Emerald Ash Borer is in Minneapolis

You may have noticed ash trees around Minneapolis that have been marked with green ribbon. They have been marked to raise awareness about impending changes that the Emerald Ash Borer (EAB) will bring to our urban forest. EAB is an invasive beetle that is killing ash trees in Minneapolis.

EAB Kills Ash Trees

All ash trees (including trees marked with a ribbon) will become infested with EAB and eventually die. The approaching loss of ash trees will cause a drastic change to the urban forest in Minneapolis.

Response

EAB Preparedness Plan

Years before EAB was discovered in Minneapolis, our Forestry Department fully activated an EAB Preparedness Plan [PDF], which sought to minimize the environmental, economic, and aesthetic impact on the city’s urban forest. Proactive measures included removal of the infested trees, establishment of trap trees, continued surveying of ash trees in the area and city-wide and continued removal of ash trees that were damaged and defective.

We have been actively cooperating with the Minnesota Department of Agriculture (MDA) in the EAB battle for several years.

Ash Canopy Replacement Plan

Once EAB was found and its population began to increase, we developed and implemented an Ash Canopy Replacement Plan that provides for the scheduled replacement of ash trees. This proactive replacement approach allows our Forestry Department to replace the urban forest canopy with a diverse mix of tree types.

Waiting to remove ash trees until they become infested is not an option because the trees will die in such large numbers that will be impossible to keep up with removal and replacement. Proactively removing trees before they die reduces the risk of damage and injury caused by limbs falling from dead and dying ash trees. We replace a small percentage of ash trees at a time instead of replacing all the trees on a block at once to minimize the impact.

Replacement Trees

We choose replacement trees with the goal of growing a more diverse urban forest. Diversity will help ensure that future generations will not go through a similar canopy loss. We will plant two or three tree types (for example, oak, honeylocust and ginko) on any given street or block. Where there is space, we are also planting “buddy trees near existing ash trees in parks to start growing the next canopy.

We try to remove less than 20% of the tree canopy on a block during a single season. Scheduled replacements are already taking place with ash trees that are defective and declining or growing in compromising conditions. The next wave of replacements will include replacing smaller ash trees and select replacement of larger ash trees in heavily populated ash areas.

Marking and Notification

If a boulevard tree in front of your home is scheduled for removal, we will hang an information tag on your front door to let you know why the tree was marked.

We mark boulevard trees as follows:

Green Paint Ring
The tree has Emerald Ash Borer and will remain marked for five days. After five days, we will remove the tree as soon as possible.

Green Paint X
We will remove the non-symptomatic tree as part of the ash canopy replacement plan.

Green Ribbon
The tree is not currently scheduled for removal. We wrap non-symptomatic public ash trees with informational ribbons to raise awareness for the ash canopy replacement plan.

We only use green to mark Ash trees.

What You Can Do

If you have an ash tree on your property (not on the boulevard), you'll need to plan for the future. You may decide to do nothing and simply enjoy your tree until it eventually becomes infested and dies. You may decide to treat your tree with an insecticide to keep EAB from killing it. To help guide your decision making process we suggest you read "Emerald Ash Borer: Homeowner Guide to Insecticide Selection, Use, and Environmental Protection" [PDF] and "Frequently Asked Questions Regarding Potential Side Effects of Systemic Insecticides Used To Control Emerald Ash Borer." [PDF] These publications along with recommendations from a consulting arborist will provide beneficial information to consider when making a plan for the private ash trees in your yard.

Treating Public Boulevard Trees

We do not chemically treat ash trees. If you would like to treat a non-symptomatic boulevard ash tree in front of your home with insecticide, you must hire a licensed and permitted tree care company. These companies know the proper way to apply insecticides in the safest way possible.

You must pay for any and all treatments.

Licensed and Permitted Tree Care Company List

Companies are listed in alphabetical order.

Bartlett Tree Experts: 763-253-8733
Branch and Bough Tree Service: 651-335-8655
Davey Tree Experts: 612-392-2405
Elijah Tree Care: 612-242-0221
Envirolawn Inc.: 952-888-7523
Meridian Tree Co.:
651-210-8228
Morgans Tree Service: 651-210-5118
Northeast Tree: 612-789-9255
Otsvig Tree: 763-479-4090
Premium Tree Protection: 612-554-0054
Rainbow Tree Care: 952-922-3810
S&S Tree & Horticulture Specialists: 651-451-8907
SavAtree: 952-881-3779
Shadywood Tree Experts: 952-933-0614
Tree Quality: 612-618-5244
Tree Trust:
612-366-4168
Treehugger Tree Care, Inc.: 612-444-3494 ext. 4
Urban Foresters: 763-566-0722
Vineland Tree: 612-872-0205
Yetzer Tree Service: 612-331-1133 

Note: This listing is not meant as an endorsement of a company or method of treatment. The MPRB does not endorse or discourage the treatment of elm, oak &/or ask trees with pesticides for the purpose of controlling Dutch Elm Disease, Oak Wilt &/or Emerald Ash Borer respectively. The companies named on this list are those that received a permit for treating public trees this year. There are other companies licensed by the City of Minneapolis [PDF] that also provide this service on private property.

Impact

How EAB Works

EAB kills trees over a period of one to four years depending on the size of the tree. It is the larval stage that does the damage. The larvae live under the bark of the tree and feed in the tissue layer directly beneath the bark. This layer contains the vascular system of the tree which transports water from the roots to the crown. As the larvae develop they create tunnels throughout this tissue. This activity kills the tree by stopping the flow of water and nutrients.

Symptoms

The most prominent symptom of EAB is dieback of the tree canopy. It is not unusual for as many as one half of a tree’s branches to die back during the first year of attack. The tree tries to compensate for this loss by sprouting new growth below the level of infestation. At this time, the bark may begin to split. Eventually, the adult beetles emerge from the bark. In the process of emerging as adults, they leave a "D" shaped exit-hole that is about 1/8 inch wide.

How EAB Spreads

EAB adults can fly at least 1/2 mile a year from the tree where they emerge. The most likely way that EAB spreads is by people moving ash logs, ash firewood or infested ash trees from nurseries. The simplest way to slow the spread of EAB is to not move firewood.

The shipping of ash nursery trees and ash logs is now federally regulated and transporting firewood outside of quarantined areas is illegal. Due to the local discovery of the infestation, Ramsey and Hennepin counties have been placed under quarantine. 

Potential Impact

The destructive potential of EAB is enormous because there is currently no known cure. It has already killed more than 40 million ash trees nationwide, most of which were in southeast Michigan. Minnesota has the potential to lose 867 million trees because it has one of the highest volumes of forestland ash in the U.S.

As bad as these losses would be, they do not address the losses that would be suffered by municipalities. In Minneapolis the impact to the total urban forest canopy would be significant because 21 percent of all trees, both public and private, are ash. This translates into more than 200,000 trees.

On public property, Minneapolis would lose approximately 38,000 ash trees growing on boulevards. The cost of removal, stump grinding and replanting of these trees would exceed $26 million. This does not include the tens of thousands of ash trees growing in parks and natural areas such as along the Mississippi River corridor.

History

EAB is an invasive pest introduced from Asia that attacks ash trees (Fraxinus spp.). This metallic wood boring beetle was first found in Detroit, MI, and Ontario, Canada in 2002. It is believed to have arrived in shipping crates. Since the initial discovery, it has been identified in multiple Eastern and Midwestern states.

EAB was discovered in Tower Hill Park in the Prospect Park East River Road neighborhood of southeast Minneapolis in March 2010. This was the first official infestation in Minneapolis and is within one mile of the first identified infestation in St. Paul in 2009.

Our Forestry Department is working to systematically replace all public ash trees in Minneapolis with a diverse and resilient forest so future generations will not have to go through a similar canopy loss. After Dutch Elm Disease killed tens of thousands of elm trees, we accomplished diversity by replanting solid blocks of streets with one type of tree. EAB has caused us to rethink this approach and we now plant two or three tree types on any given street or block.

Related Links

More Information

News

About EAB

Maps

Map of EAB infested Minneapolis neighborhoods (as of September 2, 2016) [PDF]

Neighborhood Maps of Boulevard Ash Trees [PDF]:

Contact

For more information about EAB and how we care for our urban forest, contact the Forestry Department at 612-313-7710 or forestry@minneapolisparks.org.