Distribution of imidacloprid in eastern hemlock, Tsuga canadensis (L.) Carrière, in the southern Appalachians

The hemlock woolly adelgid, Adelges tsugae Annand, is an exotic insect species dramatically reducing populations of eastern hemlock, Tsuga canadensis (L.) Carrieré, throughout the eastern United States. Systemic imidacloprid is one of the primary chemicals used to successfully control infestations of the hemlock woolly adelgid. The concentration levels for the systemic insecticide, imidacloprid, present in the sap of eastern hemlocks were evaluated from three strata within the canopy over a two year time span. Enzyme-linked immunosorbant assays were conducted every three months post-treatment to assess imidacloprid concentration within the sap. The effect of application timing (fall versus spring), three application methods (soil drench, soil injection, and tree injection) to assess the translocation of imidacloprid throughout the canopy, and the quantity of imidacloprid translocated in the sap of eastern hemlock branches and the terminal twig and needle tissue was determine.