Peach tree produced a lot of peaches but before they were ready to pick, a white mold grew on the fruit. What is this and how can I correct it?
Peaches Have White Mold
What you're describing sounds like a fungal infection, possibly brown rot? Check with your local extension office (found under gov't in your phone book) for advice on the best way to treat these type of infections, specific to your area.
I normally use copper sulfate as a fungicide on my fruit trees, but I have no peaches. The borers won that one, LOL