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

Abstract 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.