Black Oak Slime Flux: Bacterial Sap Flow Management

Understanding the Ooze

Sticky sap seeping at 4 feet on a 3-year-old Black Oak in Boise is slime flux (wetwood)—bacterial fermentation inside the trunk producing gas pressure that forces sap out. Two types: alcoholic (yeasty) or acidic (vinegary). Attracts sweet-feeding insects.

Key Facts

• Not a primary killer—symptom of internal stress/infection.
• No cure—drilling pipes is outdated and harmful.
• Often periodic—may stop and restart annually.
• Tree can live decades with flux.

Management Protocol

1. Wash trunk with water; final rinse: 1 pint bleach/gal water (discourages insects).
2. Remove loose bark in flux area; air-dry.
3. No wound dressings.
4. Fertilize: 10-10-10 at 1 lb/inch trunk diameter; water in.
5. Maintain vigor—water during drought.

Young oak (3 years) may outgrow the condition as it establishes. Focus on health, not the flux.