I dont know much about peaches but sounds like it could be peach leaf curl, but I would have had to been seeing this tree all growing season to really know. Cool, wet years are when it is worse. As a general rule of fungus, once you have the problem, its to late for that year. You treat peach leaf curl when the tree is dormant. Anyway, Im sure there are alot of good reads out there on it, UC Davis generally has great info on peaches.