Tiny wasps, chemicals, and now injections into ash tree trunks are being used to battle the emerald ash borer. Various techniques to deal with this destructive beetle will be discussed at community forums on Tuesday evening in South Park Township, and on Wednesday evening in Wexford.
The emerald ash borer is native to China, but was first detected in the United States in 2002 in Michigan, and in Pennsylvania four years ago. The beetle has since been found in twelve of the commonwealth's counties. It has destroyed tens of millions of ash trees in the United States.
Robert Gorden, Director of Urban Forestry for Arborjet, a company which developed the injection method, said the government originally tried to thwart the beetle through eradication cuts. "They literally would identify where an emerald ash borer was and then anywhere from a half mile to a mile outside of that boundary, they would cut every ash tree, haul them to a marshaling yard (quarantine area), cut them into chips and dispose of them," said Gorden. "That was the first way. What they discovered was every time they did that the pest had already flown beyond that circle of containment." He said this was very costly, averaging between $500 thousand to $1 million.
Gorden said there are three newer ways of dealing with the emerald ash borer: releasing tiny, stingless wasps to fight them; soil drenching; and trunk injection.
The U.S. Forest Service recently announced they went to China and found wasps that are natural enemies of the emerald ash borer. Gorden said the problem with those wasps is that they are not as fast-moving, not as aggressive, and not as reproductively effective as the beetle. He said the one way they could be effective is after the ash borer has swept through an area, the wasps could fight off the remaining beetles. However, the Forest Service and the Pennsylvania Department of Agriculture just began using the tiny wasps earlier this year and say it's too soon to assess their effectiveness.
Soil drenching, mixing chemicals with soil and water and leaving it at the base of a tree to absorb, is also being used in a number of places. However, there is concern over the remaining chemicals' impact on the environment. There are government limits on how much can be used in an acre of land.
Trunk injection is the newest option to fight the emerald ash borer. "The tree has a vascular system much like you and I do. So when we inject a tree we're actually tapping into the tree's vascular tissue," said Gorden. "What typically brings water and nutrients up from the soil is used to carry our product up into the wood of the tree and to hold it there to protect the tree for multiple years." He said the preventive treatment lasts about two years.