Field Note: Emamectin Benzoate Reduces Defoliation by Choristoneura occidentalis Freeman (Lepidoptera: Tortricidae) on Three Host Species

Stem injections of insecticides are generally regarded as a safer and a more environmentally friendly option (compared to foliar sprays) for protecting high-value trees against insects in sensitive areas or near homes. We carried out a three year study to determine the efficacy of trunk injections of emamectin benzoate for protection of foliage of three common host species attacked by the western spruce budworm, Choristoneura occidentalis Freeman (Lepidoptera: Tortricidae). Defoliation by C. occidentalis was significantly reduced by nearly half over a 3-year period on treated compared to control grand fir, Douglas-fir, and alpine fir. Reduction of defoliation was comparable to standards used for aerial spraying (e.g., 50%) of conifer feeding budworms in Canada.