Iowa Emerald Ash Borer Surveillance Effort - 2008

The Iowa Department of Natural Resources (IDNR) Forestry Bureau in cooperation with Iowa State University Extension (ISUE) and Iowa Department of Agriculture (IDALS) State Entomologist Office have been following the United States Department of Agriculture Forest Service (USFS) protocol to monitor Iowa for signs of the emerald ash borer (EAB). The detection of EAB in Peru, IL in July 2007 places this insect only 85 miles away from Davenport, IA, which is of concern because of its proximity to Iowa and Interstate 80 linking the two states. Furthermore, the confirmation of EAB in Missouri and Wisconsin in 2008 is of great concern. According to recent sources, Iowa has an estimated 50 million rural ash trees (USFS 2006) and 30 million urban ash trees (USFS 2008).

Visual surveys:
A surveillance effort has been in place the past five years in Iowa to look for EAB. For 2004 and 2005, this activity consisted of visual surveys of urban ash trees (towns/cities with a population greater than 1000) in all 99 counties, visual inspection of ash saw logs at 43 sawmills, and ash nursery stock. Visual surveys in 2004 involved 2078 trees on 252 sites, and in 2005 involved1318 trees on 238 sites.

During the 2006, 2007, and 2008 season, surveillance strategy shifted to the highest risk areas in the state, campgrounds. Sites were selected based on location near interstate highways, near tourism sites, and/or on the eastern border of Iowa. Up to 10 trees were examined in each campground for signs of EAB. The larger the campground and the greater the ash density, the more ash trees visually examined. In 2006, 417 ash trees were visually examined in 50 state and 10 county campgrounds. In 2007 EAB visual surveillance increased to 400 campgrounds (all federal, all state, all private and large campgrounds in 69 counties) involving 1102 trees. In 2008, 235 campgrounds in 55 counties were identified as high risk sites and 1,269 ash trees were inspected. No evidence of EAB was noted during visual surveillance in Iowa (2004 - 2008).

Sentinel trees:
Sentinel trees in Iowa were created in one of two ways: girdling standing ash trees (4-13 inch DBH) or planting donated containerized ash trees (approximately 3 inch caliper). Sentinel trees were established by June 1 each season. In general, containerized trees were used for private campgrounds or in areas with few ash trees, while standing ash trees were used on federal, state or county properties. A tree was girdled by using a folding hand saw, making two cuts through the bark (4 - 6 inches apart), and then removing the bark with a drawknife between the cuts. Every effort was made to select standing ash either in the open or with exposure on two or three sides; trees were rejected as possible sentinel trees if they were within a forest stand.

In 2005, 48 sentinel trees (23 standing, 25 container) on 12 sites were also used to monitor for EAB. In 2006, 68 sentinel trees (27 standing, 41 container) were established on 18 sites; 10 were retained for evaluation in 2007. In 2007, 237 sentinel trees (190 standing, 47 container) were established on 57 sites. In 2008, 401 sentinel trees (272 standing, 129 container). During the fall of each year, sentinel trees were bark peeled on site. New sentinel trees for monitoring the following season were girdled before leaving the site. EAB has not been detected in any sentinel tree to date.

• Map: 2008 EAB Sentinel Trees,*pdf

USDA Experimental Traps:
During 2008, 652 purple sticky traps were obtained from USDA for detection efforts in Iowa. Traps were installed in June and a midseason trap check was conducted approximately one month after placement, collecting suspect beetles, recoating panels with Tanglefoot, and reinstalling traps in the canopy. All traps were removed by the end of August 2008, suspect insects collected, and traps were discarded.

EAB was not found on any of the 652 purple traps that were hung in the 2008 trapping season. The above picture is an example of an EAB purple trap in an ash tree.

• Map: 2008 EAB National and Delimiting Survey - Iowa,*pdf