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A Vacuum Infiltration Inoculation Technique for Detecting Pseudomonas tomato in Soil and Plant Tissue. J. B. Jones, Postdoctoral associate, Department of Plant Pathology, University of Georgia, Athens 30602; S. M. McCarter(2), and D. R. Smitley(3). (2)(3)Professor, and former graduate assistant, Department of Plant Pathology, University of Georgia, Athens 30602. Phytopathology 71:1187-1190. Accepted for publication 3 March 1981. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-1187.

A vacuum infiltration inoculation technique proved to be highly effective for detecting Pseudomonas tomato in extracts from artificially infested field soil and in washings from surfaces of four of six symptomless weed species collected from fields where infected tomato plants had grown the previous year. Populations as low as 10 colony-forming units per gram of soil or per milliliter of test suspension were detected. The procedure consists of immersing the foliage of bare-root Chico III tomato plants (12–15 cm tall) in test suspensions (one drop of Tween 20 added per 100 ml) held in beakers; evacuating to 76 cm Hg for two separate periods (0.5–1.0 and 2 min), each followed by a sudden vacuum release; and placing the transplants at 19–21 C for 14 days to allow lesion development. Isolations were made from individual lesions, and selected laboratory and pathogenicity tests were run to confirm the identity of P. tomato. The vacuum infiltration method detects lower levels of P. tomato in natural habitats than other methods do and detected P. tomato when conventional plating methods with King’s medium B failed.