Epiphytic Survival of Pseudomonas syringae pv. tomato on Tomato Transplants Shipped from Georgia. W. G. Bonn, Research Station, Agriculture Canada, Harrow, Ontario N0R 1G0. R. D. Gitaitis, Department of Plant Pathology, University of Georgia, Tifton 31793, and B. H. MacNeill, Department of Environmental Biology, University of Guelph, Guelph, Ontario N1G 2W1. Plant Dis. 69:58-60. Accepted for publication 21 June 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-58.

Survival of Pseudomonas syringae pv. tomato as an epiphyte occurred during shipment of symptomless tomato transplants from Georgia to Ontario, Canada. Disease occurred on these transplants in the field. Transplants inoculated in Georgia with 10⁸ colony-forming units (cfu) per milliliter of P. syringae pv. tomato were assayed 1 hr postinoculation, 24 hr later in both Georgia and Ontario, after brief poststorage periods in Ontario, and finally after 7 days. Initial population levels of 10⁵ cfu per leaf at 1 hr declined to 10⁴ cfu per leaf in Ontario and 10² cfu per leaf in Georgia but then increased to 10⁷ cfu per leaf in Ontario and 10⁶ cfu per leaf in Georgia. Changes in epiphytic population were not influenced by cultivar or storage period. Consequently, until more effective control measures are developed, current control practices using streptomycin and copper compounds should be adhered to rigorously, even during the apparent absence of bacterial speck.