Patterns of Changes in Species Richness in Powdery Mildews (Erysiphaceae, Helotiales) and Their Host Plants in Sverdlovsk Oblast (Urals, Russia)

Powdery mildew fungi are a cosmopolitan group of biotrophic plant pathogens that cause significant losses to forestry and agriculture. Despite the importance of such data, our knowledge on regional biotas of powdery mildews and their host plants remains limited for most Russian regions. An analysis of the 150-year research history in Sverdlovsk oblast shows a significant increase in powdery mildew species richness. In the 1990s–2020s, compared to earlier decades, the overall number of powdery mildew species increased 2.3 times, with the share of alien species showing twofold growth. The number of host plant species increased almost three times; among them the share of introduced species more than doubled. Currently, ornamental plants are the main host group of alien powdery mildew fungi in Sverdlovsk oblast. The species list of dendrotrophic powdery mildews of the city of Yekaterinburg is the most similar to mycobiotas of major cities of European Russia. The most likely reasons for the increase in alien fungal species in the 1990s–2020s are the dramatic development of international trade in live plants and climate changes in the region. Further research will allow testing the hypothesis of group’s biotic homogenization under the ongoing spread of alien species.