Typical peach leaf curl damage above.
Although not as common, peach leaf curl can also sometimes damage fruit, with mottling and cracking damage shown above.
PEACH LEAF CURL MANAGEMENT
As with most tree diseases, it's generally too late for preventive measures by the time you see it. At this point in the spring, Rodale's Handbook of Natural Insect and Disease Control suggests removing all the infected leaves to reduce the future source of re-infection. These should be bagged up or added to a hot compost pile. At this stage in the season, trees will send out new leaves to replace those removed. The impact of removing infected leaves in this way is not clear, it may or may not be effective in reducing the disease next season!
Given that peach leaf curl stresses the tree through reduced photosynthesis, we strongly advise thinning your peach fruitlets to the recommended 8" apart on the tree to reduce additional stress. This should be done between now and early June. Be sure to remove the fruitlets showing signs of infection!
The only proven means of management is a copper or sulfur fungicide spray, applied in fall after leaf drop and/or in spring before bud break. If you have a tree that is severely affected with the majority of leaves showing the disease, you may need to consider one of these organic sprays this fall and/or next spring. Improving the overall health and resilience of trees through foliar applications of biofungicides, compost tea, neem oil, EM-1 or other holistic sprays can also help reduce the rate of infection.