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Emerald Ash Borer
  
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Emerald Ash Borer
Home  < Caring for Our Parks  < Trees & the Urban Forest  
    

Emerald Ash Borer (EAB) is in Minneapolis

You may have noticed ash trees around Minneapolis that have been marked with green ribbon. These trees have been marked to raise awareness about impending changes that EAB will bring to our urban forest. EAB is an invasive beetle that is killing ash trees in Minneapolis. It was found here in 2010.

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. Because the population of EAB is increasing, the MPRB has developed a canopy replacement plan that provides for the scheduled replacement of ash trees. This proactive replacement approach allows the MPRB 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 it will not be possible 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.

Emerald Ash Borer FAQ - Printable Fact Sheet

What is a boulevard tree?

The Minneapolis Park and Recreation Board is responsible for all City-owned trees, including boulevard trees. A boulevard tree is located in an area of ground in the right of way that is located between the curb and sidewalk.

Will all boulevard ash trees be removed at once?

No. The MPRB wants to reduce the impact of canopy loss. Based in recommendations from the Minneapolis Tree Advisory Commission, The MPRB hopes to remove no more than 20% of existing 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.

Can I request to have my boulevard ash tree replaced?

Yes. If you would like to beat the beetle, you may take action to have the boulevard ash tree adjacent to your property replaced by simply signing up. This is a free service for publically owned ash trees.

What is the canopy replacement plan?

The purpose of the plan is to reduce the impact of canopy loss while growing a diverse and resilient forest for future generations. The MPRB intends to reduce the impact of losses by replacing a small percentage of ash trees at a time. This is in contrast to replacing all of the trees on a block at once. Replacement trees will be selected with the goal of growing a more diverse urban forest. Diversity will help ensure that future generations of Minneapolitans will not have to go through a similar canopy loss. After Dutch Elm Disease killed tens of thousands of elm trees, diversity was accomplished by replanting solid blocks of streets with one type of tree. EAB has caused the MPRB to rethink this approach. As a result, MPRB will plant two or three tree types (for example, oak, honeylocust and ginkgo) on any given street block. Where space permits, the MPRB is also planting "buddy" trees near exsisting ash trees in parks to start growing the next canopy.

Can I treat a public boulevard tree with insecticide?

Yes. If you would like to treat a boulevard ash tree adjacent to your property with insecticide, you may hire a licensed and permitted tree care company. These companies know the proper way to apply insecticides so that the treatment is performed in the safest way possible. Homeowners are required to pay for any and all treatments.

What about the ash tree in my yard?

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" and "Frequently Asked Questions Regarding Potential Side Effects of Systemic Insecticides Used To Control Emerald Ash Borer." 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.

Contact Information

For more information about EAB and how the MPRB takes care of our urban forest call the Forestry Department at 612-313-7710 or email forestry@minneapolisparks.org

Learn more about EAB

History of EAB in Minneapolis

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 officially identified infestation in Minneapolis and is within a mile of the first identified infestation in St. Paul in 2009.

As a result, the MPRB's Forestry Department has fully activated its EAB Preparedness Plan, which seeks to minimize the environmental, economic and aesthetic impact on the city’s urban forest. Proactive measures include removal of the infested trees, establishment of trap trees, continued surveying of ash trees both in the area and city-wide and continued removal of ash trees that are damaged and defective.

The lead agency in Minnesota in the EAB battle is the Minnesota Department of Agriculture (MDA). The MPRB Forestry Department has been actively cooperating with the MDA in this effort for years.

Potential Impact

The Emerald Ash Borer (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.

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.

How EAB Kills Ash Trees & Spreads

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.

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.

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.

More Information

Maps

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About EAB

 

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