Emerald Ash Borer
Emerald Ash Borer (EAB) is a non-native (invasive) insect from Asia that kills ash trees. Across the country, it has killed millions of trees since its discovery in 2002. Minnesota is home to approximately 900 million ash trees, the most of any state, making it very susceptible to the destruction caused by EAB. Trees become infested when adult beetles lay eggs on the bark. The eggs hatch into larvae that bore into the tree, eventually killing it.
EAB in Monticello
EAB was discovered in Minnesota in 2009 in the City of St. Paul. EAB was detected in Monticello in March 2022 by City staff. The City has been working with the State of Minnesota and moving swiftly to manage this insect. Tree inspections began in the northeast section of Monticello on April 4. Inspections will continue throughout the summer; City staff will be marking infected trees with a green 'X' or a green ribbon for either treatment or removal.
EAB Signs and Symptoms
- Woodpecker activity: Woodpeckers fleck off outer darker bark to reveal lighter bark beneath and create dime-sized holes while looking for larvae. This is also referred to as “blonding.”
- Bark splits: Larvae tunneling under the bark cause it to split open on branches and trunks.
- Crown dieback: The larvae disrupt the flow of water and nutrients causing branches to die.
- Suckering shoots: Ash trees can send out shoots when stressed from an EAB infestation.
By the time signs and symptoms of EAB are noticeable on ash trees, the larvae have damaged the tree so much so that treatment becomes less effective or is often no longer a viable option for managing the pest.
If you are seeing symptoms and would like to request an inspection of your ash tree, please contact the Parks Department at 763-295-2711, or via email Parks.Info@MonticelloMN.gov.
Management Updates
March 2023
The City Council accepted a grant from the Minnesota Department of Natural Resources (DNR) in the amount of $30,000 for Emerald Ash Borer Management.
September 2023
Approved a professional services agreement with Davey Resource Group, Inc. for the Monticello Tree Inventory Project.
March 2024
Approved Davey Resource Group to perform a tree canopy assessment and develop an updated Shade Tree Ordinance in conjunction with the DNR ReLeaf grant.
January 2025
The City of Monticello was awarded an $81,160 grant by the Minnesota Department of Natural Resources (DNR) to strengthen the City's urban tree population, with a focus on community engagement and involvement. The DNR's Centering Communities in Canopy Solutions grant aims to increase canopies within specific priority areas.
This initiative will enable Monticello to proactively replant areas affected by EAB, rather than only tree removal, ensuring a balanced distribution of trees throughout the project area. The tree planting is part of the overall Strengthening Trees through Inclusive Community Knowledge (STICK) program, led by the Parks Department.
April 2025
The City Council adopted Ordinance 847 (PDF), related to regulations for planting and maintaining trees and tree canopy. The ordinance was developed with Davey Resource Group, who was contracted to complete a community tree inventory, canopy assessment report, ordinance review and revision, updated tree manual, and EAB management plan.
In addition to the ordinance is a companion Tree Manual (PDF) for the City. The manual provides property owners with a user-friendly guide to planting and maintaining trees. It references the proposed ordinance with helpful graphic and illustrations as well as provides lists of the recommended and prohibited tree species.
June 2025
The Parks Department has identified and marked over 250 ash trees in northeast Monticello for removal due to the EAB. The Department continues to mark ash trees that show signs or are at risk of EAB infestation. The trees are marked with a green "X" or green ribbon.
October 2025
The Parks Department has identified 496 public ash trees and 944 private ash trees for removal, totaling 1,440 trees. The City will begin tree removals in November. Trees marked for removal will be prioritized based on the severity of their hazardous condition.
February 2026
Parks Department crews begin removal of EAB-infected boulevard trees in the Sunset Ponds and River Mill neighborhoods during the week of February 2, 2026.
