EFFICACY AND TIMING OF PERMETHRIN MISTBLOWER SPRAYS FOR THE CONTROL OF FIRST-INSTAR LARVAE OF THE SPRUCE BUDMOTH, ZEIRAPHERA CANADENSIS MUT. AND FREE. (LEPIDOPTERA: TORTRICIDAE)

Abstract

AbstractMistblower applications of permethrin at 70 g AI per hectare to individual white spruce trees near the onset of the hatching period reduced spruce budmoth, Zeiraphera canadensis Mut. and Free., larval populations by 90% and damage to leaders to a very acceptable index of 0.49. A dosage of 35 g AI per hectare was less effective but did provide acceptable leader protection (damage index: 0.93). Further mistblower trials, designed to determine the optimum time to spray with permethrin, demonstrated that at 70 g AI per hectare, effective control (87–94%) and acceptable protection (damage indices: 0.87–1.13) were obtained during a 9-day period before the onset of hatch. An earlier treatment. 11 days before hatch, did not provide as effective control (58%) or acceptable protection (damage index: 1.60). Two later treatments, 3 and 4 days after the onset of hatch, gave less effective control (75–79%) but did provide acceptable leader protection (indices: 0.83–1.17).