Powdery mildews on <i>Fragaria </i>spp. and <i>Rubus </i>spp. - unravelling the phylogeny and taxonomy of economically relevant species within the intricate <i>Podosphaera aphanis </i>s. lat. complex

Powdery mildews from the genus Podosphaera infect economically significant crops such as strawberries (Fragaria ×ananassa) and raspberries (Rubus idaeus). Until recently, these powdery mildews have been assigned to Podosphaera aphanis, which represents a complex of species. In the present analysis, selected taxa within Po. aphanis s. lat. have been subjected to morphological and ITS+28S rDNA phylogenetic examinations. We demonstrated that the powdery mildews on Fragaria and Rubus spp. do not pertain to Po. aphanis s. str. The new combination Podosphaera fragariae (≡ Oidium fragariae) is introduced for the powdery mildew on Fragaria ×ananassa, Potentilla spp. and Dasiphora fruticosa. Podosphaera fragariae is widespread in Asia and Europe, however, sequences obtained from specimens collected in South and North America belong to an unresolved group. All sequences obtained from specimens of powdery mildew on Rubus spp. group together in the phylogenetic tree. This suggests a separate species on Rubus spp. for which the new combination Podosphaera ruborum (≡ Oidium ruborum) is introduced. Podosphaera rubi-spectabilis sp. nov. is introduced for powdery mildews from western North America infecting Rubus spectabilis and R. ursinus. Additionally, Po. septentrionalis sp. nov. is introduced for powdery mildews in North America infecting Geum spp. and Agrimonia gryposepala.