Emerald ash borer, a highly destructive insect that kills ash trees, has now pushed its way into 21 counties in Iowa. The latest county to be confirmed having an infestation of EAB is Dallas County in central Iowa. State officials made the announcement April 15. The invasive pest, already identified in Jasper, Boone and Story counties in central Iowa, is threatening the city of Des Moines. Tree experts speculate EAB is likely already in Des Moines or its suburbs, but an infestation hasn't been identified yet.
"The emerald ash borer is here in central Iowa now, after being discovered in some other counties in Iowa in recent years. Its destruction will be widespread and costly for cities, towns, rural areas and residents across the state," says Mike Kintner, the Iowa Department of Agriculture & Land Stewardship's emerald ash borer coordinator. The expected loss of millions of ash trees across Iowa will cost $2.5 billion over the next two decades. The cost will come from higher energy expenses due to lost shade trees, rising storm water retention costs and reduced property values, according to the official estimate made by the Iowa Department of Natural Resources.
It also costs to have dead trees removed and replaced by other types of trees. And some ash tree owners are opting to make preventive insecticide treatments on valuable, healthy ash trees within 15 miles of a known infestation.
EAB kills all ash tree species, as larvae tunnel into the trees
EAB is a green beetle in its adult stage, which lays eggs and produces tiny larvae which burrow and feed under the bark. The larvae tunnel into the trees, destroying the water and nutrient conducting tissues in the bark. The canopy of a heavily infested tree will lose its foliage. An infested tree usually dies within one to three years.
Iowa DNR officials say about 3 million ash trees are scattered across cities and towns in Iowa and another 52 million ash trees are in rural and woodland areas.
This latest discovery of EAB and its positive identification were in a residential tree in the southeast corner of rural Dallas County, making this the 21st county in Iowa where this invasive beetle has been found, says Kintner. This infestation was found as a result of an arborist contacting state officials about a suspect ash tree. Investigation by the Iowa EAB team revealed the characteristic galleries, recent woodpecker activity, and live larvae that were positively identified by tree specialists from both federal and state agencies. "This finding is the closest to Polk County and Iowa's capital city of Des Moines, to date" notes Kintner. "With this discovery, Iowa has declared three positive counties in 2015 where this ash-killing pest has been found."
Twenty-one Iowa counties now have confirmed EAB infestations
A statewide quarantine, issued on Feb. 4, 2014, remains in place, 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.
"We still strongly urge Iowans to not move firewood long distances," says state entomologist Robin Pruisner of the Iowa Department of Agriculture. "A large portion of Iowa is not showing signs of EAB infestation. We want to keep those areas EAB-free as long as possible by not moving wood that potentially harbors EAB or other tree pests. Be vigilant and report suspicious symptoms in counties that are not yet known to be infested to a member of the Iowa EAB Team."
The Iowa EAB Team provides EAB diagnostic assistance to landowners. The team includes officials from Iowa Department of Agriculture & Land Stewardship, Iowa State University Extension, the Iowa Department of Natural Resources, USDA Animal Plant Health Inspection Service and the USDA Forest Service.
Obey the quarantine; don't haul firewood across county or state lines
The Iowa EAB Team strongly cautions Iowans not to transport firewood across county or state lines, since the movement of firewood throughout Iowa or to other states poses the greatest threat to quickly spread EAB and other plant pests. Most EAB infestations in the U.S. have been started by people unknowingly moving infested firewood, nursery plants or sawmill logs, says Pruisner. The adult beetle also can fly short distances, approximately 2 to 5 miles.
The window for preventive treatment measures of applying an insecticide (trunk injection, soil injection, soil drench or basal trunk sprays) is mid-April to mid-May. If a landowner is interested in protecting a valuable and healthy ash tree within 15 miles of a known infestation, they should have landscape and tree service companies bid on work, review the bids and treat during the recommended treatment time.
Contact a specialist, have suspicious looking ash trees checked
Contact any of the Iowa EAB Team members if you have suspicious looking trees and have them checked, especially if you are in a county that is not currently known to be infested. The State of Iowa will continue to track the movement of EAB on a county-by-county basis, says Pruisner. Before a county can be officially recognized as infested, proof of a reproducing population is needed and an emerald ash borer must be collected and verified by USDA entomologists.
To learn more about EAB and other pests that are threatening Iowa's tree population, visit IowaTreePests.com. Contact any of the following members of the Iowa EAB Team for further information:
•Robin Pruisner, IDALS State Entomologist, 515-725-1470, [email protected]
•Mike Kintner, IDALS EAB Coordinator, 515-745-2877, [email protected]
•Paul Tauke, DNR State Forester, 515-725-8450, [email protected]
•Tivon Feeley, DNR Forest Health Coordinator, 515-725-8453, [email protected]
•Jesse Randall, ISU Extension Forester, 515-294-1168, [email protected]
•Mark Shour, ISU Extension Entomologist, 515-294-5963, [email protected]
•Laura Jesse, ISU Extension Entomologist, ISU Plant and Insect Diagnostic Clinic, 515-294-0581,[email protected]
•Donald Lewis, ISU Extension Entomologist, 515-294-1101, [email protected].
•Jeff Iles, ISU Extension Horticulturist, 515-294-3718, [email protected]
Summing up: Kintner and Pruisner offer the following advice. For trees within 15 miles of a confirmed EAB site, immediate action is recommended either tree removal or treating with insecticide. Property owners should take a few key steps: promptly identify ash trees, determine if they are infested, select and begin a treatment method or make arrangements for removal.
Treatment or removal? Preventive treatment with application of an insecticide, rather than tree removal, is a viable option for healthy ash trees that are not infested with the beetle. Infected trees with less than 30% of the crown defoliated might be saved for a few years with proper insecticide treatment, according to the tree experts.Infected trees that do not receive treatment should be removed as soon as possible. Cost of removal will rise as time progresses because of deterioration, growth in size and increased demand for tree removal service in the area.