Short term...I don't know. I tried a peroxide solution one year when there was some brown rot on the mature peaches but that was after picking just to give them a bit more shelf life.
Long term we prune to open up the tree and allow for a lot of air flow. The last several summers have been so hot and dry it has not been a problem here even for conventional growers. I pick up all of the drops daily and pick any fruit that even has a hint of oddness. My Blood peaches are supposed to be more resistent to brown rot than some others and I think it is true. Even they have some spots of it duing a wet humid summer. What varieties do you have? Mine are very slow to mature this year...about a month late and we are without much rain already.
"We're all just walking each other home." -Ram Dass
"Be a lamp, or a lifeboat, or a ladder."-Rumi
I think the problem can be minimized by growing the earliest-ripening varieties available. Same with plum curculio and probably other fruit problems....the fruit is simply not there for long enough for the problems to find it as easily...... But weather is definitely a factor. As I recall from living in GA, running chickens under the trees helped with this and all manner of insects, because fallen, infested fruit was cleaned up straightaway.....
I have the same problem. I saved a wild peach tree from a drain - it has grown beautifully, full blossom every year - but every year all the peaches are rotten inside. Have been told need to spray herbicide before and after flowering and when fruit very small. Someone else has said best to remove tree and burn, so as not to affect nectarine and apricot trees nearby. Seems a shame. Hopefully someone can recommend an ecological solution!