Evaluation of summer and winter cover crops for variations in host suitability for Meloidogyne incognita, M. arenaria and M. javanica

Root-knot nematode (RKN) is an important pathogen on vegetables; therefore, planting a non- or poor host cover crop following a susceptible vegetable crop is a promising management option. This study builds upon previous studies and evaluates the variations in host status of cover crop candidates for reducing the reproduction of RKN populations (Meloidogyne incognita, M. arenaria and M. javanica) in Georgia, USA, to shed light on previous inconsistencies regarding the host status of cover crops and effectiveness in the field. Two glasshouse trials tested the host status of 14 plant species and 18 cultivars plus susceptible tomato 'Rutgers'. Sixty days after inoculation, roots were evaluated for galling (GI) and egg mass index (EI). Gall formation was not a reliable indication of RKN reproduction for many cover crops, which had higher EI than GI. Based on GI, all cover crops were either non-hosts, ranging from non-hosts to poor hosts or poor hosts to all three RKN species, except blue lupine and hairy vetch, which were susceptible to all three RKN species and had a GI and EI equal to the susceptible tomato control. Based on EI, only bahiagrass, bermudagrass, marigold, millet and velvetbean were either non-hosts or ranged from non-hosts to poor hosts. Eleven cover crops varied in host status to the three RKN species screened, ranging from either non-host to poor hosts or poor hosts to susceptible, which could explain inconsistencies in glasshouse and field trials.

Automated summary

This study evaluates the host status of different cover crop candidates for reducing the reproduction of root-knot nematode populations. The results suggest that gall formation is not a reliable indication of nematode reproduction, and there are inconsistencies in the host status of cover crops for different nematode species, which may explain the discrepancies between greenhouse and field trials.