Forty-five green ash (Fraxinus pennsylvanica) street trees in Toledo, Ohio were photographed, measured, and visually rated for conditions related to emerald ash borer (Agrilus planipennis) (EAB) attacks. These trees were later removed, and sections were examined from each tree to determine the length of time that growth rates had been impacted. A classification system was developed to discern the health of the trees along with a proposed method for early detection of a declining state of vigor. The classification is not an indicator of the degree of infestation, but rather tree health, which may be linked to the degree of EAB infestation. An evaluation of the tree sections places the EAB establishment no later than the 2004 growing season. A three-class system formulated from the evaluation of epicormic shoots, canopy light transmission, and EAB exit holes can be used to monitor the health of ash trees during EAB outbreaks. The classification system could potentially give homeowners, property managers, and agencies a way to detect and treat this problem earlier, especially in urban and park settings, and before trees are fully infested and exhibiting later-stage signs of decline. It is probably not practical for forest applications. Early detection and treatment not only can save selected trees, but it also might slow the spread of the insect, thereby giving additional trees a chance to survive the initial invasion.
Peters, Matthew P.; Iverson, Louis R. 2009. Emerald ash borer (Agrilus planipennis): Towards a classification of tree health and early detection. The Ohio Journal of Science. 109(2): 15-25.