Spores of the fungus are produced on the surface of diseased leaves in midsummer and give the leaf the powdery appearance previously described. These spores are spread to all parts of the tree by winds and rains, becoming lodged under bud scales and rough bark, and here they remain throughout the summer and winter months. In the spring, when the young peach buds begin to swell, germinating spores of the fungus penetrate the young leaves, causing leaf curl infection. Management Peach leaf curl can be prevented by a single spray application made in late fall, after leaf drop, or in late winter, before bud swell. If buds have begun to swell or open, it is too late to obtain satisfactory control of peach leaf curl as infection has already occurred.
Control is impossible once symptoms are visible.
Follow all label instructions regarding amounts of pesticide to use, method of application, and safety warnings. If a dormant spray has been neglected, and disease develops, the fruit on affected trees should be thinned to compensate for the loss of leaves. References to products in this publication is not intended to be an endorsement to the exclusion of others which may be similar. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer. Issued in furtherance of the acts of May 8 and June 30, 1914.