Peach Leaf Curl Plant Pathology Peach Leaf Curl Deformed peach leaves have been arriving in the Plant Disease Clinic. These leaves showed a thickened, puckered appearance with a pink-red color. Later in the season infected leaves turn gray and fall from the tree. The fungus that causes peach leaf curl, Taphrina deformans , overwinters on bud scales and twigs. Infection occurs during the spring just as the buds begin to swell.
Spring rains wash spores of the fungus to newly emerging leaf tissue.
Cool, wet conditions favor the disease. Once the current year's leaves become infected, they cannot be treated. Fortunately, the disease is fairly easy to prevent with a single fungicide application. Timing is critical. Because infection occurs when the buds begin to swell, the fungicide must be applied during the dormant season, either after leaf drop in the fall or in late winter before buds begin to swell.