Powdery mildews on crops and ornamentals in Canada: a summary of the phylogeny and taxonomy from 2000–2019

Abstract

Powdery mildew diseases on crops and ornamental plants are common and cause significant economic losses, by reducing the yield and quality of crops and downgrading the value of ornamentals. In surveys published annually in the Canadian Plant Disease Survey, powdery mildews were reported frequently. In recent years, the taxonomy of powdery mildew fungi has changed tremendously as the result of the increased application of molecular phylogenetic analyses. Several generic concepts have been re-adjusted. Many traditionally considered species turned out to be a complex of several phylogenetic species. In order to facilitate effective communication in the scientific community, it is important to apply the current correct names for field identifications. In this document, we summarize the powdery mildew fungi reported in the Canadian Plant Disease Survey from 2000 to 2019, address the taxonomic and nomenclatural issues associated with the listed species, and tentatively suggest correct names based on host plants wherever possible. Nevertheless, a reliable identification of the powdery mildew must depend on DNA sequence analyses and morphological examinations.