Occurrence of southern blight disease on Strawberry saxifragae by Sclerotium rolfsii Saccardo.

Blight-like and soft rot symptoms on Strawberry saxifragae (Saxifraga stolonifera Curtis) were fi rst found on wild plants growing on a riverside in Omura, Nagasaki, Japan on July 22, 2009. White mycelia and brown, spherical, rapeseed-sized sclerotia were observed on the diseased plants. A fungus similar to Sclerotium rolfsii Saccard was isolated from infected parts of the plant. The mean optimum growth temperature for these isolates, on potato dextrose agar, was 25°C for mycelial growth and 30°C for sclerotium formation. The mycelial tufts were white to grayish brown, and the main hyphal width ranged from 4.3 to 7.8μ m(avg.=6.6μm) with clamp connections. These mycological characters are identical to those of S. rolfsii reported in other plants. The isolates were found to be pathogenic to Strawberry saxifragae in artificial inoculation test, and could be re-isolated from infected tissue. It is proposed that the disease should be referred to as southern blight of Strawberry saxifragae caused by S. rolfsii.