How to prevent and control peach leaf curl? A detailed explanation of practical technical points

I. Symptoms and damage

This disease occurs from time to time in the south, and when severe it causes branch dieback and affects ornamental value. The disease mainly damages leaves. When leaves unfold in early spring, the leaf margins curl downward, and the diseased leaves become blistered in part or entirely, the leaves thicken, become brittle in texture, and turn yellow or red, with the leaves distorted and deformed. In early summer, a grayish-white powdery layer forms on the diseased parts, and when the disease is severe the leaves fall early. When young shoots are damaged, they appear grayish-green or yellow, with short and thick internodes and slight curvature; the upper leaves cluster and curl. When the disease is severe, the branches die.

II. Pathogen and disease characteristics

This disease is a fungal disease caused by Taphrina deformans (Berk.) Tul. The pathogen overwinters or oversummers in bud scales or on diseased parts of branches and trunks; it spreads through wind and rain; it invades through stomata and other openings. Low temperatures (10°C-16°C) and abundant rain favor disease occurrence. The peak period of disease occurrence is early to mid-May. Above 21°C, disease occurrence stops.

III. Control methods

(1) Reduce sources of infection: before peach buds swell and unfold, spray 45% lime sulfur crystal at 150 times dilution, or 1% Bordeaux mixture, to kill overwintering inoculum. Continuous control for 2-3 years can eradicate leaf curl disease. After leaf fall, spray 2%-3% copper sulfate solution, and the disease will be mild the following spring.

(2) Disease prevention through cultivation techniques: apply more organic fertilizer or GA activator; drain promptly after rain; prune out diseased branches and destroy them together with fallen diseased leaves.