KEARNEY – The Nebraska Department of Agriculture announced that the emerald ash borer (EAB) was found in Kearney. A severely declining street tree located near Pioneer Park was determined to be infested with the insect. This detection adds Buffalo County to the growing list of Nebraska counties with known EAB infestations.
“Emerald ash borer is considered to be one of the most destructive insect pest of trees ever to occur in the U.S.,” said Laurie Stepanek, Forest Health Specialist with the Nebraska Forest Service. “Its impact on urban trees, native forests and windbreaks in Nebraska will surpass that of Dutch elm disease.”
It is projected that Nebraska’s taxpayers and homeowners will ultimately spend over $961 million on ash tree removal, disposal and replacement due to this pest.
EAB is named for the bright metallic green color of the adult beetles. It is the immature stage, however, that causes the most damage to trees.
“The immature stage, or larva, tunnels into the trunk and branches, cutting off the flow of water, nutrients and sugars under the bark,” said Stepanek. “At the height of an EAB infestation, trees can die in a just a few years.”
Residents in Kearney and surrounding communities with ash trees on their property should begin making plans to either treat or remove the trees. The optimal time for treatment is spring, although professional trunk injections may provide some control even if done in summer.
“Treatments must be done for the remainder of the tree’s lifespan, therefore, take time to assess the value and health of your trees to determine if they are good candidates for treatment,” Stepanek said. “Trees worth treating are those that provide much-needed shade, are key components of the landscape, or have intrinsic value. The trees should also be in very good condition with robust canopies, no large dead or dying branches, and no mower damage or other serious trunk wounds.”
Because insecticide treatments have drawbacks, trees should be located within the “treatment consideration zone”—i.e. within 15 miles of Kearney. This recommendation strikes a balance between the need to protect valuable trees and the drawbacks of unnecessary insecticide applications. Kearney’s 15-mile zone includes Gibbon, Minden, Elm Creek, Odessa, Riverdale, Amherst and Axtel.
Trees left untreated will eventually die from EAB and will need to be removed. Community Forestry Specialist Graham Herbst recommended pre-emptive removal of living ash trees when possible.
“Trees that have died from EAB are extremely brittle and pose a hazard—dropping limbs on people, buildings and cars,” Herbst explained. “There may also be a high demand for tree removals when large numbers of ash begin dying—increasing prices and the chance that homeowners will be approached by “fly-by-night” tree companies that may not have proper insurance, licensing, or training to remove hazardous trees.”
As trees are removed, they should be replaced with a diverse selection of trees, not just a few species. This will help avoid another significant loss of the urban tree canopy when the next serious pest arrives.
More information about emerald ash borer and recommended trees for replacement can be found at nfs.unl.edu/nebraska-eab