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Disease Note.

Infection of Cold-Injured Blueberry Stems by Bolryosphaeria dothidea. . W. O. Cline, Department of Plant Pathology, North Carolina Stale University, Raleigh 27695-7616. Plant Dis. 78:1010. Accepted for publication 20 June 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-1010A.

Highbush blueberries (Vaccinium corymbosum L.) planted in low-lying high-organic soils in southeastern North Carolina have a history of severe stem blight caused by Botryosphaeria dothidea (Moug.:Fr.) Ces. & De Not. (syn. B. ribis Gross. & Duggar). Stem blight is generally not observed in new plantings until the second or third season. (1). A 0.2-ha planting (cv. Murphy) in Bladen County was examined biweekly or monthly for the first 3 yr to determine conditions associated with high plant mortality in young bushes. Plants grew profusely and did not become completely dormant, and 139 of 500 bushes were cold injured at first frost in November 1992. Cold-injured stems (about 10-30 cm long) developed a characteristic dead, hook-shaped tip that persisted throughout the following growing season. The presence of B. dothidea was confirmed by isolation onto PDA Koch’s postulates were completed with randomly selected isolates inoculated onto the cultivar Bluechip. In 1993, the incidence of B. dothidea in stems injured by cold the previous November was 19, 39, and 88% for March, May. and June, respectively. Widespread infection by B. dothidea following cold injury could account for past observations of field epidemics 1-2 yr after planting.

Reference: (1) T. C. Creswell and R. D. Mitholland. Plant Dis 71:710, 1987.