April - June 2015
MDC: Emerald ash borers found in Buchanan County
Foresters say homeowners should plan now to protect trees or replant
St. Joseph, Mo. - Missouri Department of Conservation (MDC) foresters say homeowners in northwest Missouri may want to make plans now on protecting or replacing ash trees. The Missouri Department of Agriculture recently reported that the emerald ash borer, an insect that kills ash trees, was found for the first time in Buchanan County.
Adult emerald ash borers were collected at three locations: near Faucett, Mo.; at MDC's Pigeon Hill Conservation Area, and on theeastern edge of St. Joseph. The collections were not unexpected since their populations have been rapidly building in the south in Platte County, said Rob Lawrence,MDC forest entomologist. The destructive borers have also been found in the Kansas City and St. Louis areas. They are confirmed in13 Missouri counties, and they have been found in Kansas.
Emerald ash borers are an Asian beetle that tunnel under the bark ofash trees, which disrupts the flow of water and nutrients and eventually kills the tree. The metallic, dark-green beetles are about one-inch long when fully developed. Larvae leave S-shaped tunnels under bark. Adults leave D-shaped exit holes in bark when they emerge. As their numbers grow, they cause more damage to a tree.
For more information about the borers, including photos, visit http://mdc.mo.gov/discover-nature/field-guide/emerald-ash-borer. Information is also available at www.eab.missouri.edu. The borers are expected to eventually spread throughout the state.
That MDC field guide page has general info about EAB, but a much better place to send folks is our new invasive tree pests page: http://mdc.mo.gov/your-property/your-trees-and-woods/tree-and-forest-health/invasive-tree-pests. The EAB section there has the EAB CSI brochure that will help them identify ash trees and EAB signs/symptoms, a video about symptoms, and there's detailed info about managing EAB. The latter is our new EAB Management Guide for MO Homeowners. That's something that we really want to promote. It gives details about how to decide which trees to try to save with treatments, how to treat, whether you can do it yourself or need to hire a certified arborist. I suggest we stress that guide in the article, since the headline emphasizes planning to protect trees. It is also posted on that www.eab.missouri.edu website.
Ash trees can be treated to protect them from the borers. But treatments are expensive and must be done annually. Homeowners will want to decide if they want to save a valued ash tree by beginning treatments next spring, or if they instead want to plant another tree species now as an eventual replacement, said Lonnie Messbarger, an MDC resource forester based in St. Joseph.
Treatments may be expensive, depending on what you call expensive. And do not always have to be done annually. There are many types of treatments. Treatment costs vary by the size of tree and type of treatment used. Treatment costs can be as little as about $25 per tree for a do-it-yourself treatment on a small ash tree that must be repeated annually. But can range up to a few hundred dollars for a large ash tree that is treated by a professional arborist on one- to three-year intervals depending on type of treatment. Large ash trees cannot be effectively treated on a do-it-yourself basis. The info about size of tree and types of treatments are in our EAB management guide.
The emerald ash borer populations will have to build for a few years before many trees are actually killed, Messbarger said. Also, it is too late this year to consider treatment, as adults and larvae are at the end of their active cycle. They are most active mid-May into June.
It is too late this year to consider treatment, because we have passed the point in the life cycle of EAB when insecticide treatments are most effective. I would avoid saying it's because adults and larvae are not active. Yes, adults are gone for this year, but larvae are present now and some are still feeding. Insecticides are most effective in spring and early summer when adults are active and larvae are beginning to develop. That would generally be early May to June. Many insecticide treatments need to be applied prior to that time, depending on which treatment is used. Some can be applied duringthe early part of that May-June period. Lots of variables involved. Details in the management guide.
Most movement of emerald ash borers to new regions throughout the United States has been caused by people moving firewood. MDC foresters urge that firewood not be moved from one local area to another to help slow the spread of the pest. Those burning wood, including campers, are urged to buy locally harvested wood.
All Missouri counties are now under a federal and state quarantine preventing the movement of ash nursery stock, any parts of ash trees, and hardwood firewood out of the state of Missouri.