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Bacterial Canker of Tomato

Bacterial Canker of Tomato

Clavibacter michiganensis subs. michiganensis


In a Nutshell

    Interveinal chlorosis, curling and wilting of older leaves, sometimes just on one sideLeaves turn brown while petioles remain greenLeaves remain attached to the stemBrown spots with halo on leaves and fruitsRotten stalk with vertical stripes that later splits, forming cankers

Hosts: %1$s

· Tomato


Infected seedlings produce weak, stunted plants with small whitish spots on leaf veins and petioles. Symptoms in mature plants can be due to the spreading of a primary infection to new tissues (systemic) or resulting from secondary infections. Interveinal chlorosis, curling and wilting of older leaves (sometimes only on one side) characterize the systemic spreading. Later on, the leaves eventually turn brown and collapse. Petiole usually remain green and firmly attached to the stem. New infections are characterized by dark brown lesions at the leaf margin and round spots with a bright halo on the leaf blade. The stalk base is rotten and dark-brown and brown vertical stripes appear on the upper part. Stem later split forming long, brown cankers. On the fruits, brown spots with a bright halo appear. As the disease progresses, the whole plant dessicates.


The bacteria can survive on seeds, in plant residues or in the soil. The transmission occurs via infected seeds, pathogens in the soil, or during pinching. The bacteria multiply in the leaf veins and hinder water and nutrient transport. As a result, the plant starts wilting and withering. Conditions of high soil moisture or relative humidity and warm temperatures (24 to 32°C) favor the development of the disease.

Biological Control

Soak the seeds in 8% acetic acid or 5% hydrochloric acid. You can also use methyl bromide or water treatments.

Chemical Control

Always consider an integrated approach with preventive measures together with biological treatments if available. Under conditions of frequent rainfall and prolonged wet periods, use chemical sprays with copper-based compounds. These can reduce the incidence of foliar blight and fruit spotting.

Preventive Measures

    Chose certified disease-free seeds or transplantsIf available, choose resistant varietiesSoilless medium in plastic trays can be used instead of field facilities to produce transplantsIf possible, steam sterilize seedbeds and soils to kill the bacteriaKeep your tools and equipment cleanRemove weeds belonging to the Solanaceae familyMonitor fields and cut off diseased plants at the ground lineRotate tomatoes with non solanaceous crops for at least two or three yearsPlow deep after harvest and bury infected crop residue