In Naperville, Ill., a public-private partnership demonstrates removal isn’t the only option for EAB-infected trees.

Municipality maintenance budgets typically have two line items for trees: prune and remove. Cities often don’t have room in the budget to treat trees with control products, no matter how dire the need, but a public-private partnership in Naperville, Ill., over the last few years proved it can be done and it can save thousands of ash trees.

Naperville, like much of Illinois—and much of the Northeast U.S.—has an Emerald Ash Borer (EAB) problem. This tiny, green insect is lethal to ash trees if it goes undetected and untreated, and Naperville has about 16,000 ash trees on municipal property alone. The pest, which was first identified in the U.S. in Michigan in 2002, is predicted to cause $10 billion to $20 billion in losses to urban forests over the next decade.

Last year, Naperville City Council approved a plan to treat all viable municipal trees with the insecticides dinotefuran, emamectin or imidacloprid. It was no easy decision, but motivated residents, an educated city council and private partnerships made saving trees a better option than removing them.

“One common thing with all elected officials is we don’t like to spend money—especially with unknown outcomes,” says Naperville City Manager Doug Kreiger. “Our city council went to the trouble of learning and understanding the full treatment process and balanced that with the risk of no treatment or across-the-board tree removals. They determined we needed to do what we could to save our urban forest.”

Ultimately, Naperville will spend about $2.3 million to treat its municipal ash trees, says Dick Dubulinski, director of public works. Tree removal would have cost $6 million. The Care of Trees manages soil applications for 14,000 of the city’s trees and another company handles trunk injections for about 2,000 trees.

Having a record of successful treatments was an important piece of the puzzle in Naperville. That came in the form of the city being a part of Valent Professional Products’ Legacy Tree Project (LTP) since 2010. The program provides free insecticide treatments for five years for 150 to 200 municipal ash trees. The goal of the Legacy Tree Project is to build awareness about treatment as an option.

The healthy state of the LTP-treated ash trees over a two-year period helped Naperville officials understand that treatment was an effective option for the rest of the muni trees.

For cities that forgo treatment, their dead ash situations may reach an “exponential phase” in which it’s too late for treatment and reactive tree removal is unsustainable, says Joe Chamberlin a field development manager for Valent. There won’t be a large enough budget to remove dead trees and there are not enough tree contractors to remove them, which has safety implications because dead trees could fall, damaging property or injuring citizens.

That may be the fate for the city of Chicago and many other cities, too.

“I’ve heard it said that we’re going to be an island with the only ash trees around,” says Naperville City Arborist Jack Mitz. “And I think it’s true. If your intention is to save trees, you can’t wait and debate because it will be too late.”

Emerald Ash Borer management options

Removal

• Proactive

• Reactive

Treatment

• Purposes

1. For the service life of the tree
2. To stage removal (so there is not such a large exponential removal cost)

• Effective products

1. Dinotefuran (basal trunk bark or soil application)
2. Emamectin benzoate (trunk injection)
3. Imidacloprid (soil application or trunk injection)

Related

Web Extra: A connection between tree loss due to EAB and negative health effects