Dutch Elm Disease and Methoxychlor
- Download PDF (635532)
- This publication is available only online.
Res. Pap. NE-353. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 5p.
American elm trees, Ulmus americana L., in Milwaukee, Wisconsin, were sprayed with methoxychlor by helicopter or mist blower once each year for 3 years to control the smaller European elm bark beetle Scolytus multistriatus (Marsham). Twig crotches were collected from sprayed trees each year for bioassay. Methoxychlor residues persisted for at least 1 year. There were differences in beetle control between spray techniques, but these differences decreased as years of successive spraying increased, suggesting that methoxychlor residues accumulate on elms. Tree surveys were made each year to deternine the incidence of Dutch elm disease. Average incidence remained stable in the areas treated by helicopter and mist blower, while it rose sharply in the control areas. Despite differences in beetle control between spray techniques, there were no differences in disease incidence between the helicopter and mist blower treatments. Later obervations indicated that methoxychlor spraying can reduce disease incidence for several years after treatments have ceased, but unidentified factors also significantly affect disease incidence.
Keywordshelicopter mist blower elm bark beetle control disease incidence spray residue elm twig spraying
Barger, Jack H. 1976. Dutch Elm Disease and Methoxychlor. Res. Pap. NE-353. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 5p.