Eppermint, Fumibotys Fumalis Control, Washington, 1978

An infested 3-year-old peppermint field near Harrah, WA, was selected to study two insecticides for control of Fumibotys fumalis (Lepidoptera: Pyralidae) larvae. F. fumalis is a serious new rhizome-boring soil pest of peppermint in central Washington. Insecticides were applied as broadcast sprays on Sep 28, using a compressed air plot sprayer mounted on a bicycle-wheeled carriage, calibrated to deliver 25 gpa at 40 psi. Soil temperature was 72°F at a depth of 2 inches on the date of spraying. Plots were 8 x 30 ft, replicated 4 times in a randomized complete block design. Following insecticide application, plots were sprinkler irrigated for 12 hours. Mint height was 1 to 2 inches. Soil was classified as an Ashue loam, with a pH of 6.5, percent organic matter 1.4. Efficacy data were based on three 0.5 ft2 soil samples/replicate (soil depth sampled, 3 inches). Samples were placed in Berlese funnels for 48 hours for larval recovery.