Emerald ash borer 2012 surveillance summarized
DES MOINES — The Iowa Emerald Ash Borer Team said last week that final results from the comprehensive surveillance efforts undertaken again in 2012 show little movement of the Emerald Ash Borer (EAB), an invasive insect pest that kills ash trees. The pest had initially been found in Iowa on Henderson Island in the Mississippi River in Allamakee County in 2010. This year’s survey results show the pest has moved off the island but has not moved outside of Allamakee County.
In 2012 there were 1,220 purple traps set across the state by USDA. Two of the traps were positive for EAB. One was located in New Albin and the other in Lansing. EAB had originally been found in Allamakee County in 2010 — however only on a Mississippi River island in the extreme northeastern corner of the county. These two positive traps in 2012 confirmed that the beetles have moved inland from the Mississippi River.
A federal and state quarantine has been in place for Allamakee County since 2010. The quarantine prohibits the movement of firewood, ash nursery stock, ash timber or any other article that could further spread EAB.
In addition to the purple traps, the Iowa Department of Natural Resources evaluated 416 trap trees for signs of infestation; one tree each at Black Hawk Point and Plough Slough, Allamakee County, were the first positive trap trees in Iowa. Other surveillance efforts consisted of visual inspections of 1,291 trees in 58 counties for signs of EAB infestation; these inspections were negative.
USDA also conducted outreach and inspection at a variety of high-risk sites throughout the state in 2012. These efforts included visiting 120 firewood dealers, 121 logging operations, 46 pallet manufacturers, 131 private campgrounds, 93 sawmills and 274 tree services.
With funding from the state of Iowa Forest Health appropriation, 12 community tree inventories were completed by the DNR Forestry Bureau. A total of 31 other community tree inventories were completed with a combination of state and federal funds, 28 of which were from USDA Forest Service competitive resource allocation grants. In preparation for EAB all 43 communities will receive urban forest management plans this winter.
The EAB Team in Iowa has been conducting annual surveys to determine if this pest is in Iowa since 2003.
Emerald Ash Borer Management Options
The Iowa EAB Team continues to discourage homeowners more than 15 miles from known infestations from treating their healthy ash trees with insecticides to protect them from this pest. Preventive treatments for individual healthy ash trees could be done in New Albin and Lansing, but other communities outside 15 miles (most of Iowa) should only begin preventive treatments in 2013 if additional evidence of EAB is found.
From frees with a 25-inch circumference (approximately 8 inches in diameter) or smaller, homeowners can treat their own trees following Iowa State University Extension and Outreach soil drench recommendations found in the publication Emerald Ash Borer Management Options. If a tree is larger than that size, a commercial pesticide applicator should be called for assistance. Treatments will need to be done every one to three years for the life of the tree to maintain protection. The extension publication is available online at <https://store.extension.iastate.edu/>.
As a reminder, insecticide products to manage EAB work best as preventive treatments for healthy ash trees planted along streets or in yard settings. Healthy trees have full crowns, elongating branches, and bark tightly held to the trunk/branches. It is not practical or cost-effective to treat woodlot trees with insecticides.
The Emerald Ash Borer (EAB) is native to eastern Asia, and was detected in the United States near Detroit, Mich., in 2002. EAB kills all ash (Fraxinus) species by larval burrowing under the bark and eating the actively growing layers.
The metallic-green adult beetles are a half-inch long, and are active from late May to early August in Iowa. Signs of EAB infestation include one-eighth inch D-shaped exit holes in ash tree bark and serpentine tunnels packed with sawdust under the bark. Tree symptoms of an infestation include crown thinning and dieback when first noticed, epicormic sprouting as insect damage progresses, and woodpecker feeding.
EAB has killed ash trees of various sizes in neighborhoods and woodlands throughout the Midwest. Ash is one of the most abundant native tree species in North America, and has been heavily planted as a landscape tree in yards and other urban areas. According to the USDA Forest Service, Iowa has an estimated 52 million rural ash trees and approximately 3.1 million more ash trees in urban areas.
The movement of firewood throughout Iowa and to other states poses the greatest threat to quickly spread EAB even further. Areas currently infested are under federal and state quarantines, but unknowing campers or others who transport firewood can spark an outbreak. As a result, officials are asking Iowans to not move firewood and instead buy and burn it locally.