Read pest and disease clues on your trees
Holes, stain, and thin crowns are clues, not a diagnosis. Goldspotted oak borer, bark beetles, and eucalyptus longhorned borers leave different signs on different trees. Extent and tree vigor matter. A few attacks do not mean every tree will die. Photograph from the ground, keep firewood local, and get a professional ID before anyone treats or cuts.
What you'll learn
- Goldspotted oak borer clues on coast live oak, including D-shaped exit holes, and what crown thinning or bark stain does not prove
- How a few bark-beetle attacks on branches differ from a heavily infested trunk, and why death is not automatic
- How eucalyptus longhorned borer gallery signs differ from redgum lerp psyllid honeydew and sooty mold
- Why moving infested oak firewood can spread goldspotted oak borer, and who should diagnose before treatment
Step by step
- Photograph holes, stains, sap, and any sawdust-like frass. Stay on the ground. Do not peel bark to inspect.
- Record the tree species and where on the trunk or canopy the signs sit. Oaks, eucalyptus, and other hosts are different jobs.
- Compare D-shaped oak holes with nonspecific thinning using UC's goldspotted oak borer guides. Do not treat from a photo. Light damage on a high-value oak is assessed differently from a heavily damaged tree.
- For eucalyptus, separate longhorned-borer signs under bark from lerp honeydew and sooty mold on leaves. Stress and site care matter. Do not inject or spray on a guess.
- Keep suspect oak firewood on the property. UC identifies transport of infested firewood as a likely route for new goldspotted oak borer infestations. For diagnosis or treatment decisions, use a qualified pest-control professional and a licensed tree crew as the job requires.
Goldspotted oak borer is now recorded in several Southern California counties, not only San Diego. Do not diagnose from one symptom, and do not move oak wood around the region while you wait. If a standing tree is approaching a line, stay away and call SDG&E before any tree crew. If a line is down, keep away and call 911 and SDG&E at 1-800-411-7343 from a safe place.
Further reading
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