Comparison of Two Rates of Sevin 4 Oil For Spruce Budworm Control in Maine: 1976

In 1976, one of the registered insecticides for use on spruce budworm was Sevin 4 Oil, at 1 lb/acre. The Maine Forest Service (MFS) compared the efficacy of rates of 1 lb/acre to ¾ lb/acre to control spruce budworm survival and increase foliage protection. Aerial spraying took place on June 9-10, 1976 near Portage Lake on nine test blocks and spray deposit was monitored and analyzed for drop diameter and number of drops per centimeter. Monitors measured defoliation and collected 18” branch samples from the mid-crown of sample trees two days before spraying and 3, 7, and 14 days after spraying. Samples were sent to a lab where larvae were counted. The researchers found that there was no significant difference between the two application rates of Sevin 4 Oil in controlling the spruce budworm population and reducing defoliation. Therefore, reducing the application rate to ¾ lb/acre would reduce biological load on the environment and create cost savings while still effectively managing budworm populations.