Daily American Staff Writer
3:14 PM EDT, April 2, 2013
More than 17 million acres — almost 60 percent of the commonwealth — is covered by a quality hardwood forest, according to the Pennsylvania Department of Conservation and Natural Resources.
Five hundred thousand private forest landowners control nearly 70 percent of these forests. The 2.1 million acre state forest system is one of the largest public forest ownerships in the eastern United States. Combined with other state, federal and municipal holdings, public ownership accounts for 26 percent of the Commonwealth's forests.
But about 7 percent of forest trees in Pennsylvania — about 370,000 trees — are ash trees. Sometime in the next three years, about one in 10 will die from emerald ash borer infestation. The emerald ash borer feeds exclusively on ash trees.
Dave Schmit, a forest health specialist with the department, said that borer larvae live underneath tree bark. The borer kills more than 99 percent of the trees it bores into, and most trees die within three years of infestation. The ash borer has been found in Somerset County since 2010 and in Cambria County since January 2013.
“The emerald ash borer is going to change the face of our forest in Pennsylvania, both in the community and in the public forests,” Forbes State Forest District Forester Ed Callahan said.
Private landowners may decide to remove the trees and plant new ones. That can’t be done in forests, Callahan said.
“There are treatments, but they are very expensive,” Schmit said. “In communities only high-value trees — a tree that you have to keep on your property — will be treated. You have to inject the tree every 4-to-6 inches and every two years. The product alone costs $8 or $9 an inch. And it is a regulated product so you have to hire a licensed specialist to apply it. It will cost big bucks.”
The state forests won’t be treated because of the cost. The trees will be allowed to die naturally, Schmit said, unless the stand is ready to be harvested and is high quality wood. To cut down trees regardless of the wood quality would damage the remaining trees’ root systems.
“In this part of Pennsylvania the ash trees are a minor component of the forest, compared to other counties such as the northern tier,” Callahan said. “The ash borer hasn’t yet reached the northern tier.”
The U.S. Forest Service is testing two species of stingless Asian wasps that prey on emerald ash borers. The hope is that these insects will help slow, or stop, the spread of the tree-killing borers. They are known as “parasitoid” wasps. Researchers must first determine if bringing a new insect to this country will do more good for ash trees than harm to native insect species.
Since their discovery near Detroit in 2002, the tiny, shiny green borers have spread to 15 states and to two Canadian provinces. It was first found in the state in 2007 in Butler County. Thirty-one of the state’s 67 counties have confirmed infestations. Pennsylvania had banned the transport of firewood to try to limit the spread, but the ban was lifted in April 2011. People are still asked not to bring firewood into state parks. There is a federal quarantine on moving firewood between states.
“Dead ash trees are brittle,” Schmit said. “When the wood breaks an entire branch system comes down. It can hit a house, a car or people. It can be an extreme liability for homeowners.”
Other problems foresters are facing include the hemlock woolly adelgid, another invasive insect species, and elongated hemlock scale, a fungus. Hemlocks are the state tree. There is a hemlock grove where United Flight 93 crashed in Stonycreek Township on Sept. 11, 2001.
“The grove is where the plane went into the ground,” National Park Service Site Deputy Superintendent Keith Newlin said. “We know that it is infected with the hemlock woolly adelgid.”
The National Park Service has applied for a grant from the U.S. Forest Service to treat the hemlock grove, but hasn’t heard yet if it will receive the grant. There are some ash trees in the native tree area of the Flight 93 National Memorial, but they have not been checked for the emerald ash borer.
Schmit said the treatment for the hemlock woolly adelgid is a very common insecticide that lasts for five to seven years.
“We have a glimmer of hope,” he said. “There are some trees that haven’t had borer attacking them for some reason. There is something in their DNA that is making them resistant. We hope to be able to bring back genetically-resistant trees.”