Submit fungal fruiting structures to a diagnostic lab for identification. This may help determine the seriousness of the decay. Also, there are mushrooms that are associated with tree roots that are beneficial and do not cause decay. Not all mushrooms associated with trees indicate wood decay. Be sure to properly identify the fungus.
Several methods are available for determining the extent of the decay column within the tree.
These include drilling small holes in the trunk to measure resistance, and using electrical resistance or ultrasound meters. It may be difficult to interpret results of these tests. Furthermore, some of procedures can result in tree injury. Therefore, only trained arborists should attempt them. Wood decay can be prevented by avoiding unecessary wounds and proper pruning.