Podosphaera xanthii causing powdery mildew on Impatiens balsamina in China

Impatiens balsamina (garden balsam) is an annual herb and widely grown for ornamental and medicinal use in China. In 2020 and 2021, powdery mildew symptoms were found on I. balsamina in Xinxiang City, Henan Province, China. The pathogenic fungus was identified based on its morphological characteristics and molecular analysis. The internal transcribed spacer (ITS) region was amplified and sequenced. The sequence obtained for the fungus showed 100% identity with the previously reported Podosphaera xanthii. The virulence of the pathogen on I. balsamina was confirmed by utilizing Koch's postulates. Therefore, we identified the causal organism of this disease as P. xanthii. This is the first report of powdery mildew caused by P. xanthii on I. balsamina in China. The identification of P. xanthii on I. balsamina will support efforts towards its future control and management.