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Emerald Ash Borer Target of $2.6 Million Plan to Save City Trees

By Patty Wetli | April 24, 2013 2:24pm

ROSCOE VILLAGE — The city's efforts to combat the deadly emerald ash borer received a shot in the bark Wednesday with the announcement of $2.6 million in resources to treat endangered ash trees in Chicago parkways.

The funds will not only cover the city's plan to inoculate 35,000 trees in 2013 — double the total number treated since 2009 — but will also provide for seven forestry crews to conduct basic tree trimming and maintenance services.

According to Streets and Sanitation Commissioner Charles Williams, the emerald ash borer threatens approximately 85,000 of the city's parkway trees or 17 percent of the public tree canopy.

Treatment of the ash trees — which provide cooling shade, intercept stormwater and filter airborne pollutants — is expected to begin in early May and last through September. The city has already surveyed its inventory of ash trees and created a grid to identify areas in need of service, which will be tackled on a four-block-by-four block basis, according to a Streets and Sanitation spokeswomen.

John Lough, senior forester, demonstrated the technique that will be used to inoculate the trees. Working in the parkway in the 2100 block of West Roscoe Street, he drilled a series of holes at the base of an ash and injected the chemical Emamectin Benzoate into the cavities. Trees with larger trunks will require an "IV"-style method of chemical transfusion.

The chemical was first tested and proven effective on trees along South State Street, site of the initial emerald ash borer infestation in Chicago, said Mike Brown, assistant general superintendent of the Bureau of Forestry.

The average cost to inoculate a tree is $46, compared with $1,000 to remove and replace it, according to Streets and Sanitation.

The treatment has been shown to last for three years, said Brown, at which point trees will require a booster shot. Trees inoculated in 2013 will be tagged with a red medallion that's been stamped with the year — different colors will be used in subsequent years to easily identify when trees are ready for their three-year booster.

Emamectin Benzoate is not commercially available to the general public, Brown noted. Homeowners with ash trees on their private property should contact a certified arborist to inoculate their trees.

The city ceased planting ash trees in 2003 when the emerald ash borer beetle was first discovered in Chicago. The Bureau of Forestry has since opted for lindens, maples and oaks as substitutes in the parkways, Brown said.

Brown will be among the speakers Wednesday night at a public forum on the emerald ash borer. The information session is scheduled for 7 p.m. at Lane Tech High School, 2501 W. Addison St.