104 Persad and Tobin: Evaluation of Tree Symptoms Associated with EAB are thought to be several years old by the time they are detected. Confirmed EAB presence is associated with D-shaped exit holes, heavy dieback and epi- cormic branching, and S-shaped, frass-filled larval tunneling. However, detection at this stage is oſten too late for chemical or biological treatments to be effective. For example, current management guide- lines suggest that if the tree has lost more than 50% of its canopy due to EAB, treatments aimed to save the tree are not likely to be successful (Herms et al. 2009). Instead, reactive measures, such as tree removal, are the only remaining management option. Tunnels formed by all larval stages of EAB occur under the bark and are confined to the greater cambium region where they feed primarily on phloem and outer xylem (Siegert et al. 2010). At initial colonization densities, an infestation is oſten cryptic because visual cues are limited as the bark remains intact. Canopy loss may not occur until EAB infestations intensify. However, as early as one to two years following colonization, internal, and hence anthropogenically unapparent damage due to larval tunneling results in significantly lower levels of moisture, ultimately degrading the structure and material properties of ash (Persad et al. 2013). Prior research has also shown that branches aſter static loading failed closer to the union with the stem in trees infested with EAB in both early and advanced infestations (Persad et al. 2013). Unfortunately, static loading to branch fail- ure is not a practical tool in early detection efforts. However, the natural dismantling and failure of branches or stems of EAB infested trees could occur from other sources, such as wind, rain, and snow, and thus potentially provide detection cues. Documented symptoms associated with EAB infestations could include woodpecker induced bark flaking, canopy thinning, D-shaped exit holes, and the presence of epicormic shoots. Apart from the D-shaped exit holes, which are unlikely to be caused by another insect, all associated symptoms could arise from causative agents other than EAB. To help improve detection capabilities to the urban for- ester, researchers initiated a visual survey to gather data on natural dismantling and effects from early larval tunneling on EAB-infested trees. The main objective was to identify and correlate observable symptoms associated with EAB infestation prior to canopy thinning and other potential cues that ©2015 International Society of Arboriculture would be anthropogenically apparent prior to the documented late-infestation signs of EAB, such as bark flaking, EAB exit holes. These additional visual effects if identified would be very valuable especially for workers in managed urban settings to be able to detect EAB before canopy loss and dieback begin. MATERIALS AND METHODS Researchers initiated a survey in 2009 to quantify symptoms that are typically associated with the EAB–ash tree complex. Visual, non-destructive sur- veys were conducted from late June (aſter emergence of EAB) through August each year between 2009 and 2012 in northern Ohio, U.S. Selected sites were in and around the cities of Perrysburg, Sylvania, Toledo, Cleveland, Strongsville, Shalersville, and Kent, Ohio. Sites selected included those that were in the most recent regulated area (USA Code of Federal Regulations, Title 7, Chapter III, Part 301.53), had recorded EAB activity for the first time at the time of study, or were known to be infested for at least two years. Green ash (Fraxinus pennsylvanica Marsh) was surveyed along arterial roadways, city/ county rights-of-way in residential areas, and park and woodlot settings. Prior to the survey, and aſter consultation with the relevant management agencies of the properties where the survey was conducted, it was determined that no trees selected for the survey had been chemically treated, either proactively or curatively, for EAB. A total of 719 trees were in- spected across all four years, and ranged from 2.5 to 142.2 cm diameter at breast height (DBH) (Figure 1). Figure 1. Distribution of DBH among 719 green ash (Fraxinus pennsylvanica Marsh) trees sampled in this study, 2009– 2012.
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