The genus Pseudoperonospora (Peronosporales, Oomycota) comprises six accepted species,
including Ps. cubensis, which causes downy mildew on many economically important cucurbitaceous
crops, and Ps. humuli, which occurs on hops. During a survey of downy mildew flora
in Korea, a previously unreported species of Pseudoperonospora was found on Urtica angustifolia.
Based on molecular phylogenetic and morphological analyses, the causal agent was identified
as Pseudoperonospora urticae. This is the first report of Pseudoperonospora urticae occurring
on Urtica angustifolia in Korea.