Westonbirt reported on Facebook that they cut down their champion Betula ermanii × pubescens because a large branch fell off and there was considerable decay in its trunk. They went on to explain that "This tree was affected by Ganoderma applanatum, a common bracket fungus that causes rot in the heartwood of a variety of trees." I thought the rot came first and the Ganoderma opportunistically moved in. Or is that only half the story, and once it moves in, it finishes off the rot, or it moves the rot into the heartwood? Or am I confusing this story with some other fungus?
Ganoderma is usually saprophytic (decaying dead heartwood), but can be pathogenic (killing live sapwood), particularly in weak or stressed trees. Don't know about birch, but it is a common cause of death of older beeches.
Excellent question Wendy! I am glad Michael F. had some information on this. I've not been able to find anything more specific in my references beyond essentially "Usually dead wood (white heart rot or root/butt) but not always"
In this region when you see a Douglas fir stump with the shape called "barber chair" the fungus that very slowly rotted the heart of the living tree out, caused it to snap off in this manner was a Ganoderma species.
