Occurrence and field-level co-occurrence of Heterodera spp., Verticillium longisporum , and Pectobacterium sp

This study investigated the occurrence and field-level co-occurrence of cyst nematodes, Verticillium longisporum, and Pectobacterium spp. in highland kimchi cabbage fields in South Korea during 2023–2024. Three major pathogen groups and associated diseases were identified at the species level: cyst nematodes (CN; Heterodera trifolii and H. schachtii), Verticillium wilt caused by V. longisporum (VW), and bacterial soft rot caused by Pectobacterium carotovorum and P. brasiliense (BSR). Among 97 surveyed fields, individual detection frequencies for CN, VW, and BSR were 31%, 21%, and 54%, respectively. The simultaneous detection of CN, VW, and BSR was the most frequent field-level co-occurrence pattern, occurring in 29% of fields in which at least one target pathogen or associated disease was detected. This co-occurrence pattern was mainly observed in Taebaek and Samcheok, whereas V. longisporum was detected only in CN-associated fields. These findings document the regional occurrence and field-level co-occurrence of major pathogen groups in highland kimchi cabbage fields and provide a basis for future studies to determine whether these pathogens interact to influence disease severity.