Comparison of Trichoderma viride mutant and parent strains for their colony characters, tolerance to Bavistin and biocontrol efficacy against black scurf of potato

Two mutant strains Tv 34-M4 and Tv34-M5 were developed from Trichoderma viride (Tv34) by using ultraviolet irradiation. The mutants were compared with the parent strain for their colony characters, growth rate and sporulation. The Tv34-M5 grew on medium containing 30μg/ml Bavistin while the parent isolate failed to grow even at 2 μg/ml concentration. The 50 per cent culture filtrate concentration of Tv34-M4 and Tv34-M5 inhibited the colony growth of Rhizoctonia solani up to 67.8 per cent as compared to 52.2 per cent by Tv 34 after 96 h after incubation. In green house seed + soil inoculation with Tv34-M5 gave maximum, 72.8 per cent disease control. In field, seed treatment +spot inoculation with mutant strain at 2 per cent concentration gave maximum 73.1 per cent disease control.