Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Proceedings
Publication Acceptance Date: 11/6/2002
Publication Date: 11/6/2002
Citation: NYCZEPIR, A.P., RODRIGUEZ-KABANA, R. BIOFUMIGATION AND MANAGEMENT OF RING NEMATODE ON PEACH. PROCEEDINGS OF INTERNATIONAL RESEARCH CONFERENCE ON METHYL BROMIDE ALTERNAT. 2002. v.8. p.89. 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: Studies were initiated to determine if incorporating sorghum as a preplant biofumigant green manure would contribute to improved nematode control, tree growth, and survival on a PTSL site. To ensure reproducible conditions for this study, a grain sorghum variety known to suppress ring nematode under greenhouse and field conditions is being used. The experiment was initiated at the USDA, ARS Southeastern Fruit and Tree Nut Research Laboratory in Byron, Georgia. The site had a previous history of PTSL, but not of sorghum production. Plots consisted of five preplant treatments, as follows: 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. In January 1999, all plots were planted to cv.. Goldprince on Nemaguard rootstock. Results at this time indicate that 1) at four months after incorporating the sorghum as a 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 as a green manure under plastic, sorghum as a green manure w/o plastic, and methyl bromide fumigated plots; 2) no differences in ring nematode populations were detected among the unfumigated and sorghum plots at 12 months after incorporating the sorghum as a green manure into the soil; and 3) 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. Furthermore, results indicate that nematode suppression by the sorghum as a green manure did occur in the early stages of the experiment, but it did not last as long as methyl bromide fumigation (i.e., 12 months vs. 24 months, respectively). This study is still ongoing and additional sorghum `silage' and sudangrass cultivars are being evaluated.