Tomato Bacterial Cankers
Bacterial canker is one of several bacterial diseases that can seriously affect tomato plants grown in backyard gardens as well as in greenhouses. Once canker takes hold of a tomato plant, it can result in an all out epidemic that can affect young fruit on neighboring plants in the outdoor garden and all plants inside a greenhouse.
Causes and Symptoms
A particular bacterium called Cornebacterium michiganense causes canker on tomato plants. The bacteria are actually very erratic, but once it takes hold they are extremely destructive. The actual organism that causes this disease is in the seeds and can survive temporarily in the soil and in a greenhouse, but much longer in the debris of plants. Either way, it lives long enough to spread and affect future plantings.
All tomato plants are susceptible to bacterial canker, starting with seedlings all the way to plants that are already producing fruit. The symptoms are considered to be either superficial or systemic. Superficial symptoms normally appear first on the young green fruit in the form of small white spots with a dark brown center. Systemic symptoms usually show up early in the seeds or very young seedling plants. These symptoms include wilting, discoloration of the leaf veins, and lesions on the fruit and stems of the plant.
Treatments and Control
Tomato bacterial canker is one of the hardest diseases in tomatoes to get under control. This is partly due to the difficulty of detecting the disease because of the wide array of symptoms. Another reason is that the disease is so infectious and there are no chemicals that can effectively treat it. Some of the best tomato bacterial canker treatments are:
- Disease free seed selection – When growing tomatoes with seeds, it is important to obtain seeds that are certified to be disease-free. Never use seed whose source may be known to have had a bacterial canker. It is not recommended that tomato growers save and use their own seed.If non-certified seed is used, they can be treated in different ways that include soaking them in .8% acetic acid or 5% hydrochloric acid. You can also use a hot water treatment.
- Tomato crop rotation – Since the bacteria survive well in the debris of the plants, it is important to rotate your tomatoes with crops that are not infected with the canker bacteria. After three years of rotation, the disease should be under control.
- Sterilization – When reusing greenhouses and garden seedbeds in which infected plants were grown, the soil must be sterilized in order to kill the bacteria. Steam sterilization is the preferred method.