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United States Department of Agriculture

Agricultural Research Service

Title: Biofumigation and Management of Ring Nematode on Peach

item Nyczepir, Andrew

Submitted to: National and Southeast Peach Convention Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 20, 2003
Publication Date: January 20, 2003

Interpretive Summary: Ring nematodes are widely distributed throughout the world with certain species considered to be economically important to the stone fruit industry. Probably the most studied ring nematode species on Prunus is Mesocriconema xenoplax. This ring 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 has been estimated at over $5 million per year. New preplant alternatives to chemical control (i.e., green manures - biofumigation) that are less hazardous to man and also more environmentally safe must be found to protect peach trees from this ring nematode. A grain sorghum that had been found to suppress ring nematode under greenhouse and field conditions was tested as a preplant biofumigant green manure under orchard conditions in the southeastern United States. As a biofumigant, it was effective in suppressing the ring nematode population for up to 12 months, but was not as effective as preplant fumigation with methyl bromide (24 month suppression). These data provide useful insights into the use of sorghum as a biofumigant and alternative to chemical control of the ring nematode on PTSL sites in the Southeast.

Technical Abstract: The study was conducted on a site having a previous history of PTSL, but no history of sorghum production. Plots consisted of five preplant treatments: i) sorghum as a green manure under plastic; ii) sorghum as a green manure w/o plastic; iii) preplant methyl bromide fumigation under plastic; iv) unfumigated soil under plastic; and v) unfumigated soil w/o plastic. The sorghum was incorporated into the soil with a rototiller following flail mowing. An estimate of the initial soil population density of ring nematode (M. xenoplax) was determined prior to methyl bromide application and incorporation of sorghum into the soil. All plots were planted to peach in January 1999. Nematode population densities were also determined approximately every three months after planting peaches beginning in September. Results to date indicate that 1) the ring nematode populations did not differ among the five treatment plots prior to application of experimental treatments; 2) at four months after incorporation of the sorghum green manure into the soil and application of methyl bromide, but prior to planting peach trees, ring nematode populations were greatest in the unfumigated soil than in sorghum green manure under plastic, sorghum green manure w/o plastic, and methyl bromide fumigated plots; 3) no differences in ring nematode populations were detected among the unfumigated and sorghum plots at 12 months after incorporation of sorghum green manure into the soil; and 4) at 24 months after methyl bromide application, the nematode population density in fumigated plots did not differ from those in the unfumigated and sorghum plots. Peach trees have developed typical PTSL symptoms and died during the experiment. No differences in PTSL tree survival among treatments have been detected to date. This study is still ongoing.

Last Modified: 4/22/2015
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