Characterization of novel strains of <i>Trichoderma</i> spp. and their utilization in management of damping off disease in tomato

Chemical fungicides used in plant disease management may have deteriorative effects on humans, animals, and the environment. The use of native strains of Trichoderma spp. against plant diseases may help to reduce the dependence on chemical fungicides. In this study, eleven novel isolates of Trichoderma spp. from virgin forest soils of different agro-climatic zones of Kerala were characterized and evaluated for their efficacy against damping off disease of tomato caused by Pythium aphanidermatum under in vitro and in vivo; and also, against wilt pathogen, Fusarium oxysporum under in vitro conditions. Dual culture assay showed that all the Trichoderma isolates were found to inhibit the growth of P. aphanidermatum and F. oxysporum under in vitro conditions with multiple modes of action. The mycelial colour, texture, and conidial characters varied among all the isolates. The volatile metabolites by isolates of Trichoderma spp. also showed in vitro inhibition of the pathogens. Seed treatment (20 g kg-1) and potting medium addition @ 2 % (w/w) of isolates TRMW-2, TRKR-2, TRPN-3, TRPN-11 and TRPN-17 could effectively reduce pre- and post-emergence damping off of tomato. Among them, isolates TRMW-2, TRKR-2, and TRPN-11 were the most effective ones in reducing pre- and post-emergence damping off to about 72 and 90 percent respectively. Molecular identification of the isolates of Trichoderma spp. using ITS universal primers revealed similarity with certain reference strains of the NCBI Genbank database.