Quick Facts

  • Highly infectious pathogen that has a variety of hosts, especially Geranium
  • Tail is modified with a caudal horn and the posterior part of the foot acts as a catapult
  • Five races found in different parts of the world

Species Facts:

Ralstonia solanacearum race 3 biovar 2, also known as Southern Bacterial Wilt of Geranium/Potato Brown Rot, is a bacterial pathogen that causes common wilt in geraniums and infects numerous solanaceous plants (e.g. tomatoes, eggplant, and peppers). It is also a major concern to the potato industry because the disease survives well in cold temperatures and renders potatoes unmarketable.

The primary symptom of Ralstonia solanacearum in geraniums is wilted or yellowed leaves. The disease is transmitted through soil, contaminated water, equipment, personnel, and by transplanting infected plants. It is not spread through the air, from plant to plant through the splashing of water, or when sound sanitation practices are followed.

There are five races of Ralstonia solanacearum with different hosts and geographic distributions. Race 1 has very wide host range and is endemic to the Southern United States. The main host of race 2 is bananas, and this race is found in the Caribbean, Brazil, and the Philippines. Race 3 is found worldwide except in the United States and Canada. Race 4 affects ginger in much of Asia, and race 5 affects mulberries in China.

If Ralstonia solanacearum race 3 biovar 2 is confirmed in any material in the United States, all infected plants and those within at least one meter will be destroyed and the greenhouses disinfected. PPQ inspectors will determine on a case–by–case basis if additional plants that may have come in contact with infected plants must be destroyed. They will oversee the destruction of plants and the disinfection of facilities.

Portions of this article courtesy of: Animal and Plant Health Inspection Service
Image of a plant infected by Ralstonia solanacearum (Photo from: www.bugwood.org Credit to:R. J. Reynolds Tobaccoo Company)