Greenfield and West Allis ready themselves for the inevitable ash borer

Tree replacement will be the likely outcome

June 5, 2012

Both Greenfield and West Allis are bracing for the onslaught of a tree-killing beetle that has already denuded U.S. communities elsewhere of its ash trees.

The devastating emerald ash borer has been found in Franklin only two blocks from Greenfield's border, so it's undoubtedly already in the city, said Greenfield forester Dennis Fermenich.

"Wherever it has been found, entomologists almost always estimate that it was there five to seven years before they found it," Fermenich said. "Odds are, it's in Greenfield."

West Allis forester Michael Rushmer also said there is virtually no chance West Allis will escape the menace. When it will come is still anybody's guess, but the result is less in doubt, he added.

"It wipes everything out," in terms of ash trees, Rushmer said.

The valued ash tree

Both foresters estimate that almost one out of five trees in their communities is an ash.

Ash trees have been a tree of choice for most communities for decades. It grows quickly to afford both beauty and shade and it enjoys robust health.

"It's tough as nails," Fermenich said.

Until recently, Greenfield had about 1,200 ash trees on public land, he estimated.

In West Allis, Rushmer pegged the number of ash at about 4,400.

Both foresters are both bracing for the onslaught of the tree killer.

Keeping Greenfield green

Since the emerald ash borer was discovered in Michigan in 2002, Fermenich has been cutting down unhealthy ash trees and replacing them with other types of trees. He said he hopes by the time the ash borer hits in Greenfield, those new trees will be big enough to reduce the impact of now healthy ash trees lost to the borer.

Of particular concern in Greenfield are three neighborhoods where ash trees line all the streets. In those neighborhoods, Fermenich is planting a different type of tree alongside the ash trees, which won't be removed unless they fall victim to the killer beetle or otherwise become a hazard.

"I'm not going to cut a healthy tree," he said. "I don't want a stripped sun-drenched community."

Greenfield has also taken another proactive approach: No ash trees have been planted along streets or in parks since 2002, and the city hasn't allowed ash to be planted in new developments since then, Fermenich said.

Similarly, Greenfield's normal policy of making every effort to save even questionably healthy trees when roads are redone is shelved for ash trees. If they are unhealthy, they are being cut down and replaced with trees that the ash borer won't kill.

Fermenich said if a high-quality ash tree is involved, the city will look at protecting it through trunk injections.

Those injections are extremely effective, but represent a cost that may have no end, which is why Greenfield is not relying on them, he said.

Greenfield is in a better position than some other communities because its ash trees are generally not as mature and are easier and less expensive to remove, he said.

A mature problem in West Allis

But in West Allis, like Milwaukee, the ash trees are big. Because a cutting program would be extremely expensive and destructive, the city is treating their ash trees.

Last summer, West Allis started injecting larger ash trees and giving a soil treatment to smaller ones. Although not as effective as trunk injections, the soil treatments are still considered useful.

The city will continue the treatments this summer, Rushmer said.

The treatments will buy West Allis some time. However, the city's battle plan is ultimately the same as Greenfield's: thinning and replacing.

"We want to stretch out removal and replanting over a longer period of time," Rushmer said. "We could not contend with the death of 4,400 trees within a period of a couple of years, so we're trying to reduce the immediate impact."


Here are signs of ash borer damage, according to foresters:

The tree is producing a lot of new short stems, known as suckers, lower on the trunk

Woodpeckers are pulling off pieces of bark trying to get at the damage-causing larvae

The trees crown is dying back

A "D" shaped exit hole is left by the larvae making their way out of the trunk

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