Ash borer alert: It's now time to take action


IN 2018 VERMONT became the 33rd state infested with emerald ash borers. This map shows the areas in Vermont where infestations have been identified.

UNDERNEATH THE BARK of an ash borer-infested tree one will find S-shaped “galleries” that weave back and forth on the surface of the wood.

WOODPECKER DAMAGE TO live ash trees may be the first sign of an infestation of emerald ash borers underneath the bark.
Woodpeckers are your friends … when they (find emerald ash borers) they will eat up to 80 percent of the insects. — State Entomologist Judy Rosovsky

BRISTOL — Addison County communities need to be making plans — right now — to manage the emerald ash borer, which was detected in Bristol on June 5.

The towns of Bristol, Lincoln, Monkton, New Haven and Starksboro fall within the “confirmed infested area” (a five-mile radius from the detection), according to the Vermont Agency of Natural Resources.

Another nine communities that are within a 10-mile radius of the detection have been designated as “high risk”: Addison, Cornwall, Ferrisburgh, Middlebury, Panton, Ripton, Vergennes, Waltham and Weybridge.

“I cannot emphasize enough that it is important to make some game plan now for forestlands,” said Keith Thompson, Private Lands Program Manager for the Vermont Department of Forests, Parks & Recreation, at a public information meeting in Bristol this past Tuesday evening. “It’s important to know that ash trees will die and the impact will be significant.”

The emerald ash borer, sometimes known as EAB, is native to eastern and southeastern Asia, and it kills North American ash trees. It was first detected in the United States in 2002, in Detroit. By 2015 it had killed tens of millions of trees.

The mortality rate of Vermont’s three ash species — black, green and white — is estimated at 99 percent when attacked by emerald ash borers.

According to the USDA, infestations have been recorded in 35 states, plus the District of Columbia, and nearly 9 billion trees around the country are threatened. Infestations have also been reported in five Canadian provinces.

In 2018 Vermont became the 33rd EAB-infested state. All 150 million of the state’s ash trees — 5 to 7 percent of its total tree population — fall within the federal EAB quarantine boundary.

This spring Bristol became the fourth area of the state to report emerald ash borer, after the Bennington area, Burlington area and Central Vermont. A month later Orleans County reported its first EAB infestation, in Derby Line on the Canadian border.

ASH FAIL DIFFERENTLY

Communities need to act now so that dying ash trees will not become a major hazard along roads, sidewalks, trails, utility corridors and other areas.

EAB damages ash trees by boring holes through the bark and into the outer wood, and its larvae feed so voraciously that the trees are prevented from moving water and carbohydrates around.

Because of this, infested ash trees become unusually brittle. When limbs snap off, or when dead trees are felled, they’re often said to “shatter” as they hit the ground.

Just one year after an ash has been infested with EAB it should be assumed that a five-inch-thick branch has the strength of a one-inch-thick branch, said Elise Schadler, manager of forest department’s Urban & Community Forestry Program.

Unfortunately, EAB infestations do not make themselves immediately apparent. By the time the invasive species is discovered, it’s likely that several years’ worth of tree destruction will be discovered along with it.

At that point, the ash wood is about as valuable as a Styrofoam cup, Schadler said at Tuesday night’s information session in Bristol.

To give her audience an idea of just how fragile the trees can get, she described an incident in western New York state, where a utility company had been performing routine clearing along a distribution-line corridor.

The mere vibrations caused by their work precipitated the sudden collapse of several nearby ash.

For this reason, landowners and municipalities are strongly urged to engage only licensed foresters to manage the trees.

DO I HAVE EMERALD ASH BORERS?

First and foremost, landowners should learn to identify ash trees, which have a number of distinct features:

• branches and buds are directly across from each other and not staggered.

• leaves are compound, composed of 5–11 leaflets.

• bark on mature trees is tight, with a distinct pattern of diamond-shaped ridges, but on young trees it’s relatively smooth.

After an EAB infestation, several symptoms may appear.

Woodpecker damage to live trees may be the first sign, Vermont State Entomologist Judy Rosovsky told the Bristol audience.

“Woodpeckers are your friends,” she explained. “It may take them a while to find EAB, but when they do they will eat up to 80 percent of the insects.”

People should also look for woodpecker “flecking,” a minor superficial peeling of the bark.

The next piece of evidence exists underneath the bark, which would have to be removed to expose it: S-shaped “galleries” that weave back and forth on the surface of the wood.

Look, too, for canopy thinning, Rosovsky said.

“If you see dieback, go and look for some of the other symptoms.”

The adult emerald ash borer is a half-inch long with metallic green wings and a brownish head. It’s skinnier than many of the bugs it’s mistaken for, including the Japanese beetle and the green stink bug. It gets around by flying and will almost never be found crawling on the ground, Rosovsky said.

For more information about trees, bugs and symptoms, including identifying photographs and videos, head online to invasives.org.

WHAT NOW?

There are three basic approaches to dealing with an EAB-infected ash tree — leave it, cut it or treat it — and any number of physical, economic and cultural variables will affect which choice is most appropriate at any given time.

The town of Bristol, for instance, chose to remove an ash tree on North Street earlier this month because, among other things, it posed a danger to homeowners, pedestrians and drivers. Other municipalities are likely to use similar criteria in their decision-making processes.

Some may want to harvest their trees for the wood, before it’s destroyed.

Ash is used for furniture, flooring, doors, cabinetry, architectural molding and millwork, tool handles, baseball bats, hockey sticks, oars, turnings and veneer, according to the Hardwood Distributors Association. It’s also a popular species for food containers because the wood has no taste.

For those who wish to save a beloved tree, it may be possible to do so by inoculating it, using a process Schadler likened to an I.V. system or a “reverse sugar tap.”

Inoculation can be expensive, however, and the process must be repeated every other year for the entire life of the tree, so it may not be a viable choice for towns or landowners with large ash populations.

Making such choices is difficult even for the experts.

“The scariest thing for me is as a forester is to lose ash from the forest,” Thompson said, “and if I cut them prematurely, then the gig is up for ash. So I’m really thinking about how to achieve management objectives, make sure our land is safe, make sure it’s growing healthy trees, make sure I’m realizing some economic value but also retaining some of the ash in the process.”

SLOW THE SPREAD

The emerald ash borer naturally spreads at a rate of 1 to 2 miles per year, but moving firewood around greatly increases that rate.

Forestry officials are urging landowners to spread the “don’t move firewood” message and to be alert to possible infestations on their properties.

Anyone who thinks they might have discovered an EAB infestation is encouraged to report it by calling the EAB hotline at 1-800-322-4512, or by visiting vtinvasives.org and clicking the “Report It” button.

“We’d rather have false alarms than have EAB go undetected,” Rosovsky said.

More information can also be found by visiting anr.vermont.gov and fpr.vermont.gov.

Reach Christopher Ross at [email protected].

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