I have a pear tree (sorry, not sure what kind, but it produces large, yellow, traditional pear shaped fruit) in my backyard.  Last year, a few of the leaves turned black and over the winter, those branches clearly died.  I removed what I could.  I sprayed my trees with a fruit pesticide spray (not sure what kind) over the winter and twice so far since they leafed out.  Now this year, the same thing is happening.  Certain branches seemed to get infected with something and are turning black.  Doesn't seem to have bugs on them.  Maybe a fungus?  Suggestions?