Isolation, characterization, and pathogenic assessment of Sclerotium rolfsii Saac causing collar rot in Brinjal (Solanum melongena L.)

Collar rot is an emerging and destructive soil-borne disease in brinjal, significantly affecting yield and quality. The present study was undertaken to isolate and characterize the causal organism associated with collar rot symptoms in brinjal and to assess its pathogenic potential. The pathogen was isolated from infected collar region tissues collected from severely affected brinjal plants. Morphological and microscopic observations revealed typical characteristics of a white, fast-growing fungus producing abundant sclerotia. Pathogenicity testing was conducted on two brinjal cultivars under pot culture conditions. Typical symptoms of collar rot developed in artificially inoculated plants, including yellowing of lower leaves, drooping, and basal stem necrosis. The re-isolation of the pathogen from symptomatic plants confirmed Koch’s postulates. The results confirmed the pathogen’s identity and its virulence under controlled conditions. This study provides important insights into the identification and disease expression of collar rot in brinjal, serving as a baseline for future integrated management strategies.