The Wake

As you’re walking across campus take a look around you.

Among the multi-million dollar buildings sustained by poor college students, you’re bound to find one or two lined along the sidewalks or clustered on the mall.

And while many of you are thinking of those bushy-tailed rodents, I’m referring to something a bit more unnoticeable.

Trees make up only a small part of the University of Minnesota campus and yet they add so much to the university atmosphere. Their beauty stands through the seasons and they have seen students come and go for decades. But some trees are meeting an early demise due to an incurable disease known as Dutch Elm.

University land care officials says this year has been one of the worst – 30 elm trees were cut down because of the disease and one or two more are still planned to come down before the end of the fall.

Typically only four to six trees are lost to the disease each year.

“It’s a heartbreaker,” Doug Lauer says, a university land care supervisor. “It takes 50 to 100 years to grow some of these trees and even if we replace them, I’ll never get to see them again.”

Dutch elm disease is caused by a rapidly reproducing fungus that infects the tree and prevents nutrients from circulating to where they’re needed.

Think of it as a clogged artery. The more cholesterol in the system, the more likely it will become jammed and cause problems. Similarly for elms, as the fungus grows it blocks more nutrients and the tree withers and dies. Spread by a small beetle, which uses the tree to house its eggs as well as to feed on the leaves, fungus becomes attached to their bodies as they move or burrow through an infected tree. When the beetle moves to a new tree, so does the fungus.

So shouldn’t we just deal with the bugs?

“Using insecticides on the beetles isn’t very effective,” Lauer says. “The environmental impact on people and the university makes it too hazardous.”

While only infecting elms, the university has taken precautions to protect the trees it has and to deal with the ones that show signs of infection. A chemical treatment called Arbotect has been injected into elms across campus on a three-year basis, he says.

Used by the university for the last 10 to 12 years, the chemical has protected some elms from getting the disease while slowing down the rate of infection in others.

“The trees we’re losing [this year] have been treated trees,” Lauer says. “Normally we only lose one or two treated trees so this has been an exceptionally rare year.”

Arbotect is used on roughly 80 trees each year and costs the university about $300 dollars per injection, he says. So losing just one of these trees is like losing an investment.

However, not every tree infected with the disease has to come down. Usually the infection begins in the outer branches. If ground caretakers can spot signs of infection early an infected limb can be pruned and the tree has moderate chance to recover. Unfortunately by the time most signs are noticed the disease has developed into the trunk, he says. If it reaches the trunk the tree has to come down.

“The longer you leave a tree in an infected state, you’re fostering the disease and the beetles that carry it,” he says. “The sooner you get the infected tree out of there, the better the surrounding healthy trees will be.”

While many trees are being cut down, a different elm hybrid called Cathedral has been used to replace lost trees. The hybrid has shown resistance to Dutch elm disease and if kept in a healthy state can shield it from infection.