Methyl Bromide Eradication of the Oak Wilt Fungus from Red and White Oak Logs

Oak wilt occurs in portions, of the oak-growing regions of North America. To date, the disease has not been reported in Europe, but is of concern to member nations of the European Economic Community (EEC). As a result, the EEC has established regulations governing the importation of oak wood from North America. In efforts to maintain oak trade, American and European industry and government have sought methods to insure that oak exports are disease-free. This study was conducted to test the efficacy of methyl bromide as a fumigant to eradicate the oak wilt fungus from logs handled under commercial conditions during periods of cold temperatures (2? to 5?C). Export quality logs were obtained from red and white oaks that were artificially inoculated with the oak wilt fungus 3 to 6 months before felling. Each log was randomly assigned to one of nine stacks (20 to 25 logs/stack) and sealed above and below with a 6-mil polyethylene tarpaulin. Treated stacks were fumigated with 240 g/m3 of methyl bromide for 2 or 3 days; a boost was applied at 24 hours, as needed, to regain the 240 g/m3 methyl bromode level. The effectiveness of the treatment was measured by culturing slivers of sapwood taken from wood disks removed from the infected logs before and after treatment. The oak wilt fungus was completely eradicated in both the 2- and 3-day treatment periods, whereas the organism remained viable in covered or uncovered logs that served as controls. A detailed statistical analysis is presented addressing the concern that the design and sampling procedures used in this study assure treatment efficacy.

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