Answer: Mummified berries can be caused by a fungal disease, which also causes the leaves to wilt and blacken. The fungus overwinters in the ground around the bushes, so after the leaves have dropped in the fall, rake them up and dispose of them or compost them in a hot pile. Then lightly mulch with compost. Spring cultivation helps to cover or destroy the fungus. Then mulch the plants. Avoid overfertilizing, which also encourages the disease. Prune the fruit clusters so they get adequate air circulation and keep the berries picked (removing the stems also) so that the disease cannot overwinter in the fruit left on the vine.
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