Notes on powdery mildews (Erysiphales) in Japan: II. Erysiphe sect. Microsphaera

•First Japanese collection of teleomorph of Erysiphe platani is reported.•Ascomata of E. viburni on Viburnum sieboldii var. obovatifolium is described.•Morphology of E. wallrothii on Leucothoë grayana is reported.•Pseudoidium hortensiae on Hydrangea serrata var. megacarpa is reported.

Several novelties of powdery mildews in Japan are reported, including the first Japanese collection of the teleomorph of Erysiphe platani on Platanus × acerifolia, the first description of ascomata of E. viburni on Viburnum sieboldii var. obovatifolium, and the first morphological descriptions and molecular data for E. wallrothii on Leucothoë grayana and Pseudoidium hortensiae on Hydrangea serrata var. megacarpa based on Japanese specimens.