Powdery Mildew of Dandelion (Taraxacum officinale) Caused by Oidium subgenus Fibroidium

Abstract

Powdery mildew of dandelion (Taraxacum officinale) occurred in Ibaraki Prefecture in June 2010. The powdery mildew already had been known as a disease of the plant. However, this disease had not been reported formally. Hence, we analyzed pathogenicity, morphological characteristics and rDNA-ITS region of the causal agent of the disease, and identified the causal agent as Oidium subgenus Fibroidium. We formally named the disease ‘powdery mildew of dandelion’ as a new disease of the plant in Japan.