Cottonwood with Clear Ooze at Trunk Junction: Slime Flux Diagnosis

Clear Ooze at Fork = Slime Flux Pressure Release

The watery exudate at the junction of your 100+ ft cottonwood's co-dominant trunks is classic slime flux (wetwood). Internal bacterial fermentation generates gas pressure that escapes at the weakest structural point—the included bark junction.

Disease Mechanics

• Soil bacteria enter wounds → colonize heartwood.
• Fermentation produces methane, CO₂, nitrogen → high pressure.
• Pressure forces sap out through cracks, wounds, weak junctions.
• Ooze starts clear, darkens/froths as microbes colonize it externally.
• Alkaline flux kills vegetation below.

Management: No Cure, Support Vigor

• Fertilize: 10-10-10 at 1 lb/inch DBH (huge tree = large amount). Scatter to drip line, water in.
• Prune declining branches only—don't "clean out" the junction.
• No drain tubes—outdated, spreads bacteria, invites decay fungi.
• Insecticide spray on flux area (Onyx/Merit/Sevin) prevents borer entry.

Structural Reality Check

• Co-dominant trunks with included bark = high failure risk regardless of flux.
• Cottonwoods are brittle, short-lived (70-100 yr).
• At 100+ ft near structures, professional hazard assessment is essential.
• Consider cabling/bracing by ISA arborist if retention desired.

Safety First

This tree's size, species, and structural defect combine for significant hazard potential. Flux is a symptom; the fork is the liability. Get a certified arborist's written risk assessment.