County forester says Emerald Ash Beetle could threaten local shade trees

LACONIA — Ash trees represent less than 10 percent of the state's trees, and according to UNH Cooperative Extension–Belknap County forester Andy Fast, most of those ash trees are concentrated in the Connecticut River Valley. So, at least as far as Belknap County is concerned, the appearance of the invasive Emerald Ash Beetle in Concord earlier this month doesn't portend a calamity for local forests and those who make their living in them.
However, he said, the beetle could still make its mark on the Belknap County landscape, as the ash trees it infests are often planted as shade trees, both in public parks and at private residences and developments.
Kevin Dunleavy, director of the city's Parks and Recreation Department, confirmed that green and black ash trees, though not the most prevalent of trees in city parks, are often integrated into plantings of public green spaces. "We have mixed it in," he said. Ash trees, for example, are among the trees planted in the sidewalks in the city's downtown, and Dunleavy said "we have our concerns" about the appearance of the Emerald Ash Borer in Concord.
A native to much of Asia, the insect was first discovered in North America in 2002, in Michigan. In that state, the beetle decimated the ash trees, killing millions of them. Without a natural predator to balance the beetle's population, they've been spotted in 18 states since the first affected tree was discovered in Michigan.
The beetle's travel, both from Asia to Michigan and from that state throughout North America, is thought to be accelerated by human activity, especially the transport of firewood. In response to the Concord infestation, the state placed a quarantine on wood in Merrimack County, prohibiting its transport to other regions of the state.
The Emerald Ash Borer, according to a document on the USDA's website, lays its eggs on the bark of an ash tree. The larvae bore through the bark and feed on the phloem, the living tissue of the tree, directly underneath the bark. In the spring, they emerge as adults and begin mating shortly thereafter. Though adult Emerald Ash Borers live only two to three weeks, a female can lay as many as 90 eggs during that lifetime. Unchecked, a local population of Emerald Ash Borers doubles in size every year, and trees are usually killed within a few to five years of infestation.
"It's a scary prospect," Fast said about the detection of the beetle in New Hampshire. However, he advised against panicked or hasty decisions, such as proactively removing any ash trees. "From a forest management perspective, that's not going to help much." Fast, encouraged by the amount of information scientists have gained about the beetle in the past decade, that there may be a way to manage the impact the Emerald Ash Borer has on trees in Belknap County.
In the states hardest hit by the invasive species, he noted, observers have seen the beetles kill adult trees and move on to find fresh food sources. In their wake, the roots or stumps of affected trees will send new shoots of growth, only to be swept over by a second wave of beetles.
Fast said there are established pesticide treatments recommended for Emerald Ash Borer control, allowing property owners or municipalities the opportunity to monitor and protect specific ash trees. There may also be a biological counter-measure, as researchers are studying three species of stingless wasps that hunt Emerald Ash Borers in their native environment. He's hoping that an "equilibrium" will be reached, one where New Hampshire's landscape will continue to host some healthy ash trees despite the insect's existence.
"It's a huge concern, but we have a few tools. It's really going to be information that helps us," said Fast.
Until the best response is developed, Fast urged vigilance, both in terms of observing the firewood quarantines and for those who have an ash tree they care about. "Folks should definitely be vigilant," he said.
There are several signs that an ash tree will exhibit in the case of an Emerald Ash Borer infestation. The tree might show only one or two of the signs.
The first indication that something might be wrong is a thinning of the tree's canopy. Fast said, "It targets the crown of the tree first – thin and not a lot of leaves in it."
Another cause for concern would be increased woodpecker activity, as the birds seek the larvae underneath the bark. Because their quarry isn't deep in the wood of the tree, Fast said the woodpeckers will only be scratching the surface of the ash branches. "It's going to look like the bark's being scraped off," he said.
If an observer can examine the canopy of an infested tree, Fast said the bark will feature "D" shaped holes, left by adult beetles leaving their larval home. The bark may also begin to split, revealing the marks left in the phloem by the larvae as they tunnel beneath the bark.
Lastly, the tree may send out lots of long sprouts, though Fast said this is often characteristic of any stressed tree.
If a homeowner notices any of these signs, Fast said he or she may contact him at the Cooperative Extension's Belknap County Office, or may send a photo of a symptomatic tree to the extension via a link found on nhwoods.org.
As far as the city's trees go, Dunleavy hoped that they will continue to offer shade for many years to come. "There's not much we can do but keep an eye out for it," he said. "The more eyes, the better. If there's early identification, it can help."

CAPTION with ASH TREES in AA:
Although the appearance of the Emerald Ash Borer beetle in Concord means little threat to Belknap County forests, which have fewer ash trees than in other parts of the state, some of the shade trees planted in public places are ash. These two trees, planted at the intersection of Pleasant and Main streets in downtown Laconia, are at risk of becoming infested by the invasive insect. (Laconia Daily Sun photo/Adam Drapcho)