Effects of grass-based crop rotation, nematicide, and irrigation on the nematode community in cotton

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

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2022
Publication Date: 10/28/2022
Citation: Schumacher, L.A., Grabau, Z.J., Wright, D.L., Small, I.M., Liao, H. 2022. Effects of grass-based crop rotation, nematicide, and irrigation on the nematode community in cotton. Journal of Nematology. 54(1):3922. https://doi.org/10.2478/jofnem-2022-0046.
DOI: https://doi.org/10.2478/jofnem-2022-0046

Interpretive Summary: Cotton is a common crop grown in the southern United States and suffers from a variety of pests and pathogens. Farmers manage these pests and pathogens by rotating crops and using pesticides. There are many different crop rotation systems, but unique ones such as a grass-based crop rotation system need further research. Studying the soil nematode community provides insight on how farming practices affect nematodes, including those that do and do not feed on plants. Focusing on nematodes that do not feed on plants helps us understand soil health, since these nematodes help cycle soil nutrients. We evaluated the effects of irrigation, nematicide (i.e. pesticide), and crop rotation on non-plant feeding nematodes in cotton. Certain nematodes (i.e. omnivores) were significantly reduced when nematicide was applied. However, in the grass-based rotation system, nematodes that feed on bacteria and fungi were not reduced when pesticide was applied, suggesting the type of crop rotation system is an important factor in soil health. This work helps growers evaluate how their farming practices affect non-plant feeding nematodes.

Technical Abstract: Plant-parasitic and free-living nematodes–bacterivores, fungivores, omnivores, predators–comprise the nematode community. Nematicide application and crop rotation are important tools to manage plant parasites, but effects on free-living nematodes and nematode ecological indices need further study. Fluopyram nematicide was recently introduced in cotton (Gossypium hirsutum) production and its effects on the nematode community need assessment. This research was conducted in 2017 and 2018 at a long-term field site in Quincy, FL, USA where perennial grass/sod-based (bahiagrass, Paspalum notatum) and conventional cotton rotations were established in 2000. The objective of this research was to evaluate the effects of fluopyram nematicide, crop rotation phase, and irrigation on free-living nematodes and nematode ecological indices based on three soil sampling dates each season. We did not observe consistent effects of crop rotation phase on free-living nematodes or nematode ecological indices. Only omnivores were consistently negatively impacted by nematicide application. Nematode ecological indices reflected this negative effect by exhibiting a degraded/stressed environmental condition relative to untreated plots. Free-living nematodes were not negatively impacted by nematicide when sod-based rotation was used.