First report of dodder (Cuscuta australis) parasitizing the invasive Jerusalem artichoke (Helianthus tuberosus) in China.
Jerusalem artichoke (Helianthus tuberosus), a tall perennial herb native to North America, has become a significant invasive weed in Eurasia. Field surveys were conducted in summer 2018 to determine its distributions and natural enemies in Liaoning Province, China. Dodder was first found on Jerusalem artichoke along the Xinkai River in Shenyang, Liaoning. Orange leafless dodder was observed mostly wrapped around affected artichoke plants and was also occasionally present on native Humulus scanden, Artemisia lavandulaefolia, and Chenopodium album plants in the swards. Artichoke plants parasitized by dodder were chlorotic on the upper half of the stems, and necrotic on the lower half. Some parasitized plants were also stunted. Haustoria were observed clearly penetrating Jerusalem artichoke stems, and some stem tissues surrounding the haustoria connections developed grayish lesions with short longitudinal cracks. The dodder was identified as Cuscuta australis based on morphological characteristics and molecular data (sequence analysis of the internal transcribed spacer 2 (ITS2) region of the rDNA). This is thought to be the first report of C. australis on the invasive Jerusalem artichoke in China.