Maple tree canker
From other information on this site, it seems that my maple tree may have Cryptosporiopsis canker – The cankers from this fungus will affect young trees and starts out as a small elongated canker that looks as though someone pushed some of the bark into the tree. As the tree grows, the canker will continue to grow. Often, the center of the canker will bleed during the rising of spring sap. That's a start, but now what do I do about it? Thank you! B. J.