This usually means the tree is in decline. There may be internal decay. Consult an ISA Certified Arborist (lists are available from your local county extension office) for guidance regarding the potential safety hazards that may be involved and the potential longevity and potential hazards involved with this tree. There is no cure for the fungus itself, but if you wish to try to prolong the tree's life, make sure there is not any further soil compaction, cuts, fills or changes in soil grade around the tree, and do a soil test to determine nutrient needs. Keep it watered through a drought, and control any other insect or disease problems that occur. Remove any dead branches as they occur.