Saving Cedar Rapids’ best ash trees from a killer invasion

CEDAR RAPIDS - Not every ash tree among the 10,000 to 15,000 here is going to be lost to the ash-killing emerald ash borer.

City parks and forestry officials here have decided to inject an insecticide into the trunks of 1,200 to 1,900 best-quality, city-owned ash trees to save them when the emerald ash borer is first spotted in the metro area.

The assumption is that the ash killer is already here, because it's been found in Cedar County next door along with Black Hawk and 17 other counties in Iowa, said Daniel Gibbins, the city's parks superintendent and former city arborist, and Todd Fagan, the current city arborist.

Gibbins and Fagan said the city's insecticide injection plan will use the chemical sold commercially as TREE-age, the application of which must be done every two years.

They estimated that the cost will be $100 to $150 a tree per injection, depending on a tree's diameter. The total cost every two years could range from $120,000 (if the city injects 1,200 trees at a cost of $100 each) to $285,000 (1,900 trees at $150 each).

Fagan said the city is following the recommendations of the latest studies, which have found that a middle approach - combining tree removal and insecticide use - is better than trying to remove every ash tree, and more affordable than trying to inject every tree with insecticide.

'It's important to realize that not every ash is a good candidate for treatment,” Fagan said. 'This allows us to react when the emerald ash borer gets here, to pick out the really, really quality ash that we do have (along city streets) and treat those as needed.”

He said the city of Des Moines is taking a similar approach.

Fagan said the city will target trees to inject with diameters at breast height of between 18 and 28 inches, which he said represents trees in the range of 20 to 25 years of age. Some older trees also will be injected, but many smaller ones may not, because they are far less expensive to remove.

Some blocks in the city have many ash trees. One city focus will be to inject perhaps half of those and replace the others so one block doesn't lose too many trees, Fagan said.

Dustin Hinrichs, field coordinator for Trees Forever in Marion, applauded the city for moving from talk of complete removal of ash trees to saving trees in the healthiest condition. He said it made sense to concentrate on mid-aged trees because young ashes might require decades of treatment, while older trees already have begun to decline.

'When you're talking thousands of dollars and thousands of trees, you really need to drill down and make sure you're doing your due diligence, which I believe the city has done,” he said.

He said the city also is making a good choice by selecting an injectable insecticide and not one that is spread on the ground.

Hinrichs said the impact on cities of the emerald ash borer is similar to what happened when Dutch elm disease hit decades ago. Minneapolis today has beautiful neighborhood streets lined with elms because the city chose to treat the trees back then, he said.

'There is something to be said for putting your foot down and saying we're going to keep these trees alive just because that's something we've decided as a community that we value,” Hinrichs said.