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.
