Optical, Acoustical, and Fine Root Analyses of Emerald Ash Borer Infested Ash Trees

Abstract

This study on investigating change in the material properties of ash trees after infestation by emerald ash borer (EAB) (Agrilus planipennis) occurred at two locations in northeast Ohio in the summer of 2013. The trees at either site were divided into three groups based on % canopy lost from EAB (group I = 0 to 5%, group II = 6 to 25%, and group III = greater than 40%). A digital image correlation (DIC) system was used to evaluate and compare strain (tissue deformation) on ash branches that were (static) loaded to failure. Stress wave transmission times (Tm) of sound waves through stem wood and fine roots and root balls of the ash trees also were assessed. The DIC evaluations revealed that branches of ash trees that were in groups II and III exhibited significantly lower strain after static loading compared to that observed for trees in group I. Analysis of stress wave Tm revealed that group III trees had significantly higher Tm times compared to the other two groups. Fine root necrosis was significantly higher in group III trees and lowest in group I trees. Extracted root balls from group III trees had significantly higher percentage decay compared to that observed from trees in groups I and II. These data provide fundamental insight into the material properties of ash trees after infestation by EAB and can contribute to arboricultural guidelines for ash tree preservation and help develop safety protocols to address structural loss in trees after EAB infestation.