Persistence and efficacy of trunk-injected emamectin benzoate to manage emerald ash borer

Emerald ash borer, Agrilus planipennis, is an invasive woodborer that threatens to functionally extirpate ash trees (Fraxinus spp.) from North America following its accidental introduction from Asia in the early 1990s. Since that time, efforts have been underway to identify the most effective means of protecting ash trees from attack. The most efficacious and cost-effective approach for protecting individual ash trees from A. planipennis is through a trunk injected treatment of emamectin benzoate (an avermectin) with a single injection capable of providing protection for multiple years. In this study, we compare the efficacy of three insecticide injection systems and quantify the persistence of emamectin benzoate in leaf tissue during the year following treatment. Although the amount of emamectin benzoate recovered from leaves one year after injection was greatly reduced, all three injection systems provided two years of protection from EAB. Additionally, trees injected with Tree I.V. and Q-Connect systems showed no decline in crown condition three years after injection. Studies that directly compare the efficacy of commercial technologies can assist managers in optimizing the cost-benefit ratio of EAB management efforts to protect ash trees from this destructive pest.