Enter Search Below
If you live in the Willamette Valley, you may have heard the warnings of the dreaded Emerald Ash Borer (Agrilus planipennis), which was recently found in Oregon. The first documented sighting was in July of 2022 in a parking lot in Forest Grove. This is the first confirmed Emerald Ash Borer (EAB) infestation west of Colorado. EAB is a pest that has decimated ash trees in the eastern parts of the US since its initial detection in 2002. And now it has found its way here.
EAB is native to Asia, and it is thought to have been introduced here via wood shipping crates. It infests all species of ash trees, where it lays eggs, which then feed on the inner bark and phloem of the tree, causing rapid crown decline and, ultimately, death of the entire tree. Larvae overwinter in the bark of the ash tree and emerge as adults in late spring. The exit holes of the adults are distinct in that they leave a small “D” shape in the bark of the tree. From May to October, the adults fly up to seven miles to find other host trees nearby.
Not necessarily. While there is a risk of spending a lot of money on ash trees that may likely be killed by the EAB, we are also facing the threat of losing our native ash species entirely if we don’t try to continue to repopulate and save seeds of the trees for future plantings. EAB predates on ash trees that are 10 to 15 years old. It is important to protect surviving Ash trees that are outside of this age range, to continue the genetic spread of this tree despite the mortality from EAB. There have been success stories of young ash trees that were planted after the EAB infestation on the East Coast that are still surviving today. Native ash trees may be able to build resistance to the pest, or outlive the infestation, if we continue to plant them.
Although there are no trees that exactly mimic Oregon’s native ash, Fraxinus latifolia, alternative trees can provide similar benefits to the riparian ecosystems where Oregon Ash are most commonly found. It is always important to plant a diverse selection of native trees, shrubs, and forbs for best success.
The loss of this native tree species may lead to a number of impacts on environmental and human health.
Prevention is possible in some cases. Here are some methods to try to save ash trees:
It is important to always plant for biodiversity in any natural or urban area to provide resilience against pests and disease that disproportionately impact a particular species. This helps the ecosystem bounce back from disturbance and allows for wildlife to better adapt.
Research into the prevention, treatment and restoration of ash species has been constant since EAB’s US introduction in 2002. The East Coast states that have faced the brunt of this invasion have also been able to provide the most recent science informing us about the impacts of EAB. Now that the pest is here in Oregon, we have an abundance of resources to look to for best management practices to help us protect our native ash trees.
My passion for conservation is rooted in my experiences growing up camping and backpacking every summer since I was young. My favorite activities always involve being outside, whether I am hiking, snowboarding, or biking, I love to explore as much natural beauty as possible. I help Marion County residents improve the health and productivity of their land as the Conservation Planner for natural areas.