Common Ash with Cavity: Compartmentalization in Action

Your 30–40 ft common ash (Fraxinus excelsior) with a large basal cavity (arm-deep) that once hosted honey fungus (Armillaria) is compartmentalizing decay—the callused edges are the tree walling off the rot.

What's Happening

• Original wound (mechanical? lightning?) broke cambium → decay fungus entered.
• Fungus slowly digests dead heartwood (center).
• Tree builds barrier zones (CODIT model) to contain spread.
• Full crown + seeds = tree is currently winning.

Management

• Do NOT fill cavity—traps moisture, accelerates decay.
• Do NOT clean out rot aggressively—damages barrier zone.
• Remove loose debris by hand only.
• Fertilize lightly to maintain vigor.
• Monitor annually for crown thinning, new fungi, lean.

Wind Risk

Any tree can fail in extreme winds. But a healthy-crowned ash with solid outer wood and good compartmentalization is not a high failure risk. The cavity has been stable 6+ years.

Enjoy the tree. It's a veteran managing its own decay.