Integrated Plant Genetics Inc.
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Gainesville, FL 32653

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Geranium wilt

Geranium wilt, caused by Ralstonia solanacearum, is another serious bacterial disease of florists' geranium. A particular group of these pathogens, R. solanacearum race 3, biovar 2, is a USDA "Select Agent", listed on the Agriculture Bioterrorism Act of 2002 as a "Select Agent", capable of posing a "severe threat" to agricultural safety. This pathogen was accidentally imported into the U.S. on asymptomatic geranium plants in 1999 and 2003. While this disease poses no threat to human or animal health or food safety, this wilt disease affects a wide range of plants, and potatoes are thought to be especially susceptible and therefore at risk. The pathogen is subject to USDA-APHIS regulatory action, including quarantine and eradication.

In 1999, R. solanacearum race 3 biovar 2 was discovered in imported geraniums; symptoms on geraniums are visually difficult to distinguish from those caused by Xanthomonas. The problem is that the pathogen initially is very difficult to detect and it can escape into the environment via contaminated soil, where it survives well, even if the plants are destroyed. USDA-APHIS-PPQ (Plant Protection and Quarantine) inspectors found the disease in New Jersey, New York, Pennsylvania, South Dakota and Wisconsin, and the regulatory action plan demands additional screening to certify that imported geraniums are free of this disease.

In early 2003, a small number of stock plants from Kenya were discovered and reported by the industry to be infected with this pathogen, but not before infected cuttings were shipped to at least one rooting station in the US. By March, 2003, the disease was detected in 5 greenhouses in the Midwest, in cultivars Americana Dark Red, Americana Pink and Americana Violet. As of April 1st, 2003, 26 States were confirmed positive with Ralstonia solanacearum race 3 biovar 2 at 103 nursery facilities that received suspect geraniums. These nurseries plus two rooting stations are distributed as follows by state: AL (5), AR(2), CO(1), DE (1), GA (2), ID(1), IL (4), IN (4), IA (3), KS (3), KY(1), MD (3), MI (11), MN (4), MO (5), NH(1), NJ(1), NY(2), NC (12), OH (6), PA (4), SC (7), TN (1), TX (7), VA (8), and WI (4). In addition,there are 338 nurseries still on hold due to regulatory control actions pending confirmation. Samples from plants with symptoms continue to arrive at the APHIS-PPQ Beltsville laboratory after screening at state or cooperating university diagnostic laboratories. PPQ is now collecting information about the prevalence of the Ralstonia pathovar in geranium production facilities that export geraniums to the US. So far, R. solanacearum race 3 biovar 2 has not been detected in potatoes in North America.

For recent references and photographs of the effects of the disease, visit the University of Florida web site:

U.F. Geranium Wilt Pest Alert

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Copyright © April 2003 Integrated Plant Genetics, Inc. -- All Rights Reserved

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