Mercer County Park Commission Seeking Volunteers to Survey Ash Trees

The Mercer County Park Commission is looking for park patrons to volunteer in performing a Park Commission-wide ash tree survey to help monitor and manage the spread of the emerald ash borer (EAB) in the Park Commission’s ash trees.

This invasive beetle from Asia, which attacks and kills ash trees, was first found in the U.S. in 2002 in Michigan and made its way to New Jersey in 2014.  Today, the EAB is confirmed in five Mercer County municipalities: Ewing, Hamilton, Hopewell Borough, Princeton and West Windsor.

“The Mercer County Park Commission is committed to preserving natural resources and providing exceptional recreational opportunities in our county park system,” said County Executive Brian M. Hughes. “Our dedication to conservation and recreation ensures that the presence of a healthy environment will continue to be an integral part of our parks that so many people enjoy.”

In response to the beetle’s presence in the county, the Park Commission created a management plan with goals to slow down the spread of the beetle, protect healthy ash trees and remove trees that threaten park safety. A major component of the management plan is conducting a Park Commission-wide ash tree survey. This is where park patrons play a major role in the plan — they conduct the tree surveys. After becoming trained, monitors will collect a variety of measurements and observations of ash trees, including tree diameter, canopy fullness and EAB symptoms. This year’s data collection will begin in parks within a five-mile radius of Ewing Township, including Mountain View Golf Course, Baldpate Mountain, Mercer County Wildlife Center, Mercer Meadows and Howell Living History Farm. The data collected in the surveys will help guide the Park Commission’s decisions in treatment options.

Volunteer training will take place on Thursday, April 7, from 6 to 8 p.m. and Saturday, April 9, from 10 a.m. to noon at Mountain View Golf Course. All participants must attend one training session in order to take part in the survey.

“Our parks, golf courses and facilities are popular destinations within the county. Keeping them free of public safety hazards is vital to our operations, as is maintaining the valuable resources trees provide our parks,” said Park Commission Executive Director Kevin B. Bannon. “The introduction of the emerald ash borer threatens the health of our ash trees and the Park Commission is taking this infestation seriously.”

The first confirmed EAB sighting in Mercer County was in Ewing in 2014. County parklands and Park Commission facilities are located throughout the county. Due to the parks’ proximity to the municipalities with confirmed infestations, all parkland is being treated as if it has EAB activity. Ash trees are abundant in the Park Commission’s forests and high-use areas, such as golf courses, parking lots, picnic grounds, playgrounds and along trail edges.

The adult emerald ash borer is tiny, about one-half inch long, and hard to see even though it dons metallic green wing covers. Adult beetles feed on ash leaves, but this does not kill the tree. After hatching, EAB larva bore into the ash tree and consumes the tree’s cambium layer. Their feeding behavior cuts off the flow of nutrients and water in the tree, and when multiplied by many larvae, it kills the tree within three to five years. In an EAB infected area, nearly 99 percent of ash trees will die, and since 2002, the beetle has killed tens of millions of ash trees in the U.S.

Current management techniques for emerald ash borer include protecting trees from EAB infection, removing ash trees and replanting with native tree species, and the release of parasitoid wasps that kill the beetles. These efforts slow down the spread of EAB; currently there is no method to stop the beetle.

For more information regarding EAB in the parks, contact the County Naturalist at
(609) 303-0706 or

Citizens interested in learning more about EAB should visit the emerald ash borer page on the New Jersey Department of Agriculture website:

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