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Friday, March 29
The Indiana Daily Student

City fights to save ash trees

In about four years, nearly all the ash trees in Indiana will be dead.

A small, metallic, dark green bug — the emerald ash borer — is to blame. It’s considered “the most destructive forest pest ever seen in North America,” according to a U.S. Department of Agriculture Forest Service and Michigan State University website. The beetle burrows into tree trunks and destroys important tissues. It can kill a tree in four years.

Originally from Asia, the bug traveled to the United States nestled in ash wood used in cargo ships. First detected in Michigan in 2002, it has since spread to 23 states and parts of Canada. The bug was found in Bloomington in 2013.

“We knew it was coming,” Lee Huss, Bloomington urban forester, said. Earlier this year, he spent a month assessing about 700 trees and determining the best action to take for each: let it die, treat it or cut it down.

Despite efforts to save the city’s urban forest, Huss said ash tree loss will be substantial. Dr. Cliff Sadof, an entomology professor at Purdue University, predicted about 95 percent of the ash trees in Indiana’s forests will be dead by 2020.

However, that doesn’t mean there won’t be any more trees on city streets.

Huss said Bloomington doesn’t have a large amount of ash trees compared to other Indiana towns — they make up about 10 percent of the urban forest, which includes street and park trees.

“It’s a hiccup, it’s not catastrophic,” he said.

However, it is expensive.

Many of the ash trees aren’t big, so removal costs aren’t extremely high. Neither are insecticide treatments. As those numbers add up, however, the allotted budget can’t stretch to save every tree.

An insecticide is the only way to save an ash tree from the beetle, Sadof said. One injection can last three years, but it costs $10 per inch of the tree’s diameter — so an ash with a 12-inch diameter costs $120 to treat. While he said saving trees is more cost effective than cutting them down, Bloomington plans to do more cutting than injecting.

Of the roughly 800 ash trees in the urban forest, the city will remove between 450 and 500 and treat 300. Huss said 64 were cut last year, and before December 2015, 194 ash trees are expected to be removed. Injections were administered to 53 trees in some of the “hotspot” areas, Huss said.

Most of Bloomington’s ash trees were planted in the 1980s and 1990s to diversify the maple-dominated urban forest, Huss said. Now, as ash trees are cut down, “aggressive replanting” is happening. The ashes will be replaced by other varieties like honey locust, new American elm and Kentucky coffeetree. That will ultimately increase diversity, Huss said.

“Overall, that’s how we’re making lemonade out of lemons,” he said. “We’re actually introducing more diversity into the forest.”

Most trees will be left to die, after which they will be promptly cut down to avoid injuries or house damage. The city will lose many older, sturdier trees and their benefits.

“You’re going to lose 50 years of shade,” Huss said.

Homeowners are able to treat the ash trees on their property, but they must shoulder the costs. Sadof said he has helped develop apps like the Purdue Tree Doctor, which people can use to diagnose their trees and see what stage of infestation the tree is in. From there, tree owners can decide whether they want to treat them or have them cut down. Huss said next year is the last chance to treat any ash trees that aren’t infested yet.

“Next year is a really critical year,” he said.

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