Raspberry Anthracnose: Identification and Management

The spots on your 'Dorman Red' raspberries are caused by anthracnose (Elsinoe veneta), a fungal disease favored by the wet April and May. The fungus overwinters as tiny purple lesions on canes, then spreads to leaves and fruit during rainy periods.

Control Strategies

• Promote rapid drying: Avoid overhead irrigation; ensure good air circulation through proper spacing and pruning.
• Sanitation: Prune out all diseased canes each fall. In severe cases, cut everything to the ground.
• Dormant spray: Apply liquid lime sulfur when leaf buds are swelling but before leaves fully expand (critical timing—expanded leaves will burn).
• Early-season protection: Until dry weather arrives in June, spray copper-based fungicides (e.g., Dragon Copper, Bonide Liquid Copper, Kop-R-Spray) according to label.

If next spring is dry, you can often get the disease under control by summer and enjoy a good crop. For more details, see this university publication.