Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/16/2007
Publication Date: 12/1/2007
Citation: Nyczepir, A.P., Rodriguez-Kabana, R. 2007. Preplant biofumigation with sorghum or methyl bromide compared for managing Criconemoides xenoplax in a young peach orchard. Plant Disease. 91:1607-1611. 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 Criconemoides 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 $6 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 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 under plastic it was effective in suppressing the ring nematode population for up to 19 months, but was not as effective as preplant fumigation with methyl bromide (24 month nematode 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 effect of sorghum as a preplant green manure biofumigant management system of Criconemoides xenoplax was investigated from 1998-2003. The study was conducted on a Faceville sandy loam soil with a previous history of peach tree short life (PTSL). The site had no previous history of sorghum production. Plots consisted of five preplant treatments: i) sorghum as a green manure with tarp and urea; ii) sorghum as a green manure without tarp and urea; iii) preplant methyl bromide fumigation; iv) unfumigated soil with tarp and urea; and v)unfumigated soil without tarp and urea. An estimate of the Pi of C. xenoplax was determined prior to methyl bromide application and incorporation of sorghum into the soil in September 1998. All plots were planted to peach in January 1999. Preplant sorghum as a green manure with and without tarp was comparable to methyl bromide fumigation in suppressing the population of C. xenoplax in the early stages of this experiment. Nematode populations were suppressed 11 months longer in sorghum with tarp and urea plots than in sorghum without tarp and urea plots. However, nematode populations in sorghum with tarp and urea plots were not suppressed as long as in fumigated methyl bromide plots (i.e., 19 vs. 24 months, respectively).