Plantwise Factsheets for Farmers
Bacterial canker of tomato
Clavibacter michiganensis subsp. michiganensis
Recognize the problem
Bacterial canker causes wilting of the leaves and leads to dark coffee-coloured spots on the leaf margins. The stalk develops open cankers and if you cut the stalk, you will see a large discoloration or a dark coffee-colored area on it.
Canker attacks tomato and sometimes bell pepper. Canker may affect immature fruits, which present superficial spots with a dark centre surrounded by a light edge similar to the eyes of a partridge.
Bacterial canker is caused by bacteria that affect the plant leaves, stalks, flowers and fruits. A severe attack may lead to the death of the plant.
Bacterial canker is spread by raindrops along the furrow from an infected plant. The bacteria can also be carried in the seeds. This bacterium requires warm temperatures (25 - 30 °C).
- Before sowing, disinfect the seeds by soaking them for 3 minutes in hot water at 50-55 °C
- For the transplanting, use healthy or non-spotted seedlings § Use bacterium-resistant or tolerant varieties
- Do not plant in sandy soils. Fertilize the soil and the plants, but avoid nitrogen excess
- The disease can be spread on implements such as wooden stakes. Clean these with bleach between uses to kill the bacteria
- Once a field has been infested, it is advisable to practice crop rotation with non- solanaceous crops, i.e. NOT tomato, pepper, chili, aubergine, potato
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