The utility model relates to a method of biologically controlling Rhizoctonia solani Kuhn, causal agent of sheath blight of rice, using Geotrichum candidum. Sheath blight of rice is one of the major rice diseases in tropical, sub-tropical and temperate regions of Asia, Africa and Americas. Developments of rice varieties resistant to sheath blight are still uncertain due to pathogens wide host range, and variability in terms of interaction with its host and surrounding environmental conditions. Hence, fungicides are utilized as the main method of control despite the potential health risks and development of resistance by the pathogen. It is therefore the object of this utility model to provide a biocontrol agent which is both safe and effective for the control of sheath blight. The spores of Geotrichum candidum disclosed herein can be used as eradicant against Rhizoctonia solani Kuhn, causal agent of sheath blight of rice.