First Occurrence of Stem and Root Rots in Perennial Spiraea and Otacanthus caeruleus Caused by Rhizoctonia solani in Japan

Abstract

Stem and root rots of perennial spiraea (Astilbe×arendsii) and Otacanthus caeruleus occurred in Tokyo Metropolis in 1998. A Rhizoctonia species isolated from the diseased plants was identified as Rhizoctonia solani Kühn. Inoculation tests showed that the fungus was the causal agent of these diseases. This is the first report on these diseases in Japan.