Informational tree walk on Thursday about downtown's dying ash trees

posted on 8/19/2025

The invasive emerald ash borer beetle is actively killing Dover’s downtown ash trees, requiring the removal of more than 50 trees in the next 1-2 years. The effects of the invasive insect can be spotted throughout downtown (and around the region) in ash trees’ dead limbs.

Planning Department staff are hosting downtown walks to inform the public about the issue; the next one is Thursday, Aug. 21, at 6 p.m., starting at City Hall. The walk lasts about an hour, concluding at Franklin Square.

Lindsay Watkins, Strafford County Forester with the University of New Hampshire’s Cooperative Extension, leads the public walk, pointing out the ash trees that line many areas of downtown, how to identify an infestation of the invasive emerald ash borer, and how an infestation nearly always means the tree will die within a few years and become a safety hazard. Watkins will also discuss the history of the emerald ash borer infestation in the United States that began in the Midwest earlier this century and has quickly migrated east. The emerald ash borer beetle is native to northeastern Asia.

Part of the walk includes the characteristics of a successful street tree, how conditions for street trees differ from forest trees, and why native species don’t always make the best street tree. City staff are creating a tree replacement plan and seek the public’s input on the downtown’s tree canopy through an online survey.

The invasive insect has spread across New Hampshire since 2013, feeding on ash trees beneath the bark, disrupting water and nutrient flow. Early signs include canopy dieback, bark splitting, woodpecker damage, and small D-shaped exit holes. Once symptoms appear, damage is typically irreversible, and dying ash trees become brittle, posing public safety hazards. Community Services’ crews have been proactively pruning affected trees, but most of the 54 ash trees will still need to be removed within a couple of years.

“Once you see it, you can’t un-see it,” said Deputy City Manager Christopher Parker about the ash tree’s dead limbs downtown on this week’s Dover Download podcast on the topic, where he interviews Watkins and Assistant City Planner Makayla Edgecomb about this critical issue facing Dover’s downtown ash trees.

Find more information on downtown street trees and the emerald ash borer threats at https://www.dover.nh.gov/government/city-operations/planning/resilient-dover/downtown-canopy/.