Bleeding bark on a coast live oak

Dark sap on a coast live oak trunk is a photo we need. It is not a same-day prune.

Sudden oak death is a trunk disease of coast live oak and tanoak in the Bay Area. The bark bleeds a dark, sticky sap, often on the lower trunk, and the crown browns after the canker has been there a while. California bay laurel next to the oak is the usual neighbor. The pathogen moves in rain splash off bay leaves. It is not something you fix by thinning the oak.

A valley oak is not the same disease.

What it is, and what it is not

Valley oaks and blue oaks are white oaks. They are not the trees this disease kills. A valley oak with a thin crown in August is often water, soil, or a root problem, not sudden oak death. Coast live oak keeps its leaves through the year. If that canopy is browning from the tips and the trunk is bleeding, say so in the note and send the bark, not only the top of the tree.

Other things bleed or stain: sapsucker holes in rows, a wet seam after a crack, bacterial ooze, old pruning paint. A photo of the whole trunk, close enough to see whether the stain is a line of holes or a real canker, keeps us from calling a removal on a woodpecker.

We do not sell a spray for this in a blog post. If the tree is dead, or the canopy is mostly gone and the trunk is cankered over a house or a road, the job is removal, and the wood should not be hauled into a clean oak stand as firewood. If the tree is still sound and you want deadwood out, that can be a trim in the dry season, with the bay foliage kept back from the trunk where you can reach it.

Photograph the bark, the bay leaves, and whether the crown is still green.

What to send

The lower trunk, including any dark seep. A leaf from the oak and, if it is there, from the bay beside it. The full crown so we can see how much is still green. The target underneath: roof, drive, fence, or open field.

Street trees and heritage trees can still need a permit even when the tree is dying. We flag when a permit may apply — you confirm with the city. We do not pull permits unless that is scoped in writing.

Start Easy Estimate with those photos, or call 408-439-6975.