Efficacy evaluation of a reduced dosage of tebufenozide applied aerially to control spruce budworm ( Choristoneura fumiferana)

Two dosages of tebufenozide, 50 and 70 g ha −1 were applied as aqueous treatments in an aerial field trial that was conducted in 2000 and 2001 to determine if the lower dosage could effectively control spruce budworm, Choristoneura fumiferana, on balsam fir Abies balsamea. Spray-droplet densities (No cm −2) from both dosages were sparse on canopy-located kromokote surfaces, but foliar deposits of AI (mg kg −1) were extremely variable and contradictory. Although the higher dosage reduced spruce budworm larval populations and protected host trees from defoliation significantly better than 50 g ha −1, the latter's efficacy over two years was satisfactorily acceptable. These findings suggest that tebufenozide at 50 g ha −1, with its potential to further reduce environmental burden, could be a viable strategy to manage spruce budworm without seriously compromising effectiveness.