Effectiveness of Aureobasidium pullulans and Candida oleophila against postharvest strawberry rots

Many yeasts, including yeast-like fungi, were selectively isolated from fruits and vegetables. In several assays performed on strawberries, table grape berries and kiwifruit, the yeast-like fungus Aureobasidium pullulans L47 and the yeasts Candida vanderwaltii L60 and C. oleophila L66 were the most effective antagonists of Botrytis cinerea and Rhizopus stolonifer. Isolates L47 and L66 were utilized in trials on strawberries grown under plastic tunnels. They were applied at flowering (full bloom and late petal fall) and at fruit maturity (just before or after harvest). Isolate L47 was the most effective against both B. cinerea and R. stolonifer. Both antagonists were more active when applied at the flowering stage, with isolate L47 more effective than vinclozolin. The antagonist population was consistently high on flowers and developing fruits, and on cold-stored strawberries. Isolates L47 and L66 showed a low sensitivity towards some fungicides in culture and were able to grow at temperatures between those of cold storage and 33 °C. Competition for nutrients seems to be the main mode of action.