Recently, a powdery mildew anamorph infecting snowberry (Symphoricarpos albus) has been reported as a new plant pathogen in several European countries. We report here its occurrence in the UK, Germany and, for the first time, Switzerland. Based on morphological and scanning electron microscope (SEM) patterns, this novel pathogen appeared similar to the anamorph of a common North American powdery mildew, Erysiphe symphoricarpi (syn. Microsphaera symphoricarpi). A phylogenetic analysis of the internal transcribed spacer (ITS) sequences of the ribosomal DNA (rDNA) of an English and a North American snowberry powdery mildew fungus showed that they are conspecific. Ascomata of the pathogen were found only in one European collection, that being in Germany in 2002. The similarity in morphology of the ascomata also confirmed the co-identity of the European and American snowberry powdery mildews.
