Sandra, peach leaf curl, if that is what you have is a real headache. peaches are virtually not grown commercially in the Gard probably because of this disease.
It is a good idea to read up about the life-cycle of the disease. I attach one web site but there are many .
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7426.htmlAs you will read, the disease overwinters between budscales and are released in the spring with the onset of warm weather and rain as the buds open and develop. The disease spreads by asexual spores during the summer and eventually overwinters again between budscales as they close-up for winter.
The best time to control the disease is a the budscales open in the spring. Always tricky. When is open and when is not open and again in the autumn as budscales begin to close. The website gives good timing advice.
Copper based sprays are the good old standby but they have been superseded by many new and better products. If you follow thw label instructions, especially the time between the last application and harvets ie the minimum interval there is no need to worry about residues. In the case of peach épeaf curl it is not relevant because a) you spray before the fruits are formed and b) an autumn spray is made after the fruit have been picked.
If you need more advice please let me know. david