STORY COUNTY — The tree-killing emerald ash borer continues its rapid spread across Iowa with the state’s 13th confirmed infestation recently documented in Story City.
The positive identification of two emerald ash borer larvae collected by a homeowner from a residential tree in Story City marks the eighth confirmed infestation in Iowa this year, said State Entomologist Robin Pruisner of the Iowa Department of Agriculture and Land Stewardship.
A mobile beetle found earlier this year in Iowa City is not considered evidence of an infestation, Pruisner said.
Before a county can be officially recognized as infested, proof of a reproducing population is needed.
“We put up traps in the area but did not find friends and family, so we are not considering it an infestation at this time,” she said.
Iowa is just now entering the “busy season” for identifying ash borer infestations, said Tivon Feeley, forest health program leader for the Department of Natural Resources.
“We are at the point where woodpeckers start feeding on ash borer larvae in affected trees, which is probably the most readily identifiable symptom of an infestation,” he said.
The number of confirmed infestations will likely increase in the weeks ahead, though the rate of increase would be impossible to predict, Feeley said.
A statewide quarantine restricting the movement of hardwood firewood, ash logs, wood chips and ash tree nursery stock out of Iowa into non-quarantined areas of other states was issued on Feb. 4 and remains in effect.
Story City officials have inventoried the street trees in the community and are working with the Story City Tree Board to monitor, assess and address ash trees. Story City will have information available for private property owners at www.cityofstorycity.org after Sept. 1.
Until last year, only one Iowa infestation had been confirmed — in the state’s far northeast corner in 2010.
Four were confirmed last year — in Des Moines, Jefferson, Cedar and Union counties — and already this year infestations have been confirmed in Black Hawk, Wapello, Bremer, Jasper, Henry, Muscatine, Boone and Story counties.
With the exception of trunk injection, the window has closed for using other preventive methods against emerald ash borer this year.
Trunk injections can be done by certified pesticide applicators until Sept. 1.
Other control measures — soil injection, soil drench and basal trunk sprays — will need to wait until mid-April to mid-May 2015.