Nagaraja, A.KAVYA, S.2021-09-202021-09-202018-07-01https://krishikosh.egranth.ac.in/handle/1/5810175961Rhizoctonia solani Kuhn is a highly virulent pathogen with wide host range and causes different diseases on different crops. There are different strains within the species of the fungus, which affects different crops and induces different types of symptoms. Eleven pathogenic isolates obtained from different crops and regions of India were identified as of R. solani. With respect to mycelial growth, five isolates each were fast and medium fast growing while one isolate was slow growing. In majority of the isolates, the sclerotia were dark brown. The isolates took 3-15 days for sclerotial initiation; sclerotial diameter ranged from 0.65-2.46 mm. In the mycelial compatibility of the eleven isolates, out of the possible 121 combinations, 78 were found to be compatible, 35 were incompatible and 8 were found to be partially compatible. Among the different fungal antagonists tested, Trichoderma harzianum (Th-14), T. harzianum (Th-1), T. harzianum (TB-2), T. harzianum (Th-51) and T. harzianum (Th-B2) showed 100 per cent inhibition of mycelial growth, whereas among the bacterial bio-agents, Pseudomonas fluorescens recorded 100 per cent inhibition of mycelial growth. Out of the 16 plant extracts tested, Agave, clove and garlic showed complete inhibition of R. solani. ITS rDNA region amplification was at 700-750 bp in all the six isolates. Based on the sequence comparison, the identification of Rhizoctonia isolates was confirmed and all the ITS rDNA sequences of the isolates were of R. solani.EnglishThesis