MDC: Emerald ash borers found in Buchanan County

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, at MDC's Pigeon Hill Conservation Area, and on the eastern 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 in 13 Missouri counties, and they have been found in Kansas.

Emerald ash borers are an Asian beetle that tunnel under the bark of ash 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.

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 as an eventual replacement, said Lonnie Messbarger, an MDC resource forester based in St. Joseph.

Ash trees can be treated to protect them from the borers. Treatment costs vary by the size of tree and type of treatment used, Lawrence said. 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 treatments 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 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, because insecticides are most effective in spring and early summer when adults are active and larvae are beginning to develop, generally early May to June. But some treatments may need to be applied earlier in spring.

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.

For more information about emerald ash borers, visit hmdc.mo.gov/your-property/your-trees-and-woods/tree-and-forest-health/invasive-tree-pests. The emerald ash borer section includes photos and videos of the insect and symptoms found on infected trees. There is also information that guides homeowners regarding treatment methods or how to get help from a certified arborist.