KC Gardens

Emerald Ash Borer continues its advance into Kansas City

Ash tree leaves

Tip of the Week

Ever since 2002, when the Emerald Ash Borer (EAB), imported from China, was first detected in Michigan, just about everyone in the field of horticulture and forestry have been on alert. This insect quickly spread across the country, and now 20 states have been certified EAB infested.

Missouri joined this list in 2008 when the insect was detected in the Bootheel area of the state. By 2012, the pest had made its way to Kansas City, with populations found in the Parkville area and at Wyandotte County Lake. This week brought news that Johnson County is no longer EAB free.

Ash is an important tree species in our area. It can be found in the local woodlands and in countless front and back yards across the metro. Some estimate that there could be as many as a million ash trees in the area. Here in Johnson County some estimate that as many as 25 percent of the landscape trees in neighborhoods could be ash.

Now that we have the pest, our challenge is to learn how to cope with it. The first step is to learn a little more about the insects’ habits and method of spread. The following are some tips to help you better understand this pest.

  1. Make sure the tree in question is an ash tree. a. If you are certain the tree is an ash, white or green ash, continue reading. b. Uncertain of the species? Contact your local Extension for identification either by bringing a sample to the office or e-mailing photos of the tree.

  2. Symptoms of EAB to look for a. Twig dieback in the canopy or other branches of the tree. b. Sucker growth from the main trunk or around the base of the tree. c. Borer exit holes. EAB borer holes are very difficult to see. These holes are usually not seen unless you are a trained spotter or the bark is peeled away. If you can easily see the holes it is unlikely to be EAB. There are many types of borers including the very common native borers which have always been present. - Borer hole size for native borers – about the diameter of a #2 school pencil and round in shape.

  3. Borer hole size for EAB – about the diameter of the lead in the pencil and “D”- shaped, not round. d. Presence of adult insects. Adult EAB beetles are small, metallic green and 1/8 to 1/4 inch and narrow, about the diameter of a flat toothpick. They are very difficult to see.

  4. Should you treat for EAB? a. Only highly valued trees in excellent condition should be considered for treatment.
    b. Trees with defects such as decay, poor branching or in decline should not be treated. c. Treatment should be considered a lifetime investment. Depending on the method of treatment, you must treat every year or two.

  5. What are the methods of treatments? a. Trunk spraying—done every year and applied in the spring prior to the emergence of the adults from mid-May through early August. Only recommended for commercial applicators. b. Soil drench—a yearly application done by either homeowners or commercial applicators. The product is applied either in spring or fall depending on the product. c. Trunk injections—applied every two years by a commercial applicator, normally done in early spring to early summer. This is the preferred method of treatment supported by the most research. d. For complete information about control options visit: http://extension.entm.purdue.edu/EAB/PDF/EABInsecticideProduct_Guides.pdf EAB Treatment Options.

  6. Can a homeowner apply the treatments themselves? a. There are products on the market for homeowners that are a soil drench. b. Must be applied yearly. c. Only recommended for trees under 20 inches in trunk diameter, some research suggests up to 16 inches in diameter. d. For complete information about control options visit: http://extension.entm.purdue.edu/EAB/PDF/EABInsecticideProduct_Guides.pdf EAB Treatment Options.

  7. Should we start treating our trees? a. Nothing needs to be done immediately. For most highly-valued trees that are showing no signs of EAB (which at this time will be almost all) no action is required in the summer of 2013. Do your research, get quotes and make sound decisions based on science not on impulse. b. Treatment will be a personal decision based on your judgment of the tree’s value, treatment cost and tree replacement cost. c. Remember only highly-valued trees in good or excellent condition should be considered for treatment.

I hope this information will provide you with a little better understanding of the issues. Let me close by restating, don’t panic. No healthy trees should be removed because of this news. There is time to do your research and get the facts. There are treatment options for excellent healthy trees that will protect them. But, unfortunately, there are a few unscrupulous firms that will prey on your fears and be all too glad to take your money. Don’t let that happen to you. Contact our Gardening Hotline at garden.help@jocogov.org or call 913-715-7050 if you have questions. We’re here to help.

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