DESTRUCTIVE INVADER: The emerald ash borer recently arrived in Princeton. It can potentially destroy all of the town’s ash trees. Princeton Shade Tree Commission and the town Council are preparing to propose a plan to combat the infestation of this beetle, which originated in Asia.

An infestation of the emerald ash borer (EAB), a beetle that is killing ash trees in 25 states, has struck Princeton, demanding action by Municipal Council, the Princeton Shade Tree Commission (STC) and property owners. Since first discovered in Detroit in 2002, the invasive pests have killed hundreds of millions of trees in this country, that now includes an unspecified number in Princeton.

According to a tree inventory of 2013, Princeton has about 2000 ash trees, almost 11 percent of the town’s tree population, in the public right of way, as well as additional ashes in municipal parks, open spaces, and private property.

Council and the STC are in the process of creating an EAB management plan for addressing the problem. “We’re being educated on this issue every day, and we’re trying to figure out the best course of action,” stated Lorraine Konopka, Princeton Municipal Arborist.

“Council has been told this problem is coming. It’s been on the radar screen for years,” she added. “It’s an expensive proposition. You can save trees, but there is a cost. We will be triaging what trees to preserve and what trees to take down. Of course we want to save trees, but the Council has the job of balancing the budget.”

According to a report by Council member and liaison to the Commission Bernie Miller, delivered to Council at their April 25 meeting, ”The Commission will present a plan to Council and the administration containing options for dealing with the problem, including costs and a public outreach proposal. The plan will be presented in time for Council to consider including funding for management of the EAB in the 2017 budget. Depending on the plan selected by Council, it is likely that dealing with the infestation will be done over several years with a need for funding over several years as the ashes continue to die and be replaced by trees that do not host the EAB.”

Options for action, in increasing order of cost, according to Mr. Miller’s report, include:

• No Action — in which case “virtually 100 percent of the ash trees in Princeton will be dead within eight years.” There would also be increased expense for taking down trees that are already dead;

• Selective Management — using chemical treatment for high value ash trees in selected streets and parks and taking no action on the remainder;

• Pre-emptive Management — removing all ash trees on municipal property and replacing them with species that are not attractive to EAB;

• Aggressive Management — removing and replacing all dead or dying trees and aggressive chemical pest management on all remaining ash trees.

The adult EAB, 1/2” long and 1/8” wide, is metallic green in color, with a metallic-copper red abdomen, according to the New Jersey Forest Service of the NJ Department of Environmental Protection (DEP). The -female beetles lay eggs on the bark of the trees. The eggs hatch and the larvae, white or cream colored and approximately 1-11/4” long, bore into the bark, feed and develop, cutting off the flow of nutrients and eventually killing the tree.

EAB adults emerge in May or early June, creating D-shaped exit holes on the branches and trunks of infested trees and staying active through August. The EAB feed on the ash leaf and have a one-year life cycle.

The EAB, native to Asia, first infest the top of the tree, which makes spotting adult beetles or exit holes nearly impossible from the ground. Woodpecker activity and damage on live trees is often an early sign of EAB infestation. Trees live an average of only 3-4 years after infestation.

Mr. Miller’s report stated that the Shade Tree Commission is currently updating the tree inventory from three years ago to provide a guide to the location, size, and condition of the ash population. “An up to date tree inventory,” the report states, can “provide the Council with fairly accurate costs for the different options.”

Sharon Ainsworth, chair of the Princeton STC, noted that the state had established an EAB task force with an excellent resource for information on the NJ Department of Agriculture website. “It recommends a balanced approach that recognizes that untreated ash will succumb, but establishing criteria for selectively treating high value ash as an option.”

Ms. Ainsworth went on to emphasize the importance of a public awareness campaigns and an effort ”to determine what public trees are saved with a fair and balanced approach.”

Arborist Ms. Konopka urged residents with ash trees on their property to work with respected, licensed tree services, approved by the NJDEP, in determining the best course of action to take in combating the emerald ash borer.