What does it mean when mushrooms start to grow on a standing tree. It is a very tall black birch. The trunk up to about 10 ft is covered with mushrooms. My woods are very wet and many trees die or fall over. I try not to cut any living trees down but this one looks to be dieing. I get enough wood from trees that fall over. Its a widowmaker for sure so I'll cut it half way through and let the wind do the rest. Thanks