A battle plan for fighting the Emerald Ash Borer

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May 7, 2012 // UPDATED 11:07 am - May 7, 2012
By: Drew Kerr
Drew Kerr

Dan Gustafson isn’t ready to give up the ash tree outside his northeast Minneapolis home — at least not yet. 

So even as officials urge homeowners to consider removing and replacing their ash trees, fearing all will be lost as the Emerald Ash Borer eats its way through the Minneapolis canopy, he will let it stand. 

Instead, Gustafson will have it treated using a chemical designed to stop the invasive species from consuming the tree, as they have done in other parts of the Twin Cities and around the country. 

“We want to keep it around a little bit longer, just because it’s so huge,” Gustafson said recently as crews trimmed the tree and prepared it for treatment. “That’s the great thing about this neighborhood — we have so many giant trees. I’d hate to lose them.”

Local arborists and city officials say that ash trees like Gustafson’s face an increasingly uncertain future, however. And while residents can treat their trees hoping to stave off the Borer, the reality is they are likely too widespread to be stopped, and that treatments may come too late, they say. 

Because their presence often takes years to detect, officials remain uncertain about just how many trees may be infected. But Borers were discovered in St. Paul’s St. Anthony neighborhood in 2009, and in Prospect Park in 2010. 

The discoveries led officials to tear remove the trees and impose a ban on transporting ash wood outside of Hennepin County. 

Borer larvae — bright, metallic green, about a half-inch long when full grown — destroy water and nutrient absorbing tree tissue, essentially starving it. Signs of infestation typically appear at the top third of the tree and include woodpecker damage, canopy dieback, exit holes, curved galleries and split bark. 

And while treatments are available, arborists say they only work before an infestation becomes too severe, and that homeowners who apply the chemicals could be doing greater damage to the surrounding environment. 

Because of the potential for surface and groundwater contamination and unproven results, the Minneapolis City Council passed a resolution in 2010 urging residents to refrain from using insecticides on their property.

The resolution urges residents to instead replace ash trees with other species.  

Jim Walsh, a master arborist with Vineland Tree Care, said he agrees with the city’s stance. He says homeowners who are worried about losing their ash trees should think less about how to save it, and more about whether it’s worth the effort at all.  

“The discussion often comes down to how to treat a tree, and that’s not the smart place to start,” he said. “The smart place to start is to ask how important are my trees to my property.”

For those attached to their ash trees, though, the decision to remove them can be difficult. 

Matt Dosser, the owner of Matt’s Tree Service, said residents he’s worked with are evenly split on whether to treat or replace their ash trees. While there are issues of sentimentality, owners also look at costs, he said. 

Treating a tree can cost between $100 and $400, depending on its size, while replacement can cost anywhere from $150 to $4,000, depending on the size of the tree and its location. 

“If the cost of removal is similar to the cost of treatment, people tend to just go with removal,” Dosser said. “It’s an economic decision in a lot of cases.”

The question over what to do is still lingering in many communities who worry about losing their tree canopies and with it the charm of their neighborhoods. 

Leaders with the East Calhoun Community Organization are among those still deciding what to do. The group began a task force to address solutions last year, and is meeting monthly to determine what actions to take. 

“We’re wanting to be proactive, learn as much as we can so we can present the information to the neighborhood and help people make decisions that have the most positive impact for the entire neighborhood,” said Nancy Ward, who leads the neighborhood’s tree task force. 

The effort to figure out what to do is being driven by a fear of losing large blocks of ash trees simultaneously. In other parts of the country where Borers have been found, entire blocks have been stripped of their ash trees. 

Losing ash trees at once would have a significant visual impact in Minneapolis, where officials have counted nearly 36,000 ash trees on public rights of way lining city streets. 

Ash trees served as a fast-growing replacement for elms, wiped out by disease in the 1970s, and account for around 19 percent of the total boulevard trees in the city. The numbers do not include private trees or trees in city parks.  

A large number of the boulevard trees, primarily located between the curb and sidewalks, are in southwest Minneapolis. Lynnhurst has 880 ash trees on public boulevards, while Fulton has 762 and Linden Hills has 598, according to the city’s latest estimates. 

The city has opted to remove and replace such trees as they encounter them on public works projects. 

In 2010 and 2011, Minneapolis public work crews removed around 2,000 ash trees, replacing them with other varieties. Another 350 ash trees had been removed between January and early April 2012.  

City officials opted for the gradual replacement in part because of resources, but also because they don’t want to wipe out an entire block at once. 

“That’s kind of shocking approach, and it’s not very user-friendly,” said Ralph Sievert, the forestry director for the Minneapolis Park and Recreation Board. 

While the Borer’s impact may be hard to see now Sievert, said residents are rightfully alarmed, and should be doing whatever they can to prepare. 

“I don’t think a lot of people are aware of what may be coming,” he said. “But anything you can do to get out in front of the problem ahead of time means there will be 

less to deal with come 

crunch time.”