Diseases of tomatoes produced by bacteria

What diseases can bateria produce on tomates?

Bacterial diseases of tomatoes

Among the main diseases caused by bacteria are:

Bacterial canker of tomato

It is a disease produced by the bacterium Clavibacter michiganensis which is found inside the vascular system of the plant. The symptoms for greenhouse plants are manifested in wilting of the leaves with necrosis between the veins. As the disease progresses the whole plant withers and dies.

In the case of plants grown abroad, the main symptom is the drying of the tips of the leaflets in the lower leaves, possible pustules in the veins of the leaves and stems. When the disease is more advanced in the stems or the petioles, there are spots in the form of bands that can be opened, exposing yellowish or dark brown wounds in the form of chancre with an evident suppuration.

Contagion occurs mainly through contaminated seeds or infected tools. Prevention involves the use of properly treated seeds free of contamination or the proper cleaning of tools.

Once the contagion has been verified, the infected specimens should be eliminated and those that may be infected should be isolated.

Copper bactericides can be used to treat diseased plants.

Bacterial leaf spot on tomatoes

Baterial leaf spot on some leaves of tomatoes
Baterial leaf spot on some leaves of tomato plant

It is a disease caused by the bacterium Xanthomonas campestris pv. vesicatoria.  It affects both tomato and other Solanaceae especially wild herbs.

The infection occurs through infected seeds where the bacteria can remain dormant for many years. Other possible forms of contagion are made through the diffusion of particular water in the irrigation by sprinkling or by manipulation with infected hands or tools. It is characterized by the formation of wet spots of green color in the leaves that evolve to produce black necrotic spots  Fruits are crusted with small-sized wet margins

Black tomato spot

This disease is produced by the bacterium Pseudomonas syringae p.v. tomato. It is characterized by the appearance of black spots on all parts of the plant. The most serious problem is when the infection occurs in young plants and affects the flowers because, in this case, it can cut to almost ¾ of the crop.

The scab or bacterial scab caused by Xhantomas campestris also produces spots on any part of the tomato plant. It differs from Pseudomonas in that the spots are much larger and, in case of affecting the fruit, very visible. The affected  tomatoes have purulent cankers up to 1 cm in diameter.

punto rojo More information on tomato diseases and cultivation

This article was endorsed by Julián Masats - Technical agricultural engineer specialized in horticulture and gardening.
Written by Editorial Botanical-online team in charge of content writing

5 May, 2023

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