Louisville trees threatened by Emerald Ash Borer

LOUISVILLE, Ky (WDRB) -- A killer is threatening Louisville's green space and experts say it could mean big gaps in the canopy the city is known for.

Experts say this is a fairly new, but growing issue all thanks to something called the Emerald Ash Borer.

This invasive bug kills ash trees and there are only so many resources to fight back.

It was first confirmed in Kentucky in 2009 and right now there are no signs that it's leaving.

You can hardly tell by looking but the tree pictured at right is infested with Emerald Ash Borer.

"Emerald Ash Borer is the biggest tree issue in the last 80 years," said Chris O'Bryan, co-owner of Limbwalker Tree Service.

O'Bryan says 8 billion ash trees are estimated to die over the next decade.

The problem, he says, could be catastrophic to Louisville's urban forest because ash trees make up nearly seventeen percent of its canopy.

"We're already in a deficit as far as the amount of trees in this city and we're going to lose another one out of every six trees," O'Bryan told WDRB.

"It'll be a major impact on the way our parks appear and a major environmental impact too because some of these trees are fairly old and large," said Steven Ashley, a Metro Parks Arborist.

So where did this killer bug come from?

Experts believe the bug arrived in the United States in 2002 from Asia where it originates.

"They believe it entered the United States by shipping materials in Detroit," said Ashley.

They think it has spread across the nation by people hauling firewood.

That's why environmentalists encourage you not to travel with firewood. If you're going camping, you should buy firewood locally.

"If you're taking firewood out of this area and going to Owensboro where I don't think it exists yet, you could take the bug to Owensboro and they don't want it in Owensboro," said Ashley.

The Emerald Ash Borer is a half-inch, metallic-green beetle that feeds on ash leaves but it's the larva that actually kills the trees.

"They lay their eggs about now and those eggs will hatch later this summer and then the larva will burrow into the tree," said O'Bryan.

The worm chews long tunnels beneath the bark.

That tunneling reduces water and food transport in the tree, resulting in its death.

"The adults will emerge next year, fly around, mate and the cycle repeats itself," said O'Bryan.

Scientists are looking for a way to kill the bug but right now the only solution is treating the trees with chemicals.

"Nothing has come right now so we're just treating and trying to keep a few ash trees alive until science can bring us a solution that will kill the Emerald Ash Borer," O'Bryan told WDRB.

Metro Parks officials say they only have so much money to treat the ash trees. They say they're as prepared as they can be given their resources. Right now the trees are treated using a trunk injection method. They say plans call for replacing the ash trees with a different species in the future.

Louisville's Waterfront Development Corporation has been treating Waterfront Park's ash trees for about eight years. They use a soil injection method.

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