CALDWELL, NJ—The Borough of Caldwell could lose up to 60 percent of the ash trees currently existing on right-of-ways over the next several years to an insect called the Emerald Ash Borer, experts told members of the Caldwell Borough Council at Tuesday’s governing body session.

According to Ann Marchioni of the Caldwell Environment Commission, 90 percent or more of the ash trees in New Jersey could become infected by the metallic-green insect, whose larvae feed on the inner bark and disrupt the movement of water and nutrients, essentially girdling an infected tree.

Marchioni said the commission recommends that the borough treat its ash trees at a cost of $150 for each tree with a 20-inch diameter.

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Although Marchioni said there is an estimated 95 borough-owned ash trees in Caldwell, borough forester John Linson said the number is probably considerably less considering that the survey counting the trees was done about 17 years ago.

Linson said that every year, he does a “windshield survey” to locate hazards in roadside trees and that he expects to complete this year’s survey by September.

In the last five years, the forester added, he and his colleagues across the state have been treating for another disease: ash yellows, which he said causes a different type of infection in the trees.

He noted that the Emerald Ash Borer was brought to the United States several years ago in shipping crates, and first appeared in the Midwest before spreading Eastward relatively recently. It has already been seen in other areas of New Jersey.

Linson estimated that of the 95-or-fewer borough-owned ash trees remaining in Caldwell, about 15 or 20 will be worth saving—and this is only if they are treated once every two years, he said.

He added that trees with approximately 10 percent thinning of foliage are the most likely to be saved by the treatment, which involves “systemic injection” of substances to fight the borer insects. The forester said this treatment is more desirable than spraying trees because many residents fear that spraying may harm pets or have other adverse effects.

When council members questioned whether the borough could also pay to have residential trees treated, Linson suggested a program used in Chatham, which hired a treatment service for the community’s trees. He said the service offered the program to residents at the same fee as that paid by the municipality.

Although the forester said the most effective time to treat for Emerald Ash Borer is in May or June, he added that treatment at this time of year has some effect despite a slower “uptake.” He suggested that the council consider the program now so that the borough can budget for the program to begin next spring.

He added that some brochures detailing the insects, their effects and treatment are available in the borough. Council members suggested that the borough post the brochure information on its website, distribute them in the municipal building or mail them to all residents.