GROWTH AND PATHOGENICITY OF SOME ISOLATES OF SCLEROTIUM-ROLFSII SACC

Studies on variations in growth and pathogenicity of isolates of Sclerotium rolfsii from six different hosts were conducted. Results revealed that with increasing temperature the mycelial growth of S. rolfsii increased while the time required for sclerotial germination of the fungus decreased. The best temperature for both sclerotial germination and mycelial growth was 30 degrees C followed by 25 degrees C. Among the four test media the best one for sclerotial germination was PCSA (Potato Carrot Straw Agar) followed by PDA (Potato Dextrose Agar) and PA (Potato Agar) for all isolates. The maximum mycelial growth occurred in PDA followed by PCSA and PA. Aerobic condition (not submerged with water) was better than the anaerobic (submerged with water) condition for both sclerotial germination and mycelial growth. The isolates of the fungus were more pathogenic to soybean and gram where they caused 100 % pre-emergence death. The mustard Isolate was the most while the wheat isolate was the least pathogenic to the hosts tested.