Survey conducted in the paddy straw mushroom (Volvariella voivacea) farms in the east and southeastern coastal plain of Odisha during the summer season of 2010 indicated the highest (37%) bed contamination with Coprinus spp., the ink caps. Besides, sporadic appearance of Aspergillus niger, Aspergillus flavus, Mucor sp., Penicillium sp., Rhizopus sp., Sclerotium rolfsii and Trichoderma sp. were observed. Bacterial button rot was observed in 11 per cent beds. The effect of different physical, chemical and biological agents on the incidence of competitor fungi and button rot disease evaluated in the growing room of Centre of Tropical Mushroom Research and Training, OUAT, Bhubaneswar revealed that pre soaking of substrate with 2 per cent calcium carbonate was significantly superior in yielding 1016.67 g/bed with biological efficiency of 14.52 per cent followed by spraying of 2 per cent neem leaf extract after raising beds that yielded 946.67 g/bed with biological efficiency of 13.52 per cent with low severity of competitor moulds in both the treatments.