This is the year the cities of Davenport and Bettendorf will begin taking down ash trees.
In Davenport, removal of up to 300 ash trees on the public rights of way, or “street trees,” is one piece of a multi-year plan developed by city forestry manager Chris Johnson for dealing with the inevitable arrival of the emerald ash borer in the Quad-Cities.
The borer is an invasive pest from Asia that first was detected in the U.S. in Detroit in 2002. It has been confirmed in 15 states, killing at least 25 million ash trees. Although the closest confirmed infestation is about 50 miles away in Kewanee, Ill., horticulturists say it already might be in the Quad-Cities, undetected.
Another piece of Davenport’s borer response plan is to treat some of the ash trees with a preventative chemical to save them, an option that will be used on a little more than 400 trees, beginning with about 200 this year, Johnson said.
But treatment has to be continued indefinitely, so it would be cost-prohibitive to try to treat all ash trees, he said. At present, there is no permanent solution or cure for the ash borer.
“Eventually, most will be gone,” Johnson said of the city’s ash trees. “But we will treat and save some every year to keep some species diversity.”
One positive note in Davenport’s ash borer planning is that when it hired a firm to inventory all of the trees along city streets — as well as in some parks and along portions of the Duck Creek recreational path — the firm found that the number of ash isn’t quite is large as expected: about 15 percent of the total, Johnson said.
This year’s removal and treatment programs are expected to cost in the range of $20,000 to $25,000 each, Johnson said. Because Davenport has a forestry department, it can handle removal in-house. Treatment also could be done in-house, although that decision has not been made yet.
The trees the city will remove are those in the worst condition, not thriving plants. And for each one removed, the city aims to plant another tree in its place, Johnson said.
Bettendorf has not yet estimated how many trees it will remove or treat this year because it has not yet completed its inventory, parks director Steve Grimes said.
The inventory will look at all trees along major streets and in maintained areas of major parks. Once that is finished, the city will determine which trees are worth saving and which it should begin to remove.
Grimes said he will recommend spending $30,000 this year for inventory, treatment and removal, and $30,000 per year over the next five years for treatment and removal.
Removal can slow the spread of the borer to other areas, he noted. And with treatment, some specimen trees can be saved.
Still to be worked out in the borer plans is a “drop location” for removed trees, Johnson said. He doesn’t want to take them to the Davenport Compost Facility because of its close proximity to the Mississippi River. If any of the removed trees turned out to be infested, the bug might too easily “hop a barge” and be carried downriver to states that aren’t yet infested, he explained.