Tube wilt

Tube wilt was a disease affecting treants.

It was carried by tiny spores in the soil that could get into the trunk. Once inside the treant, they grew into a fungus that fed on the heartwood, the most tube-rich area of the treant, and caused rotting to occur. This was very painful for the treant and would cause death in a few months, when the trunk became too weak to support the weight of the branches.