Plant-parasitic and free-living nematodes from organically farmed fields in Illinois and Wisconsin

Authors: HAN, JAEYEONG - University Of Illinois; UGARTE, CARMEN - University Of Illinois; NUNEZ FLORES, MARIA ALEJANDRO - University Of Illinois; HANSEN, MAICYNN - University Of Illinois; Bowen, Charles; SCHROEDER, NATHAN - University Of Illinois; Hartman, Glen

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2021
Publication Date: 11/2/2021
Citation: Han, J., Ugarte, C.M., Nunez Flores, M., Hansen, M.G., Bowen, C.R., Schroeder, N.E., Hartman, G.L. 2021. Plant-parasitic and free-living nematodes from organically farmed fields in Illinois and Wisconsin. Plant Health Progress. 23:227-234. https://doi.org/10.1094/PHP-06-21-0096-S.
DOI: https://doi.org/10.1094/PHP-06-21-0096-S

Interpretive Summary: Plant-parasitic nematodes feed on soybean roots resulting in yield losses. Surveys of nematodes in certified organic soybean fields have been infrequent compared to surveys in non-organic soybean fields. We conducted a nematode survey in certified organic soybean fields in northern and central Illinois to determine the frequency and population densities of plant-parasitic and free-living nematodes. Fields surveyed included both long-term, 5 years or longer rotation with soybean, and short-term, every 3 years with soybean. Common plant-parasitic nematode taxa included spiral, lesion, cyst, stunt, dagger, and pin nematodes. Among the taxa, spiral, lesion and dagger nematodes were above previously reported damage threshold levels in some fields. Cyst nematode population densities were significantly higher in fields under short-term rather than long-term rotation with soybean. These results provide information about the occurrence of plant-parasitic nematodes and the soil ecosystem in organically farmed soybean fields. This information is useful for scientists studying nematology, soil science, and disease management.

Technical Abstract: Plant-parasitic nematodes feed on soybean roots resulting in yield losses. Surveys of nematodes in certified organic soybean fields have been infrequent compared to surveys in non-organic soybean fields. We conducted a nematode survey in certified organic soybean fields in northern and central Illinois to determine the frequency and population densities of plant-parasitic and free-living nematodes. Fields surveyed included both long-term, 5 years or longer rotation with soybean, and short-term, every 3 years with soybean. A total of 27 composite soil samples each consisting of multiple cores to a depth of 20-cm were collected from 14 fields in 2019. Common plant-parasitic nematode taxa included spiral (Helicotylenchus spp.), lesion (Pratylenchus spp.), cyst (Heteroderidae), stunt (Tylenchorhynchus spp.), dagger (Xiphinema spp.), and pin nematodes (Paratylenchus spp.). Among the taxa, spiral, lesion and dagger nematodes were above previously reported damage threshold levels in some fields. Cyst nematode population densities were significantly higher in fields under short-term rather than long-term rotation with soybean. Total abundance and free-living nematode abundance were significantly higher in fields under long-term rather than short-term rotation with soybean. A significant interaction was detected in the SI between rotation intervals with soybean and sampling season, but other diversity and community indices of free-living nematodes were similar in the two rotation systems. These results provide information about the occurrence of plant-parasitic nematodes and the soil ecosystem in organically farmed soybean fields.