October Glory Maple Bark Cracking and Black Sap: Diagnosis and Care

Assessing Bark Damage on Mature Maples

Vertical cracks extending around the trunk of a 15-year-old October Glory maple, accompanied by black sap oozing and loose bark, signal a serious vascular issue. This presentation is consistent with bacterial wetwood (slime flux) or a canker disease exacerbated by stress.

Immediate Steps

• Check mulch depth: Pull mulch back 6–12 inches from the trunk; buried root flares promote rot.
• Assess sap odor: Fermented, alcoholic smell confirms bacterial activity.
• Do not apply wound dressings—they trap moisture and worsen decay.

Supportive Care

While no cure exists for established wetwood, trees often survive for years with proper management:

• Water deeply during drought (1 inch weekly).
• Apply balanced tree fertilizer (10-10-10) at 1 lb per inch trunk diameter annually.
• Remove loose bark to encourage drying.
• Monitor for hazard potential; consult an ISA-certified arborist if structural integrity is questionable.

Many maples compartmentalize the damage and persist indefinitely. Focus on vitality, not eradication.