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Emerald Ash Borer
Emerald Ash Borer (EAB) is a serious invasive tree pest, and consequently, is regulated to slow the spread of the insect to areas not yet impacted.
Emerald Ash Borer has been identified in Steele County and since 2019 all Ash trees located on city boulevards have been treated in a three-year rotation. The Park Maintenance and Street Divisions removed approximately 125 ash trees over the last year and expect to remove move this spring as inspections take place. The removal of these trees and treatment of approximately 350 ash trees per year has helped slow the spread of the invasive insect. Slowing the spread allows for additional time for crews to handle the workload of removing and replacing diseased trees.
2025 Emerald Ash Borer Treatment began in early June.
The City of Owatonna is proactively treating ash trees for Emerald Ash Borer. There are approximately 1,200 boulevard ash trees, and the City intends to treat approximately 1/3 each year, resulting in a three-year treatment rotation. The treatment of the boulevard trees benefits private trees as well. As the bugs travel from tree to tree, they die when they eat from a treated tree. Not all trees need to be treated for the program to be effective.
Treatment Process: The Street Department begins by measuring the diameter of the tree to determine how much product and how many injection needles are necessary for the treatment. Then holes are drilled, and needles are inserted into the tree, this pressurizes the container that holds the product. Typically, it takes about ten minutes for the ash tree to absorb the product into the trunk of the tree.
Minnesota is highly susceptible to the destruction caused by EAB. The state has approximately one billion ash trees, the most any state in the nation. According to the most recent survey (1997) conducted by the Public Works Department, the City contains approximately 4,553 boulevard trees. According to a DNR Community Tree Survey conducted in 2010, Ash trees represent 21.1% of trees, within one chain of the boulevard.
The biggest risk of spreading EAB comes from people unknowingly moving firewood or other ash products harboring larvae. Follow these easy steps to keep EAB from spreading:
- Don’t transport firewood. Buy firewood locally from approved vendors and burn it where you buy it.
- Be aware of the quarantine restrictions. If you live in a quarantined county, be aware of the restrictions on movement of products such as trees, woodchips, and firewood.
- Watch your ash trees for infestation. If you think your ash tree is infested visit the Minnesota Department of Agriculture website and use resources available to identify and report.
To report a possible EAB infestation, visit the Minnesota Department of Agriculture's Report a Pest page, email the Arrest the Pest Hotline, or call 888-545-6684.
The implementation of an Emerald Ash Borer Management Plan will assist the City in taking a proactive approach to controlling the spread of EAB Infestation. This plan helps to spread the costs associated with the outbreak of EAB over a number of years. The widespread loss of every Ash tree in Owatonna will have a devastating effect on home values, quality of life, and the environment. The City’s goal is to buffer that impact in advance by implementing the most current EAB preparedness activities.
EAB Management Program
- Internal and External Communication
- Private Removal and Replacement
- Public Education and Outreach
- Public Removal and Replacement
- Treatment and Control
- Wood Utilization and Disposal
Emerald Ash Borer (EAB) is a nonnative invasive insect that infests ash trees. Many states in the nation, including Minnesota, have been negatively impacted by the infestation of EAB. The Department of Agriculture has created an up-to-date mapping tool to view quarantine and EAB report information.
The identification of the high and low activity periods helps to reduce the spread of EAB. If a tree is left alone during the High Activity Period, then EAB has a place to lay eggs and reside. Because the adults will not emerge for one year, if the tree is cut down during the Low Activity Period, the eggs and adults will not have opportunity to survive and spread.
High Activity: May 1st - September 30th
- Avoid removal of ash branches, stumps or trees. This is due to flight patterns of the insects, high risk of spreading.
- If removal is required:
- Prune and remove ash trees if absolutely necessary.
- Chip at minimum the outer 1 inch of bark and wood on-site and transport to nearest ash tree waste disposal site where they will quickly process the material.
- Or, transport at least outer 1 inch of bark and wood in an enclosed vehicle to the nearest ash tree waste disposal site that can quickly process the material.
Low Activity: October 1st - April 30th
- Prune and remove ash trees as needed.
- Transport at minimum 1 inch of bark and wood in and enclosed vehicle to the nearest ash tree disposal site where it will be taken care of before May 1st.
The City does not treat EAB, perform maintenance or inspections on private property. Homeowners who suspect they have an affected ash tree should contact a licensed arborist.
View Ash Management Guidelines for Private Forest Landowners (PDF)