Small, dark green sores appear on the branches near the ground. As it gets worse the disease will spread up the plant. The sores turn red and then brown as the disease gets worse. They also get bigger. The disease is often confused with frost damage in the spring. The disease can leave whole shoots without leaves.
To remedy the problem plant healthy plants that have not been grown around wild blackberries. Branches that have the disease should be removed and burned. Spraying fungicides has also proven effective.