Biocontrol of tomato gray mold disease by Trichoderma harzianum and Bacillus subtilis

This study aimed to evaluate the antagonistic activity of some fungal and bacterial isolates against Botrytis cinerea, the causal agent of tomato gray mold disease. For this purpose, out of six fungal isolates obtained from the gray mold symptoms on tomato and melon, isolates B1 and B2 were selected based on the pathogenicity test result for the in vitro and in vivo experiments. These isolates were identified as Botrytis cinerea based on morphological and molecular information (ITS sequence). In dual culture test of two bacterial and six antagonistic fungal isolates, Trichoderma harzianum T1 and Bacillus subtilis B43 with up to 60% and 71.54% of inhibition levels, respectively, were the most efficient treatments to limit fungal growth. In volatile compounds tests, isolates T1 and B43 inhibited pathogen mycelia growth up to 95.98 and 100%, respectively. The results of the secondary metabolites test showed that B. subtilis B43 inhibited pathogen mycelium growth by 98%. In vivo experiments showed that the isolates T1 and B43 controlled gray mold of tomato effectively, and the average inhibition rates were more than 60%. None of the antagonistic isolates significantly affected the height, fresh and dry weight of whole parts of the plants compared to healthy control.