Winter reveals local signs of emerging tree pests, threats

MIDDLEBURY | An afternoon's ramble in the winter woods of Addison County might reveal signs of underlying pest problems that we will be facing in the months and years to come. These tiny threats to local forest diversity walk on six legs. An accessible look at Vermont's rich natural heritage and forest diversity is encountered on the forested slopes of Chipman Hill in Middlebury. This Ice Age-era geological relict, rising above U.S. Route 7 in downtown Middlebury, is home to a healthy, mixed woodland that includes maple, ash, oak, beech, birch, pine, plus dozens of other tree varieties. But not all is peace and quiet in these local woods. There are signs of growing alarm. University of Vermont Forest Pest Education Coordinator Ginger Nickerson has been studying area woodlands for signs of pests that threaten Vermont trees. She said that the future viability of many of our trees is seriously threatened by a trio of aliens; invasive forest insects. In some places, she stresses, you might be the only one to spot the troubling signs. Trio of invaders "The three pests to be on the lookout for when exploring our forests are the emerald ash borer, hemlock woolly adelgid, and Asian longhorned beetle," according to Nickerson. Nickerson noted that the Southeast Asian emerald ash borer beetle was found spreading in Vermont first in 2018. It has since spread and is now living (and destroying) trees in 35 states plus a few Canadian provinces. "All of Vermont's native ash trees (green, white, and black) are threatened by this forest pest. Nearly 99 percent of them will likely die if infested," according to a recent news release by Nickerson. "You can help slow the spread of this pest by looking for signs and symptoms of the beetle. These include ash trees with patches of 'blond' bark flecked off by grub-hungry woodpeckers, a dying canopy, new branches growing low on the main trunk or s-shaped galleries or tunnels just under the bark of the tree." Nickerson points out that hemlock trees, a keystone species in northern forests that superficially resembles the Coast Redwood tree, is an important tree for local wildlife. "Hemlocks are threatened by the hemlock woolly adelgid, a small, aphid-like insect that feeds on starch in hemlock twigs," she noted. "Vermont has implemented a biological control program to keep the populations down. This tiny bug is currently in southern Vermont but has the potential to move north as it has been spotted in sections of central New York and New Hampshire. Look at the underside of hemlock branches for small, white, cottony balls lined up along the twigs. Most new detections come from residents and visitors reporting suspect trees." The threat to sugar maples And then there's another alien invader we all need to be concerned about: the Asian longhorned beetle. The Asian longhorned beetle attacks hardwood trees, but it is a looming threat to Vermont's maples, notably the economically important sugar maple. "The only known way to control this pest is to cut down infested trees," Nickerson cautions. "States with infestations have cut down and destroyed thousands of trees in their efforts to eradicate the pest. Although not yet present in Vermont, if it gets a foothold here, this pest could devastate the rural and urban landscapes we know and the maple sugaring industry we love." Hikers and other ramblers in local woods can be of big help: they can form the advance guard by helping protect Addison County maples. Nickerson considers an "early warning" approach to head-off the Asian longhorned beetle. "Look for perfectly round, dime-sized exit holes, at least a half-inch deep. Egg mass sites appear as shallow, round scars or half-inch depressions in the outer bark," she noted. "With your help, we can keep these invasive forest pests from destroying the forests that we love for outdoor recreation, sugaring, and other forestry-related activities." "If you see signs of any of these pests, take photos, snag the GPS location and submit your findings at vtinvasives.org using the Report It! link," Nickerson requests. For more online ways to learn about these pest signs, or for news updates about emerging threats, see www.vtinvasives.org.

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Winter reveals local signs of emerging tree pests, threats

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