Colletotrichum siamense causing leaf spot on Parthenocissus semicordata in China

Parthenocissus semicordata is an excellent vine plant for vertical greening of walls or buildings. A leaf spot disease has been investigated on P. semicordata in the Matoushan National Nature Reserve in Fuzhou city, Jiangxi province, China, since August 2021. The disease incidence was approximately 60–65%, which led to affecting its growth and ornamental value. The pathogen was identified as Colletotrichum siamense based on morphological characteristics and phylogenetic analysis. Pathogenicity tests were conducted by inoculating healthy leaves with spore suspension of C. siamense, and Koch's postulates were confirmed by re-isolation and identification of the pathogen from infected leaves. This is the first known occurrence of C. siamense causing leaf spot on P. semicordata in China. These findings play a crucial role in increasing the knowledge of P. semicordata diseases in China and provide pivotal information for epidemiological studies and control strategies.