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Isolation and Characterization of Fluorescent Pseudomonads from Apparently Healthy Peach Trees. W. M. Dowler, Research Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service, Clemson University, Clemson, SC 29631; D. J. Weaver, Research Plant Pathologist, Southeastern Fruit and Tree Nut Research Station, Byron, GA 31008. Phytopathology 65:233-236. Accepted for publication 13 September 1974. DOI: 10.1094/Phyto-65-233.

Pathogenic and nonpathogenic fluorescent pseudomonads were readily isolated from apparently healthy peach twig and trunk tissue samples collected monthly in Georgia and South Carolina. No pathogenic bacteria were isolated during the summer months. Morphological and biochemical tests showed that the pathogenic isolates were closely related to Pseudomonas syringae, but about 50% of the fluorescent isolates were nonpathogenic. Inoculation of mature trees in the field with these isolates during early fall pruning resulted in death of trees by the following March. Heterogeneous populations of pseudomonads exist in apparently healthy peach orchards in the southeastern United States.