Sep 19 2018

HLT Prepares for the Onslaught
Of the Emerald Ash Borer

Measuring Ash Trees at the Thomas Saeger Preserve in the Holland Highlands.

The Emerald Ash Borer is a torpedo-shaped invasive beetle, native to parts of Asia, metallic green, and 3/8 to ½ inch long – about the size of a cooked grain of rice.

It’s also a giant killer, posing an extinction-level threat to the roughly 24 million ash trees in New Jersey.

Emerald Ash Borers munch on ash trees, laying eggs in bark crevices. The larvae tunnel into the tree, disrupting its water and nutrient transport systems, causing the tree to girdle from the inside. This silent, hard-to-detect killer works ruthlessly: An infested tree survives three, maybe four, years.

Hunterdon Land Trust is preparing for the inevitable onslaught in the best way possible. We hosted a well-attended information session to teach locals how to identify ash trees and help them evaluate options to deal with the EAB threat. Options include removing trees that could pose a public safety hazard versus treating ones that offer inherent natural benefits and are irreplaceable.

We instituted an action plan to inventory and mark all ash trees near the trails on nine preserves. And we actively sought – and continue to seek – volunteers to help inventory our preserves.

On a Saturday morning with a blanket of mottled gray stretching across the horizon, a cheerful band of volunteers, led by HLT Land Steward Stefani Spence, prepare to set out on the trail at the Thomas Saeger Preserve to identify, measure and mark ash trees. Identifying ash trees isn’t a simple task. They are often difficult to distinguish from other common Garden State tree species. Ash trees have opposite branching (a pattern where side branches, leaves and leaf scars grow from the stem directly across from each other) and compound leaves of five and seven or nine leaflets. The bark is often diamond shaped, but not always.

As the group ascends the trail further into the Holland Highlands, one can almost taste the rain. They hike single file; heads swivel, eyes dart upward studying the trees. A volunteer stops, pointing at a gray sentinel standing tall amidst a clump of nearly identical trees. Everyone reaches for the binoculars draped about their necks, raising them to the tree tops, squinting to examine the leaves.

No, this one isn’t an ash tree. The search continues until, just around a bend in the trail, an ash tree is identified. A volunteer picks her way through five yards of brush to reach its trunk and measure its diameter. The tree’s diameter is measured to help determine whether to treat the tree or cut it down to protect hikers walking the trail. Spence follows, hammering an identifying tag into its trunk, while another volunteer records information about the tree on a spreadsheet.

The process of successfully identifying and marking trees repeats itself for another two hours. Sometimes the group will have to fight its way through a tangle of grapevine or plunge into the foliage to reach a tree. Along the way, the group encounters fuzzy caterpillars, spittle bugs and a variety of interesting plants. The effort is invigorating, and the splatter of raindrops on the leaves fails to dampen the enthusiasm of the volunteers.

“The ash trees we found at Saeger appeared to be in good condition,” Spence said, “although it’s very difficult to tell if a tree has EAB in it until it’s almost too late.”

Once all surveying is completed, HLT will evaluate what to do next. “We might be able to treat some of the really nice, healthy ash trees to keep EAB from attacking them, but the treatments are expensive and need to be repeated,” Spence noted. “Any tree not treated will most likely be cut down if it could cause damage or injury when it fell. Trees killed by EAB become extremely dangerous, and need to be cut while still alive to minimize risk.”

Meanwhile, miles of trails and many trees still need to be surveyed.

Want to Help?

We’re seeking volunteers to help inventory ash trees. Call Stefani at 908-237-4582 or email to learn more.

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