First Report of Dothichiza caroliniana on Southern Highbush Blueberry in Georgia. R. E. Baird, RDC, Plant Pathology Dept; CPES, Tifton, GA 31793. J. M. Ruter, Horticulture Dept., CPES, Tifton, GA 31793. Plant Dis. 80:223. Accepted for publication 4 December 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0223C.
Southern highbush blueberry (Vaccinium corymbosum L.) plants (US 41 x G-362) grown at the Coastal Plain Experiment Station (CPES), Tifton, GA. were observed to be defoliating on 2 August 1995. The leaves had lesions up to 4 mm in diameter with dark reddish borders on the adaxial leaf surface. Expanding outward from (he original lesion were secondary infections that partially or entirely surrounded the initial infection. Black pyenidia within each of the lesions were visible with a l0x hand lens and were identified as those of Dothichiza caroliniana Dcina-rce & M. S Wilcox based on the conidia and conidiogenous cells. Isolates of the fungus were obtained from the diseased tissue to confirm the pathogen's identity. In a previous study, D. caroliniana was reported to cause "double spot" on Southern highbush blueberry in North Carolina. To confirm pathogenicity of D. caroliniana, isolates Doth. 1 and 2, obtained from diseased blueberry tissue at CPES, were inoculated onto four replicate Southern highbush blueberry plants (US 41 x G-362). The isolates were cultured on potato-dextrose agar and 5-mm mycelial plugs taken from growing margins were placed onto leaves either nonwounded or punctured with a needle. Noninoculated controls were included for comparison. Plants were incubated for 14 days in moist chambers at 24 to 37°C and protected under a shade cloth from direct sunlight. All wounded and nonwounded inoculated leaves with either isolate had foliar symptoms resembling the lesions previously observed at CPES. Reisola-tion of the fungus from the necrotic tissues confirmed pathogenicity. The noninoculated leaves did not develop foliar symptoms. This represents the first report of D. caroliniana in Georgia.