Brown patches on Blue Ridge Parkway? Blame the weevil

Barbara Hootman
  • Poplar and oak trees in WNC forest are under siege from natural pests in greater numbers this year.
  • Yellow-poplar leaf mining weevil is attacking poplar tree leafs, and a fungus is killing oak leafs.
  • A weevil and fungus are attacking trees in WNC forests causing concern for forest health.
  • A weevil and fungus is attacking trees in WNC forests killing the leaves.

You see them all around the Swannanoa Valley — large patches of brown trees interspersed along the mountainsides. It looks like the trees are dying, but they're not, experts say.

Poplar trees are under attack from the yellow-poplar leaf-mining weevil that is always around in the forest. The N.C. Forest Service recently sent out a press release about the impact the weevils are having on the trees, especially in Western North Carolina. For the oaks, it's a different story.

"Oaks in Western North Carolina, particularly red oaks, are losing leaves as a result of oak leaf blister, a disease caused by a fungus," Steve Troxler, state agriculture commissioner, said in the release. "In addition, foresters are reporting damage from yellow-poplar leaf-mining weevil, which is causing widespread browning and defoliation on yellow-poplar trees."

Craig Lawing, an N.C. Forest Service forest health specialist in Morganton, said both the weevil and fungus are native pests that are always in the forest.

"The yellow-poplar weevil is damaging the leaves of the trees and defoliating them," he said. "However, it is not a total defoliation, and the trees are not being damaged, just the leaves.

"There is very little known about the weevil," he said, "but we think due to the cold spring, its natural predators were killed off. But it didn't get cold enough to kill the weevils. The result is a larger population of them this year.

"Another interesting fact is that the leaves of poplar trees will turn brown and fall off, but more leaves will grow this season. Not all trees can do that. The fungus on the oak leaves is caused by temperature and humidity. Also, it is not damaging the trees, just the leaves.

"We can't get too concerned about these conditions, unless they persist and we see them again next year. Then they will become more of a concern. People really don't need to be worried about the trees at this point."

Will Blozan of Appalachian Arborists said the yellow-poplar leaf mining weevil is cyclic and shows up in greater numbers some years. The oak leaf fungus is environmentally related through weather, he said.

For more information about the yellow-poplar weevil and oak leaf fungus contact N.C. Forest Service, Raleigh, N.C.