Goldspotted oak borer, Agrilus auroguttatus, is present in San Diego County. Coast live oak, California black oak, and canyon live oak are hosts. Engelmann oak is a less common host. D-shaped exit holes are a useful clue. They are not a confirmed pest ID. Stay on the ground. Don’t peel bark.

Branch Pro San Diego is a referral service. We connect customers with licensed, insured independent local tree professionals. You hire and pay the professional directly. We don’t diagnose, treat, or remove trees.

If people are hurt or in immediate danger, call 911. If a line is down, stay away. From a safe place, call 911 and SDG&E at 1-800-411-7343. Don’t walk closer for photos. SDG&E decides whether lines can be de-energized, covered, or moved. If a standing oak already touches overhead lines, call SDG&E first.

What is goldspotted oak borer?

Goldspotted oak borer is Agrilus auroguttatus. Coast live oak is a primary host. California black oak and canyon live oak are also hosts. Engelmann oak is a less common host.

Larvae feed under the bark. That feeding can disrupt water and nutrient movement. What you see on the outside is still a clue, not a lab result.

UC ANR’s distribution page records ongoing oak mortality in many areas throughout San Diego County, with isolated confirmed areas in Riverside, Orange, Los Angeles, San Bernardino, and Ventura counties. Moving infested firewood is a likely route for new satellite infestations.

Record the oak species if you know it, where the tree sits, and what changed. An oak in Poway and one in La Jolla still need that same record: host, location, and changed condition.

What can you see from the ground?

Look from a safe place. Don’t climb. Don’t peel bark, probe holes, or scrape staining. Don’t stand under cracked wood or near lines.

UC IPM treats D-shaped adult exit holes as a useful borer sign. Crown thinning, bark staining, and woodpecker work are not a diagnosis by themselves. Those signs have other causes.

If you can see a D-shaped hole from the ground, write that down. Note how many you can see without walking into a hazard. One hole does not settle the pest or the tree’s future. Take wide photos of the crown, the trunk, and the ground around the flare, only from where you already stand safely.

Our signs your tree is dying guide can help you describe decline. It does not name the pest.

How does UC separate management options?

UC’s management options split cases by severity.

Treatment may be discussed for a lightly damaged, high-value tree with low-level infestation. Prevention on an uninfested tree is a different conversation. Heavily damaged trees are another case. Removal and correct wood handling may be needed.

Ask a qualified pest-control professional to identify the pest and choose any current labeled protocol. Don’t treat the tree yourself. Don’t assume trunk injection is the default plan. Irrigation is not a GSOB treatment. A healthy-looking oak is not immune. Check actual soil moisture and drainage as a separate site question. Our oak care article covers that care side.

Tree health diagnosis and arborist consultation are how you request a professional tree assessment. If treatment is proposed, ask the named professional to verify the current pesticide license or certification required for that regulated work. ISA certification is a separate individual credential. Check the ISA directory, or ask for that person’s digital certificate.

If removal is on the table, tree removal is a separate scope from diagnosis. Stump work is separate again. See stump grinding. Don’t treat removal as automatic because staining is present.

How should infested wood be handled?

Infested green wood can keep producing adults. UC’s firewood guidance discourages moving infested oak wood out of local areas.

Keep suspect wood on the property until handling is arranged. Ask which disposal rules apply at that address. Don’t haul oak rounds to another neighborhood. Have a qualified professional arrange handling of infested wood. Don’t grind it at home or move it yourself.

Confirm who owns the tree before anyone cuts. A City of San Diego street oak is not a private-yard tree. The City’s street-tree maintenance program uses a no-fee permit after City inspection. A private crew’s availability is not authority to remove a City street tree.

When does an oak need a professional assessment?

Call when D-shaped holes, spreading crown dieback, or a possible target under the tree make the next step unclear. Stay back if the tree looks unstable.

For paid tree work, ask for the contractor license that matches the scope. Look it up on the CSLB license lookup. An active C-49 Tree and Palm license or an active legacy D-49 can both be valid. California’s current minor-work threshold is an aggregate price under $1,000, with extra conditions. ISA certification belongs to a named person. It is not a company license. An absent ISA directory listing does not by itself disprove it. Ask for that person’s certificate if the credential matters.

If birds could be nesting, CDFW recommends a consulting biologist’s survey. February through August is typical for many species. Nesting can occur at other times. Don’t disturb a nest to inspect it.

Frequently asked questions

Does one D-shaped hole confirm goldspotted oak borer?

No. UC treats D-shaped holes as a characteristic borer clue. Crown thinning, staining, and woodpecker work need their own look. Have the pest identified before anyone treats or removes the oak.

Can watering save an oak from GSOB?

Watering is not a GSOB treatment. A vigorous-looking tree is not immune. Assess soil moisture and drainage separately from pest identification.

Should I move the wood off my lot?

UC discourages moving infested oak wood out of local areas. Keep suspect wood on site until a professional handling plan is set. Confirm the disposal rules that apply to that wood.

Do I have to remove the tree?

Not automatically. UC separates light damage on a high-value tree from heavily damaged trees. Identification and an on-site assessment come first.

Can Branch Pro diagnose GSOB by phone?

No. The independent professional inspects the tree, explains options, and contracts with you.

Get connected with a local pro

If the oak is on a conductor, use the utility steps above first. For other GSOB questions bigger than a ground-level look, call (858) 400-4423. We’ll connect you with a licensed, insured independent local professional. Describe the tree, what you can see from the ground, and any line or safety issue. You hire and pay that professional directly.