Tests of Guthion and Dimethoate for Douglas-Fir Cone Midge Control
Abstract:In 1964 Guthion&sup(R); and dimethoate were tested for cone and seed insect control on Pseudotsuga menziesii (Mirb.) Franco. Each chemical was applied to ten trees when the conelets were open and receptive to pollen. A third sample of ten trees received dimethoate after the cones had closed and become pendant. A fourth sample of ten unsprayed trees served as controls. Significantly fewer midges, less midge damage and fewer seed chalcids were observed in cones from trees given the late dimethoate treatment when compared to controls. The other two treatments, however, did not produce significant results. Late insecticide treatments, made after midge oviposition is completed, have the great advantage of eliminating timing as a critical factor.
Document Type: Journal Article
Affiliations: Forest Entomologist, Forestry Research Center, Weyerhaeuser Company, Centralia, Wash.
Publication date: June 1, 1966
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