Tree Oozing Foam? It's Slime Flux—Not a Death Sentence

Seeing foul-smelling, frothy sap seeping from your tree's trunk? Don't panic—it's slime flux (wetwood), a bacterial condition common in mature shade trees like oak, elm, maple, and willow. It looks alarming but rarely kills the tree.

What Is Slime Flux?

Bacteria ferment inside the wood, producing carbon dioxide gas that pressurizes the sap, forcing it out through cracks, wounds, or even intact bark. The ooze starts colorless, darkens on air exposure, and attracts insects with its yeasty, alcoholic smell. Grass beneath may die.

Should You Treat It?

No curative treatment exists. Attempts to drill, drain, or seal wounds often do more harm. The flux usually stops on its own after weeks or months. The tree may show temporary leaf stunting but generally survives.

Best Practices

• Keep the tree vigorous: water during drought, avoid wounding (mowers, trimmers).
• If loose bark exists in the flux area, gently remove it and let the wood dry.
• Do not apply wound dressings—they trap moisture.

Slime flux is a symptom of stress (heat, drought, age), not a primary killer. Support the tree's health, and it'll likely outlive the ooze.