Overwintering and Distribution Pattern of Pseudomonas syringae pv. papulans and pv. syringae in Apple Buds. T. J. Burr, Associate Professor, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456. B. H. Katz, Research Technician, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456. Plant Dis. 68:383-385. Accepted for publication 9 November 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-383.

Pseudomonas syringae pv. papulans (PSP) and pv. syringae (PSS) were isolated from dormant Mutsu, Golden Delicious, and Empire apple buds showing visible internal necrosis. PSP was detected more frequently from Mutsu buds than from Golden Delicious or Empire. PSP was often associated with the necrotic bud tissue and was consistently recovered from a higher percentage of necrotic buds than PSS. Both pathovars were also recovered from apparently healthy (no visible necrosis) Mutsu, Golden Delicious, and Empire buds. A characteristic distribution pattern of both bacteria was found in Mutsu buds. Neither bacterium was detected on the outer bud scales, and the highest populations were generally associated with the central bud tissues. PSP was generally recovered at higher populations from Mutsu buds, whereas PSS was predominant in Golden Delicious.