Enzyme activity and biochemical constituents of healthy and stem rot infected tissues of susceptible variety of groundnut TMV2 were evaluated. Results revealed that higher activity of Oxidative enzymes (catalase, polyphenol oxidase and peroxidase) were present in infected leaves than healthy ones. In case of Biochemical constituents, higher amount of total and Ortho-di hydric phenols and protein content was observed in infected plants as compared to healthy plants. Higher content of sugars and chlorophyll was observed in healthy plants as compared to infected plants.
Thirty isolates of Sclerotium rolfsii, the causal agent of stem rot of groundnut obtained from different Rayalaseema areas of Andhra Pradesh, India were categorized into four groups, on the basis of oxalic acid production in the culture filtrate and severity of patrhogenicity on groundnut seedlings. The group four was more dominant than other groups and highly virulent to groundnut seedlings. There was a positive correlation between oxalic acid production and the virulence of the isolate.