Fir Tree "Dry Rot": Internal Decay, Not Fatal

"Dry rot" in fir = heartwood decay from fungi entering through bark wounds. The outer living layers (cambium, sapwood) are intact.

Reality

• Center of tree is dead wood—always.
• Decay fungi recycle it. Slow process (10–20+ years).
• If crown is full/green, tree is healthy.
• Hollow tree ≠ dangerous if outer shell solid.

Management

• No treatment needed.
• Don't fill cavity (traps moisture).
• Don't dig out rot (damages barrier zone).
• Monitor for structural weakness (large cavity + lean + wind).

Your fir is fine. Internal decay in center is normal for mature trees.