NPDN 2007 Meeting - Ralstonia solanacearum Race 3, biovar 2: a potato disease becomes a challenge for geranium growers

NPDN National Meeting 2007

Poster Abstract

Ralstonia solanacearum Race 3, biovar 2: a potato disease becomes a challenge for geranium growers

Authors: KAREN SNOVER-CLIFT (1), Margery L. Daughtrey (2), Caitilyn Allen (3), David J. Norman (4), Darryl L. Thomas (5)

Affiliations: (1) Cornell University, Ithaca, NY, USA; (2) Cornell Univ, Riverhead, NY U,SA; (3) Univ. of Wisconsin, Madison, WI, USA; (4) Univ. of Florida, Apopka, FL, USA; (5) Goldsmith Seeds, Gilroy, CA, USA

Ralstonia solanacearum Race 3, biovar 2 (R3bv2) is a devastating pathogen, causing brown rot disease on potatoes in the highland tropics and some temperate zones, as well as bacterial wilt on tomatoes, eggplants, and some weeds and ornamentals. Because this strain is thought to be relatively cold-tolerant, it is perceived as a threat to seed potato production in the northern United States and is listed as a Select Agent. Recently, R3bv2 was inadvertently imported into the U. S. in unrooted geranium (Pelargonium x hortorum) cuttings from Central America and Africa. Prompt response to these introductions, including expedited regulatory actions, allowed effective eradication of the pathogen, but unfortunately at great expense to geranium growers. Precise diagnosis of this pathogen is essential, since related but non-R3bv2 strains of R. solanacearum are endemic in the southeastern U.S. Diagnosticians have used biovar tests based on acidification of disaccharides and sugar alcohols, host inoculations, and several different PCR tests to reliably identify this Select Agent. To reduce the risk of importing R3bv2, enhanced clean stock programs with random immunological testing are now employed at off-shore geranium production sites. Geranium propagators have adopted a barcode system to track cuttings.

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