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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. [ABSTRACT FROM AUTHOR]

Trichoderma spp. are long been recognized as efficient fungal biocontrol agents for the control of plant disease and for their ability to increase plant growth and development. Management of soil borne diseases has become very much important since it causes high crop yield losses. The present study was carried out to isolate Trichoderma spp. from soil samples collected from different locations of Kerala and to test their in vitro efficacy against soil borne pathogens viz., Pythium aphanidermatum and Rhizoctonia solani. The Trichoderma spp. was isolated on Trichoderma Selective Medium (TSM) and observed that the isolates differed in radial growth and colony characters such as colony colour, texture and sporulation. In vitro studies revealed the potential of Trichoderma isolates against soil borne pathogens. Isolates TRPN3 and TRPN7 exhibited no sporulation and white mycelial colour. Isolates which completed their growth at four days after inoculation include TRKR1, TRPN3, TRPN7, TRPN10 and TRPN18. Biocontrol activities against different pathogens resulted in inhibition of pathogens. Maximum inhibition percentage was observed by the isolates TRPN7, TRPN15 and TRKR2 against both the pathogens. The maximum inhibition exhibited against both the pathogens is due to the antagonistic property displayed by the isolates. [ABSTRACT FROM AUTHOR]