Towards a Classifcation of Tree Health and Early Detection

Forty-¤ ve 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.  ese trees were later removed, and sections were examined from each tree to determine the length of time that growth rates had been impacted. A classi¤ cation system was developed to discern the health of the trees along with a proposed method for early detection of a declining state of vigor.  e classi¤ cation 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.  e classi¤ cation 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. OHIO J SCI 109 (2): 15-25, 2009 Since the discovery of EAB in the United States, much research has been conducted to help land managers, agencies, and municipalities deal with this exotic pest invasion. Currently, there are few ways of detecting EAB during the colonization phase. Detection relies primarily on visual surveys of late stage symptoms. At low to moderate densities of EAB, visual surveys are unreliable (Poland and McCullough 2006). Detection trees (i.e., girdled and sticky-trapped trees) have also been used to detect new EAB populations throughout Ohio (e.g. ~9670 trap trees placed in 2007, 9000+ in 2006). In 2008, purple sticky prism traps were deployed throughout Ohio. Detection trees and sticky-traps only con ̄rm the presence of EAB within the area aÅ er the initial infestation and do not identify which trees are infested. Symptoms of an EAB attack include crown dieback, splitting of the bark, woodpecker damage, loss of foliage density, presence of D-shaped exit holes and epicormic shoots (Cappaert and others 2005). © ese symptoms, however, are usually more prevalent in well-established infestations where a tree’s health has been severely degraded. Ash yellows, a disease caused by a mycoplasma-like organism that went unreported until the 1980s, results in several symptoms of decline similar to those associated with early EAB attack (Pokorny and Sinclair 1994). Trees lightly infested with EAB can be treated with reasonable success but with ongoing costs, while severely attacked trees have a limited chance of survival and will need to be removed in urban environments. Our objective was to develop a rating of tree health related to vigor that would be non-destructive and would provide homeowners and property managers information on which to base management decisions such as whether to treat or remove. © is index should not be considered as a measure of infestation, nor is it intended for forest applications.