All Iowans are aware by now the emerald ash borer (EAB) is being found in new counties on almost a monthly basis. As of Apri 2019, 66 Iowa counties have confirmed infestations of the borer (Allamakee, Black Hawk, Bremer, Butler, Clayton, Dubuque, Fayette, Floyd, Howard, Jackson, and Winneshiek County in Northeast Iowa). Almost all northeast Iowa communities and rural residences are now within the 15 mile treatment zone recommended by the Iowa Department of Agricultural and Land Stewardship (IDALS), ISU Extension, and the Iowa DNR. The pace of new EAB finds will no doubt pick up even faster in the next few years.
EAB infestations may take 3-5 years to be discovered because the damage is done by the larval stage feeding by tunneling out of sight in the cambium layer under the bark of the tree. EAB likes heat so it starts in the treetops and makes its way down the trunk, feeding only in live tissue. The tunneling eventually goes completely around branches and the trunk, girdling the tree and effectively cutting off the supply of nutrients and water to the tree. Crown dieback is one of the first visible signs of EAB. Individual trees can be killed in 3-5 years. Once a community is infected with EAB, all untreated ash trees will be killed by EAB in 10-15 years.
On another somber but important note, trees killed suddenly by EAB and left standing quickly become very brittle and hazardous, prone to drop branches without warning. These trees become a huge liability, dangerous and expensive to remove. Confirm any tree removal companies bidding on removals are licensed and insured.
Along with crown dieback, a highly visible sign of EAB presence is woodpeckers feeding on the larva causing flecking, or exposed areas of the branches and trunk. Many of the infestations were discovered by people noticing the flecking and calling the proper authorities. Other signs and symptoms include: suckers growing on branches and the trunk below the EAB activity, vertical splits in the bark, winding s-shaped galleries under the bark, 1/8 inch D-shaped exit holes, and leaf-edge chewing damage.
When EAB was first discovered in Michigan, Indiana, and Ohio in the early-mid 2000s, the only recourse was removal of all ash trees in infected communities whether the trees were infected or not. Fortunately, due to extensive, collaborative research by universities, governments, and private industry in those states, Iowans can take advantage of several options to preserve some of our healthy ash trees in our towns and homes. Preventive treatment before a tree is infected is the most effective. Treatments will have to be repeated every one to two years depending on the insecticide used.
Trees worth saving are healthy and have few if any signs of EAB, are valuable for their benefits to the owner or landscape (mature trees can provide $200-$450 in annual benefits), add to property value, or have emotional or historical meaning.
All northeast Iowa communities and homeowners with ash trees have a several questions to ask themselves regarding their ash trees. Do I have ash trees, and if so how many? Are some worth saving? How do I know which ones are worth saving and which ones should be removed? How often will the tree need to be treated? What effect does treatment have on the surrounding environment? Can I do it myself or should I hire a tree care professional? If I remove my ash trees, what trees should I replace them with? How much will it cost? A qualified tree care professional will be your best source for answers.
Keep in mind, our ash trees have other disease and insect problems, so contact a knowledgeable professional for a tree inspection and diagnosis before doing any treatment. A good place to start looking for a tree care professional is the International Society of Arborists (ISA) website www.isa-arbor.com, click on “Find an Arborist” then “Search by Location”, and follow the prompts.
Excellent sources for EAB information include:
IA DNR, USDA Forest Service, USDA Aphis, and ISU Extension http://iowatreepests.com/
ISU Extension publication at https://store.extension.iastate.edu/Product/Emerald-Ash-Borer-Management-Options
Emerald Ash Borer University (Purdue, Michigan State, & Ohio State) at http://www.emeraldashborer.info
Richard Kittelson is an ISA certified arborist and a State of IA Certified Pesticide Applicator, licensed and insured. He graduated from NICC in 2002 with an Associates Degree in Arboriculture and worked at Northeast Iowa RC&D for 11 years in forestry outreach and invasive species monitoring and control. He is currently doing business as Richard Kittelson Consulting Arborist, LLC based in Clermont and can be contacted at: 563-423-5520, mobile 563-605-0163 or firstname.lastname@example.org.