Emerald ash borer (EAB) continues to spread across North America and toward us. The pest was detected this year in Sioux Falls, South Dakota and Winnipeg, Manitoba (see map).

Emerald ash borer was detected in Michigan in 2002 and continues to spread, albeit sporadically in recent years (purple counties). The pest has not been detected in North Dakota (gold) but was detected this year in Sioux Falls and Winnipeg.

Will it spread to North Dakota? Yes. When EAB enters, its presence will be sporadic at first. Our bitter cold winters will slow its spread. We will combat EAB, but this is a powerful pest—it’s killed hundreds of millions of ash trees.

What if EAB came to your town? Would it really make a difference?

Absolutely. Last week I learned about a new tool that can help us understand the potential impact of an EAB invasion. An inventory of trees in public places (for example, boulevards, parks and schools) in 97 small- and medium-sized towns was completed and is available at http://ndcitytrees.org. Click on the ‘Explore Cities’ button to find your town. Privately owned trees were not included in the survey.

This online inventory reinforces our vulnerability to EAB. Ash trees make up over 40% of the public trees in most of these towns. In some towns (Abercrombie, Ashley, Buffalo, Carrington, Cooperstown, Grafton, Langdon, Mayville, McClusky, McVille, Michigan and Rolla), over 60% of their public trees are ash (see aerial photos below). Imagine what would happen if EAB invaded there! It will be devastating—and costly. 

Inventories of trees in Buffalo (left) and Cooperstown (right). Each dot is a tree on public property. Dark orange dots are ash trees. Over 75% of public trees in these towns are at risk of dying from emerald ash borer; greater diversity is needed.

Streets in North Dakota may someday be full of stumps and dying ash trees.

Our vulnerability to EAB calls us to be vigilant in the detection of the pest. First signs include dying back of the crown, lots of woodpecker activity, increased suckering along the main stem, and D-shaped exit holes in the trunk.

Communities are encouraged to increase the diversity of tree plantings. Oak, hackberry, Kentucky coffeetree, honeylocust, corktree, ironwood, buckeye and Japanese tree lilac are examples of good alternatives, depending on site.

For more information, download Emerald Ash Borer Biology and Integrated Pest Management in North Dakota.

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Photos were made available under Creative Commons licenses specified by the photographers: Emerald Ash Borer Information Network; North Dakota Community Tree Inventory/Planning Tool; David Cappaert, Bugwood.org.