The Ross Tree Company created an Emerald Ash Borer Handbook to assist homeowners decide what to do with the Ash trees on their property. The Emerald Ash Borer (EAB) is in the news because this tree insect kills Ash trees. There are over a million Ash trees in the Denver Metropolitan area with most of the trees on private land. Additionally, the EAB is now spreading along the Front Range and no telling where it will land next.

Emerald Ash Borer History

The EAB is an insect native to Asia that appeared in Michigan in 2002. The EAB is the most destructive tree insect ever to be introduced in America. This tree insect has killed tens of millions of Ash trees in central and northeastern United States. The EAB arrived in Boulder in September 2013. The Colorado State Forest Service declared the whole city of Boulder infested in 2015. It took this tree pest four years to spread to Broomfield and Westminster. Westminster is about nine miles from the Colorado State Capitol in Denver. The EAB is here to stay, so it is time for Denverites to decide what to do.

Action One – Ash Tree Identification

Emerald Ash Borers attack Green and White Ash trees. Homeowners need to determine if they have Ash on their property. Ash trees have the following characteristics:

ash tree identification

  • 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 by a property owner. As a rule of thumb, 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 managed by a professional tree service company like Ross Tree Company.

Ash trees that look sick or growing near a power line are not worth saving. Also, trees with insect infestation, woodpecker damage, bark splits, and spouting at the base of the tree are candidates for removal. Ross Tree is a professional tree removal company. Check our latest blog about removing trees in the tightest of places at a reasonable cost.

Action 3 – Professional Treatment of Mature Ash Trees

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.

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.

Action 4 – Does Your Ash Tree Have EAB?

Prevention is the best option for Green and White Ash trees because these trees have zero resistance to the EAB. So, if a homeowner values their trees, they should them get them treated next spring by professionals. 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

Since most EAB damage is inside the tree, it is probably too late once a homeowner recognizes the insect. However, Ash trees with EAB induced crown thinning between 30-50 percent are candidates for treatment. A licensed tree service company, like Ross Tree, can either treat your trees or safely remove them.

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.