EAB Now In Arvada

All city foresters along the Front Range, including Denver’s, do expect homeowners to manage the Ash in their yards. The Ross Tree Company created an Emerald Ash Borer Handbook to inform homeowners about this tree insect. EAB now resides in unincorporated Larimer County and the cities of Boulder, Gunbarrel, Longmont, Lafayette, Lyons, Superior, Broomfield, and Westminster. In 2020, the Arvada Forest Service confirmed that the insect is now in Arvada. The insect is highly destructive to White and Green Ash trees because these trees possess no immunity to the insect and its larvae. Without treatment, the tree will die. From the map below, the insect is within approximately six miles from the Denver area. Once the insect becomes established, it is just a matter of time before the EAB arrives where you live. It could be in Denver now, but the jewel borer is hard to detect because of most of the harm to Ash trees is underneath the bark. By the time someone notices the adult borer munching on their tree’s leaves, it is usually too late to save the tree. So prevention is the best approach to managing yard Ash trees.

emerald ash borer map


Ash Tree Identification

Since there are 1.4 million Ash trees in the Denver Metropolitan area, there is a about a 15 percent chance there is an Ash on a property. The first step for homeowners is to determine if there are any Ash trees in their yard. Please use the video or descriptions below to determine if your trees are Ash or not.


Ash trees have the following characteristics:

  • Compound leaves with 5 to 9 leaflets
  • Leaflets, buds, and branches growing directly opposite from one another
  • Diamond-shaped bark ridges on mature trees

Action Two – Prevention or Removal – Are Your Ash Trees Worth Saving?

Ross Tree can treat any Ash tree considered worth saving. As a rule of thumb, a mature tree landscape is worth about ten percent of the value of a home. Ash trees with a 15-inch Diameter at Breast Height (DBH) are considered mature and worth saving. To get a tree’s DBH, measure the distance around the trunk 4.5 feet from the ground, and divide it by three. Any trees higher than 15 DBH need to be treated by a professional tree service company like Ross Tree Company. Ash trees under powerlines or in poor health are not worth the cost of treatment and need tree removal. Also, trees with insect infestation, woodpecker damage, bark splits, and spouting at the base of the tree are candidates for removal. Check our blog about removing trees in the tightest of places at a reasonable cost.

Action 3 – Professional Treatment of Mature Ash Trees

Ross Tree Company prides itself on being one of the first companies to offer tree injections in Denver. We also provide soil drench and basal trunk spray treatments. One of our arborists will sit down with the property owner and discuss all options before the EAB treatment commences. Licensed tree service companies have the equipment and expertise to treat large trees in an environmentally sound manner. The best time for EAB treatment is between April and October when Ash trees are leafed out. The trees are actively transpiring and take up EAB treatments more efficiently at this time.

Hiring a licensed Colorado Department of Agriculture Commercial Pesticide Applicator, like Ross Tree Company, for EAB treatment can help save Ash trees. Ross Tree offers several effective treatment methods for controlling EAB. Ross Tree is a pioneer in the field of tree injections for tree pest control. Tree injections avoid the need for spraying, which is better for the environment. Qualified tree care personnel inject the treatment directly into the vascular system of the tree. This type of treatment can protect a tree for up to two years and is up to 95% effective against the EAB. For a free Emerald Ash Borer consultation, call 303-871-9121 or click here to fill out a service request form.

Action 4 – Does Your Ash Tree Have EAB?

Once the EAB hits Denver, it will be next to impossible to make an EAB treatment appointment because the tree service industry will be overwhelmed. So homeowners need to be proactive now to save their landscape Ash.

Below are signs of EAB infection:

  1. Sparse leaves or branches in the upper part of the tree.
  2. Vertical splits in the bark.
    splits in ash tree bark
  3. Winding S-shaped tunnels under the bark, often visible within vertical bark splits.
    eab ash tree damage
  4. D-shaped exit holes about 1/8 inch wide.
  5. New sprouts at base of trunk.
    ash trunk sprouting
  6. Increased woodpecker activity.
    ash tree woodpecker damage
  7. Leaf feeding damage and finding adult Emerald Ash Borers on trees.
    eab on leaf

Need to know your EAB treatment options? Ross Tree is at your service. Click here to request tree service or call 303-871-9121 for an appointment.