Single host plant species may harbour more than one species of - a case study on infecting .

The genus is the largest genus of the oomycetes, fungus-like members of the kingdom that also contains amoeboid (e.g., ) and plant-like (e.g., ) lifeforms. species are obligate biotrophic plant pathogens, causing high economic losses in various crops and ornamentals, including species. Several species of are used as speciality crops and medicinal plants. In this study, species parasitic on were investigated based on morphology and phylogenetic analyses using two nuclear (ITS, nrLSU) loci and one mitochondrial (2) locus. As a result of these investigations, 10 new species are added to the already known species on . Interestingly, it was found that four independent species are parasitic to , highlighting that the reliance on the host plant for pathogen determination can be misleading in . Taking this into account, morphological and phylogenetic analyses should be conducted as a prerequisite for effective quarantine regulations and phytosanitary measures. : Mu M, Choi Y-J, Kruse J, et al. 2024. Single host plant species may harbour more than one species of Peronospora - a case study on Peronospora infecting Plantago. Persoonia 52: 94-118. https://doi.org/10.3767/persoonia.2024.52.04 .