There are many diseases that can affect peach trees. I will list these below and then you can have a look at google for them.
BROWN ROT
PEACH SCAB
BACTERIAL SPOT
PEACH LEAF CURL (To be honest this is what it sounds like)
GUMMOSIS
POWDERY MILDEW
CROWN GALL
PHYTOPHTHORA ROOT AND CROWN ROT
OAK ROOT ROT
PEACH TREE SHORT LIFE

Hope that this helps.