Spread of ash tree-killing insect deemed unavoidable

Katie Parkins
Special to Colorado Community Media
Posted 7/17/18

The green beetle blamed for killing thousands of ash trees continues to spread south, most recently to the town of Superior. This marks the fifth Front Range community the Emerald Ash Borer has …

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Spread of ash tree-killing insect deemed unavoidable


The green beetle blamed for killing thousands of ash trees continues to spread south, most recently to the town of Superior.

This marks the fifth Front Range community the Emerald Ash Borer has infiltrated in five years.

Westminster foresters said they expect the Emerald Ash Borer to continue to spread into the Denver Metro area, including Westminster, over the next one to three years.

“I’ve been encouraging residents and the (Home Owners Associations) that if they want to save their healthy ash trees, the Emerald Ash Borer is close enough to Westminster, it’s time to give the trees the pesticide,” said Westminster City Forester John Kasza.

There are pesticides that can be used to treat and protect ash trees from the Emerald Ash Borer, but a licensed professional must administer the insecticide on residents’ personal ash trees.

The Emerald Ash Borer in Superior was first found on the town’s public property, which the Colorado EAB Response Team could take care of directly. However, the insect was later reported on private property ash trees nearby, and residents are responsible for deciding what to do with those trees.

The Colorado State Forest Service does not know if this most recent spread was natural or from humans accidentally providing transportation for the pest.

“We had a quiet time from August of last year until March,” said Keith Wood, the Urban and Community Manager for the Colorado State Forest Service.

In March of 2018, the Emerald Ash Borer moved into Lyons, Colorado before making its way to Superior.

“It’s hard to curb the spread of it. We do try to discourage the movement of firewood. That is one of the main ways that Emerald Ash Borer is spread,” said Kasza.

The City of Westminster Forestry Section provides firewood at the Standley Lake campgrounds in an attempt to discourage guests from bringing in wood from other places. The beetle is not an insect native to Colorado.

Wood said the state forest service and the City of Boulder did identify the Emerald Ash Borers in Colorado fairly early on, compared to communities in the north and Midwest where the pest originated.

The state forest service established a quarantine area for Boulder County and part of Weld County in 2013 when the EAB was first detected in an attempt to prevent humans from accidentally spreading the insect.

“It’s not going to spread as quickly as it did in the Midwest because we don’t have the ash tree forests between town to town,” Kasza said. “Between Boulder to superior to Westminster, there’s not a lot of ash trees. The insect can only fly about a half mile each year. The spread is primarily by humans.”

As of now, the EAB hasn’t been confirmed outside of the quarantine area in Boulder County. Once CSFS and the Colorado EAB Response Team are able to get a positive detection outside of Boulder County, the quarantine area will be expanded.

“This isn’t something we’re going to stop or eradicate, ,” said Wood. “The quarantine is designed to contain it. Let’s try and slow the spread of this as much as we can, whether that’s with pesticides or biological controls.”

Over the last five years since the ash borer was first found in Colorado, the state has spent $9 million on management the pest, according to Wood. Approximately 17,000 public trees have been treated and removed, and 17,000 replacement trees have been planted.

“In Westminster, we’ve had to spend extra time treating our ash trees, extra time removing trees, planting new trees, and also just the extra time to educate the public,” said Kasza.

Experts encourage residents to be proactive, treating their ash trees early. Once the ash borers have killed an ash tree that tree becomes unsafe to climb and can be difficult and expensive to remove.

“If you have a valuable tree, they can be saved with some of these pesticides. Without that, we could be talking about the extinction of ash,” said Wood.


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