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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Soil Type and Steam on Nematode Biological Control Potential of the Rhizosphere Community

Authors
item Mcsorley, Robert - UNIV. OF FLORIDA
item Wang, Koon-Hui - UNIV. OF FLORIDA
item BURELLE, NANCY
item Church, Gregory

Submitted to: Nematropica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 20, 2010
Publication Date: December 1, 2006
Citation: Mcsorley, R., Wang, K., Burelle, N.K., Church, G.T. 2006. Effects of soil type and steam on nematode biological control potential of the rhizosphere community. Nematropica.

Interpretive Summary: The potential of a sand and a muck soil to provide biological control of Meloidogyne incognita on pepper was evaluated in two greenhouse experiments. Steamed or non-steamed soil of each type was placed into pots, planted with pepper (Capsicum annuum) seedlings, and inoculated with 2000 eggs of M. incognita.. A soil type x steam treatment interaction occurred, with root-knot nematodes suppressed in untreated sand compared to steamed sand, but with no suppression in either steamed or untreated muck soil. A variety of organisms were monitored in both soils including free-living nematodes (bacterivores, fungivores, omnivores, and predators), enchytraeid worms, Collembola, mites, nematode-trapping fungi, egg-parasitic fungi, Pasteuria spp., rhizofungi including Fusarium and Rhizoctonia, and a variety of rhizobacteria including Gram positive bacteria, fluorescent pseudomonads, and siderophore producers. Determining relative importance of various organisms in biocontrol can be difficult if many different organisms are contributing together to the process. Most of these organisms did not show population patterns consistent with the biological suppression of root-knot nematodes observed in the non-steamed sand. For example, Pasteuria and other Gram positive bacteria were more abundant in soils that had been steamed; however, more inoculated root-knot nematodes survived in steamed soils as well. Population trends of predatory nematodes showed the same interaction and were most consistent with the observed suppression of root-knot nematodes in untreated sand.

Technical Abstract: The potential of two soil types, sand and muck, were evaluated for their ability to naturally control root-knot nematodes on bell pepper. Both soils were steamed to eliminate populations of naturally occuring organisms and both steamed and non-steamed soil of each type were compared in two greenhouse trials. After soil was treated, bell pepper seedlings were planted in pots and inoculated with 2000 eggs of M. incognita. Root-knot nematodes were suppressed in unsteamed sand compared to steamed sand, but were not suppressed in either steamed or untreated muck soil. A variety of organisms were monitored in both soils including free-living nematodes, enchytraeid worms, Collembola, mites, nematode-trapping fungi, egg-parasitic fungi, Pasteuria spp., rhizofungi including Fusarium and Rhizoctonia, and a variety of rhizobacteria. Determining importance of various organisms in biocontrol can be difficult if many different organisms are contributing to the process. Most of the organisms studied did not show patterns consistent with the biological suppression of root-knot nematodes observed in the non-steamed sand. However, populations of predatory nematodes (nematodes that prey on other nematodes) were most consistent with the observed suppression of root-knot nematodes in untreated sand.

Last Modified: 9/10/2014
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