Allen Hammer, Dept. of Horticulture and Landscape Architecture; Karen Rane, Botany and Plant Pathology Department; Purdue University
An outbreak of Ralstonia solanacearum, Race 3 Biovar 2, the pathogen that causes southern bacterial wilt, occurred in one of Goldsmith Plants geranium production facilities in Kenya. Cuttings from Kenya were only imported to two US rooting stations in MI and NH. The cultivars involved in this outbreak include Americana Dark Red, Americana Pink and Americana Violet, shipped as rooted cuttings. Unrooted cuttings of these cultivars are not known to be involved in this disease outbreak.
This pathogen 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 introduction seems to have been an unintentional introduction of the pathogen during the routine and normal importation of geranium cuttings from Kenya by a US company.
The primary symptom of this disease is wilting of leaves, followed by death of plants. The wilting can be very subtle at first. In fact, some infected plants have been reported to showed marginal necrosis rather than traditional wilt as an early symptom. If you see any wilted geraniums (when the root medium is moist), be sure to get a diagnosis of the problem. Many other factors can cause geraniums to wilt, but it is very important to determine the exact cause so that management strategies will be effective. Our plant diagnostic lab is fully equipped to identify and help you manage geranium disease problems. If you have questions, please contact the Plant and Pest Diagnostic Laboratory at 765-494-7071. It is very important that we identify and contain this disease outbreak as quickly as possible. You can help by paying close attention to your geranium crop, getting suspected plants diagnosed, and practicing all the careful sanitation we have learned over the years. Wash hands, sterilize equipment, do not carelessly remove leaves/flowers, and observe your geraniums daily for signs of problems. If you see wilted geraniums, DO NOT discard symptomatic plants right away. Isolate symptomatic plants and avoid handling them until a diagnosis is confirmed. There are special disposal protocols for discarding plants with southern bacterial wilt.
Indiana DNR, Division of Entomology and Plant Pathology Inspectors have quarantined many Indiana greenhouses that received rooted cuttings from the rooting stations. If you are quarantined, you must follow that order. You cannot sell or discard any geraniums or other plants received in the same geranium shipment under the quarantine. The USDA/APHIS are presently developing an action plan to deal with this geranium disease. That action plan will have specific instructions for dealing with infected plants.
Every Indiana greenhouse owner should be extremely concerned with this disease. It is very important that we do everything possible to contain and eradicate this disease. That means that everyone has a responsibility to help detect and destroy diseased plants following the exact protocol outlined in the USDA/APHIS action plan. Please do not discard any sick geranium by simply putting it in the compost pile. Containing and destroying this disease is possible if we all work together with a unified and careful plan of action.
We strongly suggest and urge every greenhouse grower to not move and handle quarantined plants. If the disease is found in your crop, any movement of plants can result in additional spread of the disease and contamination of additional greenhouse area. Until we get a handle on possible diseased geranium plants in Indiana greenhouses, we all need to do everything possible to not spread this disease or further contaminate greenhouses and the environment. DO NOT MOVE GERANIUMS UNTIL YOU KNOW FOR SURE THEY ARE FREE OF Ralstonia!
Additional information can be found on the following web sites:
USDA/APHIS/PPQ Action Plan for Ralstonia solanacearum,
Race 3, Biovar 2 found in nursery facilities (27 February 2003) PDF file
455 KB, 25 pg:
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:
The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by the Purdue University Cooperative Extension Service is implied. Any person using products listed assumes full responsibility for their use in accordance with current direction of the manufacturer. Purdue University is an equal opportunity/equal access institution.
Information listed is valid only for the state of Indiana.