Emerald Ash Borer

Did you know Emerald Ash Borer (EAB) is a wood-boring insect that is sneaky and hard to detect early on, taking 3-7 years for a community to notice an infestation. Without action, 80% of trees can die within years 7-12 of infestation.

Residents can direct questions or report concerns to Forestry.

The City of Moorhead's EAB Management Plan

Ash trees make up 27% of Moorhead's urban forest. The Forestry Division has developed a plan and is in the second year of implementation of EAB Management of all city property and boulevard trees.

EAB Treatment

• A 3-year treatment cycle is in place for established trees, treating approximately 1700 ash trees annually.
• If a tree has an infestation, the tree will be removed. If EAB is present in the area, treatment will need to be continued until all untreated ash trees in the area have been killed or removed, up to 10-20 years.

Tree Removal

• The City is in the process of proactively removing marginally-healthy and small ash trees.
• Trees that are removed are replaced with a diverse mixture of tree species to create a robust and sustainable future urban forest.

Because EAB is so devastating to the ash tree population, it is important for homeowners to start planning for what they would like done with their private ash trees. First of all, homeowners should know how to identify ash trees. The Minnesota Department of Natural Resources has an excellent resource here.

Secondly, after the ash trees have been identified on the property, residents should assess their condition and size. If they are small or unhealthy, it may make more sense to remove them now and get a new tree planted sooner rather than later. 

If there are large, healthy trees on the property, a homeowner could look into the treatment options available. A trunk-injection of emamectin benzoate provides two years of excellent protection against all stages of EAB larvae and feeding adults.

For optimal tree health outcomes, most sources recommend treating a tree if there is an infestation within 15 miles of your property. Trees should only be treated if less than 30% of the canopy has thinned. Monitor the trees closely and learn the signs of an infestation to be able to treat the trees in time to keep them in optimal health.

If homeowners opt to do nothing until a tree is infested, Forestry will be scouting for infested trees on public and private property. If a private tree has EAB, the city will require that the tree be removed in order to stop the population growth of EAB. If homeowners cannot get it removed, the city will hire a contractor to remove the tree and the cost will be assessed to the property.

Dead ash trees become extremely brittle and hazardous to people and property, and they are more expensive to remove after death. It is financially-beneficial to get a plan in place to remove an ash tree before it has died if there is an infestation nearby.

We can all help detect and start controlling an EAB infestation early by learning the signs of an EAB-infested ash tree. Learn how to identify ash trees here, and please monitor the trees in your yard and on the boulevard.

An EAB infestation is very difficult to identify in the early stages. Some symptoms of EAB mimic symptoms of common ash health problems in the area, such as lack of water, nutrient deficiency, storm damage, etc.

However, if you notice extensive woodpecker damage to a tree, be on the lookout for bark splits and S-shaped galleries. Start looking for symptoms in the upper canopy with binoculars, since that is where an infestation will begin.

Contact the City of Moorhead Forestry Division if you have questions for concerns.

Woodpecker Damage:

 Bark Splits:

D-Shaped Exit Holes:

S-Shaped Galleries:

Canopy Thinning:

The biggest way to help prevent EAB spread is to only buy firewood where you will burn it. EAB beetles only spread one mile per year naturally. Humans spread it much faster by accidentally moving EAB-infested firewood or other wood products.

If homeowners see signs of an infestation, report it in the following methods:

1. Contact the City of Moorhead Public Works Department and request Forestry personnel to inspect the tree. Submit an inspection request by Contacting Forestry or call Public Works at 218-299-5422.
2. Contact Arrest the Pest via email or by leaving a detailed phone message at 1-888-545-6684.
3. Send a report through the Great Lakes Early Detection Network App. 
4. Login or create an EDDMaps Midwest account and submit a report.

Useful Links for More Info:

Homeowner Guidance

• Identify Ash Trees (Minnesota DNR)
• Emerald Ash Borer (Minnesota DNR)
• Emerald Ash Borer Management Options. (Iowa State University Extension and Outreach)

Insecticide Treatment

• Frequently asked questions regarding side effects of systemic insecticides used to control emerald ash borer. (University of Minnesota Extension, Michigan State University, and Ohio State University OARDC Extension)
• Label Guidance for Use Limits. (Minnesota Department of Agriculture)
• Emerald ash borer urban SLAM (Slow Ash Mortality) program-lessons learned. (Emerald Ash Borer University)
• Chemical Control for EAB. What Works, What Doesn't and Why. (Emerald Ash Borer University)
• Emerald Ash Borer Insecticide Guide (Minnesota Department of Agriculture & Minnesota Department of Natural Resources)
• Effects of Emerald Ash Borer Treatments on Pollinators. (Emerald Ash Borer University)

Cold Tolerance

• How Cold is too Cold for Emerald Ash Borer? (Minnesota DNR)
• Cold Hardiness of Emerald Ash Borer. (Vennette and Abrahamson, 2019)
• The Unusual Case of Emerald Ash Borer in Minnesota. (Emerald Ash Borer University)