ADOPTING AN ASH: Jason Bond, plant health care specialist at Bartlett Tree Experts, injects the white ash behind the War Memorial bench at Nassau and Mercer Streets with pesticides to attack the emerald ash borer. It is Princeton’s first street tree to be injected in the selective chemical resistance effort funded by Princeton’s ongoing Adopt-an-Ash program. (Photo Courtesy of Patricia Frawley and Alexandra Radbil)

A 50-year-old white ash behind the War Memorial bench at Nassau and Mercer Streets last Wednesday became Princeton’s first street tree to receive the chemical resistance necessary to attack the invasive emerald ash borer (EAB).

Thanks to its recent “life-of-the-tree” adoption by Bartlett Tree Experts, the healthy ash was injected with the protective insecticide, emamectin benzoate, a treatment that has been effective in the Midwest.

The Princeton Shade Tree Commission (STC), as part of its ongoing Adopt-an-Ash program, is seeking contributions from organizations, residents, and student groups; with contribution checks made out to STC Tree Fund and mailed to One Monument Drive, Princeton, NJ, 08540.

According to Princeton Arborist Lorraine Konopka, if approvals are received from Princeton Council, additional candidate trees in the public right of way and possibly some park areas will be injected with amamectin benzoate. The material is injected and therefore contained inside the tree, minimizing any exposure to the technician doing the work or the general public.

First sighted in Princeton in August 2015, the EAB is expected, within five to ten years, to kill all of Princeton’s approximately 2,000 ash trees if untreated — 11 percent of the town’s tree population.

“The public is only gradually becoming aware of the magnitude of the EAB problem,” warned Pat Hyatt of the STC. “The distressed treetops you see as you drive around Princeton and look up may well be ash trees with branches likely to crash downward on the unsuspecting. Citizens are invited, make that urged, to adopt an ash to assist in saving the still-healthy trees we hope can be preserved.”

Last Wednesday Ms. Konopka, Patricia Frawley and Alexandra Radbil of the STC, and Scott Tapp, local manager of Bartlett Tree Experts, all observed as Bartlett plant health care specialist Jason Bond began treatment of the War Memorial ash. He drilled 12 entry points along the base of the tree, inserted small metal tubes, and pumped insecticide into the tree.

The procedure lasted 15 minutes, with the injections as close as possible to the soil line so that moisture absorbed by the roots would distribute the chemical evenly up the trunk to the tree canopy, where the EAB feeds.

Absorbed insecticide reaches the uppermost foliage and twigs, which are the primary food source for the destructive beetles. Without treatment, the EAB would feed on the leaves, lay the eggs that become the larvae that live under the bark, and feed on the plant tissue, killing the tree.

By the time signs of EAB presence are more easily visible, treatment would be too late, as the larvae infestation would have moved further and further down the trunk. The easier it is to detect EAB damage, the harder it is to treat because the infestation will have spread throughout the tree.

Not every ash is a good candidate for rescue. Ms. Konopka examined the War Memorial ash tree and determined that it was healthy, with no signs of EAB infestation. The next treatment for the ash is scheduled for spring 2019, and, in the meantime, Bartlett will inspect, prune, and perform soil tests to determine what kind of fertilization is needed to maintain the tree’s health.

If a tree is already infested, removal may be the best option. “If removal is the best option,” Ms. Konopka said, “it’s safer to remove now rather than later. The removal is more complicated and dangerous if the tree is dead.”

Treatments could cost hundreds of dollars, depending on the size of the tree (between $10 and $15 per diameter inch), and must be administered every two to three years.

Property owners should be sure the tree company they are working with has a current and valid NJDEP Commercial Pesticide Applicators License, and the business should be registered with Princeton to work in town. Further information on treating ash trees on private property can be found at the Shade Tree Commission website, www.princetonshadetree.org.