cv. 'Gold en Delicious', during 1989. Out of 32 different fungal species studied , 21 were present throughout the season in large numbers. Of these, 36 8 isolates were selected and tested in vitro and in vivo for antagonis tic activity against the postharvest pathogens Botrytis cinerea, Monil inia fructigena and Penicillium expansum. If applied to wounded apples , isolates of Aureobasidium pullulans, Epicoccum purpurascens, Sordari a fimicola and Trichoderma polysporum (20 mul containing 10(7) spores/ ml) provided good protection against the three postharvest pathogens a t a ratio of 100:1 (antagonists to pathogen). Better control with much smaller numbers of antagonists was obtained with mixtures, such as E. purpurascens plus A. pullutans, S. fimicola, or T. polysporum. After the application of such mixtures to freshly wounded apples, ratios bet ween 1:1 until 10:1 (antagonists to pathogen) were sufficient to contr ol postharvest decay over a broad range of concentrations of the micro -organisms.