First report of an Acorus tatarinowii leaf blight caused by Pestalotiopsis microspora in China

Acorus tatarinowii, a perennial medicinal plant belonging to the family Araceae and genus Acorus, has important economic value due to its rich bioactive compounds. From October 2023 to March 2024, leaf diseases were found on A. tatarinowii in Anhui province, China. The incidence rates reached 45.9% in Yuexi County and 66.7% in Huoshan County. Initially, small, dark-brown or black round, or oval spots emerged on A. tatarinowii leaves. The spots expanded, lightened in the middle, and developed distinct boundaries between diseased and healthy tissues. Eventually, the spots coalesced, leading to leaf yellowing and drying. To determine the pathogen, six fungal isolates were obtained from leaf lesions. The pathogen was identified as Pestalotiopsis microspora based on colony features, morphological characteristics, sequencing results of internal transcribed spacer (ITS), partial translation elongation factor-1α (TEF1), and partial β-tubulin (TUB2) regions, and pathogenicity tests. This is the first report of P. microspora causing leaf blight disease on A. tatarinowii in China.