Southern Bacterial Wilt

Ralstonia solanacearum (previously Pseudomonas solanacearum)

Southern Bacterial Wilt is a disease of tomatoes, eggplant, pepper, potato and sunflowers. It is most prevalent in the south, where it is sometimes known simply as Bacterial Wilt (which could cause it to be confused with the Bacterial Wilt of cucurbits!). It is most problematic in warm, humid conditions (above 75º F), and in alkaline soil. When the bacteria get inside the plant it multiplies and inhibits the transportation of water and nutrients. The first sign of this disease is when leaves start to wilt in the afternoon, but recover in the evening. This wilting eventually spreads to the whole plant and it suddenly dies, without even turning yellow (this is a key indicator of  Bacterial Wilt). If you split open the stem it may be dark and watery or even hollow. The bacteria can live in the soil indefinitely, so rotate your solanum crops for at least 4 years. Also provide good air circulation, fertile soil, a neutral pH and well drained soil. Remove potentially infected crop debris to minimize sources of infection. Also wash your hands after touching infected plants. Some tomato varieties are resistant (Saturn, Venus, Neptune, Tropic Bay, and Kewalo). To test for Southern Bacterial Wilt in tomatoes, cut a piece of stem from near ground level and put it in a jar of water. A milky juice will ooze from the end.

Images: Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org