Clover Cyst Nematode Dominates and Causes Damage in Kimchi-Cabbage Fields in Korea

Cyst nematodes are among the major plant-parasitic nematodes worldwide, and they cause significant damage to Brassicaceae crops, including Kimchi-cabbage, in Korea. To survey the incidence of cyst nematodes in Kimchi-cabbage fields, 469 soil samples were collected from the main producing areas between 2018 and 2021. Only cyst nematodes belonging to the genus Heterodera were investigated, and the overall nematode incidence was found to be 40%. Regionally, the highest incidence was observed in Taebaek, reaching 89%, with mean densities of cysts and eggs per 500 cm³ of soil recorded at 522 and 49,734, respectively. Based on Bayesian analysis of the mitochondrial DNA cytochrome c oxidase subunit I gene sequence, the cyst nematodes were identified as four species: clover cyst nematode (Heterodera trifolii, HT, frequency: 78%), soybean cyst nematode (H. glycines, HG, 11%), sugar beet cyst nematode (H. schachtii, 4%), and white soybean cyst nematode (H. sojae, HSo, 2%). Mixed infestations were found in some fields, with HT + HG (4%) and HG + HSo (1%). These results indicate that HT is the dominant species in the main Kimchi-cabbage producing areas in Korea. In conclusion, implementing effective HT management strategies is critical to minimize economic losses in Kimchi-cabbage production in Korea.