Help Save Our Valley Oaks
We want to make you aware of an invasive and destructive beetle that has been spreading throughout Napa and Sonoma Counties, in addition to other areas. With enhanced awareness and knowing how to help protect your trees and your community, we can all help to preserve our beautiful oaks.
What’s Happening?
The Mediterranean Oak Borer (MOB; Xyleborus monographus) is an introduced ambrosia beetle that was found infesting several valley oak (Quercus lobata) trees in Napa County in 2019. The insect was likely introduced on imported wood products. To date, it has also been detected in Lake, Sonoma, and Sacramento Counties. MOB has been found in several of the oaks in the white oak group, including valley oak, blue oak (Q. douglasii), and Oregon white oak (Q. garryana). The beetle also vectors the fungi, Raffaelea montetyi, which has pathogenic properties.
Above paragraph from: https://oaks.cnr.berkeley.edu/threats-to-oak-woodlands
The result is that this beetle has been killing Valley Oaks and spreading through infested wood. When infected trees or parts of trees are moved to new locations—such as for disposal, firewood, or landscaping—the beetle spreads to new areas.
Learn More: https://ucanr.edu/sites/mobpc/
Learn More: https://oaks.cnr.berkeley.edu/threats-to-oak-woodlands/
How You Can Help
1. Keep Your Trees Healthy
Healthy trees are less vulnerable to beetles, much like how healthy people resist disease.
- Prune regularly to maintain tree health.
- Avoid compacting soil around roots.
- Add supplemental water during drought to stressed trees.
- Consult a certified arborist if your tree appears stressed or sick.
2. Don’t Move Infected Wood
- Chip infected trees onsite and leave the chips there. Ideally you should solarize the chips with a clear plastic tarp for 2 months in winter or 4 months in the summer.
- Never transport infected trees or firewood.
- Avoid sharing or buying firewood from unknown sources.
3. Signs to Look For:
- Small round holes in the bark.
- Sawdust-like material (frass) near the base of the tree.
- Dieback in branches or canopy thinning.
- Bark peeling or dark staining.
Call your local County Agricultural Department to report infested trees.
Spread the Word
Tell your neighbors and local community about the threat. Raising awareness is crucial to stopping the beetle’s spread.
For more information or help identifying infected trees, contact Von Greiff Tree Care at (707) 295-6427. Together, we can protect our forests and save these iconic Valley Oaks.
