Present study was aimed to determine in vitro antagonistic efficacy of two different species of Trichoderma and nine different species of Bacillus against tomato damping off causing fungi Pythium aphanidermatum. Different types of assays were carried out with Trichoderma spp., in all tests they revealed growth inhibition on P. aphanidermatum. In dual culture assay and assay for volatile metabolites, Trichoderma harzianum revealed significantly (P <0.05) higher inhibition on tested pathogen, but in assay for nonvolatile metabolites Trichoderma viride showed higher inhibition. Interestingly, assay for nonvolatile metabolites of P. aphanidermatum demonstrated growth induction on both of the tested Trichoderma spp. The extracted metabolites of Trichoderma spp. showed growth inhibition on P. aphanidermatum even at 10,000 times dilution. Out of tested nine Bacillus species, four revealed antagonistic effect on tested pathogen, B. polymyxa showed significantly (P < 0.05) higher effect at 48 hours incubation. In conclusion, both of the tested Trichoderma spp. and B. thracis, B. circulans and B. polymyxa and B. sphaericus have antagonistic effect on P. aphanidermatum. Therefore, these microbes can be used for further greenhouse and field studies to confirm the feasibility of using in tomato damping off disease management.
