Fungi as such a pain!!!
You can wait until the leaves fall off in a week, or so. Prune out any new stems that have died, back to good wood,
The tree will shed the infected leaves and will try to replace them, which weakens the tree! Rake them up and burn them to kill the spore on the leaves!
You need to break the cycle so using a Dorment Oil will kill off the spores that winter on the stems and branches! So you will need a combination of Lime Sulphur, as well as Dorment Oil
Please read the directions on the Lime Sulphur, and Dorment Oil, on when to spray and the frequency of follow up spraying!
Dorment Oil is used before the tree comes out of dormency!
Lime Sulphur is used at the same time and as a follow up spray after the tree leafs out!
I haven't had to use either product for quite a few years so please read the directions on the products so you wont misuse it unintentionally!
Peach trees, as well as other fruit trees are rather high maintenance!!!