Mayor Rahm Emanuel and the Department of Streets and Sanitation (DSS) announced today a 93 percent survival rate for Emerald Ash Borer (EAB) retreatment for Ash trees treated in 2011 and 2012. DSS inoculated 5,400 Ash trees in 2011 and 2012, and of those previously treated trees, 93 percent or over 5,000 trees remain viable parkway trees and accepted EAB retreatment this year.

“The Emerald Ash Borer treatment program is a common sense investment in Chicago’s parkway trees,” said Mayor 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 EAB treatment, TREE-age, became available in 2009. TREE-age utilizes emamectin benzote to inoculate Ash trees, which has been proved to kill 99 percent of Emerald Ash Borer insects within a tree. An Ash tree receives a self-contained injection into the vascular system of the tree, which then pulls the treatment throughout the base of the tree up to the canopy. This treatment method will kill existing pests as well as prevent new infestations for two to three years. Retreatment needs to be applied after two years to continue to protect the Ash tree against EAB. The average cost to inoculate a tree is $46, compared with $1,000 to remove and replace a tree.

DSS treated a small percentage of Ash trees from 2009 to 2012, but it was not until Mayor Emanuel invested in a dedicated workforce for EAB injection in 2013 that all viable parkway Ash trees would be inoculated by fall 2014. As part of the multi-year inoculation program, over 37,000 viable Ash trees were inoculated in 2013 and all remaining viable Ash trees will be inoculated by fall 2014. Additionally, all Ash trees treated prior to 2013 received a retreatment through the dedicated workforce with 93 percent of Ash trees treated in 2011 and 2012 remaining viable.

“Mayor Emanuel’s continued investment in a dedicated workforce for EAB inoculations has shown to have a positive impact on slowing the progression of the insect and manage tree mortality,” said Commissioner Charles Williams. “The positive success rate in EAB retreatment is encouraging, and the Department looks forward to completing the remaining inoculations of all viable Ash trees this fall.”

The Emerald Ash Borer is an exotic beetle native to Asia that was discovered in southeastern Michigan in 2002. The beetle has killed over tens of millions Ash trees in southeastern Michigan alone, with tens of millions more dying in Illinois, Indiana, Wisconsin and eighteen other infested states.

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