Abstract

In this study the effect of biocontrol agents Candida membraniciens (isolates A4, A5), Pichia guilliermondii (isolate A6) and Bacillus subtilis (isolates B2, B6) were evaluated individually and in combination on gray mold of apple. Our results show that the antagonists were compatible when they were tested in vitro. Also, results show the spore germination of Botrytis cinerea decreased significantly by the combination of B2+A5 more than the other treatments. In the dual culture test, the combinations of B2+A5 and B6+A6 prevented mycelial growth of pathogen and that the combined application of the two agents was more effective in control of gray mold of apple in vivo than the application of each one alone. In different proportions antagonist test, when the inoculum size favored A5 was 70 in the mixed, the biocontrol could be improved. This study suggested that antagonists are more effective in biological control of apple gray mold when used in proper combinations than when each one is used alone.

Key words: Gray mold, biocontrol, mixtures antagonist, Botrytis cinnerea.