Variability in parasitic ability of Trichoderma isolates against sclerotia of Sclerotium rolfsii associated with chickpea

Parasitic ability of Trichoderma isolates was tested against Sclerotium rolfsii in two types of soils viz., natural and sterilized soils to assess the ecological adaptability of Trichoderma spp. to a soil. The isolate ATPU 1 (EID50 of 2.1 mycelia/gm of soil) was most effective in parasitization of sclerotia of S. rolfsii when used as live bait, under the natural soil of, when mycelial form of inoculum was used. This isolate was closely followed by KNO 2 and ATPP 6 which had the same EID50 of 2.2 mycelia/gm of soil, the next best isolates were KNP 3 and ATPPE 6 with EID50 of 2.3 mycelia/gm of soil. The isolate KT 6 (EID50 5.7) was rated as poorest competitive colonizer, requiring comparatively highest inoculum level to colonize 50% sclerotia of S. rolfsii . However the conidial form of inoculum from KNK1 (EID50 value of 2.2 conidia/gm of soil) was most aggressive isolate requiring lowest inoculum dose for 50% colonization of sclerotia of S. rolfsii .