Silicone antitranspirant increases susceptibility of eastern white pine to the white pine weevil

Abstract

Spraying 16-year-old eastern white pine (Pinus strobus L.) growing in a geographic seed-source test plantation with 10-percent silicone antitranspirant emulsion effectively increased internal water balance during the growing season when compared to control trees of the same seed sources that received no treatment. Extreme silicone toxicity was observed. Apical shoot elongation of treated trees averaged 37 percent of that of controls. Needle elongation of treated trees was also restricted. All of the treated trees were attacked by the white-pine weevil (Pissodes strobi Peck.), and leader mortality due to attack occurred in 90 percent of the trees. Only 51 percent of the control trees were attacked, and only 26 percent leader mortality occurred. High leader mortality in treated trees may have been due to increased egg production by female weevils in the moisture-favorable environment. The high numbers of treated trees attacked suggests that the antitranspirant may have initiated release of some unknown attractants of the host or directly or indirectly stimulated release of aggregating pheromone by the weevil.

Citation

Wilkinson, Ronald C. 1975. Silicone antitranspirant increases susceptibility of eastern white pine to the white pine weevil. Res. Pap. NE-326. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 5p.