Single Big Willow Tree
Some 300,000 ash trees in Chicago are at risk of contracting emerald ash borer. // Photo: filmfoto/Shutterstock

Protect Your Trees Against the Emerald Ash Borer

Chicago residents are facing a new threat to their property this year: a beetle that has destroyed more than 10,000 ash trees in the city, according to an article in the Chicago Sun-Times.

Called the emerald ash borer (Agrilus planipennis), the pest is a green beetle native to eastern Russia and Asia, according to, a website run by several states and Canadian provinces to help educate the public. It’s believed that this invasive species was unintentionally brought to the United States in 2002 in ash wood used to stabilize crates during shipping, according to the website.

Some 300,000 ash trees on private property are at risk, the Sun-Times reports. But there are steps homeowners can take to help protect their property.

Identify Your Ash Trees

Because only ash trees are at risk for this disease, homeowners first need to find out if they have any on their property.

Ash trees tend to have rounded or oval silhouettes with a dense canopy, according to Purdue University’s tree identification guide. The branches are located directly opposite each other and have compound leaves, the guide says.

Each leaf is made up of five to 11 leaflets, which are located opposite each other. The bark is light to dark gray, and younger trees have a smooth bark, while older ones have diamond-shaped bark, according to the guide.

Signs of Emerald Ash Borer

It’s nearly impossible for homeowners to detect early emerald ash borer infestations because there aren’t any outward symptoms, according to, a Chicago-area partnership of public and private entities.

Therefore, you may want to contact an arborist to determine if your ash trees can be treated and saved. When people notice they have a problem, nearly 15 to 20 percent of the canopy is already in decline, according to the group, which says that as the tree’s leaves start turning yellow and dropping, more branches die and the lower trunk spouts new shoots.

Protecting Your Ash Trees

Property owners wanting to save their ash trees need to be proactive, recommends If a tree becomes infected, the group suggests several insecticide options. These involve soil injections and trunk injections, which must be applied with the proper quantity and at the right time annually throughout an infected tree’s lifespan.

Removing Infected Trees

Each municipality sets its own rules about removing an infected tree. Chicago doesn’t require a permit unless it’s a parkway tree. Other towns will require you to get a permit before removing a tree on private property, so homeowners should check with their local government before proceeding.

The State of Illinois requires a certification in regards to disposing of emerald ash wood and logs. The arborist who removes the tree must meet the requirements regarding the size of the wood chips created from ground trees and where the infected wood may be disposed.

Replacing Infected Trees

In a move to diversify the city’s trees, the City of Chicago has created an urban tree planting list of possible ash tree replacements. They include the Triumph elm (a hybrid), Princeton elm (genetically bred to resist the disease), the Kentucky coffeetree and the American beech.