Blueberry Disease - Botrytis Blight and Fruit Rot

Symptoms and Disease Cycle

Botrytis blight is caused by the fungus Botrytis cinerea, which overwinters on infected plants and plant debris. Under favorable conditions, the fungus can infect blossoms, twigs, and fruit. Tips of infected shoots will die back and turn brown to black, eventually become bleached in appearance. Infected blossoms turn brown, and the discoloration can spread into the twig. Blighted blossoms often remain attached to the stem throughout bloom. Infected immature fruits shrivel and turn a bluish purple color, whereas infected ripe, mature fruits shrivel slightly and may become moldy. In damp weather, all infected plant parts become covered with the characteristic "gray mold" of the fungus. Spores of the fungus are disseminated primarily by wind. 

Disease Management

Cultural practices that improve air movement, such as pruning and keeping plants weeded, aid in the control of botrytis blight and fruit rot. Allow sufficient space for the plants - at least 4 feet between plants within the row and 10 feet between rows - when preparing your area for planting. Keep plants pruned and old canes thinned out to avoid dense growth. Avoid excessive use of nitrogen fertilizer in the spring which encourages growth of tender tissue that is susceptible to infection. The cultivars Elliott and Bluecrop are somewhat resistant to this disease.