Peach leaf curl is caused by the fungus Taphrina deformans and causes twisted and distorted leaves as well as characteristic puckered red patches. Organically acceptable control methods include the protective application of copper fungicides or Bordeaux mixture. Go for one with 50% or higher copper content. The fungicide should be applied when the tree is dormant i.e. before bud-break in the Spring.

In the meantime, there's not much you can do other than removing leaf litter from around the tree and picking up any mummified fruit that drops to the ground. This will help reduce inoculum. Other cultural control methods include pruning the tree properly. This allows air to circulate within the canopy, reducing humidity and making conditions less favorable to disease development. Pruning should also be carried out during dormancy. Some people pinch off the infected growth but this hasn't been shown to reduce disease severity.

When the time comes to apply fungicide, infected trees can be sprayed twice prior to bud break. Once after leaf drop and a late spray in Spring before the new leaves emerge. The key to good control is good coverage with the fungicide. Use a pressure sprayer for best results. Good luck!