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Over the next five years, Middlebury College will likely be forced to cut down more than 1,200 trees across campus due to the invasion of a pest smaller than a penny. The Emerald Ash Borer (Agrilus planipennis) is poised to kill most of the campus’ ash trees should it arrive in Vermont. The state is surrounded on all sides by the pest, with confirmed infestations in New York, Massachusetts, New Hampshire, and southern Canada and and an infestation in Vermont could lead to the loss of Middlebury’s ash population of 1,219. This includes 658 “hazardous” trees found within 50 feet of roads, sidewalks, and parking lots.
In preparation for this, students in Tim Parsons’ J-Term class, Trees and the Urban Forest, have developed a plan to mitigate and combat the effects of a potential invasion of EAB. The plan includes an estimated cost analysis, landscaping modifications, and community outreach plan. This reflects the choice to inoculate about 74 trees against the disease through the use of systemic pesticides. These priority specimens include the cluster of ash behind Forest Hall, which create a natural wall separating the building from Battell Beach. Pesticide injections will cost $12 per caliber inch of each tree. The remaining trees will likely be removed, which will be subcontracted to a tree management firm, and is estimated to cost $900 per tree. Inconvenient location, size, and condition of the tree could increase that price. If/when these trees need to be cut, the question of what to do with the lumber remains. Options include selling it to local lumber supply companies, such as A. Johnson Co. in Bristol, VT or the Middlebury College Biomass Plant. If/when EAB arrives in Vermont, a quarantine on the county level will likely be enacted, limiting the sale of infected lumber to Addison County. Following the loss of these trees, the students estimated the cost of replanting 175 “key” ash across campus, which would total upwards of $99,575. Potential replacement species include red oak, shagbark hickory, and common hackberry. The total cost for the injection, removal, and replacement of ash trees on campus is estimated to reach approximately $500,000. Agrilus planipennis was first detected in the United States in Michigan in 2002 and has since spread to nearly all of the states in the Eastern United States and southern Canada. It has yet to arrive in Vermont. Smaller than a penny, the insect bores into the bark of ash trees (Fraxinus sp.), where the larvae destroy the cambium and vascular system, killing even healthy trees within 1-4 years. The EAB infestation has killed 50-100 million ash trees in the US to date and is expected to destroy 7.5 billion in total. Many communities have begun to plan for the loss of most of their ash trees in the coming years. Strategies to limit the devastating effects of the loss of these trees include preemptive removal of all ash populations, injecting at-risk and infested trees with pesticides, and using natural enemies of the beetle such as wasp colonies and certain fungi. |
The total cost for the injection, removal, and replacement of ash trees on campus is estimated to reach approximately $500,000. |