After the emerald ash borer (EAB–Agrilus planipennis) was first spotted in Oregon in 2022, concerned folks started sharing resources on identification and how we could respond. The EAB is native to Asia, where, over millennia, Asian ash species have evolved a set of genes that are able to resist the beetle. With the recent identification of this gene, it’s been determined that the current population of Oregon ash (Fraxinus latifolia) does not have this adaptation. This leaves local ash vulnerable to the detrimental larval feeding that has already decimated the Eastern United States’ ash forests. Ash is an important habitat species that shades and feeds nutrients into Johnson Creek and is able to withstand submersion – making it a vital component of the riparian habitat in our watershed.

Various local agencies have been working on minimizing the impact of EAB by reducing spread through global best management practices. Being able to ID an ash tree and recognize symptoms of infestation is one way the community can contribute to slowing the spread of EAB. It’s also important to not transport ash, alive or otherwise, to reduce the chance of spreading EAB to unaffected areas. (It is generally best not to transport firewood of any species, since this is a primary way wood pests can spread.)

Recently, another beetle has popped up on our radar, the Mediterranean oak borer (MOB–Xyleborus monographus). Native to Europe, western Asia, and northern Africa, it targets unhealthy trees in those areas. In our region, the MOB targets apparently healthy trees by tunneling into them and depositing fungi (Raffaelea montetyi and Fusarium solani) for their young to eat; fungal growth eventually clogs water-conducting tissues in the tree. The Oregon white oak (Quercus garryana) is a critical native species whose numbers have declined due to habitat loss and forest management. Oregon white oaks provide habitat to a number of species that benefit watersheds.

How is Johnson Creek Watershed Council responding to these threats? We are working with other watershed councils and experts to gather information and create an accessible way for the Johnson Creek watershed community to monitor and report any sightings. Local and state agencies have information on how to minimize spread, what to look for as indicators, and who you can contact if you suspect either beetle is present in trees near you.