Peach leaf curl is the most common disease of the peach tree. Caused by a fungus (Taphrina deformans), its symptoms are far from subtle. Distortion and discoloration of the foliage is clearly evident in the spring. Although the leaves will drop, the second set of leaves that the tree produces will not be affected. Heavy peach leaf curl infections can stunt the growth and weaken the tree.
Fertilize the tree with nitrogen by June 15, according to plant pathologists at Penn State University. Apply the fertilizer at the rate suggested and according to the instructions on the package.
Thin the fruit on infected trees. Thinning the fruit will compensate for the loss of foliage and reduce the demand on heavily infected trees.
Prune the peach tree prior to applying the fungicide.
Prevent peach leaf curl by spraying the peach tree with fungicide every year after the leaves fall. Scientists with the University of California at Davis recommend fungicides with copper as the main ingredient, at the rate recommended on the package. Cover all parts of the peach tree with the spray.