Biological control of gray mold in pears by antagonistic bacteria

The possibility of employing antagonistic bacteria for postharvest control of gray mold on pear was studied. Approximately 175 strains of bacteria were isolated from beneath the skin of various fruits and vegetables and 14 of these possessed high levels of antagonistic properties. They significantly reduced gray mold in cv Conference pear artificially inoculated with Botrytis cinerea and stored at 20 degrees C for at least 9 days. Two strains, 3PPE (Bacillus pumilus) and 2TOE (Bacillus amyloliquefaciens), were particularly active. They did not produce antibiotic substances and their application was compatible with iprodione-based antifungal treatments. The bacterial antagonist mixed with the fungicide at 50 ppm a.i. resulted in a greater control of the pathogen compared to the single ingredient. Holding bacteria-treated fruits at 20 degrees C for 24 h before cold storage improved the efficacy of the bacteria against gray mold. (C) 1996 Academic Press, Inc.