As fall's colors emerge, it's hard to miss the striking gold and purple leaves of ash trees lining streets and roads in many Midwestern U.S. states. However, as emerald ash borer spreads, many ash trees planted in towns, cities and conservation plantings are being lost.
First detected in southeast Michigan in 2002, emerald ash borer, or EAB, is an exotic beetle that attacks and kills all native ash species, including white, green, black and autumn purple ash. As of 2018, the beetle was found in 36 states and the Canadian provinces of Ontario, Quebec, New Brunswick, Nova Scotia and Manitoba, where it has killed hundreds of millions of ash trees.
With the help of the U.S. Forest Service, state forestry agencies in many states are engaged in regional initiatives to mitigate and prepare for the insect's arrival.
Symptoms of Emerald Ash Borer include winding tunnels just under the bark, one-eighth inch, D-shaped exit holes on the trunk, as well as canopy loss, usually from the top down. Trees infested with Emerald Ash Borer also may have sprouts growing from the roots or trunk of the tree. Other symptoms include vertical splitting in the bark on the trunk and increased woodpecker activity.
The insect itself is bright, metallic green with a flat back. Adults are typically one-half inch long.
Because Emerald Ash Borer only attacks ash trees, individuals also should be sure the tree in question is an ash and not a similar-looking species.
If a tree is infested with EAB, it must be removed to help prevent the insect from spreading to neighboring ash trees. In urban areas, trees may be near utility lines, homes or other buildings, so it is often best to have the tree removed by a certified arborist.
Reputable arborists should be able to provide proof of insurance and references, as well as written documentation of the work that will be done.
For more information about identifying EAB, visit Emerald Ash Borer.
The impact of Emerald Ash Borer is expected to be similar to the Dutch Elm disease of the 1960s, which rapidly killed millions of trees in the Midwest and dramatically converted lush urban forests to barren, shadeless urban landscapes.