Brookfield’s village board will soon begin grappling with how to pay to combat a new threat — to the village’s tree stock.

Officials confirmed last week that the emerald ash borer, which was discovered in Riverside at the very end of 2011, officially made its presence known in Brookfield in mid-2012. Since then, according to Public Works Superintendent Dan Kaup, the forestry department has compiled a list of 32 trees slated to be removed because of the pest.

Those slated for removal were “actually dying from the disease,” said Kaup.

The first tree displaying hard evidence of the pest’s presence, he said, was located in the 9500 block of Washington Avenue in June 2012.

“Since then, staff and contractors have found it throughout the village,” said Kaup.

Brookfield’s 1,200 to 1,300 ash trees make up about 15 percent of the village’s public tree stock. While the trees can be found all over town, the heaviest concentration is in the northwest part of the village, in an area bounded by 31st Street, Maple Avenue, Washington Avenue and Kemman Avenue.

The youngest of the specimens in town, at least on public lands, is about 13 years old. Brookfield forestry crews have not planted an ash tree since about 2001, according to Kaup.

With the prospect of more ash trees dying from emerald ash borer infestation, Kaup is drafting a management plan that includes educating the public, tree removals and reforestation. The plan will be submitted to the village board later this month for discussion.

In addition, by the end of the month, he plans to have completed an application for a $10,000 grant from the Metropolitan Mayors Caucus to help the village mitigate the effects of the emerald ash borer.

“Right now, I’m finishing up the document, and [Village Manager] Rick Ginex will present it to the board at their next meeting,” said Kaup. “The board will have to decide on what the village’s policy will be.”

There are two different approaches to combating the spread and expense of an emerald ash borer infestation. One path, which is the policy of neighboring Riverside, is aggressively taking down trees where the pest has been identified and also removing nearby ash trees to prevent the spread of the pest.

This choice allows villages to take down trees at their own pace and manage the cost over a longer period of time. Municipalities choosing this approach believe that the pest is basically unstoppable in the long run, and that it’s easier and cheaper to deal with the problem now than wait years in the future.

Other municipalities, such as North Riverside, have chosen to treat its public ash trees with an insecticide. So far, emerald ash borer hasn’t made an appearance in North Riverside.

But treating 1,300 trees — it must be done each year — can be expensive. And in any case, the trees will have to be replaced eventually.

While the village board has the final say on the pace of cutting down trees, Kaup appears to be leaning toward recommending pro-active tree removal. His reasoning? If the village now has proof positive of an emerald ash borer infestation, the pest likely has been in the village for years and has already begun to inflict widespread damage to ash trees.

In order to control the cost of removing ash trees, Kaup said he would use in-house forestry staff to cut down 75 ash trees per year, providing that the trees have begun to show signs of dying back.

While the village may be able to save money by having tree removal done in-house, it will still be expensive to plant trees to replace those taken down. Planting 75 new trees per year would cost about $30,000. That cost, however, can be mitigated by obtaining grants, like the one Brookfield is applying for this year.

“We’re going to have to look at different places to pull funding,” said Kaup, noting that Village Forester Scott DeRoss will be conducting a village-wide tree survey, rating the condition of each public ash tree in Brookfield from 1 to 5. Any tree rated 3 or higher will be put on the list for removal, said Kaup.

The forestry department has also come up with a list of 16 tree species to assure a diverse tree stock moving forward. The list includes such species as the Accolade elm, three species of oaks, bald cypress, horse chestnut, tulip tree and others.

“Part of the reforestation plan is ensuring an adequate range of species to replace the diseased species,” said Kaup. “All of these do well in an urban environment.”

CLARIFICATION: The emerald ash borer was found infesting a tree in Riverside in December 2011. But the first time an emerald ash borer insect was discovered in Riverside, inside a purple trap in one of the village’s wooded areas, was in May 2010.

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