Plant Disease Clinic--Highlights

Peach Leaf Curl

Peach leaf curl is caused by the fungus aphrina deformans. This disease of peach and nectarines is easy to identify. Young leaves appear thickened and puckered and are often a pink or red color. The entire leaf may be affected or only small areas. As the disease progresses, leaves turn a gray color and fall prematurely from the tree. Trees that are severely defoliated may not yield well and are predisposed to winter injury.

The fungus that causes peach leaf curl overwinters on bud scales and twigs. When buds open in the spring, the fungal spores come into contact with the newly expanding leaves. Cool, wet conditions favor disease development.

Fortunately, the disease is fairly easy to control with a single fungicide application. The timing of the spray is important. 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. The disease cannot be controlled once the leaves have started to expand.

Fungicides labeled for control include chlorothalonil (Daconil 2787), Bordeaux mixture, and liquid lime-sulfur.

Plum Pockets

Plum pockets is caused by the fungus Taphrina communis. The most conspicuous symptoms occur on the fruit. Plums swell, becoming puffy and distorted. Seeds do not form and the fruit is hollow. Young leaves and shoots may be distorted but symptoms are not as common.

The same control measures used to prevent peach leaf curl will also prevent plum pockets.

This article originally appeared in the June 9, 1993 issue, p. 89.

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