Orange Cane Blotch of Commercial Blackberry in the Southeastern United States

Orange cane blotch affects commercial blackberry production in the southeastern United States, mainly in the Coastal Plain region. The causal agent is a slow-growing parasitic alga, Cephaleuros virescens, which has a wide host range. Disease development is linked to the biennial growth pattern of blackberry, whereby symptoms appear in the early fall and algal lesions expand throughout the winter, spring, and early summer of the following year. Preliminary phylogenetic analysis of 18S rDNA sequences suggests that blackberry isolates from different geographical locations cluster together and are genetically similar to each other and yet differ from isolates of C. virescens obtained from commercial blueberry.