Southern wilt could be devastating to some crops. (Crops & soils).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 recently. Cuttings from Kenya were only imported to two U.S. rooting stations in Michigan and New Hampshire. The geranium 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.
What is southern wilt?
Southern wilt is a usually lethal disease that affects over 250 plants in over 40 plant families. Susceptible greenhouse-grown ornamentals include, but are not limited to, plants in the genera Capsicum capsicum /cap·si·cum/ (kap´si-kum) a plant of the genus Capsicum, the hot peppers, or the dried fruit derived from certain of its species (cayenne or red pepper), containing the active principle capsaicin; used as a , Cosmos, Cyclamen cyclamen: see primrose.
Any of about 15 species of flowering perennial herbaceous plants that make up the genus Cyclamen, in the primrose family (Primulaceae), native to the Middle East and southern and central Europe. , Dahlia dahlia (däl`yə, dăl`–) [for Anders Dahl, 1751–89, Swedish botanist and pupil of Linnaeus], any plant of the genus Dahlia , Fuschsia, Gerbera, Hydrangea hydrangea (hīdrān`jə): see saxifrage.
Any of approximately 23 species of erect or climbing woody shrubs that make up the genus Hydrangea (family Hydrangeaceae). , Impatiens impatiens (ĭmpā`shēĕnz'): see jewelweed.
Any of about 900 species of herbaceous plants in the genus Impatiens (balsam family), so named because the seedpod bursts when slightly touched. Garden balsam (I. , Lantana, Nasturtium nasturtium (năstûr`shəm), any plant of the genus Tropaeolum, tropical American herbs (usually climbing) native to mountainous areas of South and Central America. and Pelargonium. Vegetables such as eggplant, pepper, potato and tomato, as well as tobacco, are also susceptible. Southern wilt has recently been detected in geraniums (Pelargonium spp.) in Wisconsin.
Symptoms of southern wilt in geraniums are similar to those associated with bacterial blight (caused by Xanthomonas campestris pv. pelargonii).
Southern wilt is caused by the bacterium Ralstonia (Pseudomonas Pseudomonas
A genus of gram-negative, nonsporeforming, rod-shaped bacteria. Motile species possess polar flagella. They are strictly aerobic, but some members do respire anaerobically in the presence of nitrate. ) solanacearum. This bacterium is commonly found in tropical, sub-tropical and warm temperate climates, but is not believed to survive cold temperatures such as those typical during Wisconsin winters. Several subgroups of R. solanacearum exist, each with a different host range. The bacterium can be moved in symptomless plants or cuttings, or in contaminated soil and plant debris (where the pathogen can remain dormant for many years).
No treatments available
There are no known treatments that will save plants infected with southern wilt. To prevent spread of the pathogen, wash your hands, sterilize sterilize /ster·i·lize/ (ster´i-liz)
1. to render sterile; to free from microorganisms.
2. to render incapable of reproduction.
1. 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. Also remove and destroy weeds or weed debris as these can harbor the pathogen. Because the pathogen is easily moved with soil, minimize splashing or any other movement of water or soil from plant to plant when watering. When clipping plants, be sure to clean clippers between cuts (e.g., by dipping in a 10% bleach solution or ammonia). Similarly, disinfect To remove the virus code that has attached itself to a legitimate file. Sometimes, the antivirus program cannot untangle the code, and the infected file has to be deleted. See quarantine. greenhouse benches where infected plants have grown. In the summer, you can disinfect an empty greenhouse by closing vents, turning off air-conditioning and keeping the house at a high temperature for several days. Similarly, you can use a freezing treatment during winter months.
This pathogen is cited on USDA USDA,
n.pr See United States Department of Agriculture. Agricultural Bioterrorism Act of 2002 Select Agents and Toxins List, as a serious pathogen of potatoes, tomatoes, and other solanaceous solanaceous
pertaining to or emanating from solanum. 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 U.S. company.
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): http://flowers.hort.purdue.edu/ web/USDARalstonia1.pdf
* Present Ralstonia outbreak information: www.growertalks.com/ralstonia/
* Ralstonia on geraniums in Florida 2001: http://extlab1.entnem.ufl.edu/ PestAlert/tmm-0607.htm
* Ralstonia on geraniums photographs: www.state.me.us/agriculture/pi/ pseudomonas.htm
* Information on Ralstonia: www.pestalert.org/Detail. CFM?recordID=70
* Potato Diseases--Ralstonia: www.aphis.usda.gov/ppq/ispm/potato/ ralstonia/
Ed. note: Southern bacterial wilt was first encountered in the U.S. in the 1980s, so it's nothing new. It has just made a re-appearance in the past few months.