Martin, John and I were discussion a blackberry samples that we think has the fungal disease anthracnose. An excerpt from the Arksansas newsletter available at http://plantpathology.uark.edu/Number_19_2008.pdf  describes the symptoms as follows: “Anthracnose, caused by Elsinoe veneta, can occur on leaves, petioles, pedicels, flower buds, fruit, and canes. On canes reddish purple circular to elliptical spots occur on primocanes in the spring. As the spots age, they enlarge and the centers become sunken, turning buff or ash gray, with purple margins. The lesions may merge, forming irregular blotches that girdle the cane. The cane may crack and die at that spot. Tip dieback may occur. The first signs of infection on the leaves are minute purple spots which later develop white centers. The center of the holes may later drop out, giving a shot hole appearance. Infected fruit are small, pitted, and slow to ripen.”