Biocontrol of gray mold in tomato plants by Clonostachys rosea

Abstract

Greenhouse conditions are favorable to the growth of Botrytis cinerea, and an increase in the occurrence of gray mold caused by this pathogen is therefore expected. Biocontrol using microbial antagonists is one of the approaches to control the pathogen. In previous experiments, Clonostachys rosea isolates suppressed B. cinerea in tomato leaves, but it was not evaluated in wounds caused during pruning, where the pathogen predominantly infects. Here, the efficacy of four C. rosea isolates to control B. cinerea in wounded tomato stems was evaluated. Influence of the following factors on the antagonist’s efficiency were evaluated: i) application time of C. rosea respectively to time for B. cinerea inoculum deposition, ii) conidial concentration of C. rosea, and iii) application of individual isolates versus isolate mixture. Results indicated that the four C. rosea isolates are effective in controlling gray mold, and that they may be applied either individually or as a mixture. The biocontrol efficiency of C. rosea was higher when it was applied 1 day before or simultaneously with the pathogen inoculation at a concentration of 106 conidia/mL- 1, reaching 100 % in stem segments and more than 90 % in whole plants. The antagonist has potential to be used in greenhouse tomato, especially in an integrated management context.