Technical Bulletin: Structural Integrity and Basal Splitting in Trees

/ by Jon Smith / in Blogs

Technical Bulletin: Structural Integrity and Basal Splitting in Trees

A split at the base of a tree—the root flare—is a significant structural concern. Because this area supports the tree’s entire weight and facilitates nutrient transport, any compromise here requires immediate evaluation to ensure safety and tree health.

Primary Causes of Basal Splitting

Cause Description
Frost Cracking Resulting from rapid temperature fluctuations in winter. The wood expands and contracts unevenly, often creating vertical fissures on the south or southwest side.
Internal Decay Fungi, bacteria, or wood-boring insects rot the heartwood. The external split is often the final symptom of an advanced internal hollow.
Improper Mulching “Mulch volcanoes” piled against the trunk trap moisture, softening the bark and creating a primary entry point for pathogens.
Deep Planting Burying the root flare deprives the trunk of oxygen and subjects it to constant soil moisture, leading to basal rot.
Hydraulic Stress Extreme cycles of drought followed by heavy saturation can cause internal pressure changes that stress the bark’s elasticity.

 

Action Plan: Assessment & Response

1. Immediate Site Inspection

  • Clear the Flare: Gently pull back mulch, soil, or debris from the base. The “root flare” (where the trunk widens into the roots) should always be visible and dry.

  • Categorize Severity:

    • Minor Fissures: Small, superficial cracks may be manageable. Trees often “compartmentalize” (seal off) these wounds naturally.

    • Deep/Large Splits: Fissures that penetrate deep into the wood or show signs of internal rot are critical structural failures.

2. Professional Consultation

If the split is deep, oozing, or located on a tree near a building or public path, contact Big Heart Tree Care. A professional assessment can determine if the tree requires:

  • Cabling or Bracing: High-strength hardware installed to provide supplemental support.

  • Mitigation: Strategic pruning to reduce weight and wind resistance.

  • Removal: Necessary if the tree poses an unacceptable risk of failure.

Critical “Don’ts” for Tree Recovery

[!IMPORTANT] Avoid Wound Dressings: Never apply tar, paint, or sealants to a split. These materials trap moisture and fungi against the wood, accelerating decay rather than preventing it.

Avoid “DIY” Hardware: Do not wrap the tree in chains or belts, as these will eventually girdle and kill the tree as it attempts to grow.