What is the reason for the mosaic arrangement of leaves? Leaf arrangement

Leaf mosaic is a phenomenon in which leaves are located in space on the shoots of one individual in such a way that their plates do not shade each other, the arrangement of plant leaves in the same plane, usually perpendicular to the direction of the light rays, which ensures the least shading of each other's leaves. L. m. is the result of the uneven growth of leaf petioles and leaf blades, which stretch towards the light (see Phototropism) and fill every illuminated gap (Maple leaves are arranged in a mosaic pattern). In this regard, the size and even shape of the leaves often change. L. m. can be observed on horizontal, less often on vertical branches of trees and shrubs in conditions of significant shading (lower branches of the crown of elm, linden, maple), on creeping shoots of grasses (hoofed grass), on rosette shoots (geranium, plantain, dandelion). L. m. is an important adaptation to the maximum use of diffused light and can be formed with any type of leaf arrangement - spiral, opposite, whorled.
Phototropism
(from photo..

and Greek tropos - turn), a change in the direction of growth of plant organs under the influence of one-sidedly incident light. There are positive ph., for example, the bending of a stem towards a light source, plagiotropism, or diatropism, of leaf blades that become at an angle to the incident light, and negative ph., the bending of an organ in the direction opposite to the light source (for example, the tips of some roots, ivy stems). . The same organ can be positively phototropic in weak light, negatively in strong light, and not show any phototropism at all in medium light. The ability for phlegm is not the same in plants of different species. It can also change in plants of the same species (in young individuals, ceteris paribus, it is always greater than in older ones), and in the same plant it is found in younger organs. The shape of the stems and leaves contributes to the uniform arrangement of leaves on the plant, as a result of which they little shade each other (see Leaf mosaic); Thanks to positive F., as well as negative geotropism, the tops of the seedlings reach the soil surface even when the seeds are planted very deeply.
The process of photolysis is composed of a number of sequential reactions: the perception of light stimulation, excitation of cells and tissues, transmission of excitation to the cells and tissues of the growth zone of the organ, and, finally, strengthening or weakening of the growth of cells and tissues of this zone, entailing photolysis. The perception of light excitation is carried out a specific photoactive complex, which includes carotenoids and flavin pigments. The conduction of excitation through the plant occurs with the participation of bioelectric currents, as well as plant hormones - auxins.
Unfortunately, I can’t place a picture—the “Insert Photo” function doesn’t work:((

Mosaics have been used for quite a long time to decorate gardens, patios and ponds.

Such beauty had previously only been seen in rich houses.

It was considered the calling card of the palace nobility and kings.
Nowadays, mosaics can be found in the design of country houses and plots.

It is no longer so inaccessible, and anyone can decorate their garden plot with palace chic.

Where to use mosaic?

Laying out garden paths, platforms, patios, garden furniture (tabletops, benches), vertical mosaics on the walls, fences, decorating pools, fountains, mini-pond decor for garden flowerpots, mosaic decoration of various decorative elements in the garden (garden sculpture, decor)

Mosaic materials

Materials for laying mosaics can be very different, depending on the chosen area of use:

shells, river stones, pebbles, fragments of tiles, which are more suitable for laying out paths, steps, broken borders of ceramic dishes, fragments of mirrors, glass, fragments of disks are suitable for laying out patterns on walls and fences, decorating flowerpots, benches and tabletops as a material for in mosaics, you can use coins, bottle caps, decorative chips and colored quartz sand, beads and buttons. Materials with a glossy surface create an incredible 3D effect, as each particle of the pattern shimmers with its own colors. You can lay out the mosaic either on a flat, flat surface or on a raised, convex surface, which will look even more interesting. When laying mosaics on a concrete surface, it is better to use dry construction mixtures; for a wooden surface, waterproof adhesives can serve as the basis.

Mosaic garden paths

A path paved with mosaics significantly changes the perception of the entire yard. At the same time, it should not only be beautiful, but also practical, so the ideal material would be pebbles (plain or colored), approximately the same size. You can make the entire path using the mosaic technique or combine the mosaic with concrete or brick segments.
A small yard can be completely tiled. This will give the impression of carpeting and the yard will become very cozy. For a large area, covering one or several areas is suitable - this could be an area near the pool, a dining area or a relaxation area. The mosaic is laid out with contrasting stripes or any geometric pattern of your choice. If there is a staircase in the landscape of your site, you can mosaic its steps.

Mosaic in the design of the pool

The pool itself is an interesting and vibrant object. And in a duet with a mosaic, it will become the center of the compositional design of the yard. The shimmering water and mosaics will sparkle with rainbow highlights. You can use mosaics to line the pool bowl and its outer edges. More often they use mosaic ceramic or glass tiles in one or two shades. A pool lined with a ready-made mosaic panel with a complex pattern will look impressive. Such panels are applied to the bottom, walls and sides of the pool. A small shallow pool can be decorated in SPA style. Line the bottom of the pool with pebbles and you will have the opportunity to receive a free foot massage.
You can also decorate a fountain or mini-pond with mosaics.

Vertical mosaic

Mosaic paintings laid out on the wall of a house or fence look stylish and original. You can cover the entire wall adjacent to the recreation area with mosaics, which will complete the composition. Any supporting posts and columns will also be an excellent surface for your creativity.

Garden furniture

Mosaic furniture is something! Place a table decorated with mosaics in the dining area or place a chic, bright chair in the shade. Mosaics made from ceramic or glass shards are practical for everyday use; you can remove any stain without any problems. Any other garden furniture, be it made of concrete, metal or wood, can also be decorated with mosaics. It is better to lay out the bench and chairs with mosaics to match the style of the tabletop. Remember that on a hot day such a bench will accumulate heat, but on a cool evening you can cover it with a blanket.

Mosaic flowerpots

Do you want to focus on flowers? Decorate flowerpots and containers with mosaics. Suitable materials for this would be fragments of mirrors and glass, fragments of CDs or broken ceramics. You can also use buttons, beads or coins. For bright, variegated colors, choose a mosaic of muted shades and vice versa. The borders around the flower beds are also decorated with mosaics. Use a single-color cladding to create a formal look, or a colored mosaic to accent a flower bed.

Here the flight of your imagination is not limited. You can mosaic a garden lamp, a birdhouse or feeder, a mailbox and house number, a garden figurine, or just a large stone. Such bright decorative elements will not go unnoticed.

Garden stained glass

Separately, you can consider this method of decoration as garden stained glass. It is also a variant of mosaic. It is rarely used in outdoor decorations, considering glass to be impractical and fragile. But you take the risk of using stained glass patterns in the decor of your garden, and you will see how colored glass, playing in the sun, will enliven your decor. You can decorate with stained glass gazebos, screens and pergolas, metal forged railings and fences, garden lamps and various decorative elements.

DIY mosaic

Try yourself as a decorative artist and decorate your tabletop with mosaics. This is an ideal option for experimentation, as it involves a small area and a flat surface. Broken tiles, glass, fragments of ceramic or porcelain dishes can be used as mosaic material.

What other tools will you need:

cutter or tongs rubber hammer tile adhesive cement mortar grout sponge Start by sketching out a sketch of the pattern. Wipe the table from dust, apply a layer of tile adhesive (preferably cement-based) to the tabletop. Place your mosaic on this mass, pressing it well into the solution. After complete installation, fill the seams with grout, wash off the excess with a wet sponge, and then wipe with a dry cloth. The next day, wipe the surface again with a damp sponge. That's all, your original tabletop is ready. All you have to do is wait a couple of days for it to dry completely and you can invite your friends for a tea party! They will definitely appreciate your efforts!

Biology 7th grade. What is sheet mosaic?

FIRST OPTION

Leaf Mosaic - The virus appears on the leaves in the form of specific patterns. It is impossible to cure..

SECOND OPTION

Sheet mosaic

Leaf mosaic is a phenomenon in which leaves are located in space on the shoots of one individual in such a way that their blades do not shade each other. Leaf mosaic allows the plant to more efficiently use the sunlight falling on it.

Leaf mosaic:

causes the formation of light and shadow effects under the tree crown;
will add picturesqueness and originality to the appearance of the plant. .

What is leaf mosaic? arrangement of plant leaves which provides the best supply of sunlight, characteristic of shade-tolerant plants such as Common Ivy.

With leaf mosaic, the leaves, due to the uneven growth of the petioles and leaf blades, are located in the same plane, usually perpendicular to the direction of the light rays, so that the least shading of the leaf blades is achieved.

Also sometimes called sheet mosaic mosaic plant diseases. These are plant diseases caused by a virus, which are characterized by pstraya, i.e. mosaic, coloring of leaves and fruits, alternation of spots of various sizes and shapes, colored green of varying intensity.

Leaf mosaic is the result of uneven growth of leaf petioles and leaf blades, which stretch towards the light and fill every illuminated gap. In this regard, the size and even shape of the leaves often change. Leaf mosaic can be observed on horizontal, less often on vertical branches of trees and shrubs in conditions of significant shading (lower branches of the crown of elm, linden, maple), on creeping shoots of grasses (hoofed grass), on rosette shoots (geranium, plantain, dandelion). Leaf mosaic is an important adaptation to the maximum use of diffused light and can be formed with any type of leaf arrangement: spiral, opposite, whorled.

Leaf mosaic is the arrangement of plant leaves in one plane, usually perpendicular to the direction of the light rays, which ensures the least shading of each other's leaves.

Leaf mosaic is a phenomenon in which leaves are located in space on the shoots of one individual in such a way that their blades do not shade each other. Leaf mosaic allows the plant to more efficiently use the sunlight falling on it. Leaf mosaic:

Leaf arrangement is the order in which the leaves are arranged on the stem.

There are 3 main types of leaf arrangement:

Regular or spiral

characterized by the fact that the leaves sit on the stem one at a time, alternating with each other (in birch, apple trees, roses);

Opposite

From the node there are 2 leaves, located one opposite the other (lilac, jasmine, mint);

Whorled

3 or more leaves extend from the node (elodea, crow's eye, oleander). The leaves are placed on the plant in such a way as not to shade each other - in the form of a leaf mosaic. This allows you to use the sun's rays more efficiently. The total leaf area is many times greater than the area occupied by the plant itself.

Tiered categories are nothing more than sheet formations, i.e. types of leaves of the same shoot, which differ in shape and location on the shoot. There are 3 types of leaves:
- riding - develop in the area of the inflorescence, these are bracts. They are underdeveloped, with a weakly dissected leaf blade, green (they can attract pollinators and in this case be brightly colored);
- median - develop in the middle part of the shoot. They are green (perform the function of assimilation), have the largest size, the leaf blade is characterized by the greatest degree of dissection;
- grassroots - develop in the lower part of the shoot. They are white at first, then turn brown as the leaves age, and when they die, they turn black. They perform the function of protection or storage, or both.

Leaf mosaic- arrangement of plant leaves in one plane, usually perpendicular to the direction of the light rays, which ensures the least shading of each other by the leaves.

Leaf mosaic is the result of uneven growth of leaf petioles and leaf blades, which stretch towards the light and fill every illuminated gap. In this regard, the size and even shape of the leaves often change. Leaf mosaic can be observed on horizontal, less often on vertical branches of trees and shrubs in conditions of significant shading (lower branches of the crown of elm, linden, maple), on creeping shoots of grasses (hoofed grass), on rosette shoots (geranium, plantain, dandelion). Leaf mosaic is an important adaptation to the maximum use of diffused light and can be formed with any type of leaf arrangement - spiral, opposite, whorled.

The lifespan of green leaves developed on a shoot varies among different plant species and ranges from 2-3 weeks to 20 years or more. In general, it should be noted that the leaves of perennial plants, compared to the stem and root, have the shortest lifespan. This is apparently due to the fact that the leaf tissues, once formed, are no longer renewed, but on the other hand, the leaves function very actively during their relatively short life.

Different types of plants deciduous and evergreen. The former are characterized by the fact that they are in a leafless state for a certain period every year, and this period usually coincides with unfavorable environmental conditions. For example, most of our trees and shrubs do not have leaves in winter.

Evergreens are characterized by the presence of green leaves throughout the year. But this does not mean that their leaf is preserved and functions forever, throughout the life of the individual. Evergreen plants also have leaf fall, but older leaves fall from the plant and leaves formed at a later date are always preserved.

Tropical rainforests are characterized by evergreen plants, although among them there are plants with leaves that last less than a year. But during this period of time, the buds manage to open repeatedly and give rise to new leafy shoots. Plants with leaves that last for several years are also common in tropical forests. There are plants that, although for a short period of time a year, can be in a leafless state.

Evergreen plants near Moscow - spruce and pine - have leaves that last for 5-7 (spruce) and 2-4 (pine) years. The life span of spruce needles is longer in plants growing in the region of the Kola Peninsula and the Subpolar Urals, where it reaches 12-16, and in some cases 18 (22) years. The needles of the Tien Shan spruce (Picea schgenkiana F. et. M.) are preserved for a long time in the Trans-Ili Alatau, where leaves of 26-28 years of age were found.

Leaf fall- a biological process caused by the development of a plant organism and its vital activity. Leaf fall is preceded by leaf aging: the intensity of life processes occurring in its cells (photosynthesis, respiration) decreases, the content of ribonucleic acid, nitrogen and potassium compounds decreases. Hydrolysis predominates over the synthesis of substances; end products of breakdown (for example, calcium oxalate crystals) accumulate in cells. The most valuable mineral and plastic compounds leave the leaves. Their outflow usually coincides either with the formation and growth of new organs, or with the deposition of reserve substances into ready-made storage tissues. In experiments, it was possible to extend the life of leaves by removing buds or other formations on the plant, which could receive plastic and mineral substances from the leaves. The transfer of substances to places of their reuse is considered as one of the reasons for the aging and falling of leaves.

Thus, the lifespan of a leaf is determined by the processes of growth and development of the plant organism as a whole.

During leaf fall, the leaves of most trees and shrubs change color and become yellow or purple. Their yellow color is due to the pigments of plastids (carotene and xanthophyll) and cell sap (flavones).

The reddish-purple color of the leaves is ensured by the accumulation of anthocyanin pigment in the cell sap, which changes its color depending on the pH of the environment. In an alkaline environment, anthocyanin takes on a bluish-blue color, and in an acidic environment, it takes on a pink-purple color. Some plants (alder, lilac) have leaves that remain green until they die.

In addition to the biochemical transformations that occur in the leaves before they fall, anatomical changes are also observed at the base of the leaf. Cells of the separating layer are laid perpendicular to the longitudinal axis of the petiole near the stem. The intercellular substance connecting these cells becomes mucus, and the cells separate from each other. At the site where the leaf separates from the side of the stem, by this time layers of cells are formed, the shells of which become suberized. The resulting layer of cork protects the internal tissues of the stem in place of the separated leaf.

After the formation of the separating layer and disruption of the connection between the cells, the leaf continues to remain on the tree for some time thanks to the conducting bundles connecting the leaf to the stem. But there comes a moment when this connection is disrupted, and the leaves fall.

21. types of reproduction of higher plants. Methods of vegetative propagation

Plant propagation. One of the essential properties of a living organism is the reproduction of offspring, that is, the ability of one individual to give rise to a whole series of similar daughter individuals, or at least one.

There are two fundamentally different methods of reproduction: sexual and asexual.

Asexual reproduction.

There are two types of asexual reproduction: vegetative and actually asexual. In some lower plants there is no clear boundary between these types of reproduction.

Vegetative propagation.

It is carried out by parts of the thallus, root, stem, leaf. It is based on the ability of plants to regenerate - the restoration of a whole organism from its part.

In unicellular plants (algae), vegetative reproduction occurs by cell division, in colonial and lower multicellular plants - by dividing the thallus into parts.

In higher plants, vegetative propagation is carried out by parts of the root, stem, leaf or their modifications - rhizomes, tubers, bulbs, brood buds. Based on natural vegetative propagation in agricultural practice, various methods of artificial vegetative propagation of vegetable, fruit and ornamental plants have been developed. For this, the most commonly used are: tubers (potatoes, sweet potatoes, dahlias), rhizomes (iris, phlox), tendrils (strawberries), bulbs (onions, tulips), root suckers (raspberries, cherries). Many cultivated plants are propagated by cuttings, layering, and also by grafting.

Propagation by cuttings. A cutting is a section of a shoot, root, or leaf cut off from the mother plant. When propagating by cuttings, you must remember the law of polarity.

Shoot cuttings can be winter - without leaves (but with buds), 20 - 30 cm long, at the age of 1 - 3 years, and summer - with leaves, 3 - 4 cm long, from the shoots of the current year.

Leaf cuttings consists of a leaf blade and a petiole. Adventitious roots appear more often on the morphologically lower side of the leaf in places where large veins branch; buds, and then shoots, appear on the upper side. Only a few plants (lily, begonia, aloe, etc.) can be propagated by leaf cuttings.

Root cuttings propagate plant species whose roots easily form adventitious buds (raspberries, cherries, plums, date palms, roses, phlox, etc.).

Reproduction by grafting. Grafting is the fusion of cut buds or stem cuttings of one plant (propagated) with another (rooted). In this case, the propagated plant is called scion, and the plant to which it is grafted is rootstock.

About 100 different methods of vaccination are known, but they can be reduced to three main types:

grafting by proximity, or ablation, - the scion is not separated from the mother plant before merging with the rootstock;

grafting by cuttings, or copulation, - on annual cuttings of the scion with 2-3 buds and on the stem of the rootstock, oblique cuts are made and applied to each other, while the stems of the scion and rootstock are selected to be of the same thickness so that their cambial layers coincide. If the diameters of the scion and rootstock do not match, then grafting is done split, under the bark, in the butt or by other means;

inoculation, or budding, - the scion is a dormant or growing bud, separated from the middle part of the shoot of the propagated plant, which is inserted under the bark of the rootstock.

Fusion occurs best if the scion and rootstock belong to the same species or related species of the same genus, but if they belong to different genera, fusion is difficult.

If you ask a competent botanist or biologist the question of what leaf mosaic is, you will probably get an answer that will surprise you: clarify what phenomenon you are talking about. And really, what did we mean?

It turns out that leaf mosaic is an amazing phenomenon and property of plants that Mother Nature has endowed them with. The leaves on the trees, in relation to the light flux, are positioned in such a way as to receive maximum solar energy, while distributing it evenly to everyone, without shading each other. Thus, leaf mosaic promotes maximum use of air, heat flow, space and light by the plant.

Another phenomenon is the complete opposite of the first.

Mosaic, mosaic disease or leaf mosaic. No matter what you call this viral phenomenon, the danger, severity and unenviable fate for the plant itself are unlikely to change for the better.

What is plant leaf mosaic virus?

This is perhaps one of the most harmful plant diseases. Viruses are to blame for its occurrence and spread.

Moreover, each type of green crop has its own viral enemies:

For tobacco and tomato – this is Nicotina virus 1.
The emerald coloring of cucumbers is changed by Cummis virus 2.
The Solanum virus 1 and S. virus 2 viruses are involved in the occurrence of speckled and wrinkled potato mosaics.
Beta virus 2 is to blame for the beetroot mosaic.
Brassica virus 3 “attacks” cabbage, soybeans, peas, beans, ornamental plants, fruit trees and shrubs.

The disease is called leaf mosaic because the leaves of the plant are the most vulnerable and are the first to suffer.

If you do not take into account the severity of the disease and the lethal consequences for the green crop, the mosaic color of the leaf looks fun and funny, and in some way, even aesthetically pleasing and beautiful.

The variegated coloring of the affected leaves catches your eye - an alternation of spotted formations, varying in shape, size and intensity of green color.

Viruses, regardless of their type, kill the culture at the cellular level. Fundamental pathology manifests itself in chlorophyll-bearing tissues, which leads to a decrease in photosynthesis. The foliage does not receive the required amount of carbohydrates, and cells and entire sections of leaf tissue die.

Types and ways of spreading the disease

In the previous section we talked about viruses that provoke mosaic on certain plants. According to the names of the crops, varieties of garden scourge were formed.

The greatest harm and danger comes from the mosaic of fruit trees and shrubs, tomatoes, tobacco, beets, cabbage, soybeans, peas, white and green cucumber mosaics, speckled and wrinkled potatoes, as well as ornamental plants, especially.

Rose affected by mosaic disease

It should be noted with regret that the number of communication channels for the spread of garden infections is very large. And the big problem is to completely cover them.

The pathogenic virus easily penetrates through planting material, seeds and infected seedlings, during picking through the sap of diseased plants, during pinching, through direct contact of infected and healthy individuals, as well as during banal injury.

Everything would be fine if gardeners were only concerned about these problems. However, viruses still have enough assistants, a kind of mobile vehicles - ticks, aphids, bedbugs. Moving around the area, they easily spread the mosaic pest.

It is worth noting that a comfortable environment for the development of the virus is the density of plants, temperature changes with maximum readings above 25 degrees.

How to recognize the disease?

The pest is easiest to spot on young shoots.

Characteristic visual manifestations:

Mosaic leaf spotting, which changes their structure.
Spots of irregular shape, different in size and color - from whitish to light yellow and bright green.
Pathology in development is noted, plant growth slows down.
The access to water decreases - the crop becomes limp and withers. New shoots and stems that have just appeared begin to dry out.
The fruits become covered with brown spots, which turn into rot. They are not suitable for feeding even livestock.

Depending on the type of green crop, mosaic disease has exclusive symptoms.

Fruit trees - it has been noted that the pear is the least protected genus of fruit crops from the virus.

Signs of damage:

The bark and large branches are scarred.
Foliage, especially young ones, is covered with “camouflage” spots.
Hard formations appear deep in the fruit, it changes shape, the core turns brown, rots, and the yield is significantly reduced.

Diseased pear leaf

Mosaic on flowers:

The leaves are cut with yellow arrows and brown lines.
The buds become smaller before they have time to bloom and complete flowering. The flower itself withers, dries up, fades away and dies.
The flowering period is unusually short or does not begin at all.

Mosaic on berry bushes - almost all varieties of raspberries, most currants, gooseberries, and grapes are affected.

Visual symptoms:

Leaf chlorosis is clearly visible - disturbances in the formation of chlorophyll. The foliage becomes discolored, losing its characteristic green color.
In appearance, the plane of the leaf appears scorched. The edges and corners are rolled up.
Young shoots are significantly retarded in growth.
Soon the virus completely disfigures the bush. It is decorated with yellow-brown spots of various sizes.

Potato mosaic disease:

Longitudinal stripes appear on the stem and upper crown.
The bush slows down its growth. The leaves become rough and smaller.
The disease, rushing downwards, affects the roots. The tubers change shape, as if turning inside out. They lose their taste and are unsuitable for food.

Tomato mosaic is the most common problem for this crop. It is popularly called tomato burn.

External manifestation:

The foliage is torn to a mottled color.
Dark green and light formations appear on the fruits.
The tomato becomes deformed, the inside turns black and rots.

Tomato mosaic disease

Common mosaic on cucumbers:

At the early stage of the disease, the stems of the seedlings become bent and the leaves become covered with mosaic spots.
As the disease progresses, they dry out and curl.
The number and size of flowers are significantly reduced.
With severe damage, the flowers dry out without completing the entire cycle.
The stem becomes faded or almost transparent, and cracks appear on it.
The fruits curl, covered with yellow and brown spots.
The bush, drying out, fades away before our eyes.

Cucumbers affected by mosaic disease

Cabbage virus:

The veins on the leaves become lighter.
Black spots are formed, characterizing necrosis.
The leaf loses its shape and wrinkles.
The stem rots, becomes brittle and unstable.

Black spots on the head of cabbage are a sign of mosaic disease

It is worth noting that there are no varieties of cabbage that would resist this natural disease.

Disease on peas and beans:

The leaves take on a curly, crumpled shape.
Whitish and yellow spots form on the surface.
After a stem disease, rosettes of diseased leaves appear on the lower tier.
Plant growth slows down significantly.
Yellow and brown spots scatter throughout the pods. They turn black and rot.

Mosaic on radish and radish:

The leaf is covered with a mosaic scattering.
Its shape changes, the veins darken.
Growth is slowing down significantly.
Black spots appear on the root crop, which turn into rot.
The fruit is small and unsuitable for food.

Fighting methods

The most unpleasant thing in the fight against the disease is the fact that science cannot yet offer effective means of protection. Each gardener or gardener uses his own experience or recommendations taken from various sources or communication with colleagues.

If the infection is local, then partial removal of the diseased areas is used. To do this, cut off the diseased parts (branches, shoots) with a disinfected knife. After such an operation, the entire plant is sanitized by making a solution of ten liters of water and 75 grams of Karbofos.

The cut areas can be treated with a different composition - mix a weak solution of potassium permanganate with crushed charcoal.

But if we are talking about affecting a large area, then there is only a radical way - diseased plants are removed and burned.

After diseased plants are destroyed, remove and dispose of soil to a depth of 10 centimeters.

If viruses have taken over the greenhouse, then after removing all the crops, thoroughly disinfect them using a half-percent solution of trisodium phosphate.

It will not be superfluous to carefully process and boil the clothes in which you carried out the treatment, since the virus may remain in a “dormant” state for many years.

Prevention

As it becomes clear from the previous section, due to the fact that scientists have not yet proposed effective means to combat leaf mosaics, the main hopes are placed on preventive measures in order to minimize the reproduction of harmful viruses in your yard.

Purchase planting material only from reliable specialized stores.
Carefully study the characteristics of planting material, trying to select varieties that are resistant to the virus.
Considering that different types of garden crops are susceptible to infection by different viruses, alternate them between planting seasons in greenhouses and in open areas.
Carefully remove remaining plants from greenhouses and open ground. Especially when it comes to sick specimens.
Clean the soil in the greenhouse to a depth of ten centimeters, and in the spring replace it with new, treated soil.
Don't chase to save space. Dense beds are an ideal habitat for the garden enemy.
When caring for plants (garter), do not use last year's twine.
When removing diseased plants, treat the soil with bleach. Rinse the garden tools that were used to remove infected crops with the same solution.
Plan your future beds carefully. Avoid planting cucumbers close to ornamental plants.
Remember that carriers of viruses are aphids, bedbugs,... Therefore, take proactive measures to eliminate them.

Viruses that cause mosaic plant disease are a dangerous, hidden and insidious enemy. It is difficult to fight them, but possible. Hard work and diligent implementation of all recommendations are the key to victory over your garden enemies.

LEAF MOSAIC

mosaic, arrangement of plant leaves in one plane, usually perpendicular to the direction of the light rays, which ensures the least shading of each other by the leaves. L. m. is the result of uneven growth of leaf petioles and leaf blades, which stretch towards the light (see Phototropism) and fill every illuminated gap (see figure). In this regard, the size and even shape of the leaves often change. L. m. can be observed on horizontal, less often on vertical branches of trees and shrubs in conditions of significant shading (lower branches of the crown of elm, linden, maple), on creeping shoots of grasses (hoofed grass), on rosette shoots (geranium, plantain, dandelion). L. m. is an important adaptation to the maximum use of diffused light and can be formed with any type of leaf arrangement - spiral, opposite, whorled.

Great Soviet Encyclopedia, TSB. 2012

How to recognize the disease and its manifestations

Mosaic is a disease whose main characteristics are patches of green and white 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 the 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 was 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.

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.

How it spreads

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.

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.

The soil under the root is a breeding ground for infection because it may contain plant debris such as fallen leaves. High humidity and air temperature +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.

Main affected crops

Unfortunately, mosaic has many varieties and affects almost all agricultural and horticultural crops. You can get rid of it or prevent its spread only at an early stage. It is necessary to identify diseased plants and destroy them to preserve healthy ones.

On fruit trees

The causative agent is subcutaneous spotted mosaic. Most often the pear tree suffers. Signs of damage to fruit trees:

cracks in the bark and main branches;
the foliage becomes covered with mosaic spots;
Hard clusters form in the fruits, the shape changes, the flesh darkens;
Productivity drops sharply.

On flowers

The mosaic appears as follows:

yellow arrows and lines appear on the shoots and stems;
the flowers become small, sluggish, acquire a greenish tint, most of them fall off;
The flowering period ends faster than usual.

The disease easily spreads to neighboring rose bushes, destroying entire plantings and beds.

Berries

They are affected by vein mosaics. Characteristics:

chlorosis of leaf veins (marks of different colors), curling of the edges, leaves seem to be scorched;
the development of young shoots is reduced;
affects the entire bush, covering it with yellow angular spots.

Many varieties of raspberries and other fruit and berry crops, such as currants, grapes, gooseberries, etc., are affected.

Potato

Potato bushes are affected by a type of mosaic called banded. The first characteristic manifestations:

longitudinal stripes are clearly visible on the upper tissues and stems;
they become rough and decrease in size;
affects tubers, they become spindle-shaped.

As a result, potato fruits lose their taste and yield decreases. Banded mosaic affects the entire plant and leads to its death.

Tomatoes

Tomato mosaic is the most common disease of this species. It is also called a burn. Characteristic features:

The leaves acquire a bright spotted color;
light and dark green marks appear on the fruits;
deformation and blackening of tomato pulp followed by rotting.

Due to tomato mosaic, you can lose up to 20% of the harvest. That is why it is necessary to use only high-quality and healthy seeds for planting.

cucumbers

Cucumbers are most often infected with mosaic mosaic. Symptoms:

curvature of stems and spotting of leaves while still in seedlings;
over time they dry out and curl up;
cracks in the stems;
the number of flowers and their size decreases;
Cucumber fruits are often curled and covered with yellow spots.

With severe damage, flowers may dry out, and the stem becomes almost transparent or faded. The entire bush loses color and withers.

Cabbage

Manifestations of cabbage mosaic:

the veins become lighter;
dotted spots of necrosis appear;
tissues lose shape and wrinkle;
the stem becomes brittle and breaks easily.

Affects almost all types of cabbage.

Radish

Both radishes and radishes are affected by the virus. Symptoms:

mosaic, change in shape, darkening of veins;
growth slowdown;
the appearance of black spots on vegetables, small fruit.

May be expressed differently in different varieties.

Peas

It is most often affected by the deforming mosaic virus, and occasionally by the common mosaic virus. Appears in:

bruising and curling of fabrics;
white and yellow markings on leaves;
slower growth;
spotting of pods, their rotting and blackening.

Peas in pods turn yellow.

Beans

It is most often affected by common mosaic. Symptoms:

the foliage becomes covered with irregularly shaped spots, spins and bubbles;
the stem is affected, and a rosette of diseased leaves forms below;
the seedlings remain dwarf.

The roots are infected along with the soil underneath them. The fruits have an unhealthy faded color.

Methods of prevention and protection

The first and most effective remedy for any disease is prevention.

Prevention methods

To initially eliminate the possibility of mosaic infection and get a good and healthy harvest, you should:

use only healthy material for planting;
fight insects that are carriers of mosaic by performing spring garden treatment;
choose varieties that are more resistant to infection;
destroy infected units along with the soil from under the bushes;
plant the sprouts as far apart as possible;
clear the plantings of weeds;
disinfect the blades of garden tools (with a solution of vitriol - 4 tablespoons per liter of water or potassium permanganate - 2 tablespoons per liter of water).

Prevention for seeds

When purchasing seeds, it is quite difficult to determine their quality. Also, you cannot be sure that they are healthy. Before planting, you can prevent the seeds by keeping them in hot water for half an hour, or disinfect them in a 20% hydrochloric acid solution. The seeds should then be washed and dried.

Treatment

There are no cures for mosaic, as such. The only effective treatment is the destruction of infected bushes and weeds and control of insect vectors.

To disinfect scissors or pruning blades, you can use alcohol (both medical and ordinary vodka will do) or a chlorhexidine solution. When carrying out the pruning procedure, it is necessary to wipe the cutting surface with a cotton swab or cloth soaked in a disinfectant liquid after each use of the tool. Be very careful not to break the stems when maintaining or cultivating the lawn.

If the mosaic has just begun to develop, you can treat all the bushes with a solution of karbofos. To prepare it, dilute 75 g of the drug in 10 liters of water and spray the plantings. This will help protect healthy crops from infection. Severely damaged bushes should be removed immediately.

If mosaics affected crops in a greenhouse, then after harvesting it is necessary to remove all plants along with the top layer of soil (up to 10 cm). Then thoroughly treat the entire greenhouse (including the walls) with a 0.5% trisodium phosphate solution. The clothes you used for disinfection should also be thoroughly boiled and treated, since the mosaic virus can remain on them for several years.

Result:

Mosaic plant disease is quite common. The causative agents are viruses, for which there is no cure yet. The only way to fight is prevention.

Today, selectors are actively working to resolve the issue. Their main task is to develop mosaic-resistant varieties of agricultural crops, which will eradicate the infection and increase plant productivity.