Posted: 02/08/2014 at 13:20
It might be another form of fungus, Magnum. Try poking a large screwdriver etc through one of the cracks in the bark into the heartwood of the tree. It should be solid. If it crumbles, then the heartwood is rotting and it will be terminal as the wood will have lost it's strength and the tree will be prone to being blown down by the wind, or branches may fall under their own weight, making it dangerous. Have a good sniff through the cracks too - any hint of a "mushroomy" smell would also indicate a fungal infection. Those are not treatable, unfortunately.