Podosphaera aucupariae is a species of powdery mildew in the family Erysiphaceae. It is found in North America and Europe, where it affects rowans/mountain-ashes and service-tree.
Description
The fungus forms thin, white irregular patches on the leaves of its host. It is the only species on Sorbus. On Aria, Podosphaera niesslii can also be found, so care should be taken to identify. == Taxonomy ==