Skip to main content

Coronavirus (COVID-19) Information

Visit https://www.fcgov.com/eps/coronavirus for current updates

Para integrantes de la comunidad: https://www.fcgov.com/eps/coronavirus-informacion

Forestry

 Contact Information

Dept Head: Mike Calhoon

Emerald Ash Borer

Emerald Ash Borer
 

What is the Emerald Ash Borer?

The Emerald Ash Borer (EAB) is a highly destructive, non-native insect that infests and kills all North American true ash species including green, white, black and blue ash, and their cultivars (including “autumn purple ash,” a popular white ash varietal in Colorado). The larval stage of EAB feeds under the bark of trees, cutting off the flow of water and nutrients. Infested trees gradually die over a period of approximately two to four years.

Why is this a problem for Fort Collins?

The City of Fort Collins Forestry Division maintains over 55,000 trees located on City property, 7,654 of these trees are ash trees. City-wide (on public and private property), there are approximately 70,000 ash trees which make up 33% of our canopy cover in Fort Collins. 

Do I have an ash tree?

Do I have an ash tree?
 
  • How to identify an ash tree
  • Leaves are compound, which means multiple leaflets occur on a common stalk, and typically have five to nine leaflets. The one exception is single-leaf ash which may have simple or compound leaves, with up to five leaflets.
  • Leaflets are smooth or finely toothed along the edges and are eye-shaped.
  • Seeds on female trees are paddle-shaped.
  • Branches and buds grow in pairs, directly opposite from each other.
  • Mature bark displays diamond-shaped ridges.

Locate ash trees near me

Is my tree infested with EAB?

Many of the common signs and symptoms of EAB are hard to detect from the ground early on because the beetles target branches in the mid to upper crowns first. Here are some symptoms and signs to look for:

  • Thinning of upper branches and twigs
  • Loss of leaves
  • New sprouts on the lower trunk or lower branches
  • Vertical splits in the bark
  • D-shaped exit holes about 1/8-inch wide
  • S-shaped tunnels produced by larvae under the bark

You may want a professional to help inspect your tree(s). Click here to find a list of licensed arborists who may help inspect your ash tree(s).

 

Forestry has been preparing for EAB since it was first detected in the United States starting in 2003. We’ve worked hard to make sure that ash trees were not planted along City streets or in new City parks. Since then, Forestry has received some extra funding to remove and replace ash trees in poor condition or shadow plant ash trees as space allows.

Over the last few budget cycles, we have been able to reduce our public ash tree population from 16% to 14%.

In 2019 Forestry completed an assessment of all of City ash trees accounting for their condition, size, structure, and overall health. This assessment helped establish baseline data to determine which ash trees will be treated, and which will be removed and replaced. Our goal is to replace each tree we remove with a diverse group of species to help maintain the urban canopy and increase forest resilience

What to Look For

What to Look For
 
  1. Know what pest you’re looking at: if you see exit holes in the trunk but the canopy is still healthy, then you are most likely looking at a different boring insect such as Lilac Ash Borer or Flatheaded Apple Tree Borer.
    • Learn more about wood-boring insects of ash trees in Colorado online here
  2. Look for a thinning canopy and epicormic sprouts on the trunk or larger branches.

What To Do

  1. If you have an ash tree in your yard, please call a City of Fort Collins licensed arborist to evaluate your tree.
  2. Consider the benefits that your ash tree(s) provide to your property.
    • Do they shade your house?
    • Are they large, healthy trees?
    • Do the benefits of treating the ash tree long term outweigh the costs?
    • Or, should the ash tree be removed and replaced?
  3. Next, develop a plan for removal and replacement or treatment of your ash tree(s) by working with a local licensed arborist.
  4. If you decide to treat your ash tree(s) with an insecticide, keep up with the treatments as EAB has never been eradicated out of a community. EAB is here to stay.

Best Practices

  1. The number one cause of the arrival of EAB in a community is humans. Do not move firewood!
  2. Keep on the lookout for EAB signs and symptoms.
  3. When you determine which ash trees you would like to preserve long-term, keep them healthy. Water, water, water! This will also help with better pesticide uptake once you start treating for EAB.
  4. If you have decided to not treat your ash trees, make sure that you are replacing them with a suitable species for this area. If you are planting multiple trees, make sure that you diversify so that when the next pest moves in, you are then prepared.
  5. Now that EAB has been detected within the community, it is important to keep all ash material local in order to prevent the spread of EAB to other communities.
  6. If you’d like to help Forestry Plan(t) for the Future and diversify our Urban Forest, visit fcgov.com/citygive/.

Frequently Asked Questions

Has EAB arrived in Fort Collins?

Yes, as of May 11, 2020, EAB was detected just outside of City Limits in north Fort Collins.

How did EAB get here?

Adult beetles are strong flyers, but they typically fly less than half a mile once they emerge from their host tree. This means that the pest most likely arrived in our area via human transport of infested ash wood, such as firewood or other raw ash material.

Why is EAB such a BIG problem?

EAB has never been eradicated from an area or community since its detection within the United States in 2002.

Leading entomologists suggest that EAB has the potential to bring about the extinction of North American ash species if the pest is not managed.

What is the City doing to prepare for EAB?

Forestry has been preparing for EAB since it was first detected in the United States starting in 2003. We’ve worked hard to make sure that ash trees were not planted along City streets or in new City parks. Since then, Forestry has received some extra funding to remove and replace ash trees in poor condition or shadow plant ash trees as space allows.

Over the last few budget cycles, we have been able to reduce our public ash tree population from 16% to 14%.

Forestry also just finished a re-inventory of our entire ash tree population. This re-inventory updated tree diameters, conditions and helped establish prioritization of initial EAB treatment plans going forward.

How can I help slow the spread of EAB?
  • Become educated and stay vigilant
  • Report suspect ash trees or beetles to the Forestry Division
  • Remove and replace low-value ash trees with a diverse palette of tree species that are capable of becoming large shade trees at maturity.
  • Never move firewood, ash nursery stock, or raw ash material:
    • From one community to the next
    • From one spot within our community to another, except when moving to a proper disposal site
What does EAB look like?

An adult EAB is an emerald green metallic beetle that is about ½-inch long and is bullet-shaped. The area under the wing covers of an adult beetle is coppery red. The larva is off-white and flat with bell-shaped segments and can grow up to be about 1-inch long.

I found a bug that looks like EAB, what do I do?

There are many EAB look-alikes. However, if you believe that you have found EAB, please contact Forestry at 970-221-6660 or email Zm9yZXN0cnlAZmNnb3YuY29t.

How does EAB kill my tree?

EAB larvae damage trees by tunneling under the bark, producing girdling wounds that interfere with the movement of water and nutrients. Infested trees gradually die over a period of 2 to 4 years.

Although the threat of EAB is now present in the community, the Forestry Division does not plan to start treatment of ash trees until Spring 2021. Why is that?

Even though EAB has been found on the edge of our community, there is time to be strategic and proactive in implementing the management plans for public and private trees. The presence of this pest does not automatically put us into a purely reactive mode. It is very important for our whole community to join us in this approach that works to balance the social, environmental, and economic impacts of EAB  in our community.

How do I know I have an ash tree?

All true ash trees (Fraxinus spp.) have the following characteristics:

  • Leaves are compound, which means multiple leaflets occur on a common stalk, and typically have five to nine leaflets. The one exception is single-leaf ash which may have simple or compound leaves, with up to five leaflets.
  • Leaflets are smooth or finely toothed along the edges.
  • Seeds on female trees are paddle-shaped.
  • Branches and buds grow in pairs, directly opposite from each other.
  • Mature bark displays diamond-shaped ridges.

The following App is a handy tool to help you identify what type of trees you may have on your property: search for EAB/Ash Tree ID. Not an App/smartphone user? Send pictures to Zm9yZXN0cnlAZmNnb3YuY29t or contact a Licensed Certified Arborist.

Wondering if the trees on your street are Ash trees? Find out here.

What are the signs a tree has been affected by EAB?

The presence of EAB in a tree typically goes undetected until more than a year after initial infestation. Symptoms of infested trees may include:

  • Thinning of upper branches and twigs
  • Loss of leaves
  • S-shaped tunnels produced by larvae under the bark
  • D-shaped exit holes about 1/8-inch wide
  • New sprouts on the lower trunk or lower branches
  • Vertical splits in the bark
  • Increased woodpecker activity
Who can help me with my ash tree?

We suggest hiring a licensed, certified Arborist for all pruning, removal, and pesticide treatment work. Click here for a current list of certified Arborists in your area. You can also contact us for more information at 970.221.6660 or Zm9yZXN0cnlAZmNnb3YuY29t.

Should I treat my ash tree?

At this time, the Forestry Division is advising Fort Collins residents to act now and start implementing their own EAB management plans. Residents should first determine if their property has any ash trees, and if so, evaluate the condition of each tree, with continued monitoring throughout the year. Residents should also decide whether to have infected ash trees treated, or removed and replaced. City Forestry staff urge residents to weigh the benefits and costs associated with ash removal and replacement, versus ongoing insecticide treatments. 

Should I get rid of my ash trees?

If the ash tree is in poor health or is smaller than 11-inches in diameter, Forestry recommends either planting another tree near-by (shadow planting) or removing and replacing the ash with a suitable species for the Front Range.

What else can I do if I decide not to treat my ash tree?

You can have the tree removed, but we strongly suggest that you replant it with a new tree species that is well adapted to our area. Be aware that EAB is an aggressive pest and has never been eradicated from any community, so if you chose not to treat, your tree will eventually be killed.

Can I treat my ash trees myself?

Although there are pesticides available “over the counter” for homeowners to treat their tree(s), we highly recommend that you consider hiring a certified Pesticide Applicator. Even better, take it one step further and hire a licensed Tree Care Company that operates a Plant Health Care Division. If you decide to treat the tree yourself, make sure that you read the pesticide label and understand the risks associated with applying pesticides. The label is actually the law for using that pesticide legally, so follow all instructions closely.

If I treat my ash tree, what will that do?

If your ash tree(s) are properly treated, the pesticide will prevent the ash tree from being killed by EAB. Make sure that you understand the frequency of your pesticide treatment. Some pesticides may only control EAB for one year and others for up to two years. It is important to understand that pesticide applications will need to be carried out for the duration of your tree’s life; once stopped your tree(s) will be susceptible.

What is shadow planting?

“Shadow planting” is a great option for planning or planting for the future! Plant a tree near an ash tree that you do not intend to treat. This will ensure that a new tree is well established and growing when it comes time to remove your ash tree.

What can I plant instead of ash trees?

Diversity is key to a healthy urban forest. Please consider replacing the ash tree with a large maturing shade tree. Click here for suggestions. 

What can I do about my HOA's ash trees?

The City of Fort Collins Forestry Division will speak to your entire HOA or Board and provide information on how to properly prepare for the Emerald Ash Borer before it arrives in Fort Collins. Please call 970.221.6660 or email Zm9yZXN0cnlAZmNnb3YuY29t for more information.