Preventative emerald ash borer treatment saves 5,000 ash trees in Chicago
As the invasive ash-tree destroying emerald ash borer makes its way across the country devastating ash trees, at least one Midwest city has managed to stave off the bugs and preserve thousands of mature trees.
A city of Chicago program to save the city’s ash trees from emerald ash borers has preserved about 93 percent of the ash trees treated with chemicals that kill insects on the tree, according to Mayor Rahm Emanuel's office.
Of the 5,400 ash trees treated and re-treated in 2011 and 2012, the mayor's office says 5,000 remain “viable parkway trees and accepted (emerald ash borer) re-treatment this year."
Emerald ash borer beetles (EAB) likely entered the U.S. via wood products delivered to Detroit from China in the late 1990s. Tree services and aborists noticed the devastating effects of the insect in 2002, and since then it has been found in 20 states, including Illinois, according to the U.S. Department of Agriculture.
How the tree treatment program works
“The emerald ash borer treatment program is a common sense investment in Chicago’s parkway trees,” says Emanuel. “By providing a dedicated workforce for ash tree inoculation in 2013 and 2014, we are protecting the viability of our ash tree population for many years to come.”
The city treats ash trees with TREE-age, an insecticide injected once every two to three years into the tree's base at a cost of about $12 per diameter inch. TREE-age contains emamectin benzoate, which is highly effective at killing the emerald ash borer and other insects that live in trees.
The average cost for the city to treat an ash tree with TREE-age is $46, while tree removal and replanting averages about $1,000 per tree, the mayor's office says.
City of Chicago Department of Streets and Sanitation crews have inoculated about 37,000 additional ash trees since 2013 with initial treatments on the remaining trees to conclude this fall.
The USDA predicts 17 million ash trees will be affected by ash borers by 2019, and it will cost $10.7 billion for insect treatment or tree removal and replanting.
Related: How to spot EAB tree damage