2021 年 2021 巻 72 号 p. 19-24
In June 2019, basal petiole rot of wasabi seedlings with withering symptom was observed in Iwate, Japan. Isolates from diseased tissues were identified as Rhizoctonia solani anastomosis group (AG)-2-1·Subset 2 and AG-2-1·clade HK on the basis of cultural morphology, temperature-dependent growth characteristics, hyphal anastomosis reactions, and DNA sequences of the rDNA-ITS region. Artificial inoculation with three isolates resulted in basal petiole rot and withering of wasabi seedlings. The occurrence of damping-off on wasabi caused by R. solani has been reported in Japan (Suzuki, 1976); however, details of AG and locations were not clarified. Since the AGs of R. solani causing this damping-off were initially found in Japan, we propose to the inclusion of R. solani AG-2-1·Subset 2 and AG-2-1·clade HK as one of the pathogens of the disease.