COLUMBUS, OH -- A disease that has been killing American beech trees in the eastern United States since the 1930s has found its way to Ohio, the Ohio Department of Natural Resources (ODNR) and U.S. Forest Service report.
State and federal forestry officials are investigating a case of beech bark disease at the Holden Arboretum in Lake County. A fungus indicative of the disease was discovered growing on beech tree bark in December 2003, according to the ODNR Division of Forestry.
"Beech bark disease has moved slowly, but still has the potential to change Ohio forests," said Dan Balser, of the ODNR Division of Forestry. "We will continue monitoring the disease closely and plan to expand detection surveys this year in northeastern Ohio."
Beech trees become infected with the disease after the beech scale (an insect from Europe) pierces the thin bark to suck sap. Resulting wounds become infected with a fungus known as Nectria, which creates small cankers. Eventually, these cankers grow, choking off nutrients to the trees, causing them to die. Both the soft-bodied scale and the fungus can be transported by the wind or carried by birds.
Native to Europe, beech bark disease first appeared in the United States around 1932. From Maine, it slowly spread south, killing beech trees in Pennsylvania, West Virginia, New York, New Jersey, North Carolina and Tennessee.
In March of 2000, the beech scale insect (Cryptococcus fagisuga) was discovered in Michigan, and in 2001 it was determined that beech bark disease was killing the state's beech trees. This was the first report of the disease in the Great Lakes Region.
The beech scale insect was first discovered in Ohio in 1985 at the Holden Arboretum. Since that time, the area has been periodically inspected for outbreaks of the bark disease and the arboretum has a monitoring program for its beech trees. State and federal foresters continue to watch for signs that might indicate beech bark disease has developed elsewhere in northeastern Ohio.
An early indicator of the disease's presence is a white waxy covering excreted by the scale insect as it feeds on beech bark. While the insect can be controlled with insecticides on ornamental trees in yards and parks, there are no cost-effective control measures for forest trees.
Some beech trees (1 percent to 5 percent) appear to have bark characteristics that are resistant to beech scale infestations, according to the U.S. Forest Service. These trees are relatively unaffected, while surrounding beech trees are killed during an outbreak of the disease. Preservation of healthy beech trees is recommended in outbreak areas. Scientists with the U.S. Forest Service are researching whether resistance to beech scale is something a tree can inherit.