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Identification of a New Race of Botryosphaeria corticis on Highbush and Rabbiteye Blueberry in North Carolina. W. O. Cline, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. R. D. Milholland, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. Plant Dis. 72:268. Accepted for publication 22 October 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0268D.

A stem canker survey conducted in North Carolina in 1984 to determine prevalent races of Bortryosphaeria corticis (Demaree & Wilcox) Arx and Muller revealed a 30-yr-old planting of highbush blueberry (Vaccinium corymbosum L. 'Murphy') with about 70% of the plants infected. The cultivar Murphy previously was resistant to all known races of B. corticis (1). In an adjacent field of 12- to 15-yr-old rabbiteye blueberries (V. ashei Reade 'Tifblue') 2% of the plants were infected with stem canker. Twenty isolates collected from five countries were subjected to Koch's postulates and race determination. Only the isolates obtained from cvs. Murphy and Tifblue were an unknown race. Further inoculations were performed in the greenhouse with both isolates by spraying succulent stems of differential cultivars (Wolcott, Croatan, Murphy, Earliblue, and Bluecrop) with conidial suspensions (1x 105 conidia per milliliter) (2). Inoculations were repeated three times. All the cultivars were susceptible to both isolates. Occurence of this new race, designated SC-8, is thought to be limited to this one location in Pender County, North Carolina. No resistance to SC-8 has been identified.

References: (1) R.D. Milholland. Plant Dis. 68:522, 1984. (2) R.D Milholland and G.J. Galletta. Phytopathology 59:1540,1969.