Bacterial canker is a dangerous disease that affects tomato plants and can cause significant losses in commercial and home gardens. The bacterium Clavibacter michiganensis subsp causes the disease. michiganensis and spreads rapidly, making it difficult to manage. The disease has no cure, and the pathogen can be challenging to eliminate once it has been introduced into an environment.
Bacterial Canker Management in Tomato
The Causal Organism of Bacterial Canker
The bacterium Clavibacter michiganensis subsp causes bacterial canker. michiganensis (Cmm). This pathogen primarily enters tomato plantings through infected seeds or transplants. (Cmm) can be present on symptomless plants and multiply rapidly in favorable weather conditions.
The bacterium infects the plant through leaf stomata and wounds, leading to systemic infection. The disease spreads through splashing rain and human activity. It is favored by warm temperatures and high moisture or relative humidity. Once established, the bacterium can survive on plant residues for up to 3 years and on stakes and equipment for up to 7 months.
The Disease Cycle of Bacterial Canker
- The cycle of bacterial canker in plants begins with the survival of the pathogen, Clavibacter michiganensis, on buds and bark.
- The bacteria enter the plant through wounds created by frost or pruning, primarily targeting 1-year-old stems.
- The disease can spread through various means, including wind, rain, insects, contaminated propagation wood, and pruning tools.
- The ideal conditions for the bacteria to thrive and cause infections are cold weather and high moisture levels. These conditions increase the chances of the disease spreading and infecting other parts of the plant.
Causes/conditions Favorable for Bacterial Canker Disease Spread in the Field
- Humid or wet weather conditions favor the spread of bacterial canker in the field. During these conditions, slimy masses of bacteria ooze through cracks in the stem, leading to secondary infections on leaves and fruits.
- As a result, the fruits develop small, shallow, water-soaked white spots, which become slightly raised, tan, and rough. These conditions create a favorable environment for the spread of the disease, making it important for growers to be vigilant and take preventative measures to reduce the risk of infection.
Symptoms of Bacterial Canker Disease
- Seedlings: Small white raised spots may form on leaves, with leaf edge discoloration and wilting. In severe cases, the seedling can wilt and die completely.
- Leaves: Yellow to