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Infiltration of Lenticels of Potato Tubers by Erwinia carotovora pv. carotovora Under Hydrostatic Pressure in Relation to Bacterial Soft Rot. Jerry A. Bartz, Associate Professor, Department of Plant Pathology, University of Florida, Gainesville 32611. Arthur Kelman, Professor, Department of Plant Pathology, 1630 Linden Drive, University of Wisconsin, Madison 53607. Plant Dis. 69:69-74. Accepted for publication 27 June 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-69.

Aqueous suspensions of Erwinia carotovora pv. carotovora (Ecc), rhodamine dye, and india ink in water penetrated intact potato tubers that were submerged in them and subjected to hydrostatic pressures of 180530 cm of water for 20 sec to 5 min. Stained tissues (usually located beneath or adjacent to lenticels) were more numerous in freshly harvested or warm (≥20 C) tubers than in stored or cold (4 C) tubers. The number of stained sites also increased as the concentration of Triton X-100, a nonionic surfactant, increased from 0.01 to 1% (w/v). When freshly harvested or commercially stored tubers were infiltrated with Ecc and incubated at 20 C in a mist chamber for 4 days, the severity of bacterial soft rot (surface area decayed) sometimes approached or equaled 100%. In contrast, severities seldom exceeded 50% in tubers that were submerged in suspensions of Ecc but not subjected to hydrostatic pressures resulting in infiltration. The high potential for soft rot associated with infiltration persisted for at least 4 days, whereas within that period, the increased potential associated with shallow immersion (5 cm) fell to levels that existed before inoculation.