I suspect that many North Dakotans have little or no memory of the extensive mortality wrought by Dutch elm disease. Carried by the elm bark beetle, that fungal disease devastated elm trees across the United States. Elm trees, once abundant and widely distributed in North Dakota and highly valued as an ornamental died by the thousands, mostly in the 1970s.
Something similar may occur with ash trees and the emerald ash borer. It was first documented in Michigan in 2002, and has now been documented in North Dakota in Edgeley (LaMoure County) in August 2024, followed by Fargo (Cass County) of this year. Symptoms, such as the dieback of branches or woodpecker damage (a “D” shaped hole in the bark) may not be observed until the tree has been infected for three years or more. So, it is likely new cases will soon be discovered.
Green ash is probably the most abundant and widely distributed tree in the state, and is the dominant tree in woody draws of the badlands. Plus, it has been widely planted in lawns, parks, shelterbelts, and the like.
A concerted effort will be required to curb the spread of the emerald ash borer. For example, monitoring the health of ash trees followed by prompt appropriate action. The larvae can hide under the bark of ash used for firewood, so that is also an area of concern. Treatments are available to save ash trees, for example the application of trunk-injected systemic insecticides. But that can be expensive.
But what about all those ash trees in the forests and woodlands around the state where monitoring and injecting the trees is not feasible? A recently published study by scientists from the University of Minnesota provide some encouraging news. The study found fungi native to Minnesota that were able to infect and kill or shorten the life span of the emerald ash borer. They also used a trap-like device into which the borers would enter, get coated with spores, exit, and then spread the spores to other beetles through mating. That could become an important tool in curbing the spread of the ash borers.
Visit the Emerald Ash Borer Information Network to learn more.
