An emerald ash borer larva. | Sun-Times Media file
Updated: April 11, 2013 6:37AM
HOFFMAN ESTATES — There remains no national strategy for dealing with the emerald ash borer, the most destructive of the 475 invasive forest insects that North America has seen in the last 300 years.
That was part of the message delivered Thursday by Deborah McCullough, professor of entomology and forestry at Michigan State University, during a conference at Northern Illinois University’s Hoffman Estates campus.
According to McCullough, as of last count, the pest has made its presence known in 18 states and two Canadian provinces. In Michigan alone, the EAB has claimed 60-70 million ash trees, she noted.
“It’s taken so many, they’re not counted anymore,” McCullough said.
McCullough presented information stating that borer infestation issues are costing local levels of government $850 million and households $380 million in property value losses and another $350 million in treatments and/or tree removals annually. The federal government allotted $38 million to fighting the ash borer last year and has committed significantly less this year, McCullough said.
According to a report provided by the NIU Institute for Work and the Economy which hosted the symposium, “The Illinois Department of Agriculture estimates that there are as many as 4 million ash trees in the Chicagoland area and that all of the trees will be exposed to the EAB within the next few years. The tree care industry in public accounts estimates that it will cost more than $4 billion to remove and replace these trees over the next 10 years. Ash trees are found throughout Illinois. They were commonly planted in residential areas and often constitute as much as 20 percent of a municipality’s tree stock.”
Looking at the approaches taken in several Chicago area towns and in Milwaukee, the NIU brief states, “There is no one-size-fits-all answer for all instances when the ash tree population is still salvageable at the early stages of infestation.”
Came from China
Scientists believe the insects first appeared in North America through wooden packing material shipped from China into the Detroit-Windsor area in 2002. Most likely carried in by people bringing firewood from Michigan, the insects spread across the country.
The ash borer beetles lay eggs inside a tree, starve the tree of its nutrients, and leave it for dead in a state potentially dangerous to people and property.
According to information from Scott Schirmer of the Illinois Department of Agriculture, the EABs were first detected in the state in 2006 in Lily Lake/St. Charles, Wilmette, Evanston, and Winnetka. Currently there are 237 impacted communities, including 39 first-time confirmations last year.
As of 2013, the EAB has been confirmed in 27 counties Illinois, 41 within a quarantine zone.
Current IDA estimates have 25 million dead or infested ash trees in Illinois, representing 20 percent of all ash trees here. About 40 percent of the state is quarantined and holds about 20 percent of all the state’s ash trees.
For her part, McCullough has been involved researching the emerald ash borer since 2002, when scientists were pretty much starting from scratch.
“There were no (scientific) papers at the time,” she said.
What’s been learned since is these borers prefer stressed ashes and ones standing open in the sun. Black ash is the insect’s preferred and most vulnerable host; green is preferred over white when both are present, and white is preferred over blue ash — the type McCullough said will likely survive the emerald ash borer invasion.
The borers also are extremely tough to find and often are first noticed when woodpeckers feast on them. Professor Fred Miller of Morton Arboretum in Lisle noted that it can take years to notice the EAB impact on tree canopies, with tree mortality slow at first then increasing exponentially.
McCullough and other presenters noted that several chemical treatments available on the market are meeting with success in battling the EAB. Her research thus far shows the best results for a product called Tree-äge, with the active ingredient emamectin benzoate.
McCullough created a predictive model for a neighborhood holding 2,300 ash trees. Over a decade, it would cost the area about $2 million to remove all the ash trees, which would be killed by the bug over that time or about $365,00 to treat just 20 percent of the trees, with a loss of 10 percent of the trees.
According to information provided by Morton Arboretum for the conference, the EAB was confirmed in Northbrook in May 2010, where Tree-äge is being used to manage the problem.
“Ash trees represent about 20 percent of the village’s 15,130 parkway trees. The village developed a proactive, multi-faceted management plan in 2010 that included surveying village-owned ash trees, treating a portion with insecticides, and removing and replacing dead or dying trees. About 730 declining ash trees will be removed and replaced, and 268 ash trees will be treated with the insecticide Tree-äge (emamectin benzoate) for the next four years (2011 through 2014), with a total projected cost of $426,500,” the document states.
According to Elgin Parks Superintendent Jim Bell, a tree inventory completed in 2011 found the city had 6,789 ash trees on public land. Bell said that as of December 2012, 2,152 had been removed, 1,694 were under treatment and 2,943 ash trees still need to be removed.
“Elgin’s emerald ash borer infestation is severe,” Bell said. “Basically, if the tree is not under treatment, it is infested with the insect.”
Brian Borkowicz, district manager at The Davey Tree Expert Company office in East Dundee, noted that ash account for about 18 percent of Elgin’s trees, and that the city is using an integrated approach battling the bugs.
“Towns need help on the financial side,” Borkowicz said.
Noting the roles trees play in everything from quality of life to controlling stormwater runoff, Borkowicz said he wasn’t sure if those in position to provide such aid are hearing that message.
“It’s like one of the presenters said — you address this on your schedule or the insects’ schedule,” Borkowicz said. “By putting it off, you won’t gain a thing.”