The Maine Department of Agriculture, Conservation and Forestry's (DACF) Maine Forest Service (MFS) reports evidence of spread of emerald ash borer (EAB) within regulated areas of Maine.
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This fall, EAB infestations were confirmed in the towns of Van Buren in Aroostook County, Gorham in Cumberland County, and Ogunquit, Parsonsfield, Shapleigh and South Berwick in York County. Targeted surveys by MFS staff to locate potential future biological control release sites uncovered the first detected infestation in the York County town of Newfield.
EAB was first detected in Maine in 2018 in both Aroostook County and York County. It was also found in 2019 through trapping in Cumberland County. These detections have led to quarantine regulations in all of York and Cumberland Counties and parts of Oxford and Aroostook Counties.
Although EAB has not been detected in any new counties in 2020, Maine Department of Agriculture, Conservation and Forestry (DACF) monitoring programs show EAB populations are expanding within already-regulated Maine areas.
Each spring, MFS staff and volunteers from many sectors help detect EAB by participating in the girdled trap tree network, an EAB monitoring program.
Girdled ash trees are attractive to any EAB in the immediate area. The trees are felled in the fall, and sections of them peeled to look for EAB activity. These trap trees provide a good low-tech detection tool that can be used wherever ash trees grow.
In 2020, at least 34 trees were girdled across 8 of Maine's 16 counties, and nearly all have been processed. Over the past ten years, this processing has been a social event, where interested landowners, forest managers, and others could participate in the sampling.
This year, to reduce the risk of COVID-19 transmission, processing was conducted by MFS, City of Portland, and Acadia National Park staff.
Of the 33 trees processed, nine showed signs of EAB, including exit holes, larval galleries (the tracks etched into the bark and sapwood of the tree as the larvae feed) and EAB larvae. The nine positive trees were within the area currently regulated by the EAB quarantine. First detections for a town occurred in Gorham (one tree), South Berwick (one tree) and Van Buren (one tree).
Additionally, the first evidence of within-tree damage was found in Grand Isle (three trees, positive traps in 2018), Frenchville (one tree, positive trap in 2018), and Portland (two trees, positive trap in 2019). A positive tree was also found in South Berwick. ■