First Report of Root Rot Disease on Grapevine (Vitis vinifera L.) Caused by Phytopythium helicoides in Korea

Phytopythium helicoides is a fungal pathogen belonging to the genus Phytopythium, a distinct group comprising the genera Phytophthora and Pythium. In July 2022, stem and root rot were observed on grapevine at Pocheon area. Symptoms included leaf wilting, shoot and root blight, and whitish mycelium growth on the surface of the root lesions. Samples from symptomatic tissues of the infected grapevine tree were collected and cultured on the potato dextrose agar. Morphological features and nucleotide sequences of cytochrome C oxidase subunit II and beta tubulin gene regions were analyzed. As a result, the pathogen of this disease was identified as Phytopythium helicoides. The pathogenicity test also confirmed that P. helicoides isolated from the symptomatic tissue is pathogenic to the grapevine. This is the first report of P. helicoides causing root rot in grapevine in Korea.