Emerald Ash Borer (EAB)

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Background

The emerald ash borer is an invasive beetle that was first discovered in Michigan in 2002. With origins from Asia, it is believed the beetle was transported to North America sometime in the 1990’s. 13 years after the initial discovery in Michigan, the first tree in the City of Appleton was identified as having emerald ash borer larvae in Feb of 2015.

The metallic green adult beetle emerges from the trees in in late May to early June which coincides with the blooms of black locust trees. During this time in the adult stage, the beetles are searching for a reproductive mate. The adults will feed on the leaves of the ash but cause minimal tree damage during this life cycle stage. After mating the female beetle will lay 40-200 tiny and undetectable eggs in the crevices of the ash bark. Once the eggs hatch, the real damage begins to occur as the larvae chew their way into the bark and feed in the nutritious vascular tissues of the tree. As they chew through these conductive tissues, they break the connection of nutrients flowing through the tree. After a 1 to 2 year period, the larvae will go through a short pupation period and re-emerge as an adult beetle again.

Current Inventory

The City stopped planting new ash trees on street terraces and city parks in 2003. This was the first phase of the City’s EAB plan. Since that time the plan has been enhanced to include:

Evaluating existing ash trees to identify removals versus treatment;
Removing ash trees on all construction projects;
Prioritizing and removing the most deteriorated ash trees;
Developing a private contracting method to assist with removals of ash trees.

Currently the City of Appleton is managing approximately 3,200 ash trees in street right of ways and city park turf areas. About 17% of the City’s urban forest canopy is comprised of ash trees. Since 2009 the City has removed approximately 2,000 ash trees.

Approximately 50% of inventoried ash trees (1,600) met a set of criteria in 2022 and have been evaluated for another annual preventative EAB treatment option. This number of eligible trees will continue to shrink each year due to the continued devastation being caused by this significant forest pest insect. Eligible trees need to meet a specific set of criteria that include a selected diameter class, location, and condition(health) rating. Treatment options currently utilized by the City of Appleton become less effective for larger diameter trees as well as when they become more heavily damaged by beetle activity. Those trees that continue to meet criteria for treatment will allow them to remain in urban forest providing urban tree benefits until it comes to a point that the tree would need to be removed. The Public Works Forestry Division continues to evaluate long term strategies for management of EAB and works to strategically identify ash tree to retain in our urban landscape.

The remaining 50% of inventoried ash trees have been identified for removal. The Forestry Division is currently focusing tree removal operations in areas that have higher concentrations heavily impacted trees. We have been regularly evaluating trees with decreasing condition ratings that need to temporarily remain while we work through removing the worst trees first. This also means other forestry operations such as pruning maintenance and tree planting operations will likely be impacted by this pressure on our available resources.

If you have questions about the impacts of Emerald Ash Borer or want to find more information about general forest health, feel free to contact the City of Appleton Public Works Department, Division of Forestry or visit the Wisconsin Department of Natural Resources website https://dnr.wisconsin.gov/topic/ForestHealth

Removal Budget

Funding for EAB remediation and management comes from the Stormwater Utility Urban Forestry budget account 5226.

Approved by Council with the 2024 Budget, the City entered into a private contract in Spring of 2024 to remove approximately 1,000 ash trees in an amount not to exceed $375,000. Work under this contract includes the following:

Removal of dead, dying or affected trees by the emerald ash borer.M

The tree management section selected has the highest concentrations of ash trees and logistically one of the more challenging sections for City staff. This area is south of Calumet Street and east of S Oneida St, extending to the city borders.

Majority of trees to be removed are street trees in the street right of way.

Includes the removal of ash trees in two city parks within this section (Hoover and Green Meadows).

Stump grinding and terrace restoration will also follow the removal of the above ground portions of the trees.

In-house Forestry Division staff plans to remove 500 additional ash trees in 2024. Funded through the operating budget of the Urban Forestry Stormwater Utility. For an estimated total of 1,500 ash trees scoped to be removed in 2024.

In subsequent years, DPW staff will prepare a scope and budget for continued ash tree removals within street terraces and parks until all ash trees have been effectively treated or removed. We anticipate this process to take approximately 1-2 more years, into 2026. After that time very few ash trees will remain and will either be treated to prolong their life or removed based on condition. Eventually, the ash tree inventory within the City will be completely removed.

Replanting

Currently the City completes all tree planting in-house. In 2024 there are no additional funds dedicated towards increasing the number of trees planted. Staff’s time is dedicated toward the management, evaluation, maintenance, and removal of ash trees at this time. Our top priority is securing the tree canopy and removing safety hazards associated with degrading ash trees. Once the removal operations have been substantially completed, staff will focus on a potential increase in planting efforts.

Spring plantings are currently included in the City’s budget. In the future, following the removal effort, DPW staff may explore options to complete additional annual plantings. The budgetary and staffing impacts must be considered and phased in. Maintaining and reestablishing the urban forest tree canopy is a top priority of DPW and the Stormwater Utility.

More Information:

Wisconsin's Emerald Ash Borer Information Source

Ash Borer F.A.Q.
- What is being done to protect the remaining canopy that we will have?
  Trees are the one type of infrastructure the City installs that will increase in value over time. The Forestry Division continually works to increase the long term sustainability, safety, preservation and benefits provided by city terrace trees and park trees within Appleton. While we are in “crisis mode” in addressing EAB, it’s just as important to care for and preserve the existing trees we still have. The Forestry Division continues to conduct ongoing maintenance and tree planting goals to meet these needs and continually nurture the benefits provided from our urban forest.
- Will these diversity goals include not planting entire streets with the same species?
  Although it makes tree-planting contracts slightly less streamlined, we have a goal of increasing diversity within each block so that future bugs or diseases won't wipe out trees from entire blocks. The strategy of planting the same tree species on a block has long been viewed as creating a more attractive uniform appearance while increasing adjacent property values along with benefits for applying required tree maintenance needs. Diversity needs were maintained by changing species on each block through a neighborhood. The Forestry Division will look to additional strategies moving ahead to help keep this uniform appearance while also diversifying individual blocks and building resiliency into the urban forest and individual neighborhoods.
- Why isn’t even more variety encouraged?
  Terrace trees have to be carefully selected to ensure that they have the hardiness for our climate, match the soil type, can be tolerant of road salt, fit narrow terraces, tolerate urban conditions etc. The City Arborist has compiled a list of several species of trees that are appropriate for these locations. This also may mean that some trees native to Wisconsin are not good candidates for terrace planting. It is unfortunate that the list can’t be longer!
- What goal does the City have to encourage tree diversity?
  The City’s goal is to eventually reach a point where no tree genus comprises more than 10% of the urban forest and no individual species comprises 5% of the total tree population. This will avoid the dramatic impact that Dutch Elm Disease and now the EAB would have on a community.
- Can I pay for and plant my own replacement tree in the terrace?
  At this time, we are asking residents that might be willing to plant their own trees to not do so. As stated before, there are several variables that help make the right tree for the right planting site and the long-term success of that tree. The Forestry Division will be looking at ways to reestablish these trees and canopy cover in the coming years.
- When the time comes, can I choose which tree to plant?
  In some circumstances our Forestry division can work with individual property owners to identify a species of tree that is most suitable for their terrace. In most cases this proves to be challenging. There are several factors to consider when selecting a tree species for a specific site such as soil type, exposures to road salt, overhead or underground utility conflicts, spacing from existing vegetation, cost and availability from tree nurseries. Additionally, the City’s Forestry Division needs to account for current tree populations and continue to diversify to build resiliency in the urban forest. The most commonly requested tree is a maple and one-third of tree populations are already established in a maple species.
- Will the City replace all ash trees that are removed?
  Replacement of all of these trees— and eventually having a tree in every good planting site on our streets—is the long-term goal of the City. However, during the “crisis mode” an EAB infestation, we will likely focus on removals and stump grinding. Tree replacement will likely occur at a lesser and strategic pace due to budgetary and staffing constraints.
- What is the cost for planting a new tree?
  Costs for purchasing trees can vary widely based on a number of factors such as material type, species, size and availability from nursery growers. Most trees planted by the city are bare root which allow for easy handling, cheaper costs, and increase the ability to properly plant. Some species, because of sensitivity to digging, need to be planted in other forms such as balled and burlap or containerized pots.
- What is the benefit of planting new trees?
  Trees offer many benefits to our community, including energy savings, asphalt cooling, carbon sequestration, and stormwater management. They also have been found to increase property values, business success, and the quality of life in a community. A recent analysis by the DNR showed that Appleton receives over $3.31 million in benefits each year from its street tree canopy.
- Why isn’t the City paying to treat its public trees?
  The primary reason that the City is not planning to treat all of our public ash trees is expense and diminishing returns. Treatment costs can be expensive and would be perpetual for the sustained life of ash trees. Extrapolated out to cover an entire population of ash and this ongoing and increasing cost is not fiscally responsible. The City is under strict tax levy limits from the State, and entire categories of other city services would have to be cut to make up for this budget. Further, the trees that have a favorable success rate must be taken into account. Not every ash tree will respond positively to treatment.
- What is the success rate when treatment has been administered?
  Trunk injections which are applied only by licensed applicators, and started before a tree is in decline because of an infestation, can be more than 95% effective.
- Can I treat a tree myself?
  Homeowners can purchase products from local suppliers that have the ability to prevent effects of EAB if done so ahead of initial infestations for trees on their own property. These products need to be applied according to the manufacturer’s label directions.
- What is the cost of the annual treatment of a tree?
  The cost depends on the type of treatment, and the frequency that the tree needs to be treated is affected by size, whether a tree is already infested, etc. A local certified arborist that provides this service can help most homeowners with this question.
- What is the City’s approach to treatment?
  The City’s approach has been to preventively treat ash trees since 2017 which fit a select set of criteria. Starting each year in late spring, Forestry staff will begin re-evaluating the remaining ash trees in street terraces. If certain ash continue to meet a set list of criteria, the trees will be treated to postpone EAB infestations in an attempt to help manage the tree removal workload going forward. Unfortunately, treatment is an ongoing necessity to prevent an infestation and not a long term or large scale solution for addressing emerald ash borer in Appleton street tree populations.
- What should I do with my private ash trees?
  Private ash trees can be treated by the owner, by using a private contractor secured by the homeowner. If a tree dies, it is also the responsibility of the property owner to have it removed and disposed of properly. In fact, dead trees on private property can pose a public nuisance, and these trees must be removed in a timely manner.
- Will any costs be assessed to property owners for removal?
  No. Dead trees on City right of way will be removed at no direct cost to the property owner. The removal of dead private trees will be the responsibility of the property owner.
- What information is available to help us understand the EAB problem and possible actions?
  The State web site (http://datcpservices.wisconsin.gov/eab/index.jsp) is a great resource for much more information about the EAB, including the latest finds. The Department of Agriculture, Trade and Consumer Protection also publishes updates and additional information: https://datcp.wi.gov/Pages/Programs_Services/EAB.aspx
- What will be done with the wood?
  Solid wood that cannot be chipped on site will be collected and stored at a yarding site where it will be further processed or sold to contractors for a continued higher or better use. Urban wood is unique when compared to traditional forest products so care must be taken to properly recycle or reuse this product. Much of the wood will be converted to chips for mulch, playgrounds, landscaping or biofuels in local markets.
- What will be done with the stumps of trees that are removed?
  Tree removals are followed by grinding the stumps, restoring the terrace area, and usually replanting a tree. While we continue to be committed to these steps, planting of new trees may be delayed several years as the available budget focuses on ash removal.
- How will I know if the terrace tree near my home is identified for removal?
  All City ash trees are tracked and identified in a GIS based inventory system. When our forestry staff are selecting trees for removal, they will paint a white dot at the base of the tree on the curb side which coincides with a scheduled work order. They will also provide a letter informing the property owner of the planned removal and allowing them to become an advocate for that tree.
- Can’t the trees just be allowed to stand, even after they’re dead?
  Removing trees quickly after an infestation is found may delay the spread of the beetle in that neighborhood. Unlike elms and oaks, ash trees turn brittle soon after they die. Falling limbs would create a public safety crisis within a matter of a few years. Both of these are strong reasons to remove trees once they die or are found to be infested.
- Is the EAB quarantine still in effect?
  In 2021, EAB was deregulated at the national level by the USDA Animal and Plant Health Inspection Service (APHIS), and Wisconsin’s EAB quarantine rule was rescinded in 2023. When this regulation changed, some states west of Wisconsin, including Minnesota, took steps to enact exterior quarantines for EAB. The quarantine regulations restrict the movement of ash products such as logs, nursery stock and/or firewood from Wisconsin to these states. We strongly encourage businesses and individuals to check current regulations.
- Are ash trees prevalent in the City of Appleton?
  Yes, ash trees are very popular throughout the City of Appleton and the State of Wisconsin. They grow quickly and adapt well to urban environments, so they were a very popular replacement for elm trees infected by Dutch Elm Disease. About 15% of the City’s urban forest is ash.
- What are some signs that my tree is being affected by EAB?
  The pest is attracted to the smaller branches in the upper canopy of trees, so die-back of those branches is the first sign of a problem. Increased woodpecker activity, small D-shaped exit holes from where the adults exit the tree, and epicormic shoots (where new seedlings of the tree grow up around the base of the trunk, due to the roots’ nutrients not being able to move higher into the tree) may be other indications. When these signs are seen, stripping bark from a branch may reveal the S-shaped tunnels of the larvae.
- How does it spread?
  Without human assistance, the beetle would only travel a few miles per year. However, due to the movement of infested firewood, nursery stock and pulp wood, it covers much greater distances and can be found many miles from the next known infestation.
- Where in Wisconsin has it been located?
  It was first discovered in Newburg (Washington County) in 2008. Since then, it has been discovered in nearly every Wisconsin County as of May 2023. See the spread of EAB detections in Wisconsin by county https://dnr.wisconsin.gov/sites/default/files/topic/ForestHealth/eabCountyDetectionsMap.pdf
- Is EAB is 100% fatal to all species of ash trees?
  Yes. There is one tree commonly called an ash tree (“mountain” ash) that is not a true ash, and has not been shown to be affected by EAB. There are no known cases of any immunity developed by the ash to EAB. No other tree species have been targeted by EAB as of yet.
- How does EAB kill a tree?
  The larvae of the beetle feed on the cambium of the tree, just under the bark, leaving a serpentine-shaped series of grooves in the wood. This prevents nutrients from traveling from the roots to the crown of the tree, effectively choking it.
- What is the Emerald Ash Borer (EAB)?
  The EAB is a tiny invasive beetle that is originally from Asia. With origins from Asia, it is believed the beetle was transported to North America sometime in the 1990’s. The EAB is an invasive beetle that was first discovered in Michigan in 2002. 13 years after the initial discovery in Michigan, the first tree in the City of Appleton was identified as having emerald ash borer larvae in Feb of 2015. See where EAB has been found in Wisconsin https://datcpservices.wisconsin.gov/eab/index.jsp

Background

Current Inventory

Removal Budget

Replanting

More Information:

Ash Borer F.A.Q.

What is being done to protect the remaining canopy that we will have?

Will these diversity goals include not planting entire streets with the same species?

Why isn’t even more variety encouraged?

What goal does the City have to encourage tree diversity?

Can I pay for and plant my own replacement tree in the terrace?

When the time comes, can I choose which tree to plant?

Will the City replace all ash trees that are removed?

What is the cost for planting a new tree?

What is the benefit of planting new trees?

Why isn’t the City paying to treat its public trees?

What is the success rate when treatment has been administered?

Can I treat a tree myself?

What is the cost of the annual treatment of a tree?

What is the City’s approach to treatment?

What should I do with my private ash trees?

Will any costs be assessed to property owners for removal?

What information is available to help us understand the EAB problem and possible actions?

What will be done with the wood?

What will be done with the stumps of trees that are removed?

How will I know if the terrace tree near my home is identified for removal?

Can’t the trees just be allowed to stand, even after they’re dead?

Is the EAB quarantine still in effect?

Are ash trees prevalent in the City of Appleton?

What are some signs that my tree is being affected by EAB?

How does it spread?

Where in Wisconsin has it been located?

Is EAB is 100% fatal to all species of ash trees?

How does EAB kill a tree?

What is the Emerald Ash Borer (EAB)?