{"id":98,"date":"2026-02-05T22:16:12","date_gmt":"2026-02-05T22:16:12","guid":{"rendered":"https:\/\/www.coltivobio.com\/en\/?p=98"},"modified":"2026-02-25T09:08:10","modified_gmt":"2026-02-25T09:08:10","slug":"bacterial-canker-of-tomato","status":"publish","type":"post","link":"https:\/\/www.coltivobio.com\/en\/bacterial-canker-of-tomato\/","title":{"rendered":"Bacterial canker of tomato (bacterial disease)"},"content":{"rendered":"

Clavibacter michiganensis<\/em> is a bacterium that causes a bacterial disease known as bacterial canker of tomato. In this technical factsheet, we will describe the identification, damage, and management of this plant disease.<\/strong><\/p>\n

Clavibacter michiganensis<\/em> subsp. michiganensis<\/em> is the causal agent of bacterial canker of tomato. This disease is among the most severe bacterial diseases affecting tomato, together with the other two major bacterial diseases: bacterial spot of tomato<\/strong><\/a> and bacterial speck of tomato<\/strong>.<\/a><\/p>\n

This bacterial disease causes wilting of the infected plant<\/strong>, as the bacterium colonizes the vascular tissue<\/strong>, leading to blockage and impairment of water transport. By cutting the stem or leaf petiole longitudinally, brown discoloration of the vascular tissue<\/strong> can be observed.
On the stem, the disease produces longitudinal, discolored lesions<\/strong>, which may evolve into deep cracks<\/strong>.<\/p>\n

\"Bacterial<\/p>\n

More characteristic are the fruit symptoms<\/strong> caused by bacterial canker. On immature fruits, the disease induces very small necrotic spots<\/strong> surrounded by a distinct white halo <\/strong>(see image above). Another typical symptom is the one-sided wilting or desiccation of the plant<\/strong>, due to pathogen movement through infected xylem vessels, resulting in localized damage on the side where infection occurred. In some cases, the disease may begin with the wilting of a single leaf; however, as the disease progresses, it eventually leads to general plant collapse and death<\/strong>.<\/p>\n

In some cases, fruit symptoms may be asymptomatic externally<\/strong>. This occurs when the bacterium enters the fruit through the vascular system and causes internal pulp degradation<\/strong>, which becomes mucilaginous<\/strong> and takes on a yellowish coloration<\/strong>. These symptoms can only be detected by cutting open suspect fruits.<\/p>\n

High relative humidity and temperatures between 24 and 28 \u00b0C<\/strong> favor the development of Clavibacter michiganensis<\/em>. The bacterium survives in the soil and enters plants through wounds and micro-injuries<\/strong> caused by heavy rainfall, hail, and strong winds<\/strong>.<\/p>\n

At the end of the article, you will find a video of the disease with the option to enable Italian subtitles.<\/p>\n

Prevention and management of bacterial canker of tomato<\/strong><\/h2>\n

There is no effective curative treatment for this disease; management is therefore primarily preventive<\/strong>. Control measures include the removal and destruction of infected plants<\/strong> at the first appearance of symptoms, avoiding the incorporation of infected residues into the soil.<\/p>\n

Because this bacterium persists in the soil, crop rotations of 4\u20135 years<\/strong> are essential, keeping in mind that wild species of Solanum spp.<\/strong> can also act as pathogen reservoirs.<\/p>\n

Copper-based<\/a> treatments<\/strong> are useful only for limiting bacterial spread, since the pathogen colonizes internal vascular tissues. Consequently, copper salts<\/a><\/strong> should be applied when bacterial exudates<\/strong> are produced from cankers; if left uncontrolled, these exudates increase the inoculum potential and further spread Clavibacter michiganensis<\/em>. Copper salts have a bacteriostatic effect<\/strong> against this disease.<\/p>\n

This bacterium is also capable of infecting the seed embryo<\/strong>, in addition to the external seed coat. Therefore, the use of certified, pathogen-free planting material<\/strong> is the cornerstone of prevention.
Currently, tomato cultivars resistant<\/strong> to this pathogen are available, making it possible to select nursery plants based on their susceptibility to bacterial canker.<\/p>\n