EFFECTS OF SOIL TYPE AND STEAM ON NEMATODE BIOLOGICAL CONTROL POTENTIAL OF THE RHIZOSPHERE COMMUNITY
Keywords: enchytraeids, Meloidogyne incognita, microarthropods, nematode-antagonistic fungi, Pasteuria, predatory nematodes, rhizobacteria, rhizosphere fungi, root-knot nematodes
AbstractMcSorley, R., K.-H. Wang, N. Kokalis-Burelle, and G. Church. 2006. Effects of soil type and steam on nematode biological control potential of the rhizosphere community. Nematropica 36:197-214. The potential of the rhizosphere community 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, but not in steamed sand and not in any (steamed or untreated) muck soil. A soil type x steam treatment interaction occurred, with root-knot nematodes suppressed in untreated sand, but not in steamed sand and not in any (steamed or untreated) muck soil. nematode-trapping fungi, egg-parasitic fungi, Pasteuria spp., rhizosphere fungi including Fusarium and Rhizoctonia, and a variety of rhizosphere bacteria 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 were most consistent with the suppression of root-knot nematodes observed in untreated sand.