Vertical distribution of plant-parasitic nematodes in peanut-cotton cropping systems

Authors: Schumacher, Lesley; LIAO, HUI-LING - University Of Florida; SMALL, IAN - University Of Florida; GRABAU, ZANE - University Of Florida

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2024
Publication Date: 5/23/2024
Citation: Schumacher, L.A., Liao, H., Small, I.M., Grabau, Z.J. 2024. Vertical distribution of plant-parasitic nematodes in peanut-cotton cropping systems. Applied Soil Ecology. 200:105445. https://doi.org/10.1016/j.apsoil.2024.105445.
DOI: https://doi.org/10.1016/j.apsoil.2024.105445

Interpretive Summary: The overall focus was to study vertical distribution (i.e., depth) of plant-parasitic nematodes in different peanut-cotton cropping systems with and without irrigation. One of these cropping systems is called sod-based rotation, which improves cotton root growth, but information about its vertical effects on plant-parasitic nematodes (reniform, ring, and spiral) is limited. This study aimed to investigate these plant-parasitic nematodes at different soil depths in sod-based and conventional rotation with or without irrigation. Soil samples were collected using to 120 cm deep in the soil profile using a hydraulic probe and nematodes extracted at three sampling points per season (before crop planting, after crop harvest, and during the winter) ranging from spring 2017 to winter 2019. All plant-parasitic nematodes were present up to 120 cm deep but were generally more abundant closer to the soil surface. We observed that unlike ring and spiral nematodes, reniform nematode was more stratified throughout the soil profile. There were no irrigation effects on nematode population densities observed in any of the sampling dates. There were crop by depth interactions for reniform nematode abundances only in harvest sampling dates. For these interactions, sod-based rotation reduced reniform nematode abundances at all depths compared with conventional rotation for post-harvest sampling dates. This study was the first to show vertical distribution of ring and spiral nematodes as well as individual reniform nematode life stages in these two crop rotation systems.

Technical Abstract: Reniform nematode (Rotylenchulus reniformis) is a pathogen of cotton (Gossypium hirsutum) 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. High population densities of reniform nematode are found below plow depth in the soil profile, yet conventional chemical management is often not able to manage these deeper populations, nor is much known about other plant parasites such as ring nematode (Mesocriconema ornatum) and spiral nematode (Helicotylenchus dihystera) at these deeper depths. Our study aimed to investigate how long-term cropping history affects crop yield and the vertical spatial distribution of plant-parasitic (reniform, ring, and spiral) nematodes under different irrigation regimes. Between March 2017 and January 2019, soil samples were collected to a depth of 120 cm before planting, after harvest, and in the winter using a hydraulic probe. Nematode abundances (including enumeration of all reniform nematode life stages) were analyzed in 30 cm-sections. There were no significant effects of irrigation on nematode abundances (P>0.05). In each sampling date, all reniform nematode abundances decreased stepwise as soil depth increased, but spiral and ring nematodes were nearly absent below 30 cm. Sod-based rotation generally reduced reniform nematode abundances at all depths compared with conventional rotation, although differences were more pronounced in the shallower depths (0-30 and 30-60 cm). Conversely, at 0-30 cm soil depth, ring nematode abundances were generally greatest in the peanut phase of sod-based rotation. Similarly, spiral nematode abundances, at 0-30 cm soil depth, were generally significantly greater in bahiagrass phases than other phases and variously greater in first-year cotton (sod-based or conventional). Overall, sod-based rotation helped manage reniform nematodes up to 120 cm deep in the soil profile. Sod-based rotation was detrimental for managing minor plant-parasitic nematodes spiral and ring nematodes, and those nematodes were scarce below 30 cm deep in the soil profile.