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

Authors: MARQUEZ, JOSIAH - University Of Georgia; HAJIHASSANI, ABOLFAZI - University Of Georgia; Davis, Richard

Submitted to: Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2022
Publication Date: 6/29/2022
Citation: Marquez, J., Hajihassani, A., Davis, R.F. 2022. Evaluation of summer and winter cover crops for variations in host suitability for M. incognita, M. arenaria, and M. javanica. Nematology. 24:841-854. https://doi.org/10.1163/15685411-bja10172.
DOI: https://doi.org/10.1163/15685411-bja10172

Interpretive Summary: Root-knot nematode (RKN) is an important pathogen on vegetables. Growing non- or poor-host plants between susceptible vegetable crops (a cover crop) is a promising management option. This study builds upon previous studies and evaluates the variations in the degree of nematode reproduction on cover crop candidates for suppression of important RKN populations (Meloidogyne incognita, M. arenaria, and M. javanica) to help explain previously reported inconsistencies regarding host status of cover crops and effectiveness for nematode suppression in the field. Two greenhouse trials tested the host status of 14 plant species and 18 cultivars plus susceptible tomato (Solanum lycopersicum) cv. Rutgers. Sixty days after nematodes were added, roots were evaluated for galling (GI) and egg mass index (EI) to evaluate RKN damage and reproduction. Gall formation was not a reliable indication of RKN reproduction for many cover crops, which had significantly higher EI than GI. Based on GI, all cover crops were either non-host, ranging from non-host to poor-host, or a poor-host 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. Based on EI, only bahiagrass, bermudagrass, marigold, millet, and velvetbean were either non-host or ranged from non-host to poor-host. Eleven cover crops varied in host-status, ranging from either non-host to poor-host or poor-host to susceptible among RKN species, which could explain inconsistencies in greenhouse and field trials.

Technical Abstract: Root-knot nematode (RKN) is an important pathogen on vegetables, therefore, planting a non- or poor-host cover crop following a susceptible vegetable is a promising management option. This study builds upon previous studies and evaluates the variations in host status of cover crop candidates for suppression of RKN populations of Georgia (Meloidogyne incognita, M. arenaria, and M. javanica) to shed light on previous inconsistencies regarding host status of cover crops and effectiveness in the field. Two greenhouse trials tested the host status of 14 plant species and 18 cultivars plus susceptible tomato (Solanum lycopersicum) cv. 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 significantly higher EI than GI (P < 0.05). Based on GI, all cover crops were either non-host, ranging from non-host to poor-host, or a poor-host 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-host or ranged from non-host to poor-host. Eleven cover crops varied in host-status, ranging from either non-host to poor-host or poor-host to susceptible among RKN species, which could explain inconsistencies in greenhouse and field trials.