‘It’s pretty devastating;’ Ash tree killer could be coming, says parks director

Posted 9/9/14

About 60 to 70 percent of trees in Powell are ash of one kind or another. Around 500 of those are city-maintained trees, according to Parks Superintendent Del Barton, who also is the city arborist.

But Les Koch, Wyoming State Forestry Division …

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‘It’s pretty devastating;’ Ash tree killer could be coming, says parks director

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Powell is at risk of losing its Tree City USA recognition if a nasty little insect arrives.

The emerald ash borer, which kills ash trees, is devastating Boulder, Colo., after having devastated urban forests across the Midwest. Experts believe it’s a matter of time before it arrives in Wyoming. The Powell City Council discussed that during its Sept. 2 meeting.

About 60 to 70 percent of trees in Powell are ash of one kind or another. Around 500 of those are city-maintained trees, according to Parks Superintendent Del Barton, who also is the city arborist.

But Les Koch, Wyoming State Forestry Division forest health program leader in Cheyenne said the ash borer may or may not arrive in Powell.

“Yes, it’s possible, I would say distinctly low-risk at this time,” Koch said.

Boulder is the only place this side of the Mississippi River that the ash borer has been discovered. And, it’s being contained.

There are thousands of privately owned ash trees in Powell, Barton said. All are at risk from the small bugs with the metallic green shell.

Emerald ash borer eggs are laid on the outer bark of trees. After the eggs hatch, the larvae burrow beneath the bark. The larvae eat phloem, the nutrient-transporting system under the bark, and that creates tunnel-like galleries.

As more galleries are eaten, the tree soon begins to exhibit symptoms of dieback (begins to die), including thinning and dying treetops, and sprouting from the base or trunk.

It costs $1 per circumference inch to treat a tree, likely with a chemical known as imidacloprid. If the trees range from 20- to 40-inch circumference, that’s $20 to $40 per tree.

“Estimating about 500 public ash trees, the math shows the cost at $10,000 to $20,000 per year just for the imidacloprid,” Barton said.

On average, when factoring labor at $25 per hour and transportation, the cost doubles. For example, if the chemical treatment cost $20,000, it would cost an additional $20,000 in labor and transportation, Barton added.

Powell City Councilman Floyd Young’s figure is significantly higher. He estimated it would cost $300,000 annually to treat the city’s trees.

Imidacloprid-based insecticides can kill the insects, but it is not a guarantee that a tree can be saved.

“Imidacloprid is an insecticide that was made to mimic nicotine. Nicotine is naturally found in many plants, including tobacco, and is toxic to insects,” the National Pesticide Information Center states on its website.

The most effective means to insert imidacloprid into a tree is by injection, but it must be done by a professional arborist, Barton said.

Bayer makes an over-the-counter tree and shrub insect control concentrate that kills emerald ash borer. A 1-gallon container costs around $140 and will treat three to five trees, Barton said.

City Councilman Josh Shorb, who also is the supervisor of the Park County Weed & Pest Control District, said the district may stock the insecticide.

“There are a couple of issues on our end of things to deal with,” Shorb said.

“First, we did not budget for us laying in tens of thousands of dollars of this insecticide,” he said. “You know how government budgets work — we only have so much budget space, even if it’s a dollar-in and dollar-out proposition. We may have to amend our budget.”

Barton said the best time to treat trees is in the spring.

“That’s what I recommend,” he said.

Bayer states that it provides 12 months of protection. For those who prefer a natural insecticide, there is not enough research proving any organic compounds are effective, Barton said.

If ash trees are to be saved, landowners and the city will be required to treat the trees for as long as they stand, Barton said.

If the tree has less than 50 percent infestation, the tree may survive with treatment, especially if it is young. More than 50 percent and the tree will likely die, even with treatment, Barton said.

“It’s pretty devastating,” Barton said.

The emerald ash borer works from the top down, so the crown of the trees become brittle. That can cause other problems as well, he said.

Removing dead trees is costlier than removing live ones, because the dead trees are brittle and prone to break, causing damage to buildings, so more care and time is required, Barton said.

Local arborists charge between $135 and $200 per hour to remove a tree, said Jennifer Pomeroy of Blue Ribbon Tree Services.

The city has a number of options to deal with an infestation, according to Barton. They are:

1. Treat all trees each spring indefinitely.

2. Treat some trees, like those around City Hall and the parks, and remove others.

3. Treat no trees and run the risk of the insects killing all of them, Barton said.

He recommends No. 2, but it all depends on funding. “Obviously this is going to be cost-driven,” Barton said.

There may be some help in funding.

The Arbor Day Foundation could not help the city with funding for its ash tree plight, but the foundation could steer the city toward organizations with available grants.

The Wyoming State Forestry Division would like to see Powell create an arboretum, a botanical garden for trees with a wide variety of species. Forestry wants arboretums around the state to ascertain what species of trees thrive in those locations.

The state would provide $20,000 in seed money.

“And then you’re on your own,” Barton said. “That’s the drawback.”

The arboretum wouldn’t have to be in Powell. It could be a joint effort by area towns. But it must be at least 1 acre and be located on public land, Barton said.

Ash firewood is the culprit. Boulder and Boulder County, Colo., is under federal quarantine prohibiting any ash products from leaving, Koch said.

He advises homeowners and municipalities to be vigilant and watch for signs that the emerald ash borer has invaded trees. Koch also said plant different species like oak, hackberry and linden.

— Tribune Managing Editor Tom Lawrence contributed to this report.

The emerald ash borer can be fatal to trees, but they can be treated. A state official said there’s no need to treat or remove any trees, since the insect may not arrive in Powell.

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