Ralstonia solanacearum, Race 3 Biovar 2 found in U.S. Greenhouse

Gail Ruhl and Karen Rane, Plant Disease Diagnosticians, Dept. of Botany and Plant Pathology, Purdue University

January 16th. 2004 New Pest Response Guidelines (Action Plan) may be found in the Ralstonia Menu (at the far right of your screen) at the APHIS web site http://www.aphis.usda.gov/ppq/ep/ralstonia/.

According to Dr. Richard L. Dunkle, Deputy Administrator, Plant Protection and Quarantine, the Plant Protection and Quarantine (PPQ) Center for Plant Health Science and Technology laboratory in Beltsville, Maryland, confirmed Ralstonia solanacearum, Race 3 Biovar 2, the pathogen that causes southern bacterial wilt, in geraniums from a commercial greenhouse in New York State. The disease was confirmed in rooted cuttings of the Americana Coral variety on December 31, 2003, as well as in direct–ship material of the Americana Bright Red variety on January 2, 2004. The New York state greenhouse had received both varieties in infected propagative material originating from the Goldsmith Plants, Inc. facilities located in Guatemala. The rooted plants were received via Glass Corners Greenhouse in Michigan, where this pathogen was eradicated earlier in 2003. The New York State greenhouse was not implicated earlier in 2003. As per the Pest Alert by Dr. Margery Daughtrey, Long Island Horticultural Research & Extension Center, at http://www.hort.cornell.edu/greenhouse/, "Weather conditions would not ordinarily have allowed symptom expression, but the crop had been grown for a while at an unusually elevated temperature due to a malfunctioning vent. The grower reported the suspicious symptoms to his NYS Ag & Markets horticultural inspector, and the pathogen was promptly identified to genus and species."

The APHIS announcement states that approximately 300-400 customers have already received geraniums of the suspect varieties from Goldsmith’s facilities in Guatemala this growing season and that APHIS, in cooperation with State Departments of Agriculture (and the DNR in Indiana), are notifying customers and assuring appropriate actions are taken to destroy suspect plants and disinfect facilities.

Ralstonia solanacearum, Race 3 Biovar 2, is cited on USDA Agricultural Bioterrorism Act of 2002 Select Agents and Toxins List, as a serious pathogen of potatoes, tomatoes, and other solanaceous plants. However, the present outbreak (similar to the 2003 occurrence) is due to an unintentional introduction of the pathogen during the routine and normal importation of geranium cuttings from Guatemala.

It is important that growers do not move or discard any cuttings of the suspect Goldsmith cultivars (rooted or unrooted) until they have been contacted by USDA APHIS or state regulatory officials. Movement of these plants from bench to bench or between greenhouses will increase the chances of spreading the bacterial pathogen and could result in greater losses. Special protocols are required for disposal of infected plants to make sure the bacterium is not introduced to the environment.

There has been no formal announcement of the 2004 USDA Action Plan for Ralstonia solanacearum in geraniums. Special survey, sanitation, destruction and disposal protocols will be forthcoming.

For excellent photographs of the symptoms of southern bacterial wilt in geranium and other hosts check out the following USDA APHIS PPQ website (http://www.aphis.usda.gov/ppq/ep/ralstonia/index.html).

Excellent photographs of geranium wilt symptoms may also be viewed at http://www.floricultureinfo.com/ in an article titled Pictorial Guide to Geranium Wilt Disorders by Dr. Brain E. Whipker; Dept. of Hort Sciences, NC State University. You can view this article by choosing "Ralstonia Information - January 2004."

The Purdue Plant and Pest Diagnostic Laboratory is fully equipped to identify and help you manage geranium disease problems. If you have any questions, please contact Dr. Karen Rane (765-494-5821), Gail Ruhl (765-494-4641) or Dr. Allen Hammer (765-494-1335).

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