Emerald Ash Borer: A Serious Threat to Missouri Landscapes

Emerald Ash Borer Larvae

With our global economy and the free movement of nursery stock around the US, there is an ever-increasing list of "exotic" insect pests that we should be aware of. However, given our busy schedules and the seemingly steady stream of alerts in the press or in gardening publications, it is easy to become desensitized. We cringe a little less every time we read about Asian Longhorn Beetle killing thousands of trees in Chicago or Gypsy Moth moving ever closer. Until a pest, such as Japanese Beetle appears on our doorstep, we are not forced to develop a strategy to deal with it. Emerald Ash Borer, a pest recently discovered to be a serious problem in the Detroit area, is an insect that stands a good chance of changing the face of the nursery industry in Missouri over the next 10 years. We should do what we can to keep this pest out of Missouri for as long as possible.

Adult Emerald Ash Borer

Emerald Ash Borer (EAB) should be considered a serious threat to Missouri landscapes and forests for several reasons. First, while it was only first identified in the U.S. in July 2002, it is estimated that, during the previous five years, EAB had killed millions of ash trees in forests and landscapes in Michigan and Ontario. Second, the insect is thought to attack trees of all species of ash, including apparently healthy trees. In China, where the insect is indigenous, ash trees typically die within two or three years of infestation. Third, ash trees make up a major portion of trees used in Missouri landscapes, but also a significant component of our forests. Interestingly, EAB is a Buprestid beetle in the same genus (Argilus) as Bronze Birch Borer, which has essentially eliminated the use of European white birch and several other birch species in Missouri landscapes. EAB is of even more concern because we have millions of ash trees in our forests that can serve to spread an infestation if it were to get started here. The pest was recently discovered near Toledo, Ohio, the infestation probably arising from insects harbored in the wood of shipping crates from China. It is not difficult to imagine a similar scenario in St. Louis. Also, since infestation with EAB is not easily detected during the early stages, it is highly likely that shipments of nursery stock from infested, but not-yet-quarantined areas, will serve to spread the insect to new regions.

According to a friend who is a nursery sales representative in the quarantined area of Michigan, essentially no ash trees are being sold or planted in the Detroit area. Since ash has traditionally been so widely planted in the area, this is having a tremendous impact in the nursery and landscape industries in Michigan. It is unclear whether or not the infestation can be eradicated in Michigan. If not, ash may eventually go the way that European white birch has in the Midwest as a whole. We do not want EAB in Missouri.

Ash Tree in Decline Due to Infestation of Emerald Ash Borer

What can you do as a concerned citizen?

• Familiarize yourself with the identifying characteristics, signs and symptoms of the insect. Go to http://www.na.fs.fed.us/spfo/eab/index.html or http://www.michigan.gov/mda/ to view images of adults, larvae, bark galleries, D-shaped exit holes, branch dieback and trunk sprouting.
• Inspect all ash trees, timber and firewood under your control carefully for the above signs.
• Keep an eye out for signs and symptoms on declining ash trees in landscape plantings and forests in your area.
• If you find evidence of EAB, notify the Missouri Department of Agriculture at 573-751-5505 or 751-2462.

Chris Starbuck, Woody Ornamental Horticulture, UMC (573) 882-9630