Six Years After Emerald Ash Borer Arrived in Arvada: Status Report

Six years ago, Emerald Ash Borer (EAB) was discovered in Arvada. Since then, the tiny metallic-green beetle has quietly munched across neighborhoods throughout the city. What began as an isolated infestation near Homestead Park has spread across Arvada, leaving a visible mark on the community’s urban forest.

 

The Emerald Ash Borer is a 100% Mortality Insect

Untreated, infested Ash trees experience nearly 100% mortality. As EAB larvae feed beneath the bark, they destroy the tree’s vascular system, preventing water and nutrients from reaching the canopy. Once this process begins, the decline is often irreversible without early intervention. At Ross Tree, we’ve watched this progression firsthand.

Then and Now

The photographs above were taken by Ross Tree approximately two years ago in Arvada. Even then, these mature ash trees had already suffered severe canopy loss. Last week, our general manager spent time at a job in Arvada and noticed something even more striking. Driving through the neighborhoods, he observed the same pattern repeatedly. Streets that once featured continuous rows of mature Ash trees now show trees with sparse, declining crowns.

Why Ash Trees Decline So Quickly

Emerald Ash Borer attacks from the inside out.

Adult beetles lay their eggs on the bark of ash trees. After the larvae hatch, they tunnel beneath the bark and feed on the cambium—the living tissue responsible for transporting water and nutrients throughout the tree. As more feeding galleries develop, the tree gradually becomes girdled from within and can no longer transport nutrients to all parts of the tree, causing dieback.

Below are symptoms of EAB presence.

1. Leaves become sparse.
2. Branches begin dying back from the tips.
3. Woodpeckers often become unusually active as they search for larvae beneath the bark.
4. Epicormic sprouts may develop along the trunk.
5. Eventually, large sections of the canopy die.

Can an Ash Tree Still Be Saved?

The good news is that Ash trees can be saved if treated early. Trees with more than 80% of its canopy remaining can often be successfully protected through professional trunk injections. Early treatment is critical.

As a general guideline:

• More than 80% canopy remaining: Treatment is usually the best long-term investment.
• Less than 80% canopy remaining: Removal and replacement are often the better long-term solution.  https://rosstree.net/tree-services/tree-removal/

An ISA Certified Arborist can evaluate the condition of your tree and recommend the most cost-effective option.

Replacing Lost Ash Trees

While no one wants to lose a mature shade tree, replacement creates an opportunity to diversify home landscapes with species that are resistant to Emerald Ash Borer.

Catalpa

Catalpa is an excellent replacement for homeowners looking to restore shade quickly. It grows significantly faster than many hardwood species and develops a broad canopy with large heart-shaped leaves. In late spring, it produces showy white flowers that attract bees and other pollinators. Catalpa does produce long seed pods, but most homeowners consider that a small tradeoff for its rapid growth and impressive appearance.

Kentucky Coffeetree

Kentucky Coffeetree is another outstanding choice for Colorado landscapes. It is exceptionally hardy, drought-tolerant once established, and develops a distinctive and attractive branching structure. Like Catalpa, it also produces seed pods. Its primary drawback is its slower growth rate

If your goal is to restore shade as quickly as possible, Catalpa is generally the better choice.

The Lesson from Arvada

When Emerald Ash Borer was first discovered in Arvada, the City’s Forestry Division did an excellent job educating residents about the threat. The city proactively treated mature Ash trees in parks and public rights-of-way, while encouraging homeowners to protect their Ash trees and remove marginal trees.

Fast forward six years. Many homeowners with Ash trees did not treat their trees and are now dealing with declining yard trees. Today, entire neighborhoods have lost much of the mature tree canopy that took decades to establish. Replacing those trees will take another generation. Homeowners with Ash trees, now is the time to have it inspected. Ross Tree Company’s ISA Certified Arborists can inspect the tree’s canopy for signs of Emerald Ash Borer and recommend the best treatment options.

Schedule you’re arborist visit at: https://rosstree.net/request-service.

Frequently Asked Questions