Rhizoctonia solani AG-2-1 によるキョウナとコマツナの葉腐れ症状および立枯れ症状

抄録

Leaf blight, damping-off and bottom rot of potherb mustard and komatsuna were found in Hokkaido, Japan in March 2010 and February 2011. Rhizoctonia-like fungi were isolated from diseased portions of both plants. We identified five isolates of the fungi as belonging to the Rhizoctonia solani anastomosis group（AG）-2-1 on the basis of cultural appearance, mycelial growth temperature, hyphal anastomosis and the result of PCR using an AG-specific primer pair. Each of the isolates obtained from leaf blight, dampingoff and bottom rot induced all the symptoms on the original host by inoculation, indicating that all the symptoms are caused by the fungi. We propose that the name of potherb mustard disease caused by R.solani be changed from ‘Shirigusare-byo’ to ‘Rhizoctonia-byo’ in Japanese, because the occurrence of leaf blight and damping-off was confirmed. Sato et al（. 1999）reported the occurrence of komatsuna leaf blight caused by R. solani AG-2-1, and they considered it as a new disease different from damping-off. However,we confirmed that both symptoms are typical of the same disease.