Phytotoxicity to Douglas-fir megastrobili and efficacy against Douglas-fir cone gall midge of five fatty acid derivatives

Abstract

Five fatty acid derivatives were applied to developing megastrobili of Douglas-fir, Pseudotsugamenziesii (Mirb.) Franco, to test their efficacies against the Douglas-fir cone gall midge (Contariniaoregonensis Foote). The abortion rate of megastrobili was increased dramatically by potassium oleate, potassium caprate, and potassium undecylenate but not by methyl coconate or lauryl alcohol. Damage by C. oregonensis was reduced only by potassium oleate. The fatty acid derivatives tested are not suitable for use against C. oregonensis.