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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Southern Bacterial Wilt of Geraniums

This article was published originally on 3/7/2003

Southern bacterial wilt of geraniums is caused by Ralstonia solanacearum. Ralstonia can be spread through soil, water, and propagation. However, it doesn't move through the air. Southern bacterial wilt symptoms are almost identical to those of bacterial blight, caused by Xanthomonas campestris pv. pelargonii, which is fairly common in the United States.

Ralstonia solanacearum occurs in the United States, but there's a strain of the bacterium called race 3 biovar 2 that was recently introduced, unintentionally, from a greenhouse in Kenya. Race 3 biovar 2 can cause serious disease problems on potatoes and other food crops.

The list of host plants for Ralstonia solanacearum race 3 biovar 2 is below.

Cultivated Hosts Weed Hosts
Geranium Pelargonium spp. Black nightshade Solanum nigrum
Tomato Lycopersicon esculentum Climbing nightshade Solanum dulcamara
Pepper Capsicum spp. Horsenettle Solanum carolinense
Eggplant Solanum melongena Jimsonweed Datura stramonium
Potato Solanum tuberosum Purslane Portulaca oleracea
Bean Phaseolus vulgaris Mustard Brassica spp.
Bittergourd Momoridica charantia Lambsquarters Chenopodium album
Beet Beta vulgaris Bitterbourd Momoridica charantia
Tobacco Nicotiana spp.

U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) is using a trail of paperwork to locate, evaluate, and destroy, if necessary, all infected plant material. State and Federal inspectors have visited all Iowa greenhouses that received shipments of geraniums from the Kenya facility. Suspect plants were collected and the Iowa State University Plant Disease Clinic has been conducting tests determine whether the plants are infected with Ralstonia. Once the bacterium is found, the plant is shipped to USDA, APHIS at Beltsville, Maryland, for genetic testing to determine whether the bacterium is race 3 biovar 2.

Please see the links below for more information.

  • Present Ralstonia outbreak information
  • Ralstonia on geraniums in Florida 2001
  • Ralstonia on geraniums photographs
  • Information on Ralstonia
  • Potato Diseases - Ralstonia
  • USDA Bans Geraniums From Kenya Due to Ralstonia



This article originally appeared in the March 7, 2003 issue, pp. 22-23.

Year of Publication: 
2003
Issue: 
IC-489(4) -- March 7, 2003