I live in Oregon and have good luck with Apples and Pears (and of course
Blueberries) in my orchard. When I tried Peaches though, they made fruit
one year, then for the next two years, right after they flower, all of the
leaves curl up and fall off. The branches don't die though, and gradually
recover, but no fruit!

I don't prefer to use chemical sprays as I have an otherwise organic garden,
but does anyone have some advice as to how to treat such a thing?