Tobacco mosaic virus - description, what it looks like, how to fight

Tobacco mosaic on cucumbers

The discovery of the tobacco mosaic virus in 1886 and the beginning of its study became the basis for the development of modern virology. During this time, science has conducted many studies that have determined the influence of various viruses not only on plants, but also on humans and animals.

For the first time, the effect of the tobacco mosaic virus was studied on tobacco, a representative of the nightshade family. Today, the disease affects more than 350 species of various vegetable, garden, and ornamental plants, as well as annual and perennial weeds.

First of all, the virus infects weak cells in the leaves, which contain little glucose and organic acids. Because of this, the process of photosynthesis changes and chlorophyll is destroyed. Affected leaves become covered with mosaic stains and tubercles. Dark green areas alternate with beige, light green or yellow spots. Outwardly, these signs are similar to boron starvation.

As a result of damage to the protective layer of cells, the plant as a whole weakens, becomes thinner and cannot resist the penetration of other bacteria. Tobacco mosaic virus reduces yields and worsens the presentation of fruits.

Tobacco mosaic virus: methods of control

Tobacco mosaic virus is a crop infection that settles in the tissues of nightshade plants: peppers, tobacco, cucumbers, and tomatoes.
The disease inevitably leads to crop losses. Let's look at how to recognize it, how to treat plants and how to protect them from the spread of the virus in more detail. Infection of leaves and plant cells by the virus leads to the destruction of chlorophyll, and therefore photosynthesis. The following appears on plant leaves:

Mosaic, emerald-beige stains on the surface.
Tubercles as a result of intense cell division. The areas become mottled, sometimes light green, dark green, resembling a mosaic.

The virus is tenacious. If it gets into the soil, it can harm plants for 4–5 years. The skin of the affected plants becomes thinner, allowing bacteria to penetrate unhindered.

Cells poor in glucose and organic acids are destroyed and die, which affects the fruit yield; fewer of them appear, and those are underdeveloped and small.

Description of the virus

Tobacco mosaic is a virus that infects various crops, settling in their tissues. The most commonly affected plants are nightshade plants (peppers, cucumbers, tomatoes and tobacco).

This disease significantly reduces crop yields. You need to figure out how to deal with such a scourge.

The virus destroys plant cells, destroying chlorophyll and leading to disruption of photosynthesis. Because of this, the following may appear on the surface of the sheet:

stains in the form of a mosaic of emerald-beige shade;
tuberosity due to increased cell division;
spotting of various shades of green.

TMV is not easy to destroy. Once in the soil, it can harm various crops for up to five years. The nature of the action of the virus leads to the fact that the skin of the plants affected by it becomes very thin and pathogenic bacteria can easily penetrate inside. Plant cells, deprived of nutrients, organic acids and glucose, begin to gradually deteriorate and die, which negatively affects productivity. The fruits ripen in smaller quantities, but even those are small and inferior.

What does it cover?

The virus is able to spread, that is, penetrate healthy plants through the sap of sick plants. Occurs when:

sowing seeds infected with a virus;
the presence of any sucking pests in the soil: mites, nematodes, which with infected saliva subsequently transmit the virus to new seedlings;
picking, replanting, pinching, pinching plants when the virus gets into the wounds of the shoots and roots;
juice getting on equipment used to process plants, breaking off hairs, covering stems, leaves, causing wounds to them.

Spheres of Damage

It should be remembered that the tobacco mosaic virus infects healthy plants by penetrating into them through the juice of infected crops. This can happen when:

sowing seeds infected with this virus;
the presence of various sucking pests in the soil: nematodes, mites, which transmit the virus along with their infected saliva to other plants;
diving, pinching, pinching and replanting crops (wounds of roots and shoots become infected);
the sap of plants gets on the equipment with which they are processed, damaging the hairs and causing wounds to the surfaces of the stems and leaves.

As you can see, there are many ways to become infected with this insidious virus.

Prevention

It is necessary to protect cultivated plants from infection by the virus at the initial stage, that is, when choosing seeds for planting seedlings.

Seeds, boxes, garden tools must be disinfected with a solution of potassium permangate (5%). It is better to repeat the procedure at least 4 times, that is, within 4 days. To protect the future harvest for preventive purposes, you need to:

vaccinate plants, in particular tomatoes, with an aggressive strain against the virus;
carry out protective measures when planting plants in greenhouses;
disinfect the seeds by keeping them in hydrochloric acid (20%) for at least 30 minutes, then rinse the seeds with running water;
steam the soil by pouring boiling water over it for 2–3 hours;
treat the seedlings once a week with milk diluted with water in a ratio of 1x10;
promptly remove plant residues from the area before planting new ones;
fight in different ways with sucking insects that carry the virus;
disinfect boxes for seedlings, equipment used in work, tools.

Seedlings become more resistant to viruses when they are sprayed with boric acid (1%) 7 days before planting and a couple of weeks after planting. It is important to process greenhouses by burning and collecting leaves and roots in the fall. Replace the soil in the greenhouse in the spring, removing a layer of at least 10 cm or steaming it with boiling water.

Preventive measures

It is necessary to prevent infection of cultivated plants by tobacco mosaic at the initial stage, when seeds are selected for planting. Planting material, boxes and work equipment must be disinfected with a special five percent solution of potassium permanganate. This manipulation should be carried out once a day for at least 4 days. In addition, in order to protect the future harvest, you should not neglect preventive measures, which include:

vaccination of crops with an aggressive strain against the virus (tomatoes need this procedure most of all);
compliance with protective measures when planting plants in a greenhouse;
disinfection of seeds using a 20% solution of hydrochloric acid, in which it is necessary to soak the seeds for half an hour and then wash them under running water;
steaming the soil, which is carried out while watering it with boiling water for 2-3 hours;
treating seedlings once a week with milk diluted with water in a ratio of 1:10;
timely removal of plant residues from the site immediately before sowing new ones;
combating sucking pests, which are the main carriers of tobacco mosaic;
disinfection of all tools, work equipment and containers used for seedlings.

In addition, seedlings become more resistant to the virus if they are sprayed with one percent boric acid a week before planting and a few weeks after it. You should also treat greenhouses in the fall, collect and burn roots and leaves. In spring, it is necessary to change the greenhouse soil: remove the top layer of at least 10 cm or steam it with boiling water.

Treatment on different vegetables

TMV is omnipresent. Once settled on the site, it is impossible to completely get rid of it. The main thing is to prevent viruses from spreading further, so it is imperative to take preventive measures, especially during the growing season of plant growth. .

The mosaic virus is tenacious even in winter, attacking the rhizomes of some weeds. It appears in various forms on cucumbers.

Ordinary mosaic affects cucumbers planted in open ground, first the tissue, the leaves on the plants when they reach 6-8 pieces become yellow-green, then in the form of a mosaic, the plants are slow in growth, flowering is weakened. The fruits become covered with dark areas and acquire a convex warty shape. The main carrier of the disease is aphids. Already 10 days after infection, unsightly symptoms appear on plant leaves.
Green speck affects cucumbers planted in protected soil. Already young leaves become wrinkled, spotted with alternating light and abnormally colored areas. The development and growth of the plant is inhibited, the petals of the corolla become stained, and the fruits that are set fall off before they have time to ripen.
White mosaic affects leaf tissue at temperatures above 25 degrees, and star-shaped yellow-white spots appear between the veins. The main thing is to prevent the spread of the virus, since it is impossible to cure the plant from it.

Treatment consists of timely removal of diseased plants and the application of fertilizers on time in excess doses. It is advisable to check all varieties of cucumbers and hybrids for resistance before sowing, and also, after planting in the ground, remove weeds as they appear: alfalfa, sow thistle, aphids.

Mosaic virus is often present in tobacco, so keep the seeds away from it and avoid even touching it.

When a pepper becomes infected with mosaic disease, the leaves are affected, their color changes, they become variegated, mosaic-colored with alternating dark, yellow, light green and even black colors on the plates. The leaves become deformed and fall off quickly.

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Virus infection of plants prevents their growth, the fruits are formed ugly, small in size, covered with spots. The virus affects the root system of peppers.

Prevention consists of checking seeds for resistance, which is found in some cultivated varieties: Flamenco, Zarya, Jiminy, Atlant, Fidelio, Dar Kaspiya, Yubileiny, Semko.

Treatment for the virus is:

collecting seeds from healthy peppers;
disinfection of seeds after collection with a violet-saturated solution of potassium permanganate for at least 30 minutes;
watering the pepper with a solution of potassium permanganate at least once every 3 weeks;
feeding plants with microelements (solution) immediately after planting in the greenhouse;
spraying the bushes with milk and water and 10 drops of iodine in a ratio of 1x10;
covering with film after spraying for several days so that the virus does not spread to healthy seedlings through contact;
treating seeds with sodium hydroxide (2%) for 10 minutes to destroy the pathogen and increase energy for germination of seedlings.

Tomato leaves acquire a light-dark green color, and the tomatoes themselves become covered with yellow spots. Virus damage is especially high if there is insufficient lighting during cultivation. Tomatoes oppressed by mosaic may simply die. The virus cannot be cured.

Take seeds only from healthy plants, disinfect them immediately after collection, as well as equipment when pinching tomatoes, thinning, hilling, treating them with a solution of potassium permanganate. In a greenhouse, a layer of soil up to 15 cm must be changed every year or disinfected. In the evenings, it is good to spray the tomatoes with microelements, a solution of boric acid several days before planting.

Disinfect the tool before starting work. Create normal conditions for tomato growth, take care of good lighting.

Resistant tomato varieties to mosaic: wild rose, dina, Andreevsky surprise, golden andromeda, Nastena. The virus is not afraid of drought, survives winter, and can live on equipment: hoses, seedling boxes. It affects tobacco, tomatoes, legumes, potatoes, beets, eggplants, and spinach.

When incubated, it can be transmitted through plant sap. A dangerous pest reduces crop yields, inhibits their growth and development. It is difficult to get rid of it, the main thing is to follow preventive measures, treat everything that can come into contact with it.

Take care of the plants even when planting. Only from a healthy seed can a healthy fruit grow. Take this into account.

VTM model

The rod-shaped tobacco mosaic virus was discovered by Adolf Mayer in 1886. No methods have been developed to combat this disease, which largely destroyed food vegetation. And only in 1892, the famous scientist Dmitry Iosifovich Ivanovsky began to study this issue, studying the Nicotiana tobacco variety, which itself died from its own virus. It was he who was able to fully recreate the model of the tobacco mosaic virus: the protein molecule is folded into a helix, the capsid (shell) of which hides a strand of RNA.

The virus has a spiral shell

The scientist has established a certain pattern - a virus molecule can consist of equal-sized spirals, and the larger the turn, the stronger the virus is in terms of infecting plants that are more resistant to it.

Ivanovsky found out that the main sources of infection are not healthy flora, but sick, weak plants and soil. Moreover, he was able to discover a new fact: a hitherto unknown protein passes through a porcelain filter, which was impenetrable to all bacteria known at that time. Such devices were developed specifically to check for the presence of infectious pathogens in liquids. At the first results, he even came to the conclusion that either poison was dissolved in the liquid, or the molecules were so small that they penetrated the filter. Subsequently, it was the second option that was confirmed.

The tobacco mosaic virus contains a single DNA molecule, which contributes to the transmission and improvement of the properties of the disease.

In the vastness of our state, scientists believe that the report on the tobacco mosaic virus by D.I. Ivanovsky confirms the fact that it was he who became the discoverer of this disease. Foreign colleagues are sure that their comrade-in-arms is behind this. Meanwhile, TMV is the first representative of a viral disease that was discovered throughout the world almost simultaneously.

The tobacco mosaic virus infects the leaves and cells of the plant, which causes the destruction of chlorophyll and, as a result, the processes of photosynthesis are much worse and slower.

When damaged, chlorophyll is destroyed and the process of photosynthesis stops

Description of the signs of tobacco mosaic virus:

the diseased leaf is covered with mosaic stains of an emerald-beige hue;
the appearance of tubercles due to accelerated cell division;
the affected TMV segments become spotted, sometimes light or dark green, and resemble a mosaic in appearance.

The tobacco mosaic virus, a photo of which you can see in this article, belongs to the group of viable diseases and can survive in the soil for a long time. It will take several years to clear the soil of this disease. And if we talk about complete disposal of the virus, then the minimum period for eliminating the disease is 4 years. It all depends on weather conditions and the use of effective methods to combat this problem. In a plant cell, the tobacco mosaic virus infects its protective layer, which leads to thinning of the plant. And this, in turn, facilitates the unhindered penetration of bacteria into the culture.

First of all, TMV tries to infect cells that are poor in glucose and organic acids. The infected particle is destroyed, dies, and a chain reaction of chlorophyll destruction begins. Ultimately, the yield decreases, and some fruits remain either underdeveloped or small.

If several different crops are grown in a greenhouse, tomatoes are the first to become infected. Therefore, it is tedious to inspect them first for damage, including other diseases.

VIDEO: Tomato diseases

TMV can be transmitted from a diseased plant to a healthy one through the sap of the first. It can occur when:

planting seedlings when the seed is already affected by a viral disease;
the presence in the soil of various kinds of sucking parasitic organisms: mites, nematodes, the saliva of which may contain infection;
grafting, replanting, removing excess shoots, pinching seedlings or seedlings when speckled grass gets into open areas of shoots and root systems;
contact of sap from affected vegetation with mechanical equipment for cultivating soil and caring for crops: hoes, shovels, rakes, sprayers, etc.

Tobacco mosaic virus infects the chloroplasts of the following plants:

tomato;
cucumber;
bitter and bell peppers;
paprika;
tobacco.

As you can see, this is mostly a nightshade type of vegetation. How to protect yourself from this problem?

It is necessary to prevent the spread of green speck across a plot of land at the stage of selecting seedlings or plants for planting.

Check the leaves carefully before purchasing seedlings

For the purpose of prevention, seeds and containers for growing seedlings must be treated with a 5% solution of potassium permangate. And in order to completely eliminate the appearance of TMV, experts recommend carrying out such disinfection measures for five days. An identical process must be carried out with regard to garden tools.

vaccination of plants, in particular the cucumber genus and the tomato family, with an aggressive stamp against TMV;
performing protective procedures when planting crops in greenhouses;
disinfection of seedlings by keeping them in 20% hydrochloric acid for at least half an hour, after which they are thoroughly washed under running water;

Seedlings will become more resistant to viral infection if they are irrigated with a solution of 1% boric acid a week before planting and two weeks after it. In addition, it is extremely important to carefully process greenhouses, collecting and burning the remains of leaves and roots after harvesting.

steaming the soil - watering with boiling water for two to three hours;
treating seedlings once every six days with milk diluted with water in a ratio of 1 to 10;
timely removal of remaining vegetation on the land plot before planting new ones;
eliminating sucking insects using all kinds of traps and pesticides;
disinfection of boxes for seedlings, garden tools used in work;
replacing the soil in the greenhouse once a year - the procedure is carried out in the spring, in which case it is necessary to remove the top layer of soil (at least 10 cm) and steam it with boiling water;
spraying plants with serum, adding 3-5 drops of iodine to it;
heating the seeds at a temperature of 60°C for three days;
It is better to keep crop seedlings away from tobacco.

When growing crops in a greenhouse, be sure to treat the frame, soil, and internal surfaces in the fall.

When settling on a land plot, VTM cannot be completely eliminated. Therefore, the main task of the landowner is to prevent the possibility of further spread of the viral infection.

Treatment consists of immediately eliminating infected plants and fertilizing the soil with doses higher than normal. It is important to check all seedlings before planting for the presence of green specks, and also after planting in the soil to destroy weeds as they grow.

It is better to give preference not to purchased seeds, but to those collected with your own hands from the land. Moreover, it is extremely important that the vegetables from which the planting material will be collected are healthy.

For a good harvest, give preference to your seeds

By following these recommendations, you will be able to avoid the appearance of green speck on your land.

VIDEO: Tobacco mosaic virus on tomatoes

A great variety of all kinds of plants exist on the globe. All of them have their own unique beauty and unique properties. However, many of them are susceptible to various diseases that negatively affect their vital processes, as well as their appearance. One of the common plant diseases is tobacco mosaic virus (TMV).

Signs of the disease

This virus settles in the tissue of vegetable and flower crops, where it multiplies intensively and leads to its further death. The spread of this disease leads to disruption of the photosynthesis process.

In order to quickly get rid of this scourge in the garden, you need to know the main signs of infection.:

Whitish stains appear on the leaves of vegetables, and the leaf becomes discolored.
Yellow spots on leaves.
The leaves lose their green color, become spotted, the cells begin to divide and form tubercles that resemble a mosaic.
The surface of the infected plant becomes thin and prone to brittleness.
As the virus spreads, the leaves begin to become deformed.
Vegetable fruits become small and ripen late.

If you ignore the signs of infection, the infected crop will become a source of infection and affect healthy individuals.

Which plants are susceptible to infection?

The virus penetrates healthy cultures through the contact of the patient’s juice with healthy ones, this happens when:

Planting seeds from previously infected fruit.
Through the entry of infected vectors of mites, nematodes, aphids, and bugs onto the plant.
When planting, pinching, vegetative propagation, when there is a high probability of infection getting directly to the plant.
Penetration of infected juice onto garden equipment, and subsequently onto vegetable crops, by mechanical means.
In case of accidental injury to the plant.
When transferring pollen.

This infection combines well with other viruses and becomes destructive as the plant begins to rot and dry out.

Causes

How does the infection get to healthy plants? This happens naturally and with human help.

The main carriers of the virus during natural spread are harmful insects: aphids, leafhoppers, mites, thrips, scale insects, nematodes. They feed on plant juices and, sucking the nutrient fluid from diseased plants, capture the virus. It remains in the vector for several hours and is transferred to a healthy plant when the pest moves to a new food source.

In addition to pests, the infection is spread through pollen, seeds, plant debris and weeds.

With human participation, the disease spreads through vegetative propagation if infected bulbs, tubers, cuttings, rootstocks and scions are used. Even if the vaccination is unsuccessful, if fusion does not occur, the infection manages to get into healthy tissue. It has been observed that infection occurs faster on herbaceous plants than on trees, and more easily on young than on old specimens.

Often the spread occurs with the help of gardening tools: a grafting knife, pruning shears and scissors during pruning, when gardeners ignore their disinfection.

How to treat?

It is quite difficult to cure the tobacco mosaic virus, but if you immediately begin to take action at the first symptoms, then you can save the culture. In advanced forms, the plant must be burned, since there is a high probability of transferring bacteria to healthy individuals.

Methods:

At the first appearance of color changes on the leaves, it is necessary to immediately treat with a whey solution (100 ml of whey per 1 liter of boiled water) with the addition of any microfertilizers.
It is necessary to replace the top layer of soil (15-20 cm).
Spray with a milk solution (1 liter of milk per 10 liters of boiled water) and add a few drops of pharmaceutical iodine.
Treat with a solution of any fungicide.

Prevention

Since this disease is very difficult to get rid of, gardeners recommend following preventive measures; in order to prevent the occurrence of the virus, this requires:

Plant seeds only from proven healthy vegetables and flowers.
Periodically disinfect all equipment in the garden.
Replace the top layer of soil in greenhouses annually.
If possible, vaccinate tomatoes.
Disinfect seeds by treating a solution of potassium permanganate or 20% hydrochloric acid for 30-35 minutes.
Steaming the top layer of soil for 2-3 hours is effective.
Periodically spray nightshade plants with a milk solution.
Water once every 2 weeks with a weak solution of potassium permanganate.
Remove weeds and tops in a timely manner and burn them.
Fight insect pests.

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Varieties resistant to the virus

Despite the fact that the disease affects many nightshade crops, there are varieties that are resistant to it:

Cardinal F1 Pepper:
Atlant;
Gift of the Caspian Sea;
Zarya;
Cardinal F1;
Fidelio F1;
Aries F1;
Indalo F1;
Anniversary Semko F1.
Beryl F1 Tomatoes:
Garfield;
Celebrity;
Ovation;
Beryl;
Abelus;
Shady Lady;
Camry;
Caracas;
Jaguar.
Tobacco:
Variety T.1.245.
Natalie F1 cucumbers:
Pasadena;
Octopus;
Masha;
Natalie;
Darling;
Martin;
Baby Crane;
Phoenix plus.
Policeman F1 Eggplant:
Joker;
Goliath F1;
Vakula;
City F1;
Airship;
Sperm whale;
Torpedo;
Philemon.
Jalapeno Hot peppers:
Indian summer;
Magic bouquet;
Haeckel;
Goldfinger;
Jalapeno;
Coral;
A little prince;
Jellyfish;
Small miracle;
Ogonyok;
Fire bouquet;
Orange miracle;
Flame.

Despite the fact that all varieties are resistant to TMV, the risk of disease still exists, therefore even these varieties must be properly cared for.

Quick tips for preventing the occurrence of TMV:

Plant only healthy seeds, having previously treated them with a solution of potassium permanganate.
Treat periodically with a milk solution or whey solution.
Fight all pests, such as mites, aphids, bedbugs.
If possible, change the top layer of soil annually.
Antisepticize all equipment in the garden.
Water once every 2 weeks with a weak solution of potassium permanganate.
Promptly remove and burn tops, leaves and weeds in your summer cottage.
Spray all the crops in the garden in the evening with a solution of any microelements to boost immunity.
At the end and at the beginning of the sowing season, steam the top layer of soil.
If possible, minimize any damage to vegetable crops, since TMV is transmitted through sap.
Create the right conditions for growth in the garden (lighting, watering, etc.)

By following simple preventive measures, TMV will not be a threat to the garden. At the first appearance of infection, it is necessary to begin timely treatment. In severe cases of the disease, infected crops must be removed from the garden and burned.

How to recognize the disease and its manifestations

Mosaic is a disease whose main characteristics are green and white spots on leaves and fruits. They come in different sizes and shapes and cause leaf damage and changes in their contour.

Seedlings affected by infection slow down their development and growth, and adult plants gradually wither and die. Before the characteristic spots appear, entire fields can be completely infested.

History of appearance

At the end of the 19th century, the first symptoms were discovered on tobacco plantations. At first, one bush was infected, it became covered with bright marks, lost its shape and eventually died. Gradually, one after another, neighboring ones fell ill, and soon, entire plantations were unsuitable for further tobacco production.

The only way to combat it at that time was to destroy infected seedlings at the first manifestations in order to preserve the rest. The disease is called “tobacco mosaic.” Only a century later, Dr. Ivanovsky D.I. A virus has been discovered that causes mosaic plant disease.

What caused

Mosaic completely affects tissues at the cellular level. Occurs as a result of damage to chloroplasts and partial destruction of chlorophyll. Plastids disintegrate, resulting in a decrease in carbohydrate levels. The death of individual tissue sections begins. The pathogens named are Nicotina virus 1, Cummis virus 2, Solanum virus 1 and many others.

Mosaic plant disease

How it manifests itself

There are many viruses that only infect certain varieties. In garden crops, mosaic can be expressed in different ways. The first manifestations characteristic of it are:

Spots of different colors and sizes: can be light yellow, bright green or whitish. They have an irregular shape and deform the structure of the leaf plate.
The development of the crop slows down in comparison with others, water metabolism is disrupted, which is why the stems and leaves dry out. First of all, this concerns young shoots.
Brown marks on vegetables and fruits. Due to damage, the process of rotting begins, so they become partially or completely unsuitable for food.

Infection can occur due to mechanical damage during processing or normal contact with infected crops. This often happens when picking dense seedlings. But the disease can also be transmitted by the wind touching leaves or stems together.

Trimming or breaking off infected leaves or stems is not recommended, as the sap will remain on the blade and hands. With further work on the site, there is a possibility of multiple infections.

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The disease can be spread by vectors. They can be insects such as aphids, mites, bedbugs, etc. Mosaic is also transmitted through fruits and seeds carried by birds and animals.

Methods of spreading mosaics by insects

The soil beneath the root is a breeding ground for infection because it may contain plant debris such as fallen leaves. High humidity and air temperature of 20-25°C contribute to the development of mosaic infection.

Spread can also occur through raindrops running down an infected plant containing small particles of diseased plants.

Pestro is not always beautiful: description and photo of the disease

Mosaicism appears in the form of light (white or yellow) spots on the leaves. Sometimes the pattern can be the same as that of variegated plants. But over time, it becomes noticeable that the variegated leaves lag behind in growth, become deformed and dry out. Some types of mosaics appear as dark green “stains”.

The reason lies in the changes occurring in chlorophyll-bearing tissues. Plastids disintegrate, the chlorophyll content decreases, as a result of which photosynthesis slows down and individual cells and tissues die.

Fruits also suffer from the mosaic virus. It leads to a reduction in the yield of pumpkin crops and tomatoes by 40-50%. The fruits that do grow on infected plants are not marketable. Damaged cucumber fruits are speckled, have a bitter taste, deformed shape, and underdeveloped seeds. Light, dense spots appear on the tomatoes.

Treatment methods for various crops

TMV can spread anywhere. If it has already entered the area, then it is almost impossible to completely destroy it. The most important thing is to prevent its spread in time. To do this, preventive measures should be observed, which is especially important during the growing season of the plant.

Tobacco mosaic does not die even in winter, attacking the root system of some weeds. It can also affect cucumbers, manifesting itself in various forms:

Common mosaic usually affects cucumbers in open ground. In the first stage, the virus infects the tissues and leaves of the plant, which subsequently acquire a yellow-green color in the shape of a mosaic. At the same time, plant growth noticeably slows down, flowering becomes weak. Dark areas form on the vegetable itself, and it takes on a convex, pimply shape. The main carrier of infection is aphids. Already ten days after infection, the first signs of the disease begin to appear.
Green speck affects cucumbers planted in closed ground. Even young leaves are already covered with wrinkles and spots; alternation of light and very bright areas is noticeable. The growth and development of such plants is very slow, the petals on the corolla also become spotted, and the fruit ovaries fall off before they even have time to ripen.
White mosaic can affect leaves at a temperature of +25 ° C, forming yellowish-white star-shaped patches between the veins. The most important task is to prevent the virus from spreading further, otherwise it will subsequently be impossible to rid the plants of it.

The treatment procedure consists of timely removal of infected plants from the site and application of increased doses of fertilizers. Before planting seeds, it is recommended to test their varieties and hybrids for resistance to TMV. It is also necessary to promptly remove weeds (alfalfa and sow thistle) after planting, as well as fight aphids.

This disease is extremely difficult to treat, therefore, it is necessary to take all necessary measures to prevent its occurrence. For this purpose, it is necessary to sow seeds that are no more than two years old, and also spray the seedlings with whey with the addition of a few drops of iodine.

It is very useful to warm up the seeds at a temperature of +60 °C for three days. You can also keep them near the battery for several days. Often, TMV lives well in tobacco, and therefore it is necessary to keep the seeds of other plants as far as possible from it, avoiding their contact.

When a pepper becomes infected with this disease, its affected leaves become variegated in color: yellow, light green and black alternate between the veins. Shortly after this, such leaves become deformed and fall off quite quickly.

Tobacco mosaic hinders the growth of plants, and their fruits become spotted, ugly in shape and small in size. In addition, the virus also attacks pepper rhizomes.

Variety of mosaics

The fight against mosaic is complicated by the fact that almost all cultures suffer from it. There is often a situation where symptoms of infection by several types of virus can be detected on one plant.

Potatoes can be affected by mottled and wrinkled potato mosaic.

Tomatoes are attacked by tobacco mosaic virus, tomato mosaic virus (ToMV) and sometimes green mottled virus (English).

Cucumber mosaic virus (CMV) and mottled mosaic virus (CGMMV) destroy cucumber crops. In addition to cucumbers, ordinary mosaic can develop on peppers, parsley, cabbage, peas, and lettuce. Speckled blight can be called “highly specialized”, since it affects only watermelons, melons, cucumbers from the cucurbit family and some types of nightshades.

In addition to the listed diseases, in the garden plot you can encounter the mosaic virus of beets, cabbage, and legumes.

Mosaic patterns are also found on fruit trees and shrubs, ornamental grasses and tuberous flowers (tulips, lilies, daffodils, hyacinths, dahlias).

Symptoms

In the first week, the stems may wilt, but when the temperature drops, they recover. Then bright symptoms appear:

Light specks appear on the bushes, which increase in size and turn into a mosaic spotting of light green and dark green shades.
The stems wrinkle, become deformed, and can become thread-like.
Thread-like leaves have cup-shaped or ear-shaped tubercles on the underside (they are called enation, and enation mosaic is considered one of the most dangerous subspecies).
The fruits become smaller and ripen unevenly.
Dark gray-green areas appear inside the eggs; over time, they die and partial necrosis develops.
Bunches of dead blood vessels are visible through the skin in the form of a brown mesh.

The fruits of a diseased plant should not be eaten.

Distribution routes

The mosaic virus is resistant to negative factors. It does not die at extremely high and low temperatures. It overwinters successfully in the garden on plant debris in the soil, on host plants, and remains active in collected seeds.

If the source is seeds, then signs of infection appear in the early stages of seedling development. If it all started during planting, then external signs appear within a month.

The common cucumber mosaic actively develops when the temperature drops sharply, while the speckled and tomato mosaic, on the contrary, “bloom” at an ambient temperature of 30°C and above.

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A healthy plant can be infected during picking, pinching or grafting. In this case, the virus is transmitted through gardening tools and tools.

The spread of the disease in the area is also caused by sucking pests (aphids, mites). 70 species of aphids are known to carry mosaic disease. After the virus enters the body of an insect, it goes through an incubation period (multiplies) and at the next “meal” it is transmitted to the tissues of a healthy plant.

The speed of spread is affected by the age of the plant and growing conditions. Young seedlings experiencing various types of stress (high or low air and soil temperatures, lack of moisture or nutrients) are more often susceptible to diseases.

History of discovery

In 1886, Danish scientist Adolf Meyer showed that tobacco mosaic disease was transmitted from one plant to another.
In 1892, Russian botanist Dmitry Ivanovsky tried to isolate the causative agent of this disease. He showed that an extract from a mosaic plant retained its infectious properties even after passing through a ceramic filter with pores that retained the smallest bacteria known at that time. Further studies, in particular those carried out by Martinus Beerink in 1898-1900, made it possible to fully appreciate the significance of Ivanovsky’s discovery. He noticed that the tobacco mosaic pathogen reproduces only in living cells, but can persist in a dried state for a long time. It was Beerinck who began the teachings about viruses, which he called lat. "Contagium vivum fluidum" - live soluble microbes.

1935 Wendell Stanley finally showed that the tobacco mosaic virus is not a liquid, but exists in the form of small particles, which, however, are strikingly different from other microorganisms in that they can be crystallized as a chemical substance due to the simplicity and homogeneity of the structure. In the 1930s, electron microscopes also began to be used to study biological objects. The first STM electron micrograph was published in 1939.

Mosaic Protection Plan

You need to understand that it is almost impossible to cure an infected plant. Therefore, the main task is to prevent the spread of the virus in the area.

Despite the variety of viruses that cause spotting, they all have the same ways of spreading. And accordingly, methods of prevention and protection are similar for different cultures.

To prevent infection, you must adhere to the following action plan:

carry out pre-sowing seed treatment;
disinfect the soil before planting crops susceptible to the disease;
treat the garden with insecticides and acaricides that act on sucking insects (disease carriers);
treat with preventive fungicides.

Choosing drugs

To destroy the virus contained in the seed material, before sowing, the seeds are soaked for at least 50 minutes in a 15% solution of trisodium phosphate or potassium permanganate. After chemical treatment, the seeds are spilled with hot water.

At a temperature of 60-70°C, the common cucumber mosaic dies in 10 minutes, and heat treatment is not effective for the speckled and tomato virus.

To treat seeds, you can use the fungicide Maxim or Lamador. These drugs not only fight viruses and bacteria, but also increase plant immunity.

Soil disinfection can be carried out with any fungicide with a wide spectrum of action. If the virus was detected on indoor plants, then the fertile layer 10 cm thick is removed. Then the entire greenhouse (racks, walls, soil) is treated with a 0.5% trisodium phosphate solution.

When the first affected plants are detected, it is urgent to treat all plantings with Aktara or Aktellik. Insecticides will quickly destroy insects and you can hope that neighboring plants will not be infected.

Iodine helps us

If mosaics are extremely rare in a garden plot, then you can try more gentle preparations.

For example, it has long been known that iodine has a beneficial effect on the soil, increases plant immunity, helps in the fight against infectious diseases and reduces the number of harmful insects.

You can prepare a solution based on iodine yourself or purchase a ready-made factory preparation. Farmayod is produced in liquid form from 10% iodine and surfactants. It is diluted with water and used for:

soil disinfection;
disinfection of greenhouses;
seed treatment;
spraying plants.

A solution for preventive spraying of beds with tomatoes and cucumbers is prepared from 7-10 ml per 10 liters of water. The fruits are suitable for consumption 3 days after processing.

If a bed of cucumbers is 20-40% infected, then you can save the crop with skim milk. For spraying, 1 liter of milk is diluted in 10 liters of water. To increase efficiency, add 0.1% iodine solution.

Life cycle

After entering the cell, STM first of all “undresses,” that is, it releases its RNA. This is due to the special properties of the capsid proteins; they contain clusters of acidic amino acids that are stable outside the cell in the presence of a sufficient amount of calcium ions. However, in the cytoplasm of low calcium concentrations, they repel each other, which is why the first few protomers leave the capsid.

Since the STM capsid consists of only one type of protein that spontaneously combines with purified viral RNA, the collection of STM particles could be studied in detail. The process begins with the formation of flat two-layer disks, 17 proteins in each circle, and proteins from such disks are attached to the OAS site.

Origin of assembly") of viral RNA located between nucleotides 5,444 and 5,518. In this case, the disk takes the form of a spring washer and contains 16.3 proteins in each circle. Subsequently, more and more disks are added to the structure, accompanied by a change in their conformation. The RNA then passes through a channel in the center of the rod, and as it grows, it fits into a helix.

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