Peach leaf curl is one of the most common and widespread diseases affecting peach plantings in the United States. Recognized as a common peach trouble since 1821, it occurs in almost every region where peaches are grown. It has been known by names such as, curly leaf, curly blight, and leaf blister.
Although peach leaf curl is primarily a foliage disease, it also may affect blossoms, young twigs, and fruit. The disease causes loss of foliage early in the summer. This stimulates the affected tree to produce another crop of leaves, resulting in decreased tree vigor. Lowered tree vigor usually increases the danger of winter injury.
Peach leaf curl is first noticed early in the spring when leaves start to unfold. Diseased leaves are noticeably red and soon become distorted, thickened, and greatly curled as they develop. When diseased leaves are fully developed, they are lighter colored than normal; frequently flushed with red; and greatly curled, puckered, and distorted.
Leaves infected with leaf curl are also thicker than normal leaves and have a firm and leathery consistency. The entire leaf or any portion of it may become infected. A few or nearly all of the leaves on a tree may fall, depending upon the severity of the attack. As the growing season advances, the upper surface of diseased leaves turns gray and develops a powdery appearance. Dry weather soon withers the leaves causing them to fall early. However, cool weather delays defoliation.
Young infected peach fruits become distorted and seldom remain on the tree very long. Infected fruits show irregular, swollen, colored areas on their surfaces. These areas are usually wrinkled, without the normal peach fuzz, and look like they have been polished.