An estimated 15 percent or more of all urban and community trees in Colorado are ash species susceptible to being killed by EAB.

A majority of these trees are on private land.

The most important action homeowners all over Colorado can take now is to determine if they have ash trees. Other actions homeowners can take to help mitigate EAB are outlined below.

Determining an EAB presence is often difficult to the untrained eye.

Symptoms include:

  • Sparse leaves or branches in the upper part of the tree
  • Vertical splits in bark possibly showing S-shaped galleries underneath
  • Increased woodpecker activity
  • Miniature leaves at the tips of branches late in the summer

Ash trees have been widely planted in Colorado, but because EAB is always fatal to untreated ash trees, avoid planting any true ash species (genus Fraxinus). Instead, consider the following recommendations:

  • Focus on tree and landscape-plant diversity. No one tree species should comprise more than 10 percent of the planted trees growing in any urban or community setting.
  • “Plant ahead” and get new trees in the ground that can someday replace ash trees lost to EAB and the shade and other benefits they provided.

An ash tree replacement tool, which includes a list of trees suitable for ash replacement, is available on the Colorado Tree Coalition website.

While effective insecticides are available to protect ash trees from EAB, other management strategies also exist for dealing with the pest:

  • Monitoring trees for the presence of EAB
  • Removing and/or replacing ash trees
  • Planting new trees preemptively in an effort to get them established before the arrival of EAB

Decisions about how to manage ash trees should take into account the overall health of each tree and its value to the property owner.

The closer ash trees are to an area of known infestation, the higher the risk that they will become infested by EAB through natural spread.

Chemical Treatment

Consumers should educate themselves when purchasing chemical products to protect trees against EAB, and talk to a professional forester, extension agent or arborist before applying any treatment.

For more information about chemical treatment options, view Insecticide Options for Protecting Ash Trees from Emerald Ash Borer (3 MB PDF).

Never transport hardwood firewood or any other raw wood products from ash trees, as this is the most likely method of accidental spread.

A quarantine is in place in Boulder County and surrounding areas to try and prevent the human-assisted spread of EAB.

Regulated articles include:

  • EAB specimens
  • Ash nursery stock
  • Ash logs
  • Branches and chips
  • Green lumber
  • All hardwood firewood
  • Any other article, product or means of conveyance that may present a risk of spreading EAB
Don't Move Firewood