Emerald Ash Borer: Killed trees confirmed this summer

Emerald Ash Borer (EAB) has been known to be a problem in Iowa for a few years, but Decorah is just seeing the first deadly effects of the invasive insect this summer.

Emerald Ash Borer is an insect native to eastern Asia where it is considered only as a pest, and found in low densities due to predators.  It was confirmed in Michigan in 2002, after shipping across the ocean in wooden pallets, but has now spread to nearly 30 states in the eastern U.S. and is widely considered to be the most destructive forest pest ever seen in North America.

In North America, EAB lays its eggs in ash trees. These, at the larval stage, eat away at layers of wood just beneath the bark, cutting off the circulatory system for the tree, which prevents the passage of nutrients and water and eventually leads to the death of the host tree.

Arborist Drew Stevenson has done work involving the EAB infestation, and noted that tree experts have confirmed some EAB killed trees in and around Decorah this summer.

Stevenson and others are concerned for the potential effect on Winneshiek County's ecology with the loss of the ash.

"The loss of ash trees in our forests will impact insects species such as butterflies, beetles, moths and plant bugs that feed exclusively off ash trees," Stevenson said. "And the loss of canopy in the cities and towns will impact the amount of energy we use for heating and cooling, the quality of the air we breathe, the amount of rain water moving through our sewers and the life expectancy of our roads."

Stevenson advises residents to prevent the spread of EAB by keeping and burning firewood in the county in which it was cut, as that is one of the most effective methods for keeping the insect from spreading.

Currently, local efforts are being put forth to combat the invasive insect.  "Locally, we are completing a tree inventory to determine the impact EAB will have on the the city of Decorah," Stevenson said. "The information will allow the city to implement a plan to best manage EAB."

Stevenson urges Decorah residents to educate themselves about the very real danger of EAB so that they will be able to effectively deal the effects.

"It is likely that most people have an ash tree on their property or on their neighbor's property that will be affected by EAB or will require some form of action, whether treatment or removal," Stevenson said. "It is important that property owners know what threats are present to their trees and what options they have as tree managers."