A Tale of Two Cities: Emerald Ash Borer

Photo: The  Davey Tree Expert Company

Photo: The Davey Tree Expert Company

Maybe you’ve heard of it. Emerald Ash Borer is wreaking havoc on ash trees around a large chunk of the country, including Minnesota.

The emerald ash borer (EAB) is an exotic beetle from Asia that was first discovered in the U.S. near Detroit in the summer of 2002.

While the adult beetles that nibble on ash foliage cause very little damage, it’s the larvae that feeds on the inner bark of ash trees that disrupt the trees ability to transport water and nutrients.

Although it can take years to build EAB populations large enough to infest entire trees, once an ash tree is infested it has almost no chance of survival.

The EAB spreads quickly and sadly, there is evidence of it in the Twin Cities metropolitan area.

What’s more, there are plenty of ash trees all over the Cities. In fact, there are close to one billion ash trees in Minnesota! Many of the trees infested with Dutch Elm Disease in the Cities in the 1970s and 80s were replaced with ash trees. Now, it’s a different infestation in a different type of tree, but similar situation.

So what are cities doing about it?

Emerald Ash Borer has not yet hit Columbia Heights, although the city started thinking about their EAB management plan in 2011.

We spoke with Kevin Hansen, Columbia Heights Director of Public Works and Gail Nozal, Area District Manager of S&S Tree and Landscaping Specialists, who outlined what they are doing.

First, the city took an inventory of ash trees on public land and created a ranking based on the tree’s condition and location.

Out of the 1,000+ ash trees on public land, they deemed about 500 to be of low quality and in a bad location. These trees will be removed over a three-year timeframe, with each removed tree being replaced with a different type of tree.

The approximately 500 trees deemed high quality will be saved over the same three-year timeframe.

The city is contracting with S&S Tree and Landscaping Company to treat these trees with an insecticide that has been shown to be highly effective when used before EAB damage is visible.

Photo: The  Davey Tree Expert Company

Photo: The Davey Tree Expert Company

The city is using a trunk-injection application method for the insecticide, with the first treatment of 120 trees taking place this past June, a time when trees are photosynthesizing and respirating.

The fate of ash trees on private land in Columbia Heights is the responsibility of the homeowner. A homeowner can treat an uninfected tree at their own expense.

The City of Minneapolis, on the other hand, is taking a different approach.

Photo: Minneapolis Park and Recreation Board

Photo: Minneapolis Park and Recreation Board

You may have noticed green ribbons around ash trees on public lands. Those ribbons are there to educate and increase awareness of EAB, which was found in the city in 2010.

The city’s plan, according to the Minneapolis Park and Recreation Board website, is to remove and replace all ash trees on public land, even before the trees become infested. The spread of the disease cannot be stopped and is going to kill all the ash trees at some point.

According to the city, waiting to remove ash trees until they become infested is not an option because the trees will die in such large numbers that it will not be possible to keep up with removal and replacement. After all, there are about 30,000 ash trees on boulevards across the city and an additional 10,000 on park properties. 

Ash trees found on private property in Minneapolis are the responsible of the homeowner, just as in Columbia Heights.

Of course, EAB is a concern in all cities across the metro and other parts of Minnesota. This gives you an idea of just two city’s approach to the impending problem.

For more information on Emerald Ash Borer and to see where it is in Minnesota and other states, check out EmeraldAshBorer.info

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