Catherine W. Idzerda" />

Advice for battling the emerald ash borer

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Catherine W. Idzerda
Wednesday, June 27, 2012
— The emerald ash borer has arrived in Janesville.

Interestingly, the announcement comes when Phyliss and Bill Williams of K&W Greenery are on a garden center tour in Michigan, one of the centers of the ash borer infestation.

"We are looking around at all the devastation it has caused here," Phyliss Williams said. "It's so sad to drive around and see the stumps and the dead trees everywhere."

Her advice to homeowners? If you want to save your trees, start now.

Q: What kind of ash trees are affected?
A: The borer feasts on green ash (Fraxinus pennsylvanica), white ash (F. americana), black ash (F. nigra) and blue ash (F. quadrangulata). Plants such as mountain ash or prickly ash are not true ash trees and are not affected by emerald ash borers.
Q: What's the easiest way to identify an ash tree?
A: For more information about distinguishing ash trees from other trees, go online to, a website run by the U.S. Department of Agriculture Forest Service in conjunction with Michigan State University, Purdue University and Ohio State University.
Q: Can I save my trees?
A: Williams has been recommending Merit, a Bayer product containing imidacloprid.

Several professional formulations of insecticides contain imidacloprid.

They compete with a handful of other insecticides designed for use by arborists and other professionals, according to

Homeowners, however, can buy and use Merit.

The product is mixed with water and then poured around the base of the tree. The water is a carrier for the chemical, which travels up the tree at a rate of one foot every two days, Williams said.

Professionals can apply the product in other ways, including soil or trunk injections.

UW Extension horticulture educator Mike Maddox said that for best results, homeowners should follow product instructions carefully.

Most insecticides containing imidacloprid recommend applying the product in the spring.

"You can put an application down now and get some level of protection," Maddox said. "For optimal results, I believe it should be put down in spring or late spring."

Maddox recommends homeowners wait until we get some significant rain before applying any product.

"Trees are not taking anything up right now," Maddox said.

The Forest Service recommends that systemic trunk and soil insecticides be applied when the soil is moist but not saturated or excessively dry.

Q: How much will it cost?
A: The cost depends on the size of the tree, Williams said.

The amount of chemical needed depends on the diameter of the tree.

Treating a large tree might cost between $50 and $75 a year, she said.

Homeowners should weigh that expense against the cost of having a professional remove a full-grown tree, Maddox said.

In addition, a mature shade tree can save that much or more on air conditioning, Williams said.

Homeowners who want to protect trees with trunk diameters of 15 inches or more might want to consider having a professional apply the pesticide, according to university specialists at

Q: Is there anything else to consider?
A: Consumers should exercise care when choosing a tree specialist, especially if they need to have trees removed.

"There's no need to just go crazy," said Mick Skwarok, plant pest and disease specialist with the state Department of Agriculture, Trade and Consumer Protection.

Legitimate pesticide dealers or tree care professionals will say there's not much point in chemical treatment now because trees aren't taking up water like they do in spring, he said.

"Time is on their (consumers) side," he said. "They've got time to make a few phone calls, do some research, get some quotes."

He equates the task to finding a contractor to shingle your roof.

He has responded to calls from residents planning to cut down trees they suspect are infected only to find the ash borer is not the cause. The trees might look bad and have problems, but emerald ash borers aren't necessarily to blame.

"Not everybody who can operate a chainsaw (or) inject a chemical into your tree knows what EAB looks like," he said. "It really does pay to do homework. If it's not emerald ash borer that's infecting the tree, there might be some remedy that doesn't involve Husqvarna, Stihl or some other chain saw manufacturer."

Chris Ranum, owner of L.P. Tree Service, reminded consumers that state law requires homeowners receive a document stating what product was used on a tree, how much of the product was used and for what the tree was being treated.

Homeowners always should ask for proof of general liability insurance and workman's compensation insurance.

"This shouldn't come out of a folder in the guy's hand," Ranum said. "It should be faxed or sent to you from the insurance company itself, and it should have your name and address in the lower left hand corner."

American Family Insurance Agent David Pierce agreed.

"You want something that shows that the business' insurance is current and active," Pierce said.

His formula?

"You want someone who is local, reputable and insured," Pierce said.

Last updated: 8:42 pm Thursday, December 13, 2012

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