Rot on tomatoes is gray, white and black: what are the differences from leaf spot, how to fight, how to treat tomato fruits in a greenhouse, how to get rid of it on seedlings?

Leaf mold or, as it is also called, brown spot, known to agronomists as cladosporiosis, in the vast majority of cases affects tomatoes growing in a greenhouse. Even in situations of long rainy periods, plants in open ground are usually protected by temperatures in such weather that are insufficient to activate the pathogen.

Disease Prevention

In closed ground, where conditions may be ideal, the disease can not only reduce the volume of the harvest, but also lead to the death of the bushes.

What it is?

Rot is considered a dangerous fungal disease that affects many vegetables, including tomatoes. There are the following types of rotting:

Black rot is caused by the fungus Diplodina destructiva Petr.
Gray mold is caused by Botrytis cinerea Pers.
White rot is caused by Sclerotinia sclerotiorum.

As a rule, tomato rot develops in the absence of good soil disinfection and proper watering.

Reasons for appearance

There are many reasons for the appearance of rot on fruits. The most common are the main ones:

Using untested seeds.
Excess nitrogen, potassium, salt or magnesium in the soil.
High air humidity.
Damage to the root system.
Lack of soil disinfection.
Lack of sunlight.
Lack of vitamins, especially calcium.
Excessive soil irrigation.

Important: lack of moisture in the soil during the wilting period contributes to the formation of rot. Due to lack of moisture, the plant actively seeks it and takes it from the fruits. However, excess moisture can also cause rot.

Causes of the disease

Cladosporiosis is caused by the fungus Cladosporium fulvum Cooke. In an inactive state, the viability of the spores remains for 12 months. At the same time, the colony can withstand a decrease in temperature and a long stay without access to moisture. The fungus is able to overwinter in the soil without access to plant debris. With the onset of spring, the causative agent of the disease again moves to tomatoes.

Important! The depth of penetration of fungal conidia into the ground is 10 cm. Therefore, when this disease appears, it is better to remove this layer of soil and replace it with fresh one.

Soil contamination in a greenhouse occurs through water, air, tools and workers' clothing. Favorable conditions encourage the fungal condia to actively develop. The disease affects all cultivated plants and weeds in the greenhouse.

The causative agent of leaf mold is sensitive to humidity levels. For successful development of the disease, this indicator must be at a level exceeding 80%. The best conditions occur when the humidity in the greenhouse reaches 90-95%. High temperatures promote rapid reproduction and spread of fungal colonies. Usually, the first to suffer are weakened plants that are stressed due to a sudden change in temperature as a result of improper ventilation or watering with cold water.

Signs of defeat

Tomato rot is often confused with a disease called anthracnose. In this case, the leaves become covered with a layer of pinkish mold, which does not happen with any type of rot. The only symptom common to them is black-brown spots on the fruits. However, it is not difficult to distinguish these two diseases.

Symptoms of gray mold can be confused with late blight. With this disease, round watery spots appear on the fruits, and gray mold develops on the leaves and stems. The spots on the fruit enlarge and a brown liquid is released. In the case of gray mold, plants become covered with a fluffy coating, which is a characteristic sign of the disease.

Tomato diseases caused by bacteria

The largest and most diverse group of microorganisms on the planet are bacteria. They cause the most significant damage to agriculture, regardless of their varieties and names. Bacterial diseases are more difficult to treat than viruses. Pathogens attack the roots, leaves, stems and fruits of plants. Bacteria can be considered the most resilient microorganisms - they survive in the soil for two to three seasons, are transported through air and water, and are spread by insects and birds.

Any plants on the site can become the object of an “attack” of bacteria, and gardeners should take this into account in the fight against the disease. In addition to treating infected plants with visible signs of disease, prevention is necessary for healthy-looking plants.

How to recognize the presence of bacteria on tomatoes?

Bacterial canker of tomatoes

The cause of the disease is bacteria that penetrate into the plant through damaged leaves and stems, sometimes through roots that damage tomato pests underground, or in the underground part waterlogging and rotting of the roots occurs due to violation of the watering regime and soil aeration.

Optimal conditions for the development of the disease are temperature 18-240C and high air humidity, over 80%.

Secondary infection occurs in the absence of disinfection of equipment used for seedlings, as well as for caring for plants. The bacteria remain in the soil for up to 5 years and are transmitted by infected seeds and weeds.

In the initial stage, the disease manifests itself in leaf curling, and this phase is a signal to begin treatment. The next phase is cracking of the stems and their deformation. Dotted white spots appear on the fruits. A characteristic sign of the disease is the appearance of yellow-brown juice, which is released when pressure is applied to the stems.

If it is difficult to establish a “diagnosis”, but the first noticeable signs clearly indicate the presence of an infection in tomatoes, treat with universal preparations - in any case, such support will not harm the plants.

Advice! Give preference to biological treatments, and use chemicals as a last resort.

Bacterial spotting (spotting)

Prolonged unfavorable conditions for growing tomatoes and violation of agricultural technology requirements are fertile ground for the development of bacteria. In cool and rainy summers, brown to black spots surrounded by a yellow halo may form on the leaves, stems and fruits of tomatoes. They gradually grow and lead to the death of leaves, spoilage of fruits at any stage of maturity, and a significant reduction in yield and shelf life.

The worst thing is that bacteria of this type quickly spread to all vegetable and fruit plants. Pathogenic microorganisms persist for several seasons, are spread by seeds, and are therefore difficult to treat.

Today microbiologists know three races of bacteria in this group. In addition to the one described above, there are bacteria that cause similar symptoms of tomato disease, but they form convex watery spots, surrounded by a white halo, which, when dry, crack and form black dots with an oily coating, or, conversely, concave inside the fruit, with a scaly surface. The second group of bacteria is also spread by weeds and tomato pests.

Bacterial (sclerotial) wilt

There are at least three types of pathogens that cause this tomato disease. Infection of tomatoes can be identified by the appearance of the lower leaves drooping “for no reason” with normal watering. If the cut stem of such a plant is immersed in water, you will see a milky cloudiness. At a later stage, the entire bush “withers”, the stems become hollow, and a yellow-brown mucus is released from them. This tomato disease is the most dangerous, since it is transmitted in all possible ways, and the bacteria “master” not only tomato beds, but also more than two hundred types of vegetable and garden crops.

The disease is characteristic of tropical and subtropical regions, with high temperatures and humidity, so it is also called southern wilt.

Necrosis of the stem core

The disease can be noticed by the withering and yellowing of the upper leaves, when the fruits appear on the first cluster, which begin to deform and become covered with black depressed spots. The spots on the stems are watery at first and then crack. Sometimes growths or adventitious lateral roots form in cracks. In a longitudinal section of the stem, you can see voids and dying areas covered with dark spots.

The spreader of the infection is a pathogenic microorganism, but its appearance on tomatoes is associated with excess nitrogen in the soil and mechanical damage to the plant. The causative agents of pith necrosis are common in all areas of agriculture. Effective treatment is carried out in combination with agrotechnical measures.

Types, their descriptions and photos

Among the diseases of tomatoes, there are several types of tomato rot. These include gray rot, white rot and black rot. Each type of rot is caused by different pathogens and manifests itself differently.

Gray

This disease affects fruits grown both outdoors and in greenhouses. Gray mold is caused by high humidity and too much nitrogen fertilizer.

White

Compost and soil are considered the main source of the disease, so infected plants should be destroyed and not composted. White rot is caused by poorly disinfected soil. High humidity and low air temperature (below 18ºC) during planting also contribute to the development of white rot.

Black

The pathogen enters overripe fruits through cracks. Excess moisture in the air causes disease.

Possible causes of the disease

Even if he decided on a greenhouse, prepared seeds, and grew seedlings, the time for rest has not come for the gardener. By carefully regularly assessing the condition of the shoot, it is important to protect it from all sorts of diseases. Even if the entire technological process is followed correctly, the plant can get sick. There are enough reasons for the occurrence of the disease, as well as their varieties.

The appearance of viruses in a greenhouse is apparently possible due to various shortcomings: when caring for seeds, crop rotation, and planting.

The reasons may be:

Improper disinfection of greenhouses. After the autumn harvest, it is necessary to carry out a complex of disinfection both on the soil itself and with regards to structures and coatings. Completely free from vegetation: roots, stems, seeds. The first layer of soil of a few centimeters is removed, and fertilizer, sand, and ash are added. The frame and protective coating are washed, primed, and dried. The entire area is ventilated and fumigated.
Incorrect watering. It can be either excessive, or the moisture gets not on the root, but on the leaves. Constant dew is not conducive to healthy growth.
Temperature conditions. Watering should be done with water at room temperature.
Lack of circulation. Insufficient ventilation, it is necessary to open the openings and ventilate well.
Seedling density. When planting in the ground, they are too close to each other.

The main pests that attack fruits are microscopic fungi, viruses, bacteria. Mold spreads quite quickly and it is difficult to stop its spread completely. To prevent mold from affecting the tomato, it is necessary to carry out prevention.

How do diseases develop and why are they dangerous?

The fruits are covered with a white coating.
Leaf spotting.
Black rot. Black, spotted spots appear on the fruit, usually near the stalk or in damaged areas. The diseased tissue softens, the spots increase, and the plant dies.
The leaves of the plant become watery and discolored.
Fruit rot with a gray tint.
White rot. This type of rot usually occurs on damaged parts of the fruit and usually appears during storage of the crop. External signs of the disease:
Plant stem infection.
A characteristic pubescent flower is formed.
Gray rot. The disease spreads from plant to plant. Infected tomatoes quickly wither and die. The disease manifests itself as follows:

Viral diseases of tomatoes

The virus lives outside the body of the “host” for no more than half an hour, and therefore, unlike bacteria, which consist of a core and a shell, and can survive on their own for a long time in soil, air or water. But this does not mean that viruses cause less damage to the tomato crop.

In terms of external signs, viral diseases of tomatoes are often similar to bacterial diseases, and the methods of treating and preventing the disease differ. To choose the right treatment tactics, you need to learn to distinguish viral infections from bacterial diseases by the external signs of tomatoes.

Since viruses do not have a complete cellular structure, like bacteria, and not all of them can travel by airborne droplets, viruses often use insect pests of tomatoes as a vehicle: leafhoppers, aphids, whiteflies, thrips. Therefore, it is necessary to treat viral diseases of tomatoes in a complex manner, using insecticidal agents.

Tobacco mosaic

If the tobacco mosaic virus is present in the soil, then tomato leaves signal this by changing their shape and the appearance of dark or yellow spots. Curling leaves and spotting not only spoil the appearance of the bushes, but also indicate that there is no hope for a good harvest. The virus inhibits the plant until it dries out completely.

The best way to treat tobacco mosaic is timely prevention. Spray tomatoes with urea solution once every 10 days. The norm is 1 tablespoon per 10 liters of water.

Double streak of tomato

Infection of tomatoes occurs when two viruses are simultaneously present on the above-ground parts of the plant. Visible signs of the disease are small and gradually growing brown spots, longitudinal necrotic stripes on stems and leaves, deformation of the fruit and coarsening of the pulp, curling of the leaves.

Infectious chlorosis of tomato

The carrier of the virus is the whitefly, a pest of tomatoes that prefers to lay numerous eggs on the lower part of the leaves. By feeding on plant sap, the pest not only dehydrates the plants, but also infects them with a virus. Eggs laid on the back of the leaf may not be visible to the naked eye, but discoloration of the leaves should serve as a signal that it is time to deal with the pest. The presence of the virus in the internal tissues of the plant in the initial growing season leads to significant yield losses. Treatment is carried out along with the destruction of the tomato pest.

The external manifestation of infection becomes noticeable after a few weeks, when it is already too late to treat, so you need to ensure that pests do not appear on the site or in the greenhouse, and fight them first.

Whiteflies also spread other viruses, such as tomato yellow curl. If plant leaves lose chlorophyll, turn yellow and crowd inward, then the tomato pest is to blame, which acquired an infection from weeds.

Another tomato pest is thrips, which, like other tomato pests, in addition to causing wounds, are carriers of all possible infections. Dark and shiny stripes on the stems and petioles of tomatoes, dying tips of leaves and rainbow circles on the fruits signal the presence of tomato pests.

Stolbur (mycoplasmosis)

An infectious disease that infects tomatoes when leafhoppers appear on the site. If you do not scare away these pests, then soon unopened buds, green flowers and absence of ovaries will be found on the plants. At a later stage of the growing season, when the ovaries have formed, infection with stolbur is fraught with the appearance of small and hard fruits that are unsuitable for food.

This type of infection is not typical for tomatoes, and leafhoppers transmit it from other plants growing nearby. In addition to representatives of the nightshade family, which also suffer from infection, mainly plants that are the “hosts” of the infection are weeds.

What should I do to get rid of it?

So what is the most effective way to combat tomato rot? There are basic rules that, if followed, will help you save your harvest. In addition, it is best to choose varieties that are most resistant to these diseases, and do not forget about crop rotation.

How to fight with agrotechnical methods?

Proper growing techniques are a great way to prevent tomatoes from rotting. Just follow the rules below to keep your plants healthy and strong:

It is recommended to plant mustard, marigolds or calla lilies on the affected area. These plants secrete special substances that prevent the development of rot.
In dry and sunny weather, it is recommended to cut out the affected parts of the plant with a knife.
When watering the plant, avoid getting water on the leaves.
Ventilate the greenhouse often.
Maintain proper watering schedule. Water regularly, but do not overwater.
Remove diseased fruit regularly.
Mulch the soil. This will help distribute moisture evenly and keep the soil loose.

How to treat with folk remedies?

To combat rot, gardeners often use folk remedies. Here is one of the most effective:

For the same purpose, plants can be sprayed with calcium. Spraying of tomatoes is carried out before they begin to flower, several times in the first week after transplanting into the soil. To prepare the solution you will need 40 g of calcium per 10 liters of water.
The soil can be sprayed with a solution containing calcium. To prepare this fertilizer, dissolve 2 tablespoons of chalk in 10 liters of water. Fertilize moderately with this mixture. This way you will help the soil restore its calcium levels.

How to treat with chemicals and fungicides?

Disinfection of diseased plants with disinfectants plays an important role in the fight against rot of tomatoes:

The vitriol solution is carefully poured into the lime solution. The resulting mixture must be thoroughly mixed.
Pour 2 liters of hot water into any 10 liter non-metallic container and add 100g of copper sulphate (180p per 1kg). Mix thoroughly and add another 3 liters of cold water.
Pour 4 liters of cold water into another container and then add the lime solution. Mix everything thoroughly and strain through a non-metallic sieve or cheesecloth.
Prepare lime mortar. Mix 140-150g lime (170p per 20kg) in 1 liter of water.
Cover the plant with a fungicide. The timing and frequency of application of fungicides for tomatoes are indicated in the instructions for the specific product. Here is one recipe for spraying: mix 300-330 g of CMC glue and 20-50 g of fungicide in 10 liters of water. Using chalk, make the mixture into a paste-like consistency. Cover the rotted areas so as to cover about 3 cm of healthy tissue. We recommend using fungicides such as Topaz (4880 rubles per 1 liter), Oksikhom (60 rubles per 10 g), Kuproskat (4830 rubles per 10 liters).
Treatment with Bordeaux mixture. Infected tomatoes are treated three times with a break of up to 10 days. Gardeners recommend carrying out no more than 4 such treatments per season. If the disease has spread to seedlings, treat them with Bordeaux mixture 10-14 days before planting in a greenhouse or soil. The mixture is prepared according to the instructions:

We invite you to watch a video about gray mold prevention:

Biological drugs for treatment

Biological preparations are quite effective in combating gray mold. Natural remedies such as:

Fitosporin-M.
Gamair.
Alirin-B.
Agate 25K.

Biological preparations are considered safe for humans and non-toxic for bees.

Signs of leaf mold

Only tomato foliage suffers from cladosporiosis. The pathogens do not affect the rest of the plant. The development of this disease occurs gradually:

The infection initially manifests itself during flowering. Irregularly shaped yellowish-green areas appear on the lower leaves. On the reverse side of the leaf, a velvety coating of a light gray shade, similar to mold, forms on the affected area.
At the next stage, if untreated, the disease moves to the upper tier of leaves. Disruptions occur in the process of photosynthesis. This causes a deficiency of useful elements and affects the condition of the fruits and stems.
In the final phase of the disease, the color of the spots changes to yellow-brown, they spread to the entire leaf blade. The gray shade of plaque turns into brown. Leaves curl and die. Then the fungus moves to a new plant.

Sometimes the spots spread to the leaf petioles or stems. This indicates a critical level of infection. These tomatoes can no longer be saved.

Prevention measures

There are certain rules, following which you can avoid the appearance of rot and ensure the ripening of healthy and beautiful tomatoes. Prevention of this disease is as follows:

Do not use large doses of fertilizers.
Avoid damaging the plant's root system.
Spray tomatoes with anti-rot preparations. Experienced gardeners recommend using Topsin M, Bayleton, Euparen multi.
Shape the plants.
Maintain the salt balance in the soil. Saline soils cause insufficient water supply to plants, which leads to calcium deficiency. Do not overfeed plants with magnesium and potassium.
Get rid of the stems in a timely manner.
Maintain a comfortable temperature for the tomatoes. Ventilate the greenhouse in hot weather. Shade plants with fabric or tint glass.
Plant the seedlings at a distance from each other.
Spray the tomatoes with a solution containing calcium.
Do not allow plants to dry out or overwater.

Disease prevention

It is easier to prevent the appearance of fungus than to cure already infected plants. For prevention, unfavorable conditions for the development of fungus are created and maintained. First of all, they monitor the microclimate in the greenhouse. Before flowering, during the daytime the temperature is kept within 20–22˚С in sunny weather, 18–19˚С in cloudy weather, and 16–18˚С at night. When the bushes bloom, the temperature regime changes to 26–32˚С during the day and 14–16˚С at night. The optimal soil humidity is 80%, and air humidity is not higher than 65%.

The greenhouse is equipped with a high-quality ventilation system. If it is not possible to constantly monitor the microclimate, summer residents try to plant tomato varieties resistant to cladosporiosis. Popular varieties: Red cherry and arrow, Favorite, Admiralteysky, Olya, Ogorodnik, Verlioka plus, Titanic, Gunin, Blagovest, Crown, Donna Rosa, Leopold, Druzhok, Northern Express. What else will help prevent the development of leaf mold:

planting tomatoes at a sufficient distance (as described in the recommendations for the variety) so that they are properly ventilated and receive a lot of sunlight;
cleaning, burning of all plant residues (leaves, tomato bushes with roots, weeds);
disinfection of the greenhouse (walls, windows, doors) at the end of the season. For this purpose, sulfur bombs or formaldehyde are used;
moderate watering in the morning or evening;
mulching beds;
trimming excess shoots and leaves;
weeding;
ventilation of the greenhouse after humidification.

Owners of heated greenhouses often plant new tomato seedlings immediately after harvesting fruit-bearing, overgrown bushes in order to obtain a year-round harvest; this cannot be done. Firstly, crop rotation must be observed, and secondly, if the plants suffered from brown spot, then new planting of tomatoes is permissible only 10 months after harvesting the old plants, when the fungal spores die.

Disinfection of planting material

The first step in the fight against rot is seed treatment. Planting material should be disinfected with a solution of potassium permanganate or ferrous sulfate:

Ferrous sulfate is dissolved in the ratio: 1 g of the drug per 1 liter of water. Soak the seeds in the solution for one day and then dry them.
First, soak the seeds in a 3% solution of potassium permanganate for half an hour, then rinse with warm water and dry.

Why do tomatoes have few ovaries and mold on the flowers?

Dear gardeners, tell me how to save tomatoes? They bloom profusely, but there are few ovaries and many of the flowers seem to be moldy.

For a bountiful harvest, try the “ovary” preparation

How often can this product be sprayed?

There are instructions there, I don’t remember exactly what interval, but we saw fruits almost immediately

I've already sprayed twice and it doesn't help

What kind of rot is on flowers? How to deal with it?

Oh, then I don’t know, sorry

It is better to treat with phytosporin against fungus. Then potassium humate. It’s not normal that there is mold wherever it is... Mold-dash-fungus... But any fungus is already bad!

Spray two tablets of succinic acid per liter of water over the tomatoes.

But my flowers are just drying up, why?

hope, but I’m not good with peppers. There are few ovaries. Maybe they are too hot!

Peppers usually lack minerals. tomatoes will not set at temperatures above +30

Well, if it’s hot outside, it’s hot in the greenhouse too, and I tear off all the doors so it doesn’t burn, but if it’s +15 outside like today, then in the greenhouse it’s 23-25 with the doors closed. In general, the greenhouse is in its first year and I don’t know how to handle it correctly; there is no way to constantly monitor it. I’ll open it in the morning because I’ll go to work all day, and suddenly it’ll be hot and everything will burn.

How else can you make the temperature in the greenhouse lower if it already rises by 40?

yes, like Dionysus which protects from UV, but I’m still afraid.

These greenhouses just need to be ventilated at all times! even if it’s +10 outside. Open the window doors in the morning and evening, at least for 15 minutes. All the complexity of polycarbonate is in the condensate, so there is a high probability of fungal development. I treat it in the fall and spring with either vitriol or a fungicide (usually just leftovers from the summer). Well, mulch is a must, at least for tomatoes (hay is better). It is also not advisable to mix crops in such greenhouses, but with proper care and constant monitoring, it is possible (I mix). This is because tomatoes are susceptible to fungal diseases and can spread from them to the rest. Cucumbers love mites and, accordingly, can also switch to other plants... The whitefly flies to the peppers, and at the same time eats tomatoes and everything that comes along... Do you understand? Well, the heat is a separate conversation - I had no ovaries at all for 3 weeks, although I cooled it (put buckets of cold water and changed it 2-4 times a day), covered the outside of the greenhouse with branches... In general, there are many difficulties, but the main thing is ventilation and prevention of fungal diseases.

My neighbor accustoms cucumbers and tomatoes to micro-ventilation from the very planting. Her door is always ajar 10 -20 cm at night, and from condensation in the spring, a thin covering material is passed between the polycarbonate and the arches. But I only have tomatoes in a glass greenhouse, there constant draft. I somehow sealed everything up in the rain, I immediately felt stuffy and humid. I thought it was bad for them too, and now it’s at least a little, but open. And it’s good for the windows and gauze, better than non-woven material. Good harvests to you.

And I recently read that tomatoes need phosphorus more than any other plant, they take a lot of it from the ground, so they recommend feeding it every 10 days with an extract of superphosphate, 1 tablespoon per 10 liters of warm water.

source

Gray leaf spot

Gray leaf spot is also called macrosporiosis and has nothing in common with gray mold. Tomato leaf mold is caused by the fungus Stemphylium solani, while gray leaf mold is caused by the bacterium Botrytis cinerea Pers.

When macrosporosis occurs, gray spots form on the leaves, which then completely affect the leaves and the plant dies. Gray rot affects the stem: the stem becomes covered with gray, ashen-colored spots. At a later stage, vascular necrosis develops in the stem, and the leaves begin to turn yellow.

How to easily remove leaf mold on tomatoes in a greenhouse

In closed ground, where conditions may be ideal, the disease can not only reduce the volume of the harvest, but also lead to the death of the bushes.

Advice from gardeners

Experienced gardeners recommend the following method of combating rot: adding ash from burnt oak bark when transplanting seedlings (a glass of ash per hole), and also spraying during the period of bud formation.

An infusion for foliar feeding is prepared from 200 grams of ash and 10 liters of water. Pour water over the ash, bring the solution to a boil, boil for 10 minutes, and then leave to infuse for 24 hours. Then drizzle it over the tomatoes.

Tomatoes are often susceptible to various types of rot. To prevent this, it is enough to follow the rules of agricultural technology, water regularly and well, care for the plants and pay attention to varieties that are least susceptible to rotting. All these simple measures will help you reap a bountiful harvest and keep your plants healthy.

Treatment and prevention of tomato diseases

From a brief description of common tomato diseases and the reasons for their occurrence, we can conclude: the risk of all kinds of diseases increases many times if basic agrotechnical rules are violated. Therefore, we can say with confidence that the best treatment for the disease is prevention.

Chemical and biological agents for treatment

The most effective way to treat tomatoes is to regularly treat the entire area with targeted fungicides, with an interval of 10 - 20 days, depending on the persistence of the infection that caused the disease. It is advisable to carry out the first treatment a week before planting tomatoes in the ground in order to destroy the source of infection before it has time to spread to young shoots of plants.

Be sure to treat the soil for seedlings, seed material, equipment and tools with disinfectant solutions of manganese, boric acid and other special preparations.

The following drugs have proven themselves to be effective:

Barrier;
Biosporin;
Screen;
Oksikhom;
Baikal.

Water the area with a solution prepared from fungicides before planting the tomatoes in the ground. Regularly irrigate planted tomatoes, trying to tie the treatment to each new phase of growth: the appearance of flowers, ovaries, right up to harvesting and cleaning the site.