Tomato diseases and solutions to combat them

Tomato is one of the most widely grown plants in orchards around the world for its nutritional properties and excellent flavor. Coming from America, today there are hundreds of varieties of different sizes, shapes and colors, but none of them are disease free.

The tomato, whose scientific name is Solanum lycopersicumbelongs to the nightshade family and is one of the most popular horticultural fruits in the world.

It is a plant capable of adapting to all types of soil, although its cultivation is recommended on land rich in nutrients and well fertilized.


Care of tomato plants

Its growth form is bushy and with long stems, which, due to the weight of the fruits, facilitates their guidance with structures such as canes.

As the plant grows, small pruning and thinning are carried out. This will facilitate ventilation and access to sunlight for fruit ripening, also preventing the appearance of certain fungal diseases.

Concerning irrigation, it is preferable to carry out deep and spaced irrigations, without wetting the foliage and the fruits.

To keep the plant in good health and obtain good fruiting, it is also advisable to make fertilizers during the different growth periods.

The main tomato diseases

The three main diseases that affect the tomato plant are fungi called mildew, powdery mildew and rust. These appear in conditions of high humidity and temperature, lack of ventilation and due to the sensitivity of the crop variety itself.

It is possible to prevent and treat these diseases with various ecological methods, without harming the environment or compromising our health.

On a large scale, organic farming uses fungicides based on copper or sulfur, but on a smaller scale, it is possible to prepare homemade fungicides for tomatoes.


It is a fungus that affects the leaves causing spots of different shades of green, until they turn completely dark. Finally, the leaves die.

powdery mildew

This is another fungus that manifests as whitish, powdery spots on the upper side of the leaf. Then it causes yellowish spots until the leaf dries out completely.


This fungal disease appears as orange pustules on the underside of the leaf, revealing corresponding yellow spots on the upper side.

A new alternative for the tomato industry

Ozone systems in agriculture offer great benefits as they also improve production, prevent and treat disease and promote rooting.

Ozone is a product of nature itself, therefore, applied correctly, it does not pollute. It is made up of three oxygen atoms and behaves like a natural disinfectant.

When it has already acted, ozone decomposes into oxygen and does not leave any type of chemical residue harmful to the environment.

Most plant diseases are caused by contagion, but ozone manages to destroy micro-organisms both by its direct action on water and by the amount of oxygen it releases.

Ozone is useful in eliminating viruses, bacteria, fungi, algae, spores and any other microorganisms from soil and roots.

Several studies have shown that ozone is an effective alternative to prevent and control root and stem diseases such as Phytophthora, Fusarium, PythiumRhizoctonia and airborne diseases such as Mycosphaerella, botrytisSclerotinia, Moldalternate, powdery mildew.

In practice, agronomic ozone is applied with irrigation water and can also be used for foliar treatments.

Thus, ozone treatments guarantee a better root system of plants, better transplantation and less aggression by phytosanitary products.

Artisanal and ecological methods to treat tomato diseases

Sodium bicarbonate

Sodium bicarbonate It is a readily available soluble white compound that is frequently used to control fungal diseases on many plants and is also useful on tomatoes.

can make homemade fungicide with baking soda only mix 4 teaspoons of baking soda, 1 teaspoon of horticultural oil and citrus oil or molasses, in about 4 L of water.

It is well mixed and applied with a spray to the parts with symptoms of fungal diseases. This will prevent more fungus from developing.

White vinegar

The vinegar It is also a common element that has antifungal properties.

To prepare it, you must dilute about 3 or 4 tablespoons of white vinegar in 4 L of water. Tomato seedlings are sprayed daily with this dilution until the fungus disappears.

As a precaution, the application must be done at dusk, when the plant no longer receives the sun’s rays.

White vinegar is the most effective for treating plant fungus, you can also use apple vinegar.


This spice, which can also be found in any home, can be sprinkled to treat fungal diseases of tomatoes. If the fungi do not disappear within 72 hours, the application is repeated.


It is possible to prepare fermented garlic and take advantage of its excellent antifungal qualities.

Using a mortar, crush all the cloves of a head of garlic well and leave to macerate for 24 hours in 1 liter of water.

After this time, boil for 5 minutes, cool and strain. We fill a sprayer and apply early in the morning or at sunset.


This easy-growing grass in humid areas contains silicon. This element is able to regenerate plant tissues, and also acts as a powerful fungicide.

It is generally used in curative or preventive mode. A porridge is made by mixing about 100 grams of horsetail with 1 liter of rainwater in a plastic container.

We will remove for 5 or 10 minutes once a day for a period of between 15 and 20 days. After this time, we will cover the drum, letting some air in. We will leave the drum in a cool place.

The fermented product will be ready 15 days after the bubbles of the fermented product have diminished. We filter and package.

This is the best time to use it as a remedy and preventative for tomato diseases.

Horsetail slurry is applied both to the soil and to the rest of the plant. But when spraying on the leaves and stem, it is better to dilute this liquid in a proportion of 1 liter of slurry to 15 liters of water.

Do not use an iron element so as not to alter the preparation.

Essential oils

There are several types of essential oils with antifungal properties which are effective when applied to plants such as tomatoes, both in preventing and treating fungal problems. These oils include:

  • Citrus oil.
  • Oregano oil.
  • Orange oil.
  • Garlic oil.
  • Tea tree oil.

To make fungicides based on these essential oils, we can add a few drops with one of the homemade fungicides mentioned.

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