Leaf Curl Control
LEAF CURL CONTROLPeach leaf curl, also known as leaf curl, is a disease caused by the fungus Taphrina deformans. Peach leaf curl affects the blossoms, fruit, leaves, and shoots of peaches, ornamental flowering peaches, and nectarines, and is one of the most common disease problems for backyard gardeners growing these trees. The distorted, reddened foliage that it causes is easily seen in spring. When severe, the disease can reduce fruit production substantially.
HOST PLANTS: Common in peaches and nectarines. Can be spread to tomatoes and potatoes via insects such as Whiteflies.
SYMPTOMS: Peach leaf curl first appears in spring as reddish areas on developing leaves. These areas become thickened and puckered, causing leaves to curl and severely distort. The thickened areas turn yellowish and then grayish white, as velvety spores are produced on the surface by the leaf curl fungus. Later affected leaves turn yellow or brown and can remain on the tree or may fall off; they are replaced by a second set of leaves that develop more normally unless wet weather continues. The loss of leaves and the production of a second set result in decreased tree growth and fruit production. Defoliation in spring may expose branches to sunburn injury.
The peach leaf curl pathogen also infects young green twigs and shoots. Affected shoots become thickened, stunted, distorted, and often die. Only rarely do reddish, wrinkled to distorted (or hypertrophied) areas develop on fruit surfaces. Later in the season these infected areas of fruit become corky and tend to crack. If leaf curl infection builds up and is left uncontrolled for several years, the tree may decline and need to be removed.
FAVORED ENVIRONMENT: Disease fungi overwinter as spores (conidia) underneath bark, around buds, and in other protected areas. Early in the growing season, during cool, wet spring weather, the spores infect new leaves as they emerge from the buds. Later, the fungus produces great numbers of new spores which are splashed or blown from tree to tree. Leaf curl is most active at temperatures between 50 and 70 degrees F. Because the disease can occur at relatively low temperatures, cool weather is thought to extend the infection period because the new leaves are growing slowly. Wet weather is necessary for infection.
LEAF CURL CONTROL: Select resistant varieties whenever possible. Leaf curl can be controlled by applying sulfur or copper fungicides. Spray the entire tree after 90% of the leaves have dropped in the fall, and again in the early spring, just before the buds open. Keep the ground beneath the trees raked up and clean, especially during the winter months. Prune and destroy infected plant parts as they appear. If leaf curl is severe, growers must maintain tree health and vigor by cutting back more fruit than normal, watering regularly (avoiding wetting the leaves if possible), and applying extra nitrogen fertilizer.
Products for Leaf Curl Control