Bacterial Leaf and Stem Rot of Geranium in Minnesota. B. W. Kennedy, Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108. F. L. Pfleger, and R. Denny. Professor, and Junior Scientist, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 71:821-823. Accepted for publication 4 May 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0821.

A severe and widespread epidemic of leaf and stem rot of geranium (Pelargonium × hortorum) caused by Xanthomonas campestris pv. pelargonii occurred on both greenhouse-and field-grown plants in Minnesota in 1983. The pathogen survived up to 221 days in air-dried leaves placed on the soil surface of a greenhouse bench but was not detected after 11 days in diseased leaves that were buried in soil. When introduced onto leaves or into wounds of 17 common nonhost species of commonly propagated greenhouse ornamental plants, the bacterium could be detected in wounds of 11 and on leaves of three of the species 28 days later. Removal of significant amounts of foliage from host plants significantly increased disease severity in two of four cultivars. Plants subjected to long photoperiods did not appear to be more susceptible. All commercial geranium cultivars tested were susceptible.

Keyword(s): host range, predisposition, survival.