Trees . . .

The sight of workmen cutting down an elm near the Green and the prospect of a cold winter recently prompted us to ask if we might, as a public service, toss a few of the logs in the back of our truck and cart them home. We talked with Bob Thebodo, tree warden for the town and the College, who explained why scavenging wood infected with Dutch elm disease is discouraged: The beetles carrying the disease will infect healthy trees near a woodpile. He also described what is being done to combat "a very extensive problem, a serious epidemic."

The College's elm-maintenance program has been in operation since the 1950s, Thebodo said. Right now he is looking after 212 elms on the campus plus about 100 more on adjacent town property. "We're doing everything we know of that there is to be done," he noted, "and although we've been quite successful, considering what we're up against, it's an endless and expensive effort."

"We spray in the spring to kill beetles, the carriers of the disease, but you have to do more. We used to spray DDT, but of course that's out now and the sprays aren't quite as effective. If your sprays are off by a week or two, the beetles spread and you have a bigger problem. The disease is caused by a fungus, Ceratocystis ulmi, so besides spraying we also use fungicides. We even use fungicides as a preventive treatment. Recently we experimented with something new. We made an air survey of the area using infrared to try to detect the healthy trees. If we can keep the healthy trees strong, they'll be able to withstand the disease better."

Thebodo explained that the beetles themselves are actually harmless until they are inoculated with spores from an infected tree. Beetles carrying the spores "innocently" deposit them while feeding. The spores germinate and spread through a tree's vascular system, choking off nutrients and water. Once a tree is badly infected it must be removed and the wood disposed of in order to prevent contamination of neighboring trees.

No cure for the disease has been developed, but the maintenance program seems to be keeping the destruction of elms around campus in check. "A good percent age of the large elms are surviving quite well," Thebodo pointed out. "Elms grow quickly. Some of the trees we've cut down have had four-inch annual growth rings. The very large trees we've had to remove near the Green were less than 100 years old." He added that "every elm we cut down we replace. We don't always replace it with another elm but we put a new tree in. Maybe I should say we replace almost every tree. With sidewalks, construction, underground power lines, and pipes we're running out of viable planting spaces."