Nematode vertical distribution in peanut-cotton cropping systems

Authors: Schumacher, Lesley; GRABAU, ZANE - University Of Florida

Submitted to: International Congress of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Reniform nematode (Rotylenchulus reniformis) is a pathogen of cotton (Gossypium hirsutum) capable of reducing lint yields and crop rotation is commonly used for its management. One specific rotation system is a sod-based rotation, which uses two years of bahiagrass (Paspalum notatum) followed by one year each of peanut (Arachis hypogaea) and cotton, versus a conventional peanut-cotton-cotton rotation. Peanut and bahiagrass are poor hosts of reniform nematode but are good hosts for ring (Mesocriconema ornatum) and spiral (Helicotylenchus dihystera) nematodes, respectively. Additionally, reniform nematode is present deep in the soil profile, but not much is known about other nematodes at deeper depths. Our study aimed to investigate both plant-parasitic and free-living nematodes (fungivores, bacterivores, omnivores, and predators) at different soil depths in sod-based and conventional rotation with or without irrigation. Soil samples were collected to a depth of 120 cm before planting, after harvest, and in the winter of 2017-2018 using a hydraulic probe. Nematode abundances were analyzed in 30 cm-sections. There were no significant effects of irrigation on nematode abundances (P>0.05). All nematode trophic groups were present up to 120 cm deep in the soil profile except for predators, which were only found from 0 to 30 cm. There were significantly greater abundances of reniform and omnivore nematodes in the conventional rotation than the sod-based rotation. Conversely, ring, spiral, bacterivore, and fungivore nematode abundances were significantly greater in the sod-based than conventional rotation. There were significant crop by depth interactions for omnivore abundances for all sampling dates, but only in harvest sampling dates for reniform nematode abundances. There were no differences in omnivore abundances at the 0-30 cm depth, but from 30-120 cm depths abundances were greater following two years of conventional cotton. Sod-based rotation reduced reniform nematode abundances at all depths compared with conventional rotation for post-harvest sampling dates. Fungivore abundances were greater following two years of bahiagrass at the 0-30 cm depth while at deeper depths there were no differences between the rotations. Overall, nematode trophic group abundances varied by crop rotation system and depth, with the majority of nematodes present from 0 to 30 cm deep in the soil profile.