Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: July 21, 2009
Publication Date: December 10, 2009
Citation: Timper, P. Davis, R.F. Jagdale, G.B. 2009. Response of a nematode community to tillage and nematicide application in cotton. Presented at the Society of Nematology Annual Meeting in Burlington, VT. on July 12-15, 2009. Journal of Nematology. 41:388 Technical Abstract: We hypothesized that tillage and nematicide use would reduce the relative abundance of predatory and omnivorous nematodes, which in turn would result in greater survival and reproductive potential of plant-parasitic nematodes later in the season. To test this two-part hypothesis, we conducted a split-plot experiment in a cotton field where half the main plots had been in conservation tillage (strip tillage) for 4 years and the other half in conventional tillage (subsoiled and bedded). The subplots received either the fumigant nematicide 1,3-dichloropropene (Telone) or no nematicide. The field site was naturally infested with the southern root-knot nematode, Meloidogyne incognita. To determine the nematode community structure, soil samples were collected pre-tillage and fumigation, post-plant, and midseason. We also assayed the survival and population increase of plant-parasitic nematodes in soil collected from different treatments. We found that the numbers of predatory and omnivorous nematodes were unaffected by tillage, but were lower in the Telone than the control plots in the post-plant and midseason samples. Predators were also reduced in the pre-fumigation samples from Telone plots, suggesting a residual effect from fumigation the previous spring. The Structure Index (SI), a measure of the relative abundance of omnivorous and predatory nematodes in the community, was lower in Telone compared to control plots in the post-plant and midseason samples. In the pre-fumigation samples, the SI was only reduced in the conventional tillage plots (tillage x nematicide interaction). In the first bioassay, survival of M. incognita juveniles was generally greater in soil from the control compared to Telone plots; however, this result was confounded by a larger population of resident juveniles in the control plots. Reniform nematode will be used as an assay nematode to avoid this problem in the future. In the second bioassay, population increase of M. arenaria on peanut was similar in soil from Telone and control plots, and was less in conventional tillage than in strip tillage. In summary, conventional tillage had only a small impact on the relative abundance of predators and omnivores; whereas, Telone application had a large and lasting impact on both the absolute and relative abundance of these two trophic groups. Nevertheless, we were unable to demonstrate that the reduction in predators and omnivores following Telone application resulted in greater survival or reproductive potential of plant-parasitic nematodes.