Marion trains staff, gardeners to prepare for emerald ash borer infestation

MARION - Residents and officials are not idly awaiting the eventual destruction of their ash trees by the emerald ash borer.

'We're doing everything we can to get ready,” said Mike Carolan, director of the city's Parks and Recreation Department.

Wednesday's announcement of an ash borer discovery in Clinton increased to 20 the number of Iowa counties with confirmed infestations. With one of those infestations, in Cedar County, just 30 miles distant - 'It's not a matter of if, it's a matter of when,” Carolan said.

'I'm guessing it's already here and we just have not seen it yet,” City Manager Lon Pluckhahn said.

Pluckhahn said the five years since the state's first infestation - near the Mississippi River in Allamakee County - has given Marion ample time to prepare.

The recent establishment of an urban forestry department with a dedicated funding source puts the city in position to handle the expense of removing dead ash trees from city property and replacing them with less vulnerable species, Marion Tree Board Chairman Scott Hansen explained.

A $2-per-month fee added to water bills will enable the city to staff its urban forestry department with a forester and a forestry technician - one to be hired in July and the other in January, Pluckhahn said.

'That will enable us to do a lot of the necessary work in-house,” he said.

Those funds also will enable the city to meet ash removal and replacement expenses estimated, at $350,000 and $166,000, respectively, Hansen said.

To help prepare for the coming infestation, about 30 people - city staff, master gardeners and members of the City Council and the Tree Board - are receiving advanced training this year under a grant by the U.S. Forestry Service and the Department of Natural Resources.

Last year the city developed its Emerald Ash Borer Readiness Plan, which may be updated based on some of the information acquired through this year's advanced training, Carolan said.

According to a Street Tree Inventory Data Base developed in 2011 by Marion and Trees Forever, the city has 3,055 deciduous trees in city right of way, with 764 - about 25 percent - being ash trees.

The city estimates that an additional 700 ash trees exist on other city property that includes parks and green space.

In the 273 Iowa communities that have completed tree inventories, ash trees make up 17 percent of the canopy on municipal property, according to DNR forester Matt Brewer.

Hansen attributes the high percentage of ash trees along Marion streets at least in part to an overreliance on ash trees to replace elms killed by Dutch elm disease in the 1960s and '70s.

'We won't make that mistake again,” said Hansen, noting that when the approximately 1,500 ash trees on city property are killed by the borer, they will be replaced with diversified plantings of more than a dozen tree species to reduce the odds of another catastrophic loss.

As maple trees make up more than 40 percent of Marion's right of way hardwood tree population, they will not be included in the replacement mix.

Brewer said the DNR highly recommends oak and hackberry as ash tree replacements.

Although Marion has not inventoried privately owned trees, it is estimated that private ash tree numbers equal the right of way ash tree estimate.

Property owners are responsible for infested trees on private property and will be required to remove them within a specified time after notice has been served.

The city's main approach will be to remove infested trees as they are identified.

Unless specifically mandated by the state, Marion does not plan to remove healthy ash trees. But in situations in which an ash tree of marginal value needs trimming, the city will remove it and plant its replacement, Carolan said.

Because of the cost and frequency of preventive treatment, the Marion Tree Board has recommended the city not try to treat all its ash trees. Exceptions can be made, however, for significant, sizable or otherwise important ash trees.