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Emerald Ash Borer coming soon

BY NICK MOFFITT | OCTOBER 22, 2014 5:00 AM

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Iowa City will gear up in the coming seasons to stop the emerald ash borer from infesting Johnson County.

The Iowa City City Council heard a presentation Tuesday from the city Forestry Department about the impending problems that will come with the spread of the invasive beetle, originally from Asia.

“The time to react on this is definitely now,” Superintendent of Parks & Forestry Zac Hall said.
Hall said the beetle will make its way to Iowa City, and that can present a danger.

“Because devastation happens so rapidly,” he said. “Quite literally, you have physical mass suspended in the air.”

The city’s inventory of ash trees on city property has the number of trees at around 2,000, but that does not include the interior of more dense forests and parks, Hall said.

“It’s coming; it is inevitable,” Mayor Matt Hayek said. “We need to figure out what to do in response.”

The emerald ash borer has a life cycle of around one to two years, Hall said. But in 10 years, the potential family from one female beetle is 50 billion, which quickly spreads infestation.

The larvae of the beetles eat through the top cell-layer, which inhibits the uptake of nutrients the trees need to survive, Hall said.

All 99 counties in Iowa are under quarantine for all hardwood, wood chips and ash logs crossing the Iowa border. Johnson County is not currently infested, but an adult male beetle was found on the East Side of Iowa City this past summer.

Neighboring Cedar and Muscatine Counties have been declared infested according to the state.

People largely spread the beetle, Hall said, through the transportation of firewood. He said when the beetle originally spread in Michigan in 2002, and followed campers on the NASCAR circuit.

In recent years, the city has increased efforts to remove ash trees that have shown signs of decay or previous distress, Hall said. The city has removed around two-thirds more trees than they it plants.

“We have really ramped up the ash-removal program in last three years of those that are already declining in just trying to get them out of there,” Hall said.

Councilor Jim Throgmorton said the trees are a vital part of Iowa City and the way it looks.

“The streetscape depends overwhelmingly on those trees; at the minimum, we need a tree replacement strategy in mind,” he said.

Throgmorton said while it is important to stop the spread, the removal rate of trees needs to be kept in mind.

“That two-thirds number worries me,” he said. “This will be very harmful for those core neighborhoods.”

Hall said the city Forestry Department would ask for an increase in its budget to potentially deal with the invasive beetles.

Treatment of the trees, which prolongs their life but may not save it, would cost around $60 per 20 inches of tree if done in-house, or $240 per 20 inches of tree if contracted out.

The preliminary cost of chemical treatment of inventoried trees is $480,000 if contracted out, or $120,000 if done in-house, according to Hall’s numbers.

“From what was cited, I’m questioning whether chemical treatment would be effective if it is only going to prolong the trees,” Hayek said.

The current consensus for fighting infestation in Iowa, Hall said, is removal and replacement of infected trees.

Hall cited a study from Professor Dan Herms of Ohio State University that shows that over 10 years of infestation can devastate the population.

Hall said the quick demise of the trees is why it is important to take preliminary action.

“What we’re seeing is that after four or five years the devastation really ramps up,” he said.


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