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Title: Impact of solarization, rootstock and Pseudomonas synxantha on Criconemoides xenoplax populations and tree growth in peach tree short life site

item Nyczepir, Andrew
item Kluepfel, Daniel

Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 3/14/2007
Publication Date: 4/1/2007
Citation: Nyczepir, A.P., Kluepfel, D.A. 2007. Impact of solarization, rootstock and Pseudomonas synxantha on Criconemoides xenoplax populations and tree growth in peach tree short life site [abstract]. Journal of Nematology. 39:75.

Interpretive Summary: Probably the most studied ring nematode species on Prunus is Criconemoides xenoplax. This nematode is the only plant-parasitic nematode that has been associated with the peach tree short life (PTSL) disease complex in the southeastern United States. Tree loss due to PTSL in South Carolina alone was estimated at over $5 million per year. New alternatives to chemical control (i.e., biological control) that are less hazardous to man and also more environmentally safe must be found to protect peach trees from this ring nematode. In the early 1990's, a bacterium [Pseudomonas synxantha (BG33R)], was isolated from a ring nematode-suppressive soil in South Carolina that was later shown to inhibit ring nematode reproduction under laboratory and greenhouse conditions. The efficacy of BG33R on suppression of the ring nematode population was then investigated in conjunction with soil solarization and the improved Guardian peach rootstock under peach orchard conditions from 2002-2006. Results indicate that the nematode populations were suppressed for up to 19 months in soil solarized plots. Tree growth was greatest in soil treated with both solarization plus the bacteria biocontrol agent than in untreated soil. Trees budded to Guardian survived longer on this PTSL site than those budded to Nemaguard rootstock. These results provide useful insights into the potential use of BG33R, solarization, and Guardian rootstock as a pre- and postplant alternative to chemical control of the ring nematode on PTSL sites in the Southeast.

Technical Abstract: Soil solarization, alone or in combination with other disease management practices, has been shown to be effective in reducing inoculum density of many soilborne diseases, including nematodes. In 2002, a field study was initiated to determine the influence of combining solarization, application of a bacterial antagonist [Pseudomonas synxantha (BG33R)] through the irrigation system, and an improved peach rootstock for management of the ring nematode (Criconemoides xenoplax) and prevention of peach tree short life (PTSL) tree death. Soil treatments include: i) solarized soil alone; ii) solarized soil + BG33R; iii) non-solarized soil; and iv) non-solarized soil + BG33R. Rootstocks examined included Guardian and Nemaguard. Solarization suppressed nematode populations for up to 19 months post-solarization. No differences in tree growth were detected between the rootstocks; however, trees growing in solarized soil + BG33R soil were larger (P < 0.05) than trees in non-solarized plots. In 2005, PTSL tree death was more prevalent on Nemaguard vs. Guardian rootstock, but no significant differences were detected among soil treatments.