Submitted to: International Congress of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2008
Publication Date: 7/15/2008
Citation: Nyczepir, A.P., Kluepfel, D.A., Wechter, W.P. 2008. Impact of Pseudomonas-based biocontrol agents and solarization on Mesocriconema xenoplax populations and tree survival in a peach tree short life site [abstract]. International Congress of Nematology. 5:299. Interpretive Summary: 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. A bacterial biocontrol agent, BG33R, isolated from a peach orchard site suppressive to peach tree short life (PTSL), was demonstrated to suppress ring nematode reproduction in field soil under greenhouse conditions and inhibit egg hatch under laboratory conditions. A field study was initiated to investigate the effect of soil solarization alone and in combination with a cocktail of five biocontrol agents delivered through irrigation system to manage ring nematode and PTSL. Results to date indicate that solarization has more of an effect on decreasing PTSL tree mortality than the cocktail of biological control agents. These data provide useful insights into the benefit of soil solarization when establishing a peach orchard on a PTSL site 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. Pseudomonas synxantha (BG33R), isolated from a peach orchard site suppressive to peach tree short life (PTSL), was demonstrated to suppress ring nematode, Mesocriconema xenoplax, reproduction in field soil under greenhouse conditions and inhibit egg hatch in vitro. In 2005, a field study was initiated to determine the influence of combining solarization and application of BG33R plus four additional bacterial, nematode-antagonists through the irrigation system for management of M. xenoplax and prevention of PTSL tree death. Soil treatments include: i) solarized soil alone (S); ii) solarized soil + biocontrol cocktail (SB); iii) nonsolarized soil alone (NS); iv) nonsolarized soil + biocontrol cocktail (NSB); v) solarized soil + wheat (SW); vi) solarized soil + wheat + biocontrol cocktail (SBW); vii) nonsolarized soil + wheat (NSW); viii) nonsolarized soil + wheat + biocontrol cocktail (NSBW); and ix) methyl bromide (MBr) fumigated soil. Controls include, fumigated and nonsolarized nonfumigated soil. Four and 13 months (June 2005 & March 2006) after planting trees, ring nematode populations were greatest in three nonsolarized treatment plots (NS, NSBW, and NSW) than in all four solarized (SW, SB, SBW, S), or MBr fumigated plots. Twenty-one months after MBr application (November 2006), ring nematode population density did not differ among most of the treatment plots. In May 2006 and 2007, more trees in the nonsolarized treatment plots (NSW, NS, & NSB) developed typical PTSL symptoms and died than in the solarized (S, SW, SBW, & SB) or MBr fumigated plots. Soil solarization alone significantly reduced PTSL tree mortality.