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Bitter rot (Colletotrichum acutatum, C. gloeosporioides) lesions begin as small, sunken localized areas on outer surfaces of fruit. As they mature, they remain sunken and circular, and develop red halos (outer rings). Under rainy conditions, salmon/pink spores appear in circular patterns. During arid conditions, black fruiting structures called acervuli are visible in lesions. Infected flesh develops cone-shaped rots that are brown and firm.

Bitter rot with spores.

(Photo: Nicole Ward Gauthier, University of Kentucky)

Bitter rot internal decay symptoms.

(Photo: Nicole Ward Gauthier, University of Kentucky)

Management:

• Sanitation (removal of infected fruit, cankers, and dead wood)
• Resistant cultivars
• Fungicides (applied soon after bloom)

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