Spot a pest or disease infestation early
The difference between saving a tree and removing it is usually a 3-month head start.
What you'll learn
- Gold-spotted oak borer (GSOB): D-shaped 0.1-inch exit holes on coast live oak
- Invasive shothole borer (ISHB): pinhead-sized holes and staining on a wide range of species
- Eucalyptus longhorn borer: larger D-shaped holes, sap flow, bark peeling
- Fungal signs: conk mushrooms at the base, discolored bark, cankers
Step by step
- Photograph any unusual holes, stains, or sap runs on the trunk.
- Note the species of tree and the location of the signs.
- Check for sawdust-like frass (beetle waste) at the base.
- Compare to CAL FIRE and UC Davis pest ID guides (linked below).
- Call an ISA-certified arborist before treating anything yourself.
Safety note
San Diego County is in a GSOB quarantine zone. Moving infested oak firewood is illegal and accelerates the outbreak. If you find it, don't move the wood.
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