Tomato now it is one of the most popular and beloved by Russians vegetable plants. This very light and heat-loving culture is grown both in greenhouses and in the field. However, in order to obtain a stable tomato harvest, a whole range of agrotechnical measures is required. In our North-West region with its capricious weather due to changes in temperature and humidity, with some heat deficit during the summer, gardeners, as a rule, grow tomatoes in greenhouses and greenhouses.
But there are also such experienced amateur vegetable growers who rely on the warm summer, who get harvests of tomatoes in the open field. Of course, in the initial period of development, they still use temporary shelters. Moreover, now there is a wide choice various films... Alas, tomato plants are affected by several bacterioses, the intensity of development of which depends both on the characteristics of the cultivation of this plant, and on their general condition.
When grown indoors, there is often high humidity and sometimes insufficient light. This greatly weakens the plants, which as a result leads to damage by these pathogens. The spread and development of these diseases can be contained or completely excluded if the air humidity in a closed ground is reduced to 65-70%, and the daytime temperature is tried to be maintained within 22 ... 26 ° С or 24 ... 28 ° С (in cloudy weather it can be 4 ... 5 ° C lower). Nighttime temperatures should be 12 ... 14 ° C and 17 ... 20 ° C (before and after flowering, respectively). It is also necessary to regularly monitor the temperature of the soil in greenhouses - to maintain it equal to 19 ... 21 ° C throughout the growing season.
The prevalence of this disease is quite wide, the disease is very harmful, especially in greenhouses. It brings especially great harm in years with hot summers. In this case, the seedlings are affected by up to 50%, and the fruits - up to 20%, because the increased humidity at high temperatures contributes to the increase in the defeat of the greenhouse tomato. The disease is manifested by the defeat of the ground part of the plants, as a result of which the tomato does not produce fruit at all or it is of low quality. The disease affects the cotyledons, leaves, petioles, stems and fruits of tomato, and young tissues are more susceptible to the pathogen than aging ones. Seedlings and young plants suffer greatly from bacteriosis. At the first stage, very small depressed watery brown spots of irregular shape appear on the leaf blades of young leaves, which are translucent in transmitted light. They quickly increase in size (up to 1-2 mm), then the center of the spots gradually turns black.
Under favorable conditions for the development of the disease, the spots merge, often this affected tissue necrotizes and falls out, and after a while the leaves themselves curl and dry out. Black elongated spots are formed on the stems and petioles, but sometimes the lesion begins to appear on them in the form of strokes and even dots. Often, with the course of the disease, these spots merge, and the plant may die. The same picture is observed on the stalks, shoots and pericarp.
With a strong lesion of the pedicels, a massive fall of flowers occurs. In young fruits (up to 2.5-3 cm in diameter) bacteria penetrate through damaged hairs or, at later stages, through wounds. The incubation period for the development of bacteriosis often lasts only 3-7 days (depending on temperature). When fruits are affected in the early phase of development, dark convex points, surrounded by a watery border, appear on their surface, which eventually take the form of ulcers. Unlike typical symptoms of bacterial bird's-eye cancer, scab-like dark spots are not surrounded by a light border.
The development of black spot largely depends on meteorological conditions: the lower the temperature, the slower the development of black spot. Bacteriosis is transmitted by seeds and plant debris. On seeds, the infection can persist for more than a year. Even with a latent infection, seeds can give outwardly healthy seedlings, which in the future can serve as a source of spread of bacteriosis. For this reason, it is important to purchase guaranteed healthy seeds. During the growing season, bacterial infection can enter through the stomata of plants. The pathogen persists for a very long time in parts of plants that are difficult to rot.
It is also ubiquitous. This disease is typically of a vascular nature. Signs of this disease are manifested in the form of wilting of plants: bacteria, penetrating into the vascular system, cause wilting of tomato shoots. This process begins with the lower tiers of the leaves: they have a loss of turgor (sometimes on one side of the leaf), while the wilting parts of the leaf turn yellow along the edge and curl. In some cases, such a manifestation of bacteriosis may be its only external symptom. From the onset of wilting to the complete death of the plant, it can take 1.5-2 months.
In case of primary infection, the vascular ring is damaged (in the form of its darkening) in the stems and at the base of the petioles of diseased leaves. Early damage to fruits by the causative agent of the disease leads to their ugliness: at the same time, the seeds darken and lose their germination. Infection of the terrestrial organs of fruiting plants manifests itself in the form of brown ulcers on young sepals, stems, petioles, especially on the stalks, which causes the fruit to fall off. With a later infection, the fruit may have a healthy outward appearance and a normal pulp consistency.
Local manifestation of symptoms of bacteriosis on fruits occasionally occurs in the form of a characteristic spot, which is called the "bird's eye". At the first stage, small affected areas of green fruits look like white spots, at the next stage, when the fruits ripen and color, the center of the spots turns yellow. These signs of "bird's eye" can develop on both affected and unaffected by wilting of plants. Diseased fetuses are delayed in their development, usually unevenly colored in comparison with healthy ones. With a strong development of the disease in plants, light brown stripes, cracks and ulcers appear on the petioles and stems, from which yellow mucus protrudes. On the cross section of such affected organs, the browning of the bundles of the vascular system is clearly distinguishable.
The causative agent of bacteriosis enters plant tissue through mechanical damage: through injured roots, stems, leaves. At high air humidity, it is able to infect the plant through open stomata. Infection with bacterial tomato cancer is spread by plant debris, seedlings, soil, but the dominant role here belongs to infected seeds, infected superficially or from the inside. The pathogen is also transmitted by pinching and pruning of plant leaves. With a permanent tomato culture in the same place, the soil serves as a reservoir of bacterial infection. The most favorable conditions for the development of bacteriosis are a temperature of 20 ... 28 ° C and a relative humidity of 80-85%.
Read part 2 Bacterial diseases of tomatoes: hollowness, mottling, apical rot of fruits
Alexander Lazarev, candidate of biological sciences,
Senior Researcher, All-Russian Research Institute of Plant Protection, Pushkin
Photo by E. Valentinov
Fungicides from the chemical classes phthalimides and strobilurins (Quadris, c.c. (0.8 l / ha), as well as a new drug Dinali, KD (0.6-07 l / ha))
In the article we will talk about the diseases of tomatoes, descriptions of the most common are given. From the material, you will learn how to prevent them and treat affected plants.
The content of the article:
Such diseases are not caused by fungi or parasites. They can be provoked by weather conditions, improper care.
Cracking of the skin of the fruit can be caused by sudden changes in temperature, a sultry period, insufficient humidity. Often, thick-skinned hybrids themselves crack when ripe.
After pinching, the pressure of water in the stems increases, which also causes cracking.
Fruits begin to deform while still being a flower. A yellow tomato bud replaces the fused terry mutant. It has many stamens and petals.
Large-fruited varieties are most prone to deformation. On them, similar mutants bloom earlier than other flowers, not allowing others to form fruits. Double flowers should be removed.
Symptoms of hollowness are observed at the very beginning of the culture turnover. The appearance of the tomato is not attractive: protruding large ribs of the septa of the seed chambers. Hollowness is caused by many factors.
First of all, the anomaly develops due to a violation of fruit set. This may be an elevated temperature, a lack of pollen grains.
Black spots on fruits can appear due to physiological disturbances in plant development. The most common reasons are irregular watering, lack of calcium, lack of nitrogen.
Systematic airing, feeding with the necessary elements will help to correct the situation.
Tomatoes are sprayed with calcium nitrate, starting with the smallest fruits. Affected tomatoes are removed.
This state of the tomato is caused when irrigation is disturbed. Oedema is not contagious, it is not a disease. The leaf plate oversaturated with moisture visually swells. You can observe this phenomenon in the early morning hours, when the soil is still warm and the air has cooled. Under the action of the root pressure, more moisture is supplied than necessary.
Castings and stems can burst and water spots appear on them.
Fungal infestations appear on fruits, stems and leaves. The leaves get sick in such a way that brown spots form on them, and a pale yellow zone appears around them. If the weather is humid and warm, these spots grow quickly. A bloom appears on the bottom of the leaves. It is located over the entire surface of the infected area, or along the contour. Fruits can be sore at different stages of development. Green fruits, after they become ill, become covered with hard spots. The inner tissue of the fetus turns light brown. The size and shape of the spots can be different - from concentric to annular. If tomato disease develops successfully, the fruit turns brown completely.
Late blight refers to fungal diseases. In addition to the usual manifestations, this tomato disease is characterized by the formation of spore-bearing signs, which are the result of repeated, or secondary infection. On diseased stems such negative factors as irregular spots appear.
The color of such spots is dark brown. They often join together and form necrotic interceptions. Fungal plaque does not appear on the surface of the plant. Prevention - soil sterilization, removal of diseased tomatoes. For chemical influence, sodium humate and pseudobacterin are suitable.
Dry spotting, also called Alternaria, produces concentric, rounded brown spots. The first manifestations of tomato disease can be seen on the lower leaves. Further, the disease spreads up the plant, and the manifestations become noticeable in the upper tiers. The affected areas are covered with spots with a diameter of 4-7 millimeters. After some time, their size increases, they become larger and can reach 10-15 millimeters in diameter. In protected ground, early manifestations are removed by Quadris, and for open ground, other substances are used - Ridomil and Metaxil.
The roots of adult plants are exposed to anthracnose. They become covered with brown spots, the bark peels off, and microsclerotia gather under it. Ripe fruits are affected after ripening and can become infected when fully ripe or transported. The causative agent is a fungus that can spread in high humidity, which can be in protected ground. If the leaves and stems of the plant are covered with droplets, they can spread the disease. Treatment can be carried out with chemistry, Agatom-25, spraying. Breeders have bred varieties and hybrids of tomatoes that are not susceptible to disease, and are called F1 Life, Longf, Shelf.
White spot (septoria) is very dangerous, as it can lead to the loss of half of the entire crop. Old leaves, those that are closer to the ground, are affected. After covering with persistent stains, they turn brown and dry out. The best temperature for the development of mottling can be 15 to 27 degrees with a humidity of 77%. Even in the remains of the plant, spores of the fungus remain. It is impossible to protect a plant from infection even with the help of chemicals. Some hybrid tomato varieties may be immune to spotting.
Gray mold is very dangerous. Infections spread to the entire stem, and tissues die off as a result of necrosis. Visually, the rot resembles a grayish-white bloom, its appearance destroys the fruits, and the entire plant simply withers after infection. The generative organs are affected by high humidity. Also, the infection can be transmitted to other crops (which can be very likely in protected ground) that can grow with or near tomatoes. For treatment, experts advise the use of timely agricultural measures, chemicals, such as growth regulators and chemical protection. The names of the drugs are Bayleton and Euparen.
White rot is also called sclerotinosis. A plant can become infected with a disease as a result of mechanical damage. The effect of the disease can increase as a result of a decrease in temperature and an increase in humidity - after cold rains. Poor ventilation in the greenhouse and the density of the planting can also cause the development of the disease. Signs - wilting, stem rot, cavity formation, the appearance of black sclerotia, white fluffy bloom, plant death. The causative agent of the disease can remain on the remains of the plant and in the soil.Disinfection of the soil, which must be done after the previous planting of plants, will help to get rid of the pathogen.
Powdery mildew infects tomatoes through the air, infection is carried out by the spread of conidia. The result of infection is a white bloom that appears on the top or bottom of the leaf. Sometimes appears on petioles and stems. The tissues then die off, and the leaves may fall off.
Low air humidity is quite sufficient for infection, but the first signs appear at a humidity of 80-90% and a temperature of 16-20 degrees. Diseased plants grow poorly, the number of fruits and their size decrease. The causative agent is a fungal infection. It is treated by spraying, sodium humate completely destroys the fungal infection. There is one stable hybrid, Milano F1.
Symptoms are most severe during the growing season and during the flowering period. First, the lower leaves fade, stains form on them, which lead to twisting and drying. Then the symptoms spread to the whole plant. The fungus passes through the vessels and clogs them. Under a microscope, you can see the mycelium, it is not pigmented, that is, colorless. The main thing for the fight is the cultivation of disease-resistant tomatoes, since there is no chemistry for treatment and prevention. Breeders have created a variety Zasolochny, resistant to verticillosis.
Root rot is very harmful and it manifests itself in those areas of land that are over-watered.
It can appear on the plant immediately after planting if the soil is already infected with it. On the substrate and open ground, it occurs in areas with excess moisture. The development of the disease occurs throughout the life of the plant. Symptoms are blackening in the area of the root and neck, black leg. As a result, you can observe the wilting of the sprout. Sometimes rot can provoke the appearance of other diseases. Non-sterile soil and excessive watering can stimulate the development of this defect. Treatment and prevention - disinfection of the soil, dressing of seeds and seedlings, treatment with Rodomil Gold as a prophylaxis, treatment of the substrate.
Stalk cancer does not manifest itself everywhere, and its appearance depends on the place where the tomato grows. In the open field, stem cancer is rare, but in greenhouses it can destroy the entire crop.
In stem cancer, the stems are most often affected, and sometimes the leaves. Gum begins to ooze from the stems, and the flowers become underdeveloped. The development of the didimella virus occurs in wet weather and low temperatures. Treatment - disinfection of the soil, the use of the drug Trichodermina. Sprouts and stems are sprayed with drugs to stimulate growth, Agat-25 or Immunocytophyte. Painful spots are treated with a paste of Rovral and chalk.
Fusarium affects adult tomatoes and seedlings. Plants wither and die, may be underdeveloped. The first sign is the wilting of the top. Tissues become sluggish, and individual leaves wither and curl. The process starts at the top of the leaf. If the stem is cut off and examined, you will notice the browning in the vessels. Sometimes healthy plants can die in one day, namely at night. The infection spreads through the soil, which should be light and structureless. Fluctuations in temperature and humidity contribute to the development of fusarium. Watering before planting with pseudobacterin, growing resistant varieties - these are the methods of struggle.
Tomato viral diseases can be very harmful. Everyone depends on the virus that has infected the sprout, the place of growth and the tomato variety itself. The fight against them comes by the destruction of insects that carry bacteria, the cultivation culture is maintained, and agromechanical influences on plants and the process of their growth are carried out.
The harmfulness of aspermia has been proven, and depends on the type of virus and the conditions in which the tomato grows. Underdevelopment of generative shoots, strong bushiness - these are the signs of this disease. Any varieties are exposed to it, and a spider mite is considered a peddler, which must be fought against for this reason. The leaves become small, change pigmentation, and the flowers acquire the ability to grow together. In order to prevent the development of the disease, it is necessary to destroy the insects that carry the infection, not to use reservators.
The wilting of the leaves and their curling is called bronze. The virus gets stronger every year. Plants grown in greenhouses are very susceptible to problem wilting. In addition, a complete loss of the entire crop is possible. Brown patterns appear on the fruits, and later on the leaves, which leads to the death of the tops. The disease is not cured, however, at a temperature of 45 degrees, the activity of the virus is canceled.
Yellow curl can be a very unpleasant moment. It affects the appearance of ripe tomatoes. Their presentation is lost, the plants are colored unevenly, and the leaves curl, become small and deformed as a result of curling. The carrier of the virus is a whitefly, which must be dealt with, and treatment is carried out in any possible way. One of the hybrid varieties is disease resistant and is called F1 Senzafin.
It manifests itself in winter, dots appear on the leaves, which turn white. They darken and cause necrosis. Leaves stretch and curl. Infected plants grow poorly, deform, and their leaves become coarse. The infection is transmitted by aphids, there is no protection against the disease, and agromechanics are used to get rid of the problem.
Mosaic can quickly damage many plants. It can also lead to a complete lack of harvest.
Leaves are the first to succumb to infection. They become covered with spots, their original shape and color are lost. Together with other viruses, a new tomato disease can form. The virus is resistant to changes in temperature and humidity and is carried by insect pests. For prophylaxis, normal conditions for plant growth are observed. Fighting, or rather, preventing many diseases will help observance of the rules of crop rotation. It is necessary to monitor the place and sequence of planting, find varieties that are resistant to common diseases.
Pests are animals (mainly insects) that use tomatoes for food and / or their home. In addition, insects are carriers of viral diseases. Moving from one tomato bush to another, the pests spread the infection to all tomatoes. As a result, the disease of one plant turns into an epidemic. Such a neighborhood could be reconciled if the vital activity of parasites did not cause colossal damage to tomatoes.
Nematodes are small roundworms that attack tomato roots. Because of this, tomatoes wither quickly.
In addition, nematodes carry various infections and viruses.
To destroy the pest will help karbofos, Fitoverm P, Nematofagin.
Slugs and snails are carriers of fungal infections. By eating the fruits of tomatoes, they infect the plants, which leads to the death of the tomatoes.
In addition, slugs are able to destroy all the green mass on the bushes.
Chemicals will help destroy slugs (Thunder, Ulicid) or folk remedies (infusion of garlic, infusion of mustard, infusion of pepper).
These small insects live in colonies and feed on the sap of the plant. As a result of their activity, tomatoes lose their vitality and wither.
Also, aphids on tomatoes cause the development of chlorosis and leaf deformation.
You can fight this insect both with the help of chemicals (Fitoverm, Fufanon, Alatar), and folk remedies (soapy water, ammonia).
Ants themselves do not eat tomatoes, but they breed aphids, which feed on the sap of the plant.
In addition, when building an anthill, the roots of tomatoes are damaged. This can lead to infection with fungal infections.
Against ants, remedies like Anteater.
These insects are considered one of the most dangerous pests. They settle on the bottom of the leaf plates.
The larvae feed on the sap and tissues of plants, and the adults fly from one plant to another. This is what whiteflies are dangerous for. In addition to the fact that they themselves damage tomatoes, they also spread infection (fungal and bacterial diseases).
Help to cope with the pest Biotlin, Iskra, Tanrek.
Note that the whitefly adapts well to chemicals. Therefore, alternate them for greater effect.
IMPORTANT! When fighting whitefly, it is important to process the lower part of the leaves, where these insects mainly settle.
The life span of these insects is only 20 days, and they multiply very quickly. Thrips are dangerous because they are carriers of the spotted wilting virus.
In addition, eating tomatoes, they provoke fruit spotting.
It is necessary to fight thrips at the first signs of its vital activity.
Biotlin, Alatar, Aktara - effective insecticides that will help get rid of the pest.
Absorb nutrients and destroy the tissues of tomatoes by making their moves and laying eggs. They are carriers of the tomato tops curl virus and the causative agent of tomato stump.
Chemicals are used to combat leafhoppers. Aktara, Accord, Tanrek.
Through low-quality seed material, future seedlings can pick up the virus. The danger lies in the fact that it does not appear immediately. Three diseases of tomatoes are considered the most merciless.
This infection manifests itself at the stage of planting seedlings in the ground, and causes its rod-shaped virus. The leaves change color, a mosaic of yellow and green patches is formed. A little later, the affected leaves quickly curl up, dry out and fall off. Infected bushes are destroyed, and healthy ones are treated with a weak solution of potassium permanganate (potassium permanganate) or urea.
The causative agent is the tobacco mosaic virus. In a popular way, the disease is called streakiness. Brown streaks appear on the surface of the leaves, which later degenerate into ulcers. In an infected plant, the top soon disappears and such a bush can no longer be treated. It is dug up and burned.
This disease is manifested by the general underdevelopment of the plant. The bushes are low, the foliage is small, the fruits are deformed and small in size. A distinctive feature is the complete absence of seeds in tomato. Therefore, infection has a second name - seedlessness. At the initial stage of cultivation, it cannot be detected, but can be prevented with the help of preventive seed treatment.
Fighting viruses is not easy and often played.
Therefore, special attention is paid to prevention: