Bacterial diseases of the tomato plant

Bacterial diseases that infect the tomato and their symptoms

As any product becomes increasingly important in the economic sector, any factor that will increase the efficiency of producing that product will usually be explored, including the impacts of bacterial diseases in tomatoes. This is no different for the tomato crop, as great efforts have been undertaken to not only to identify any bacterial diseases that might negatively impact the growth of the plant and its fruit, but also to find the correct treatments and agricultural practices that will reduce the incidence and impact that these diseases have. All of this is done with the goal of improving the quality and quantity of the seasonal tomato harvest.

One such agricultural practice that has repeatedly been proven to be essential is the use of a tutoring system. This tutoring system will reduce the spread of disease in your tomato crop as well as aid their growth. When a proper tutoring system is used, it allows the agriculturist to provide improve ambient conditions to his crops. These improved conditions are beneficial to the plant as they also allow the workers that tend them to apply nutrients and other agrochemicals more efficiently. To ensure that all these actions result in a good harvest, you should ensure that you have a healthy seed stock and implement other good agricultural practices.

Bacterial Diseases
If the plant is infected with a virus, it affects both the plant and the tomatoes presenting different symptoms.

Bacterial diseases that attack the tomato crop

Bacterial Canker

The bacterial species that provoke Bacterial Canker is named Clavibacter michiganensis. This is considered one of the most destructive bacterial diseases that can happen to greenhouse crops. This disease will cause your plants to wither, starting asymmetrically in the leaves. If the plant has any immature fruit, they will begin to fall off, meanwhile the plant will start to look burnt. The stem of the plant will start to form stretch marks where any leaves attach. The rest of the stem will then start to observe linear discolorations that go from a whitish yellow color all the way to dark brown. The formation of cancerous looking spots and blisters on the stem and leaves is not an uncommon occurrence. Mature fruit will often form discolorations that have a dark center surrounded by a white opaque halo.

Bacterial Canker
The canker bacteria is the bacteria that causes the most damage in the crop because it will cause the plant to start to wilt, starting with the leaves.

Bacterial spot

There are two species of bacteria responsible for Bacterial Spot: Xanthomonas axonopodis and X. vesicatoria. These bacterial diseases is considered to be fairly damaging to the tomato crop because it provokes wounds on the surface of the fruit, making the fruit look unsightly. These wounds will have different characteristics depending on which state of development the fruit is in. When the infected fruit is still immature, the spots will have a woody appearance, sort of like scabs surrounded by halos. The mature fruit on the other hand will still have the spots that look to be made of wood, but will not have the halos surrounding them. The bacteria that cause this disease are transmitted by both wind and rain splash.

Bacterial Speck

The cause of Bacterial Speck is the bacterium Pseudomonas syringae. This bacteria attacks the leaves of the plant and causes them to turn an off-green to brown color that is surrounded by a yellow line. The areas that are the most damaged by this disease are around the edges and at the apex of the leaves. If the disease spreads sufficiently, the leaf will turn a yellowish color before ultimately falling off, leaving the plants fruit exposed to the sun. The fruit will also acquire circular brown spots that are delimited by a dark green halo. These spots will eventually turn crusty, but unlike several of the other diseases that affect the tomato fruit, does not actually affect the epidermis of the fruit. Nonetheless, it does make the fruit look rather ugly, severely reducing any chance that it had to be sold in the market. This bacteria is spread through the air, rain splash, and the clothing, tools, and hands of anyone that happens to be working the fields.

Bacterial Speck
The bacterial speck causes the leaf to turn yellow and begin to fall and leave the plant exposed to the sun.

Spinal necrosis or hollow stem

Hollow Stem disease is caused by Pseudomonas corrugata, P. mediterranea, and P. viridiflava. The wounds that this infection causes are primarily observable in the stem, which will start showing dark spots that eventually start to crack. If the stem is cut open, you will be able to observe that the inside has turned a significantly more pale color than normal, and you will see the formation of several hollow holes. The leaves of the tomato plant will turn yellow and start to wilt, before eventually falling off. The tomato plant reacts to this disease by growing new adventitious roots. These bacteria are dispersed both by irrigation water and whoever happens to be working on the tomato crop that particular day.

Spinal necrosis
Hollow stem disease causes the stem to open and the leaves turn yellow.

Bacterial Wilt

The bacteria Ralstonia solanacearum is responsible for the disease called Bacterial Wilt, and is considered one of the world’s most important pathogenic bacteria in plants due to the vast losses that it provokes in a wide range of crops. This disease is characterized by a sudden wilting of the tomato plant where before you had a perfectly healthy plant. The bacteria that cause this disease will infect the xylem of the plant, but this will not show up until there is a significant buildup of bacteria in the plant. Once there is a significant population in the plant’s vascular tissue, you will be able to observe stains on the exterior that look like dark wounds, and if you open up part of the stem, the sap will be more viscous. This disease is spread through irrigation water or contact with laborers as this disease will take advantage of any wound on the plant to spread itself.

Bacterial Wilt
Bacterial wilt can be transmitted through water or through contact with the plant if the plant is damaged.

Soft Stem Rot

Soft Stem Rot is caused by Pectobacterium carotovorum. The observable symptoms of this bacterial diseases will show up in the stem as a dark stain that will be colored a dark green with a somewhat viscous consistency. If the stain happens to develop near the root of the flower, the entire flower will be overtaken by the disease. This infection can cause a sudden wilting or even death of the plant. If there are any wounds caused by either workers or insects, the fruit can be infected leaving them looking cloven with a dark coloration and a watery texture. The fruit will eventually deform into a viscous mass that will eventually fall to the ground.

Soft Stem Rot
The symptoms of the soft stem rot will show on the stem as a dark green viscous spot this disease can kill the plant if it spreads.

Advantages brought by an adequate tutoring system

As is demonstrable, the infection of these bacterial diseases in your tomato crops will usually be caused by the responsible bacteria entering the plant either through stomata, or through a wound that is available on the plant. These wounds can either be caused by workers that are doing their normal duties while tending the crops, or through the actions of some insects that feed on your plants. When you use a tutoring system such as one provided by HORTOMALLAS, you provide your crops with an adequate growing area to distribute itself. If you add an adequate drainage system to your field, the combination of the two systems will ensure that your crops have the perfect humidity concentrations. By avoiding the exposure of your crops to long periods of excessive humidity, you avoid one of the prime factors that trigger the development of several diseases.

By using HORTOMALLAS crop support netting to cultivate your tomatoes, you reduce the probabilities that your crops will become infected by bacterial diseases.

HORTOMALLAS crop support netting
The HORTOMALLAS trellis net is a good option because it reduces the possibility that the plant will contract any of these viruses.

Agrochemical treatment against tomato bacteria

A list of the various chemicals that can be used to treat these diseases of the tomato crop are: Acibenzolar-S-methyl, Bacillus subtilis soil inoculation, Streptomycin, Copper(II) hydroxide, Kasugamycin, Mancozeb+copper, Dicopper chloride trihydroxide, Dicopper chloride trihydroxide 39% + Mancozeb 30%, Copper(I) Oxide, and Dicopper chloride trihydroxide + Kasugamycin.

In order to ensure that the process of disinfection is run as efficiently as possible, it is highly recommended to apply a combination of these products that contain copper in order to reduce the total bacterial population. Also, do note that the vast majority of agrochemicals for the control of diseases are preventative, and do not work nearly as well if they are used to a disease that is already in place.


FAO. (2013). El cultivo de tomate con buenas prácticas agrícolas en la agricultura urbana y periurbana. Recuperado el 28 de septiembre de 2015 de

Productores de hortalizas. (2006). Plagas y enfermedades del tomate. Guía de identificación y manejo. México. Recuperado el 28 de septiembre de 2015 de

Sosa, Mirta. (2013). Guía para el reconocimiento de enfermedades en el cultivo de tomate. Formosa, Argentina. Recuperado el 28 septiembre de 2015 de

Argerich, C.; Troilo, L.; Rodriguez Fazzone, M.; et al. ( Manual de buenas prácticas agrícolas en la cadena de tomate

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