Synopsis of genera of Erysiphales (powdery mildew fungi) occurring in the Pacific Northwest

Abstract

The Erysiphales (powdery mildew fungi) are Ascomycetes of major economic significance. Recent taxonomic research, mostly in Asia and Europe, has produced major changes in genus concepts complicating identification of powdery mildew fungi and communication about the diseases they cause. This paper provides a summary of genus concepts applicable to powdery mildew fungi known in the Pacific Northwest, as well as dichotomous keys based on both anamorphic and teleomorphic features, and brief summaries of diagnostic features. Salient morphological features are illustrated with photographs made from recent collections from the region. The following genera are included: Arthrocladiella, Blumeria, Erysiphe, Golovinomyces, Leveillula, Neoerysiphe,Phyllactinia, Podosphaera, and Sawadaea. Consistent with modern systems of classification, Microsphaera, Uncinula, andUncinuliella are subsumed within the modern concept of Erysiphe, and Sphaerotheca species are included in Podosphaera.