Bacterial Diseases of Tomatoes
Tomatoes are susceptible to a wide variety of both fungal and bacterial diseases. The most commonly encountered bacterial tomato diseases are bacterial canker, speck, spot, pith necrosis, stem rot, crown gall and bacterial wilt. Below is a brief description of each disease. Click on the names for more detailed information. This website also contains a detailed section on viral tomato diseases.
Bacterial canker can affect any part of a tomato plant but it most often affects the stems, leaves and roots. Often, tomatoes leaves and stems will turn brown and sometimes a plant's stems may crack. Bacterial canker is often the cause of wilted tomato plants and can be distinguished from other forms of tomato wilt by the fact that the leaves of tomatoes that wilt as a result of bacterial canker usually remain attached to the plant whereas the leaves will often fall off with other diseases.
Bacterial speck most often affects the stems, leaves and fruit of tomato plants. Symptoms includes very small, dark brown or black spots that are surround by a yellow ring. Tomato plants that are infected with bacterial speck usually fail to grow properly and become stunted.
Bacterial spot usually affects the stems, leaves and fruit of tomato plants. Tomato plants infected with bacterial spot often lose a lot of the leaves from the lower part of the plant. Dark brown, oval spots and long streaks on the leaves and stems of tomato plants are a good indication that a tomato plant has bacterial spot.
Bacterial wilt is a tomato disease that causes leaves to yellow and eventually shrivel and die. In later stages of the disease, the entire plant will start to wilt. The insides of the plant stems also turn brown and eventually become hollow.
Crown gall primarily affects the roots and leaves of tomato plants. Galls (large growths or lumps) typically form on tomato roots and this tomato disease also causes plants to wilt and become stunted as they grow.
Pith necrosis is usually seen on the leaves and stems of tomato plants. Symptoms initially include yellowing and wilting tomato leaves and later the whole plant will turn yellow and wilt.
Stem rot causes the stems and leaves of tomato plants to turn black.