Multiple-year protection of ash trees from Emerald Ash borer with a single trunk injection of Emamectin Benzoate, and single-year protection with an Imidacloprid Basal Drench

Abstract

Green ash (Fraxinuspennsylvanica Marsh.) street trees ranging in size from 25 to 45 cm dbh were trunk injected with emamectin benzoate at rates of 0.10-0.60 g ai/2.54 cm dbh at three Michigan, U.S., locations in 2005 or 2006. Tree health was monitored by annual canopy thinning and dieback ratings for up to four years after a single treatment. Branch samples were collected in the autumn and the bark removed to count emerald ash borer larvae for most treatments over the same period of time. A single trunk injection treatment of emamectin benzoate at the 0.1,0.2, or 0.4 g ai rate gave 100% control of emerald ash borer larvae in 98 of 99 treated trees for 2-3 years. Canopy ratings for treated trees remained similar for 2-4 years following trunk injection, while >50% of the control trees died during the same period of time. Ash trees that received a combination of an imidacloprid trunk injection and an imidacloprid basal drench or an annual imidacloprid basal drench had similarcanopy ratings, but more larvae were found in branches from trees receiving the annual basal drench. © 2010 International Society of Arboriculture.