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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Emerald Ash Borer Update: Holding Steady in NE Iowa

This article was published originally on 1/12/2011

In May, 2010, four larvae of the invasive beetle, emerald ash borer (EAB), were found under the bark of one ash tree growing on Henderson Island in the Mississippi River, in northeast Allamakee County, Iowa (2 miles south of Minnesota). The news was not unexpected, as EAB was found across the Mississippi River in southwest Wisconsin (April 2009) and across the border in southeast Minnesota (April 2010). 
 
Since that initial discovery, no additional EAB infestations have been found in Iowa.
 
EAB detection efforts in Iowa carried out by collaborating partner agencies in 2010 are listed below. The agencies involved are the Iowa Department of Agriculture and Land Stewardship (IDALS), Iowa Department of Natural Resources (DNR), USDA APHIS Plant Protection Quarantine (PPQ), and Iowa State University Extension.
 

  • 1,846 purple sticky traps were placed in 70 counties at high risk areas in or near ash tree canopies during the summer months, then removed and insects caught in glue were checked.
  • 412 sentinel trees (standing ash trees) were bark peeled (see photo below) to inspect the cambium layer for EAB larvae; only native borers were found. These trees were set up during the fall of 2009 in campgrounds and other high risk sites.
  • 1,267 trees were visually surveyed for signs/symptoms of EAB. These trees were located in 235 campgrounds, 29 active sawmills, and selected residential areas.
  • Approximately 350 ornamental plant nurseries, involving 2,200 acres were inspected.
  • 79 wood product industries (22 firewood dealers, 14 logging/timber buyers, 5 mulch operations, 10 pallet manufacturers, 15 sawmills, and 13 tree services) were visited. Compliance agreements were started between ten of these industries, IDALS and PPQ.
  • Hundreds of phone calls and emails from concerned citizens asking about EAB or to report suspect ash trees were received.  IDALS and PPQ inspectors visited several suspect sites.
  • Numerous outreach activities were conducted, including media interviews, public information meetings, educational articles, displays at the state and county fairs, and one-on-one events.

The result of all these various efforts to look for emerald ash borer during 2010 is that the only site confirmed to have EAB in Iowa is Henderson Island, in the Mississippi River, in Allamakee County.  In addition to the initial EAB find (one tree), one positive purple sticky trap (13 adult specimens) was found there. To date, no other site in Iowa has been confirmed with EAB.
 
Starting January 1, 2011, IDALS will require all firewood sold in Iowa to have the county and state of harvest location on the label packages and the delivery ticket for bulk firewood. It is hoped that this will slow the primary long-distance spread of this destructive insect. See the firewood regulation article in this newsletter.
 
Background
 
EAB is a small dark metallic green beetle, about as long as Mr. Lincoln’s image on a penny. Adult beetles produce minor feeding damage to ash leaflets, but the flat, white, legless larvae kill ash trees by cutting through the plant’s internal plumbing just beneath the bark. Trees affected display thinning/dieback of branches in the crown, water sprouts (epicormic shoots) along the trunk and major branches, “D-shaped” exit holes cut through bark, and extensive woodpecker feeding on the tree.
 
This pest was first discovered in Detroit, Michigan in 2002. Since that time, people have unknowingly transported EAB into 14 other states (IA, IL, IN, KY, MD, MO, MN, NY, OH, PA, TN, VA, WI, and WV) by moving infested firewood, landscape trees, and other ash wood products. The USDA PPQ has states/counties under quarantine in an effort to slow the spread.  See the US Forest Service distribution map
 
Things that can be done to help Iowa minimize the spread of EAB are:

  • ASSIST collaborative partners in their survey efforts by permitting access to property.
  • VOLUNTEER to help your community develop a tree inventory.
  • PROTECT your trees from mechanical injuries; WATER during dry periods.
  • REPORT suspect ash trees or beetles to ISU Extension Entomology (515) 294-1101 or the State Entomologist (515) 725-1470.
  • TALK with city managers, county officials, state legislators, and US congressional members. Ask them to include EAB prevention in fiscal budgets.
  • ENCOURAGE local firewood purchases when friends or relatives come to Iowa for camping, fishing, or hunting. Look for the new IDALS label when purchasing firewood.
  • RESIST the urge to apply a preventive insecticide until EAB has been confirmed 15-20 miles away. Refer to ISU Extension publication PM2084.
  • KEEP INFORMED through ISU Extension offices and specific Web sites:  ISUE Pest Management & The Environment, Iowa Tree Pests, Iowa DNR Forestry, and Emerald Ash Borer-dot-info.

 
 
Shannon Peterson [Iowa Department of Natural Resources, Bellevue] bark peeling a sentinel ash tree. Photo by M.H. Shour, ISU Extension.Shannon Peterson [Iowa Department of Natural Resources, Bellevue] bark peeling a sentinel ash tree. Photo by M.H. Shour, ISU Extension.