Nematicidal plants for root-knot nematode (Meloidogyne spp.) management in vegetable cropping systems

Root-knot nematodes (RKN), Meloidogyne species, are a top global threat associated with economic crop yield losses. They are difficult to detect and control, especially given the recent restrictions on environmentally harmful chemicals. Thus, there is a need for alternative solutions for sustainable RKN management, such as nematicidal plants (non-hosts or poor hosts). Despite the advanced literature, the information for nematicidal plant species, cultivars, and specific RKN species is incomplete or inconsistent. We evaluated the host suitability of 28 nematicidal plant candidates in controlled climate chambers using a susceptible tomato and pepper as controls. The assessment was based on gall and egg mass counts after one RKN cycle. All screened candidates were less infected with M. incognita , M. arenaria , and M. enterolobii than tomatoes, suggesting all the candidates are either non/ poor hosts, except Allium fistulosum . Only Tagetes patula and T. erecta were consistently non-hosts to the three RKN species. Other candidates exhibited RKN species-specificity and varied in their poor host or non-host status depending on the variety. Selected nematicidal plants were further assessed for RKN juvenile penetration and had significantly lower M. incognita penetration than tomato. However, Crotalaria juncea had significantly higher M. incognita penetration than tomato. This suggests that the tested plants inhibit root penetration of most M. incognita juveniles at the rhizosphere level while C. juncea attracts the nematodes and restricts reproduction. There is potential for most of the nematicidal plants to be used in cropping systems for sustainable integrated RKN management.