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Lincoln prepares for invasion of deadly ash borer

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A beautiful insect that has decimated trees in other regions is headed this way.

The emerald ash borer is now 80 miles from Bellevue in Creston, Iowa, on the east, in Boulder, Colo., on the west and Kansas City on the south.

“So it’s starting to flank us,” said Lincoln City Forester Bob Weyhrich.

"In fact, there is a possibility it could already be here,” he said, noting that it often takes a few years for the borers' damage to show up on trees.

But once the ash borer arrives, it’s goodbye ash trees; so long to the tree with gray, corky bark that is a popular tree in Lincoln parks, lawns and along the streets.

The emerald ash borer is a beetle that nibbles on leaves, and the females lay eggs, tucking them in bark crevices. The larvae do the damage, chewing through the outer bark to an inner layer called phloem, the tissue used to carry nutrients to the roots. Eventually, the density of the larvae builds and the tree succumbs.

“It’s a pretty bug," Weyhrich said. "Nasty disease, but pretty bug.”

In Toledo, Ohio, ash trees that lined neighborhood streets in 2006 were all dead by 2009.

The progression of the disease is dramatic.  Once it starts, the number of trees affected increases tenfold each year, Lincoln Parks and Recreation Department Director Lynn Johnson told the City Council recently.

Four the first year means 40 the second year, 4,000 the third, 40,000 the fourth.

“We could lose them all in three years,” Johnson said of Lincoln's ash trees.

An estimated 20 percent of the city's 139,000 public trees are varieties of ash — Autumn Purple ash, Patmore ash, Hessei ash, Marshall seedless ash.

That means the city could lose an estimated 21,000 street trees and another 7,000 to 8,000 park trees, said Weyhrich.

The city forestry office is doing an ash count by zone as part of the cost analysis in preparation for the infestation. Between 70th and 84th streets and the city limits north to south, there are 3,025 public ash trees, a variety that grows well in our clay soils.

The staff expects to have cost estimates in a couple months for removing dead trees and saving live ones.

Chemical treatments can prevent or slow down the infestation, but for the city to treat all its trees, it would be “fairly expensive,” Johnson told the council.

The product for a 15- to 16-inch tree costs about $2.70, not counting the personnel cost of applying it, said Weyhrich. And the treatment has to continue, sometimes annually, for years.

If the city treats street trees and homeowners don’t treat theirs, the insect will still be here, he said.

In addition, the city won’t like be able to immediately replace every dead tree, Johnson warned. The city commits to watering every new tree for two years and can water about 600 trees a year, according to Weyhrich.

The ash borer will not be as devastating to Lincoln's public tree population as the Dutch Elm disease that wiped out about 60,000 public trees in the 1970s and '80s.

But it's bad.

"It’s coming,” Weyhrich said, "and I’m not looking forward to it."

Reach Nancy Hicks at 402-473-7250 or



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Nancy Hicks reports on Lincoln city government, but she’s been following the leaders of local and state government for more than 40 years.

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