Root-knot nematode species and the frequency of resistance-breaking nematodes in major green pepper production regions of Japan

Abstract

Species of root-knot nematode (RKN) from 50 green pepper fields in Miyazaki, Kagoshima, Kochi, and Ibaraki prefectures were surveyed. Ten to 25 second juveniles (J2s) and female adults were collected, respectively, from each field and the species were identified individually by PCR-RFLP method. As a result, all RKN specimens, except one, were Meloidogyne incognita. Then each infested soil sample from 31 of the fields was inoculated to 3 breeding lines of nematode-resistant chili peppers (CM334, LS2341 and PI322719). Many galls and egg masses were observed after the inoculation in 6 (ca. 19%) of the infested soils. This indicates that resistance-breaking nematodes dominated at a high frequency in these fields.