PEACH LEAF CURL looks pretty bad this year. The weather, I think, made it difficult to find the right time or even remember to spray (lime sulfur is the usual organic control) for it.
If your trees got it as badly as mine, there’s NOTHING YOU CAN DO NOW to control it, per se. The fungus is actually inside the leaf tissues and is protected from any organic fungicide. HOWEVER, you can give your trees a little feeding to help it re-foliate. There is only one infection period a year, and it’s over and done, so trees that were very infected will often try to put out a new crop of leaves. So use compost tea, fish emulsion, Miracle-Gro (which is not organic, in case you want to know)–anything that is soluble and becomes available to the roots quickly.
If you want more do a web search, but here are some photos:https://www.google.com/search?q=peach+leaf+curl+organic&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla%3Aen-US%3Aofficial&client=firefox-a&channel=sb#channel=sb&q=peach+leaf+curl+images&rls=org.mozilla:en-US:official