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Bacterial leaf spot (Xanthomonas campestris pv pruni) affects all stone fruits, but it occurs most frequently in peach. The bacterium can infect fruit, leaves, and shoots, particularly if conditions are warm and wet from petal fall until 3 to 4 weeks after petal fall. Red to purple leaf spots are small and angular with a yellow halo. Spots are usually concentrated on tips of leaves and along midribs; diseased leaves rapidly turn yellow and drop from trees, even with minimal spotting. Spots expand and centers of spots drop out, causing shot-hole symptoms. Infection may spread to fruit. Twig infections occur on current season’s wood and serve as sites for overwintering. Twig dieback is more common in apricot and plum than peach.

Bacterial leaf spot lesions.

(Photo: U. Mazzuchi, Universita di Bologna, Bugwood.org)

Bacterial leaf spot shot-hole symptoms.

(Photo: John Strang, University of Kentucky)

Management:

• Space plants to improve air circulation.
• Apply copper products as a dormant spray and antibiotics during the growing season.
• Consider resistant cultivars.
• Avoid planting new trees near infected trees.
• Practice proper sanitation (remove diseased wood before spring growth begins; discard debris away from orchard).
• Plant windbreaks to reduce damage/ abrasions by driving rain, wind, and blowing sand. 

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