జర్నల్ ఆఫ్ ప్లాంట్ పాథాలజీ & మైక్రోబయాలజీ

నైరూప్య

Occurrence, Virulence, Inoculum Density and Plant Age of Sclerotium rolfsii Sacc. Causing Collar Rot of Peppermint

Arjunan Muthukumar and Arjunan Venkatesh

Roving survey was conducted during 2011-2012 around Coimbatore, Dindigul, Erode, Hosur, Krishnagiri, Namakkal, Salem and Theni districts to assess the incidence of collar rot of peppermint. The maximum incidence of 32.33% was recorded in Therkupalayam village of Coimbatore District. The pathogen was isolated from infected samples and 8 Sclerotium rolfsii isolates were maintained. The level of pathogenicity of these isolates revealed that S. rolfsii (I1) from Therkupalayam in Coimbatore District was the most virulent and caused higher levels of collar rot incidence (93.66%). An inoculum load of S. rolfsii at 5% to 1 kg of soil registered the maximum incidence of 92.66% collar rot of peppermint. Significantly higher per cent of wilting of 92.66% was recorded in plants at 20 days after emergence and it was found significantly more susceptible compared to rest of the treatments.