Internal Decay from Tree Impact Injury: Gelatinous and Spongy Fungal Masses in Oak

Q: A few years ago a healthy oak was struck hard by another falling tree. Eventually a wound developed. I cut it down for safety. Inside was a ring of gelatinous material and white spongy material. Disease or from injury?

The falling tree bruised the bark, causing it to fall off. Rainwater entered and began fungal invasion. The spongy stuff is fungal mass feeding on the trunk interior, causing hollowness.

You were right to take it down.