Ability of Gliocladium virens Miller, Giddens and Foster to colonise groundnut stem pieces used as organic bait in soil was studied under varying conditions like inoculum density, soil pH, soil moisture and temperature. High temperature (40°C) was lethal for the saprophytic activities of the antagonist as colonisation of the bait was completely inhibited. In air dry soil (ca. 6.0% mhc) colonisation of bait was low (ca. 5.0 - 8.0 %) particularly at lower temperature (20°C) and low level of inoculum (20 mg/100 g soil). Acid soil (pH 5.6) at 50% soil moisture and 30°C temperature gave maximum colonisation of bait. Per cent colonisation of bait was less at either side of this temperature moisture optima.