DES MOINES - Iowa's estimated 52 million rural and 3 million urban ash trees are facing certain death after the emerald ash borer was found on an island in the Mississippi River, near New Albin.
Emerald ash borer kills ash trees by the tunneling activity of its larvae under the tree bark, which disrupts flow of water and nutrients, and starves the tree.
"Right now, we are trying to buy time to allow scientists to come up with solutions," said Tivon Feeley, forest health program leader with the DNR's forestry bureau. "Everything we know about EAB we have learned in the past eight years."
Emerald ash borer is fairly new to this country. It was imported into the United States within the wood of shipping crates from Asia and discovered in Detroit in 2002. It has been expanding its presence mainly by being transported through wood products, like logs, nursery stock and firewood.
EAB has been found in Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, West Virginia, Wisconsin and Virginia. It has also been found in Ontario and Quebec, Canada.
In Iowa, foresters are looking for signs across the state with an emphasis in eastern counties for evidence of the metallic green one-half inch long beetle and its white grub like larvae. Counties with the most ash trees are Allamakee, Clayton, Jackson, Van Buren, Winneshiek, Lee, Appanoose, Decatur, Dubuque and Monroe.
Feeley said forestry staff visually surveyed 1,267 ash trees at 235 campgrounds and 29 sawmills, bark peeled 412 sentinel trap trees looking for larvae, and helped place 1,554 purple sticky traps primarily in counties along the Mississippi River. The monitoring effort produced one confirmed presence, with 13 adult beetles in one sticky trap on the island in the Mississippi River in Allamakee County in 2010. That trap was placed on the same island where EAB was discovered in a standing tree in 2009.
While EAB has been confirmed in Iowa, it can only fly a few miles per year, which helps slow its natural spread. What accelerates the spread is the movement of firewood from quarantined areas.
Feeley said there is still time for landowners and communities to work with foresters to create a management plan before EAB comes to town.
The most cost effective method for cities and towns is usually removal of some ash trees before the beetle arrives to spread the cost over a number of years, rather than all at once.
"This not only spreads out the costs, but reduces the public safety risks that standing dead ash trees may cause," said Emma Bruemmer, urban forestry coordinator with the DNR's forestry bureau.
The average tree removal and stump grinding cost is about $500 per tree. Iowa cities and towns have an estimated 3.12 million ash trees, bringing removal costs to $1.56 billion.
Ash tree removal is already underway in many Iowa communities. In Cedar Rapids, the city will remove about 325 ash trees during the next three months. Those trees will be replaced with a diverse mix of tree species. Cedar Rapids has an estimated 10,000 to 15,000 ash trees along its streets.
"What we are advising for communities or landowners is to have diversity among the trees. Do not have more than 10 percent of any one species represented," Feeley said.