Powdery mildews are a group of economically and ecologically important plant pathogens. In the past 25 years the use of ribosomal DNA (rDNA) in the powdery mildews has led to major taxonomic revisions. However, the broad scale use of rDNA has also revealed multiple species complexes that cannot be differentiated based on ITS + LSU data alone. Currently, there are only two powdery mildew taxonomic studies that took a multi-locus approach to resolve a species complex. In the present study, we introduce primers to sequence four additional regions (CAM, GAPDH, GS, and RPB2) that have the potential to improve support values in both broad and fine scale phylogenetic analyses. The primers were applied to a broad set of powdery mildew genera in China and the United States, and phylogenetic analyses included some of the common complexes. In taxa with nearly identical ITS sequences the analyses revealed a great amount of diversity. In total 154 non-rDNA sequences from 11 different powdery mildew genera were deposited in NCBI’s GenBank, laying the foundation for secondary barcode databases for powdery mildews. The combined and single loci phylogenetic trees constructed generally followed the previously defined species/genus concepts for the powdery mildews. Future research can use these primers to conduct in depth phylogenetic, and taxonomic studies to elucidate the evolutionary relationships of species and genera within the powdery mildews.

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A new aquatic hyphomycete, Xylohyphopsis aquatica, is described and illustrated from specimens collected on submerged wood in Jiangxi Province, China. Xylohyphopsis aquatica is morphologically characterized by its 0–1-septate, thin-walled, smooth, pale brown conidia in simple or branched chains, usually with a germ tube or short germination hypha at the distal end. A key to Xylohyphopsis species is provided.

Deutzia parviflora var. amurensis is a common ornamental shrub in the Hydrangeaceae. In July and September 2017, powdery mildew infections were first noticed on this shrub in Yichun, China. Powdery mildew colonies on leaves and nonlignified stems were conspicuous, especially when the plants were growing in shade. Based on morphological characteristics and sequencing of the nuclear ribosomal internal transcribed spacer (ITS) region, the pathogen was identified as Erysiphe deutziae. To our knowledge, this is the first report of powdery mildew caused by E. deutziae on Deutzia parviflora var. amurensis in China.

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