'Natural disaster' looming for Fort Collins ash trees

The beetle to blame for the devastation of Fort Collins’ lush urban forest hasn’t even been born.

It’s an odd thought, but not an unfamiliar one for the city’s forestry department. They say waiting for the emerald ash borer to migrate from Longmont to Fort Collins, where about one in five trees are ash, is like watching “a tidal wave that’s taking forever to crash.”

“We’re just one truckload of wood away from it being here,” said Ralph Zentz, assistant city forester. “We’re hoping we have five years, but there’s no way of knowing.”

Emerald ash borers kill untreated ash trees.

All of them.

Immature beetles sprout from eggs laid on ash bark, burrowing into trees and feeding on the tissues that keep them alive.

Within three years of the invasion, the ash tree is dead.

That means Fort Collins will lose most of its ash trees, which make up one-third of the tree canopy on city property, within the next 10 to 15 years. Saving the trees will cost homeowners tens of thousands of dollars and even more for the city, which will have to pay to protect some trees and responsibly dispose of the carnage.

And cost aside, the devastation will dramatically alter the face of Fort Collins, a city whose beauty depends largely upon its trees.

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Kendra Nash was examining an ash tree in Boulder in September 2013 when she saw holes in its bark that looked familiar.

She remembered them from training — the tiny holes were symptoms of an emerald ash borer infestation.

At that point, the closest the insect had come to Colorado was Kansas City. Nash, who recently transferred from Boulder’s forestry department to Fort Collins’, had just discovered the first emerald ash borer outbreak in the state.

“This tree was riddled,” Nash said, recalling tunnels bored inside the tree and dead beetles stuck in its bark. “It was just dead, standing.”

Since then, the beetle has taken root in Boulder and is beginning to cause major destruction of ash trees. Earlier this year, the insect was spotted in Longmont, 30 miles from Fort Collins.

Boulder County is under quarantine, making it illegal to take ash wood outside its boundaries. But it’s not like police officers are hovering around the borders to check cars for contraband wood.

Eventually, an emerald ash borer will illegally immigrate across county lines and the infestation will spread. Foresters have branded the spread a "slow-moving natural disaster."

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Zentz, Nash and the rest of the Fort Collins forestry department are watching the slow spread of the ash borer the way most Coloradans watch a Broncos game — with great interest. When the beetle enters Berthoud, Fort Collins could be considered on “yellow alert,” Zentz said, and people should start thinking about treating their trees.

When it shacks up in Loveland, Fort Collins will be on red alert, Zentz said. At that point, people who don’t treat their ash trees will probably lose them.

Treating an ash tree with pesticide can safeguard it against infestation, but the treatment costs upward of $125, and it needs to be repeated every two to three years.

The city is working on identifying 2,400 ash trees on city land that are worth treating. These trees — in fair condition or better, and at least 12 inches in diameter — will be the sole survivors among more than 8,000 ash trees on city land, if the treatment works. The forestry department will request additional funding to treat 800 of these trees each year for three years.

The 59,000-some ash trees that sit on private land might see an even lower survival rate. The city can’t force residents and business owners to treat their trees, although officials can force removal of dead trees rendered a safety hazard.

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Regardless, it’s time to start making decisions about your ash trees. There’s no need to treat them yet. But if you have an ash tree that doesn't have value in the form of shade, aesthetics or history, consider replacing it with a less vulnerable tree.

Emerald ash borers can survive in a community long after most of its ash trees are gone, lurking in creek bottoms or subsisting on twigs.

“Remove that tree if it doesn’t provide a lot of value to your house and start new, because otherwise you’re going to be treating it for the life of that tree, potentially,” Nash said.

We’re in this bleak situation because Fort Collins, like a lot of places, has way too many ash trees.

Widespread loss from the last tree epidemic, Dutch elm disease, left people in the 1970s onward looking for a fast-growing tree that stood up to pollution.

“It was a good go-to tree for a long time, so too many of them got planted,” Zentz said.

At that point, the emerald ash borer was nowhere to be found outside of Asia. That’s hard to imagine now.

Another thing hard to imagine: What we'll do with all the dead ash trees.

Putting them in the county’s near-capacity landfill is a bad idea, city leaders say. But the community doesn’t have the infrastructure to turn them all into mulch, treated wood or wood chips.

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One solution could be a biomass burner, which would convert the trees to energy. But the city currently has no plans for one, environmental planner Honore Depew said.

“Without viable opportunities to utilize that wood, it’s probably just going to go where it’s cheapest, and that’s unfortunately the landfill,” Depew said.

But a lot could change by the time the emerald ash borer hits Fort Collins. The city could find a private partner for a biomass burner. Better treatment options could be available.

There’s nothing wrong with hoping. It’s become part of the MO for Zentz, who’s loved trees since he was a kid.

“To lose so many trees — I think it would change the whole look and feel of Fort Collins,” he said during an interview at the forestry office, which overlooks an ash-filled City Park. “We’ve seen people cry over trees being removed. It’s something you can’t put a price on. I’ve got trees at my house that, if I lost them, I would grieve.”

Lilac ash borer

The emerald ash borer is often confused with the lilac ash borer, a less detrimental pest. Ash tree owners, note that the emerald ash borer is a bright, metallic green color while the lilac ash borer is a clear-winged moth.