By Joe Zeleznik, Forester

NDSU Extension

In case you missed it last week, emerald ash borer (EAB) was found in Bismarck, North Dakota. City crews were removing some declining ash trees and noticed the telltale signs of EAB – serpentine galleries beneath the bark and D-shaped exit holes. The arborists looked closer and found the insect itself.

Bummer.

EAB is a very destructive pest, and its impact on North Dakota will be big. That’s pretty vague, so let’s look at EAB “by the numbers.”

Three: the number of North Dakota counties with known EAB infestations. The first find was in LaMoure County in August 2024. No new infestations were found in 2025, but both Cass and Burleigh followed this year.

90 million: the estimated number of ash trees in North Dakota’s native forests, shelterbelts and urban forests. There’s a lot at stake.

22%: Bismarck’s current population of boulevard ash trees. Since 2008, the city forestry department has worked hard to reduce the percentage of ash trees by removing those in poor condition or those in poor locations. In 2008, 36% of Bismarck’s urban forest was ash trees.

Up to 80%: the amount of boulevard ash in some communities in North Dakota. The cost to remove and replace those trees will be substantial. Many communities have already begun diversifying their urban forests, but some have not. Find out more about your community’s urban forest via the ND Tip Tool, courtesy of the North Dakota Forest Service: https://ndcitytrees.org/NorthDakota/.

$950,000: the amount of funding allocated by the North Dakota legislature for communities to prepare for emerald ash borer. The funds were distributed via a grant program managed by the North Dakota Forest Service. It’s unknown if funding for these efforts will continue.

250-plus: the number of EAB traps placed across the state by the North Dakota Department of Agriculture. Traps have been placed every year since 2008 in high-risk areas such as campgrounds, rest areas and large rail yards. While EAB will spread only about one to two miles per year on its own, long-distance spread mainly occurs through the movement of firewood and through wood packing materials.

$5,000: the fine for moving firewood out of a quarantined county. Quarantines are set by the North Dakota Department of Agriculture; a map of quarantined counties is available at https://www.ndda.nd.gov/eab.

Two to three years: the duration of protection against EAB provided by injections of emamectin benzoate, a highly effective insecticide. The insecticide must be injected, most often by a professional. Injections are pricey but highly effective for two years, sometimes three.

Approximately 40%: the maximum amount of canopy dieback that an ash tree can suffer due to EAB and still respond to injections of emamectin benzoate. This measurement is approximate – sometimes, a tree with 40% dieback won’t recover, even with a timely insecticide treatment.

15 miles: the distance from an EAB find, where injections are recommended. Another way to look at this is that injections are not recommended unless EAB has been found within 15 miles of your location. It might take 10 years or more before EAB reaches your area, and giving unnecessary treatments can be a waste of both time and money.

Emerald ash borer is in our state, and it’s not going away. Prepare your own yard, farmstead or community for this pest.

NDSU Extension has more information about EAB biology and its management: ndsu.ag/EAB-26.

Managing EAB in communities has its own challenges, and NDSU Extension has information to help prepare your town: ndsu.ag/EAB-community.

NDSU Agriculture Communication – Sept. 2, 2026

Source: Joe Zeleznik, 701-231-8143, joseph.zeleznik@ndsu.edu

Editor: Dominic Erickson, 701-231-5546, dominic.erickson@ndsu.edu