Diseases of tomatoes – preventive and control measures

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Tomatoes are not only the most favorite vegetables of Russian summer residents and gardeners, but also very delicate plants that are susceptible to a number of diseases. An epidemic of late blight or gray rot can cause loss of tomato crop, therefore gardeners pay great attention and a lot of time to the prevention and control of viruses and pests.

Ripe tomatoes

In this article we will consider all the main diseases that often affect tomatoes even in lovingly groomed beds, we will study the reasons for the occurrence of such unpleasant and destructive phenomena for the plant, and also propose measures for the prevention and control of tomato diseases.

Diseases of tomatoesTreating tomatoes already thoroughly affected by late blight or anthractosis is a difficult task. Therefore, it is better to try to do everything possible to prevent diseases.

Late blight

“Help, late blight!” – this is how summer residents react when they see brown spots on the leaves and fruits of tomatoes, which later turn black and quickly spread to all plants in the garden. Indeed, late blight is able to completely destroy the tomato crop and is common in all regions of cultivation..

Brown rot, as phytophthora is often called, is caused by the fungus Phytophthora infestans, which also affects potatoes and is able to winter well in tubers or on the remaining tops of tomatoes, starting its triumphant march through the beds in the spring.

Late blight of tomatoesLate blight manifests itself in the form of brown, and then blackening spots on the leaves, trunk and the fruits themselves, causing rotting of the entire plant

First, brownish-brown spots most often appear on the leaves of tomatoes, and then affect the fruit, which as a result completely rot. Most often late blight occurs in cold and rainy summers – for active development it needs moisture in large enough quantities and the temperature is not higher than plus 22 degrees. Abundant fog, dew, poor ventilation in the greenhouse also contribute to the development of brown mold..

Phytophthora on tomatoes

To prevent the appearance of late blight, you must follow these rules:

  1. Carefully remove all potato tubers and tomato tops from the beds in the fall. Thus, you will not leave late blight a chance to overwinter..
  2. It is impossible to plant tomato seedlings in the same beds the next year after planting potatoes; it is better to wait at least one season. You should also not plant tomatoes next to potatoes..
  3. Watering tomatoes should not be too abundant – it is better to water more often, but little by little. Drip irrigation system that delivers water directly to the roots is great for tomatoes.
  4. It is necessary to provide the tomatoes with sufficient ventilation, do not plant vegetables too densely, tie up tall plants so that they do not interfere with each other, pick off low-lying leaves.

Drip irrigation of tomatoes

In addition, many modern varieties of tomatoes have increased resistance to late blight, therefore, when buying seeds or seedlings, you should ask if this variety has such a beneficial property.

Also, for prevention or at the first signs of the appearance of brown rot, tomatoes can be sprayed with 0.5-0.7% Bordeaux liquid, 0.1% copper sulfate solution, infusion of crushed garlic or celandine.

For the prevention of late blight, you can use the biological products “Pentafag” and “Mikosan”, and at the first signs of infection – the chemicals “Infinito” and “Tatu”.

By the way, scientists distinguish a separate type of this disease – southern late blight, which occurs in the case of early planting of seedlings in the ground, that is, in early spring. In this case, the spots on the plants are darker than usual..

Dry spot

This disease is also called macrosporiosis, as it is caused by the fungus Macrosporium solani. Dry spot appears as brown spots on the lower leaves. Then the disease spreads to the already ripening fruits.

Dry spot of tomatoesDry spot spoils not only the presentation of tomatoes, but also their taste – such tomatoes can no longer be used for food

The spots are depressed, darken with time, a white bloom appears on top. Dry spot can affect about 40% of all fruits and spreads especially quickly under conditions of frequent alternation of dry and rainy weather..

Measures for the prevention of macrosporiosis are:

  1. Growing modern, disease-resistant tomato varieties.
  2. Isolation of beds with tomatoes from planting potatoes and other nightshades.
  3. Collecting seeds only from absolutely healthy fruits.
  4. Thorough cleaning of tops from the site. Remember not to use such leftovers for composting..

In addition, the use of nitrogen and phosphorus fertilizers contributes to the prevention of dry spotting..


A very common disease that can affect tomatoes even at the stage of planting seedlings. As the name implies, the disease primarily affects the root collar, which darkens and becomes covered with a grayish coating. If the plant is severely affected, the rot spreads to the roots, which simply disappear, as a result of which the entire plant perishes, which is easily pulled out of the ground. Other vegetables, such as eggplant, can also suffer from black leg..

Black leg tomato seedling diseaseA black leg may appear even at the stage of growing seedlings, such plants should be discarded immediately

Prevention of this disease consists in the following measures:

  1. Planting plants at a sufficiently large distance from each other, since a strong thickening of the crops contributes to the spread of the black leg throughout the garden.
  2. The infection persists in the soil, therefore, the beds should be watered with potassium permanganate (5 grams per 10 liters of water), sand should be added to healthy seedlings or the soil should be liming. The soil in the greenhouse should be disinfected.
  3. Seed treatment also helps.

Apical rot

A widespread and virtually incurable disease that affects only the fruits of tomatoes, can also appear on green tomatoes – it affects the top, which turns black or brown. There are several reasons for the appearance of this unpleasant phenomenon:

  1. Lack of calcium in the soil.
  2. Low location of fruits that are in contact with the soil.
  3. Lack of moisture at the stage of fruit setting.

Top rot on tomatoes Top rot initially occurs precisely on the top of the tomato, affects both green and already ripe fruits

Accordingly, in order to prevent apical rot, regular watering should be ensured, especially at the stage of fruit formation, fertilize the soil or spray green fruits with calcium nitrate. You can also add wood ash to the soil..

Soaking the seeds before sowing in a 0.2% solution of copper sulfate helps in part. But after the manifestation of the disease, it will no longer be possible to save the affected fruits, although if you cut off the affected top, then the rest of the fruit can be crumbled into a salad or used in the production of tomato juice or fruit drink.

Fruit anthracnose

Anthracnose is a widespread fungal disease of tomato and pepper. In the case of anthracnose development, softened, slightly depressed zonal spots appear on the fruits, which differ slightly in color from the main color of the tomato..

Anthracnose on tomato fruitsAn anthracnose-infested tomato looks, to put it mildly, unappetizing

This disease manifests itself not only in greenhouses, but also in the beds, often leading to a 50% loss in yield. In addition, anthracnose may appear after harvesting tomatoes – during storage and transportation..

Prevention and control methods:

  1. Timely harvest – let it be better for the brown fruits to “reach” already in a dry and clean box.
  2. Mulching the soil with straw, as zonal spots often appear on fruits that are in contact with the ground.
  3. Tying tall plants.
  4. Correct and timely watering.
  5. Compliance with the rules for planting seedlings.

Gray rot

This is also a fungal disease, which is more susceptible to greenhouse tomatoes. It actively appears in cold and rainy weather, gray rot spreads at temperatures up to plus thirty degrees. Initially infects the lowest, oldest leaves, then moves to younger foliage, stems, inflorescences and already ripening fruits.

It differs from its “colleague” brown rot precisely in color, otherwise the main symptoms of the disease – unpleasant spots on the leaves, trunk and fruits and the subsequent rotting of the plant – are very similar. But gray rot, unlike late blight, sometimes goes away on its own if the weather improves quickly enough. Another important difference is that in the event of gray rot, not just spots appear on the plants, but a gray fluffy coating.

Gray rot on tomatoesGray rot looks very unsightly, often completely destroying the tomato bush, but it is easier to deal with it than with late blight

In addition, it is easier to deal with gray mold – often it is enough to simply tear off the lower leaves of the plant to prevent the spread of the disease and ensure good ventilation in the lower tier..

But agronomists have not yet brought out varieties of tomatoes that are resistant to gray rot.

Parasites and pests

Tomatoes are affected not only by bacterial diseases caused by various fungi, but also by parasites that want to eat the juicy pulp of leaves, trunks and fruits. The most common of these misfortunes include:

  1. White flies or whiteflies. Tiny insects, which usually hide on the underside of tomato leaves, are especially fond of greenhouse plants, as they cannot stand strong winds and good ventilation. In this regard, in order to fight white flies, it is enough to open the greenhouse for airing or completely remove the film from the greenhouse for a while. Also often used is the biological product “Boverin” or glue yellow baits – these are usually used to catch the most annoying insects – flies.
  2. Spider mite. This insect, only one millimeter in size, is difficult to see with the naked eye. At the same time, it leads to damage to the plant and may not allow the gardener to get a high yield of tomatoes. If a spider mite has wound up on tomatoes, small specks appear on the leaves, they lose their green colors and turn yellowish-white. The biological preparation “Aktofit” is used against spider mites; often, to preserve the harvest, it is enough just to remove the film from the greenhouse.
  3. The common garden aphid loves not only roses, but also tomatoes, so it can appear on plants that “live” in greenhouses and on tomatoes already planted in the beds. Fortunately, there is a whole arsenal of effective remedies against the voracious aphid, which can destroy the tomato crop even at the stage of flowering and ovary. Aphids can simply be knocked down with a stream of water, rubbing leaves with ash, spraying plants with a decoction of tobacco or chamomile, a biological product “Verticillin”, as well as various chemical preparations helps. Some summer residents spray tomatoes infected with aphids, soapy water, or diluted dishwashing detergent. But, firstly, for the plants themselves, such a solution, to put it mildly, is not very useful, and secondly, ready-made preparations usually turn out to be more effective.
  4. Slugs. Very nasty pests, the gluttony and appearance of which simply infuriate summer residents. Slugs most often eat only those fruits that have sunk to the ground – having picked up such a fruit, you may be unpleasantly surprised to find that nothing but the skin is left. But they eat slugs and young tender trunks. You can fight these pests by mulching the soil with straw – slugs simply cannot move on such a cover. In addition, after harvesting tomatoes from the beds where slugs were previously found, the soil should be covered with lime and dug up.
  5. Medvedka. This insect is often called cabbage, but it is omnivorous and can feed on young tomato shoots and pepper seedlings. Medvedka prefers to breed in warm heaps of manure and compost, so such organic storage should be placed away from the beds. Fighting the bear is most effective with chemical methods – scattering poison into holes.
  6. Colorado beetle. This striped pest, of course, loves potatoes more, but can eat both eggplants and tomatoes. If you do not want to fight the Colorado potato beetle with chemical means, there is only one thing left – to “bow low” to each bush of tomatoes and collect not only the larvae and adult insects, but also to pick off the leaves, on the underside of which eggs are laid.

Potato aphid on tomatoesWhen choosing an aphid remedy, remember that these pests can be different – brown, black, red and even blue. Accordingly, the drug should be chosen for a certain type of these pests.

As you can see, almost all tomato diseases are much easier to prevent than to cure. Moreover, it is quite easy to do this – you just have to adhere to reasonable rules for planning a garden, water your tomatoes on time, but do not flood, fertilize the soil, do not leave the remnants of the already harvested crop and tops on the beds. Of course, climatic conditions and weather also have a great influence on the development of most tomato diseases, but an experienced summer resident usually already has a real “arsenal” prepared that can help cope with all the problems and, in spite of everything, get a solid harvest.

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