Question
as a volunteer tree person I have been asked to check out a number of "street" trees with blackened sides, one side.  I thought sooty mold but in rubbing your hand over the bark, nothing comes off.  Trees in poor shape, probably-50 years old and many of them with this blackened condition...any ideas..this is in East Meadow Long Island New York

Answer
My guess would be sooty bark disease.
Sooty bark disease, caused by Cryptostroma species, can kill trees which are under stress due to drought. I could not find any controls except keeping the tree healthy and not getting the tree into a drought situation by watering. I did find one reference to removing the canker part of the bark bark to good bark and spraying with a cooper fungicide. This would depend on how big the canker area is and if it is all the way around the tree trunk. Sorry that is the best I can come up with.