Sheath blight caused by Rhizoctonia solani Kuhn is a threat to rice cultivation in different agroclimatic conditions. Many bacteria and fungi from rice field soils are antagonistic to R. solani (Gogoi and Roy 1993, Roy 1984, 1993, Sen et al 1993).
We tested the ability of Aspergillus niger AN27 and its bioformulation to suppress sheath blight. Seeds of Pusa Basmati 1 were planted in four nursery trays (650 seeds tray-1). Seeds of one tray were treated with the bioformulation Kalisena SD at 4 g kg-1 before planting. Untreated seeds were sown in the other three trays. At transplanting, root and shoot length of plants and biomass were measured for each treatment. Twenty-five-day-old seedlings were transplanted at 15x15-cm spacing in a randomized block design with four treatments. Three replications of two 3-m rows were maintained. Standard agronomic practices were followed. The experiment was conducted for two continuous crop years (1997 and 1998). Plants were inoculated with a virulent isolate of R. solani by placing two colonized typha bits (Bhaktavatsalam et al 1978) in the center tillers of each hill at 40 d after transplanting (maximum tillering). At 45 d after inoculation, number of total tillers, infected tillers, effective tillers, lesion height, and disease reduction were measured.