When the deadly Beech Bark Disease was discovered recently at Holden Arboretum in Lake County, Ohio, the U.S. Forest Service was armed and waiting.

Biologist Jennifer Koch of the USDA Forest Service’s Delaware, Ohio laboratory has been working in conjunction with the arboretum since 2002 developing disease-resistant varieties of the American beech (Fagus grandifolia) that may lead to a better prognosis for one of American’s most-loved tree species.

“We know there are trees that survive while adjacent trees succumb to this disease,” Koch said. “The question is what is the tree’s survival secret and can we capitalize on that secret to benefit forest and communities across the eastern United States.” She said between 1 and 5 percent of beech trees survive in areas hard hit by the disease.

The disease occurs from an interaction between the beech scale insect (Cryptococcus fagisuga, not native to the United States) and either one of two Nectria fungi. The fungus infects bark wounds created by the scale insect. Both the insect and fungus must be present for the deadly interaction to occur.

Beech Bark Disease is native to Europe and first appeared in Maine around 1932. The disease has slowly spread, killing American beech trees throughout the New England states and continuing as far south as North Carolina. In 2001 it was determined that both the scale insect and the Nectria fungus were present in Michigan.

The insect half of the deadly duo, which gives the bark a characteristic whitewashed appearance, was first discovered in Ohio in 1985 at Holden Arboretum, according to Brian Parsons, the Arboretum’s Director of Conservation. Since then, the area has been inspected periodically for Beech Bark Disease and the Arboretum set up an aggressive program to monitor its beech trees. In October of 2003, Arboretum personnel noticed a bright orange fungus present on some of their most heavily scale-infested beech trees. Forest Service pathologists collected samples and preliminary results have recently confirmed that the fungus is one of the Nectria species associated with the disease, although precise identification of which of the disease-causing forms of the species is pending.

Koch and associates have already identified disease-resistant trees in Michigan and performed controlled crosses between resistant beech trees. The resulting seeds were collected, and along with open-pollinated seeds from resistant trees were brought back to the Delaware laboratory and germinated in the greenhouse. Six months later (June 2003) the seedlings were taken to the Arboretum to be challenged with scale eggs to determine if they are resistant. Preliminary findings will be available in the summer of 2004.
“We hope to determine how this resistance to the beech scale may be inherited, and whether resistance is a dominant or recessive trait,” Koch said. “This kind of information will allow us to eventually establish an American beech breeding program to produce resistant beech seedlings.”