First report of powdery mildew of mango caused by Erysiphe quercicola in Japan

Powdery mildew disease was found on mango ( Mangifera indica ) in Okinawa Prefecture, Japan, in April 2013. During and after flowering, infected panicles, leaves, and young fruits became coated with a whitish powdery fungus. Fungal growth was usually severe on panicles, then plants became brown and defoliated. The fungal sample collected from conidia on diseased panicles was identified as Erysiphe quercicola based on morphology and rDNA-ITS sequence analysis. Inoculation with the isolate reproduced the symptoms on mango leaves and the fungus was reisolated from the inoculated leaves. In addition, the fungus infected Japanese oak ( Quercus crispula ), konara oak ( Q. serrata ), and ubame oak ( Q. phillyraeoides ). This is the first report of powdery mildew (udonko-byo in Japanese) on mango caused by E. quercicola in Japan.