'Curly leaf' on stone fruit has been helped by placing eucalyptus branches around trees in springtime; trees without this treatment producing the worse fruit.
Curly Leaf on Peach or Nectarine trees
I've taken care of this problem while growing peaches in Auckland using two copper sprays and more importantly seaweed nutrient
which I sprayed at seven day intervals. This seemed to take care of the
problem and also the possibility of overwintering spores in the
ground. I hope this info is of some use to you.
Ron Browne, Meremere
Pyro Clay is the answer for this problem, I have used it with 100% success on many fruit trees. I first read about this product in an article written by Wally Richardson in a Christchurch paper. It is organic easy to use, cheap and has the effect of also making the plants resistant to many other pests, can be used in the vege garden and makes them grow real well.