Trees in Trouble: Woolly AdelgidArborist Matthew Foti approaches two multitrunk hemlocks that tower above the front of the house. Reaching up to pull a small branch from the tree, he points to a fluffy whiteness on the needles. Early snow? Dryer lint? "It's woolly adelgid," he says. "And it's devastating hemlocks all along the Eastern seaboard."

According the the USDA Forest Service, the hemlock woolly adelgid arrived in this country in 1924, most likely from Asia. The sap-sucking insect attaches tiny, cottony egg sacs to the base of needle clusters, depriving them of nutrients and quickly turning the needles brown. Defoliation and death happen fast — often in just a few years. Infestations have occurred from the Smoky Mountains in the Appalachians to southern New England. "For a long time, the adelgid stopped at the Massachusetts?New Hampshire border," says Foti. "But it's now gotten as far as Maine."

Sprays are the most common method of killing adelgid. But according to Foti, "Sprays can wash off in the rain, and the overspray gets on everything from picnic tables to neighbors' cars.""His preferred method of combat is to treat the trees systemically with an insecticide called Bidrin, which he injects into the tree's cambium, the outermost layer of cells where water and nutrients climb upward to the top of the trees. "It's like getting IV drugs in the hospital," he says.

Foti drills small holes around the trunk's circumference, then taps in small, hard plastic tubes. Flipping down his face shield, he twists a Bidrin vial onto each tube. "It's a powerful chemical," he says, "not something you want to get in your eyes." (Similar-shaped vials of fungicide or fertilizers can also be applied this way to restore the health of ravaged trees.) The insecticide is carried right up to the topmost needles. "It's amazingly effective," he says. "We use the same methods for gypsy moths and when we come back four hours later to remove the vials, it's raining dead caterpillars." The semiannual treatment, which must be done by someone with a pesticide-applicator license, costs from $200 to $550 a year per tree. "It's worth every penny," he says. "How could you put a replacement value on mature trees like these?"
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