A year ago Oregon State University Extension Service encouraged homeowners to not take down their ash trees before they are infested bu the Emerald ash borer or unless the insect has been detected nearby. Homeowners have the option of using a systemic pesticide to keep the insects at bay, but once the beetles arrive, pesticides won’t kill them.

Now it has become real for four counties. The USDA Animal and Plant Health Inspection Service (USDA APHIS) has detected the Emerald ash borer (EAB) and expanded the EAB Quarantine Alert to Yamhill, Marion, and Clackamas counties. This brings the number of counties with EAB populations to four, including Washington County, where APHIS first confirmed EAB in Oregon in June 2022.

This highly destructive wood-boring pest targets ash, white fringe trees, and olive trees. The Oregon Department of Agriculture (ODA) has expanded the quarantine per the Oregon Administrative Rule (OAR 603-052-1075) on ash, white fringe trees, and olive tree material in these counties.

The four counties are on permanent quarantine status for ash, olive, and white fringe tree. They must remain within the quarantined counties, and wood waste must be processed as regulated. The Oregon Department of Forestry warns that the establishment of Emerald Ash Borers will likely devastate ash woodlands and riparian zones where native Oregon Ash (Fraxinus latifolia) is a dominate species. These trees provide important shade, food and habitat resources in riparian areas where soils can be poorly draining and where seasonally high water tables can exclude other tree species.

Oregon ash (Fraxinus latifolia), a member of the olive family (Oleaceae), is one of 16 species of ash in the United States. It is the only ash species that is native to the Pacific Northwest; however, ornamental ash species from other parts of the country and world are commonly used in landscaping in Salem, including: white ash (F. americana), flowering ash (F. ornus), Raywood ash (F. oxycarpa), green ash (F. pennsylvanica), European ash (F. execelsior), black ash (F. nigra), and velvet ash (F. velutina).

City of Salem staff is moving quickly to implement Emerald ash borer management plans after ODA confirmed detection of the Emerald ash borer in Marion County on August 28, 2024. The loss of ash trees caused by EAB infestations could lead to a reduction in urban tree canopy, an increase in invasive plants taking hold within communities, and loss of shade and habitat along streams, to name just a few of the anticipated impacts.

Milan Davis, Salem’s Urban Forester said, “We are collaborating with the Oregon Department of Forestry and the Oregon Department of Agriculture and have plans in place to start implementing preservation strategies this coming spring and to complete an overall management strategy to protect urban tree canopy against EAB for years to come.”

Since the first observation of the Emerald ash borer in Oregon on June 30, 2022, Salem officials have been working on a plan for responding to the arrival of this aggressive tree pest in order to slow its spread and preserve Salem's tree canopy.

The quarantine does not allow the movement of tree materials from ash, olive and white-fringe trees outside the county unless they meet certain conditions. Live plant material is eligible for compliance agreements with the Oregon Department of Agriculture if one of the following conditions is met:

• Diameter at the base of the plants is less than 0.75 inches
• Plants were grown in a screenhouse approved by the ODA
• Plants have been properly treated with an approved insecticide
• Debark wood and remove at least 1 inch of underlying wood
• Grind or chip to 1 inch or less
• Heat wood to a minimum of 140°F for at least 60 minutes
• Bury under at least 12 inches of topsoil
• Incinerate wood materials
• Secondary processing to produce wood by-products (i.e. paper)
• Other methods specified within a compliance agreement with the Oregon Department of Agriculture.

A D V E R T I S E M E N T

A D V E R T I S E M E N T

Suggested care for Ash trees includes keeping trees from stress:

• Water your trees in the dry months and maintain a layer of woodchips or mulch around the base of your trees.
• Avoid pruning, especially during high EAB activity (April through October). Pruning can send signals to insects that a tree is in stress. A professional arborist can also provide guidance on other things you can do to improve the health of your trees.
• If planting new trees on your property, carefully inspect plant materials before purchasing. Avoid planting new ash trees.
• Report observations of EAB or trees with symptoms by calling 1-866-INVADER or reporting online to the Oregon Invasive Species Online Hotline.
• Enroll in OSU Extension's Oregon Forest Pest Detector Program to learn more about recognizing and reporting signs and symptoms of high-priority, invasive forest pests like EAB.

--Donna Bleiler

Post Date: 2024-08-30 11:26:32

Last Update: 2024-08-29 19:15:49