Foreign beetles infect trees on campus

October 19, 2009 —

A small green beetle has found its way to Saginaw Valley and burrowed a home in its ash trees, forcing campus officials to become active in the fight against the exotic pest.

The emerald ash borer is native to Asia and was first discovered in southeastern Michigan in 2002. It can fly no higher than six-and-a-half feet above ground, but that’s good enough for this bug to spread throughout the country. Infestations have also been found in Illinois, Indiana, Kentucky, Maryland, Minnesota, Missouri, New York, Ohio, Pennsylvania, Virginia, West Virginia and Wisconsin.

Scientists estimate that the borer has destroyed 40 million trees in Michigan and 70 million overall. If the bug isn’t dealt with, the cost of its consequences could reach billions of dollars nationwide.

While the adult bore chows on the tree’s foliage, its larvae burrow just beneath the bark into the tree’s circulatory system to feed on the sap of the inner wood and vascular tissue, carving an S-shaped pattern in the wood. The bark and tissue eventually detaches, and the tree dies.

Since ash is one of the four types of trees that can endure the clay-like soil on campus, many were planted before the arrival of the green parasites.

Ash borers tend to attack trees that are under stress, said Jerry Stevens, SVSU’s assistant grounds foreman. Trees living in less than ideal conditions — such as clay-like soil — are more likely to become infected.

Most of the ash trees are infected now, said Stephen Hocquard, assistant vice president of Campus Facilities.

According to Hocquard, 11 trees on campus recently received treatment. At $30 each, he added that it is not feasible to treat every infected tree on campus. The limitation raises questions of priority.

“If it’s a ditch-bank tree that doesn’t really matter, we aren’t going to treat it,” Stevens said. “But if it’s in a place where it might mean something if it died, like a parking lot, we would.”

During a treatment, a pesticide is injected into tree’s circulatory system, killing any ash borers living inside. Since the discovery of the bug at SVSU, about 55 trees have been treated.

Despite regular treatments (every two to three years), the tree might still die, depending on the degree of the infection at the time of the initial treatment.

It would make sense to treat a tree before it gets infected beyond repair, but Stevens says it’s not always that simple. Sometimes the infection isn’t apparent until the tree’s canopy begins to die back and thin out, which may mean it’s already too late.

Trees that cannot be saved are cut down, but they do not go to waste. Thanks to the tree’s flexibility and wood grain, they are useful in creating products such as baseball bats, tool handles and furniture.

The Michigan Department of Agriculture has put many counties under quarantine, advising vacationers against moving firewood. Experts hope this will prevent the emerald ash borer from spreading.

Owners of infected trees are urged to either treat the tree or eliminate it.

If a person spots the bug or an infected tree, they are encouraged to call the emerald ash borer hotline at 866-325-0023.