In situ efficacy of Trichoderma harzianum as mycoparasite on Sclerotium rolfsii and Rhizoctonia solani

Indiscriminate use of synthetic pesticides to control plant diseases poses serious ecological problems. Biocontrol agents, on the other hand, not only control diseases effectively, but are also ecofriendly. In the present pro ject, the ability of Trichoderma harzianum Benth, to parasitize Rhizoctonia solani Kuhn, and Sclerotium rolfsii Sacc, was evaluated. The latter pathog ens are known to cause serious damping-off of seedlings and wilt of some ag ricultural crops, respectively. Vigna radiata (Moorg) seeds were pre-coloni zed with R, solani and S, rolfsii separately and placed on the surface of p ot soil. A control constituted pathogens inoculated separately without T, h arzianum, After four days, sclerotia appeared on the mycelia of both S, rol fsii and R, solani, and after six days, T. harzianum had begun to colonize the sclerotia, In control sets, there was no colonization. Surface-steriliz ed selerotia grown on potato dextrose agar from the treated pots showed no growth and after six days only colonies of T, harzianum were observed, sugg esting the successful control of R, solani and S. rolfsii.