Plant Disease (2002) 86, 987-991

Lynn Williamson, Kazuhiro Nakaho, Brian Hudelson and Caitilyn Allen (2002)
Ralstonia solanacearum race 3, biovar 2 strains isolated from geranium are pathogenic on potato
Plant Disease 86 (9), 987-991
Abstract: Ralstonia solanacearum race 3, biovar 2 is a soilborne bacterium that causes potato brown rot disease in temperate and subtropical climates. Recent outbreaks of this disease in Europe have caused serious losses, but the pathogen had not been identified in the United States. However, in 1999, strains of R. solanacearum were isolated from wilting geraniums growing in Wisconsin greenhouses. Physiological and biochemical tests of the Wisconsin strains and a similar strain from South Dakota demonstrated that the strains belong to R. solanacearum subgroup biovar 2, which is largely synonymous with the race 3 subgroup, a classification based on host range. These results were confirmed by polymerase chain reaction analyses in which race 3, biovar 2-specific primers amplified a fragment of the expected size. This is the first report of race 3, biovar 2 in the United States, and it is the first known occurrence of race 3, biovar 2 in Wisconsin. The geranium strains were highly pathogenic on both geranium and potato. The presence of R. solanacearum race 3, biovar 2 in the United States raises concern that the bacterium could move from ornamental plants into potato fields, where it could cause both direct economic damage and quarantine problems. A commercial indirect enzyme-linked immunosorbent assay for R. solanacearum produced some false negatives for these strains, indicating that current indexing may not be sufficient to identify this destructive pathogen.
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Database assignments for author(s): Kazuhiro Nakaho, Caitilyn Allen

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Ralstonia solanacearum	Potato (Solanum tuberosum)	U.S.A. (mid N)
	Ralstonia solanacearum	Geranium (crop)	U.S.A. (mid N)