Control of red elm bark weevil (Magdalis armicollis) in American elm (Ulmus americana) by trunk injection of azadirachtin

Abstract

Trunk injection of azadirachtin into elm trees (Ulmus americana) using the Ecoject™ Microinjection System to reduce emergence numbers of red elm bark weevil (Magdalis armicollis) was evaluated. Twelve mature trees were each injected with TreeAzin™ in early August 2010 at a rate of 16 ml per 15.2 cm trunk circumference at breast height. The following year, weevil activity was monitored at weekly intervals for four weeks using sticky traps placed in the canopies. There was a significant reduction of 55%-60% in weevil activity in early summer in the treated tree canopies as compared to the control, suggesting that this method may be an effective management tool for this pest. © 2012 International Society of Arboriculture.