Viral Diseases Of Seedlings And Adult Plants. Causes, Signs, Treatment. Photo

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Viral Diseases Of Seedlings And Adult Plants. Causes, Signs, Treatment. Photo
Viral Diseases Of Seedlings And Adult Plants. Causes, Signs, Treatment. Photo

Video: Viral Diseases Of Seedlings And Adult Plants. Causes, Signs, Treatment. Photo

Video: Viral Diseases Of Seedlings And Adult Plants. Causes, Signs, Treatment. Photo
Video: Plant Disease | Plant | Biology | FuseSchool 2024, March
Anonim

As a passionate gardener, I plant a large number of flowers and vegetables in seedlings every year. Moreover, almost every year I observe the obvious oddities of some of them. Earlier, I tried to find various rational explanations for this behavior of individual seedlings. However, as I became a more experienced grower, I was able to figure out that in many cases I was dealing with viruses. In this article, I would like to talk about the signs of viral plant diseases and about modern methods of combating them.

Viral diseases of seedlings and adult plants
Viral diseases of seedlings and adult plants

Content:

  • How a plant can pick up a virus
  • Signs of viral infection in plants
  • How to differentiate a virus from other plant diseases
  • How to treat viruses in plants
  • Prevention of viral diseases of seedlings

How a plant can pick up a virus

Viruses do not have a cellular structure, but consist of tiny particles (from 20 to 300 nanometers). They can only be seen with an electron microscope. Viruses penetrate into plant cells, where they begin to actively multiply, as a result of which a number of changes in the external appearance of plants can be observed, as well as suppression up to a complete cessation of growth and death.

Affected plants may not bloom at all, or they may dissolve deformed flowers that will not produce seeds. If the plant has been infested after flowering, the virus-infested fruits become severely deformed and grow much smaller. Viruses are very dangerous for agriculture and lead to crop loss. The annual damage from viruses in the world is estimated at about 60 billion US dollars.

There are four main routes of transmission of viruses from plant to plant.

Direct contact. The easiest way to get the virus is through direct contact with broken or broken plants, for example, when transporting seedlings. But often for infection, even rubbing the leaves or stems of a sick and healthy plant against each other is enough. There is evidence that the virus can be transferred even through the dirty hands of a plant breeder, when, having touched infected plants somewhere, he touches others, including his own. It is believed that smokers, in contact with tobacco products, may well transfer the tobacco mosaic virus to their green pets.

Vegetative reproduction. Propagation of plants by cuttings using non-sterile tools also leads to viral contamination. Such cases are especially common in industrial greenhouses. In addition, plant grafting leads to the spread of viruses. If the plants get sick with the virus after flowering, then the virus can also be transmitted to the offspring along with the seeds.

Soil and garden tools. Such ways of transmission of the virus as infection through soil are not uncommon. If you plant a plant in a container where a diseased specimen previously grew, there is a high risk that the new settler will also get sick. Particles of the virus are also spread through tools for soil cultivation: shovels, rakes, looseners, etc. In addition, the virus is actively carried by nematodes in the soil.

Insect pests. The transmission of the virus through harmful insects is the main and most extensive way of infecting plants with viral diseases. According to scientists, 76% of known plant viruses are transmitted by insects. The main vectors are pests with a piercing-sucking and gnawing mouth apparatus (spider mites, aphids, thrips, whitefly and mealybugs). Locusts also carry the virus outdoors. Infecting more and more new plants, pests, at the same time, carry virus particles to other specimens.

Yellowing and rolling of leaves - the beginning of necrosis
Yellowing and rolling of leaves - the beginning of necrosis

Signs of viral infection in plants

Most often, I observed signs of various viruses on summer seedlings grown from professional seeds, and above all - petunias. I cannot determine the reasons for this state of affairs. But if you also grow such annuals through seedlings, you need to be especially careful.

With my own eyes, I had the opportunity to repeatedly observe the mosaic virus (variegated foliage), the curl virus and the virus that causes changes in the color of the leaf blade in the form of separate sectors, painted in unusual shades of green. I naively considered the latter to be some kind of genetic feature that arises in hybrid plants, since the virus, in principle, did not prevent the plants from fully developing.

But the first two greatly slowed down growth and subsequently led to the death of seedlings. However, in any case, it is better not to leave any viruses unattended so as not to contribute to their further spread.

Let's look at what signs of viruses are observed in plants:

Mosaicity is the appearance of an uncharacteristic variegated color on leaves: white or golden streaks, spots, dots, circles, borders, chaotic patterns (for example, Tobacco Mosaic Virus (TMV)).

Variegation - uneven color or discoloration of petals, the appearance of variegated marks, strokes or sectors not characteristic of the variety (for example, tulip variegation virus).

Necrotic spots - death of leaf tissue. Most often it can be a consequence of the progress of leaf mosaic and chlorosis, but it often develops as an independent syndrome. There are both local necrosis (in the places where viruses enter the plant), and systemic, or disseminated necrosis (manifests itself in all parts of the plant). For example, Necrotic Spot Virus (INS).

Chlorosis (jaundice) - yellowing of the tissues of the leaf blades. In this case, the veins can either remain green or turn yellow with the leaf. For example, Tomato Yellow Leaf Virus (TYLCV).

Leaf deformations - leaf twisting in one direction or another, wrinkling, "wrinkling", curly foliage, change in the shape of the leaf blade, tumors on the veins, reduction in leaf size.

Stem deformations - swelling of the stems, curvature of shoots, "overgrowth" (appearance of filamentous shoots).

Anthocyanosis - staining of leaves, edges of leaf blades, veins and stems in purple, red-violet or bluish tones.

Failure to produce offspring - flowers do not open, or flowers and ovaries crumble, set fruits or individual seeds inside the fruit dry out, the appearance of "seedlessness" in fruits. Sterile flowers may also develop.

Inhibition of growth - can manifest itself as dwarfism of plants, shortening of internodes (especially at the tops of the shoots, complete cessation of growth). With severe damage to the vascular system of plants, wilting may occur.

In most cases, the virus does not manifest itself as a single symptom, but combines several different manifestations at once. In particular, curliness is most often combined with inhibition of growth, and variegation is combined with deformation, and so on. In most cases, plants affected by the virus appear depressed. On seedlings, the virus can manifest itself already on the first true leaves.

Leaves acquired an uncharacteristic wrinkled surface and deformed
Leaves acquired an uncharacteristic wrinkled surface and deformed
Young shoots with shortened internodes and small, clumsy foliage, growing points die off, the plant completely stopped growing
Young shoots with shortened internodes and small, clumsy foliage, growing points die off, the plant completely stopped growing

How to differentiate a virus from other plant diseases

Unfortunately, there are currently no available methods that allow an ordinary gardener or florist to diagnose viral diseases in a plant with 100% certainty. In the West, there are special test strips that detect some viruses in various crops, but they are very expensive and are mainly produced for farmers and owners of large greenhouses.

Experienced plant breeders might have noticed that the above symptoms can appear on plants and in the presence of other problems, completely non-viral in nature. In particular, necrosis and spotting are most often a manifestation of fungal and bacterial diseases. Leaf deformations, twisting and chlorosis can be observed under stress and nutritional deficiencies.

Changes in flower color and variegation are sometimes the result of genetic mutations, and new varieties are then obtained from such plants. Necrotic spots also sometimes appear when infested by pests that are not easy to see with the naked eye (thrips, spider mites).

Therefore, before you panic, isolate the plants and try to carry out resuscitation measures: sprinkle with a growth stimulant, treat fungal and bacterial infections, treat with an insecticide, acaricide. If your efforts are unsuccessful, then most likely you still have a virus in front of you.

The pronounced mosaicism and variegation, unfortunately, are most often associated with the manifestation of the virus, and not with mutation, so more drastic measures must be taken here. You need to be especially vigilant when growing seedlings, since later you can bring viruses along with the plant to the site.

How to treat viruses in plants

Until recently, there was only one method of "curing" viral diseases - to destroy the diseased specimen along with the earth and container. And today this method also has a right to exist. If this is not some valuable specimen in the collection of plants, but, for example, a seedling in a separate glass, then it is really easier to destroy it together with the container and soil than to endanger the garden and vegetable garden.

But today we have the opportunity to compete for our green pets with drugs. Such agents as fungicides (antifungal), insecticides (against insects), acaricides (against ticks) and others are well known to us. And now, finally, scientists have managed to get to viruses and get a group of drugs that can fight viral diseases - virucides.

Currently, there are two drugs on the market from the group of virucides from different manufacturers.

Viron. The supplier is the Turkish company Innako, in the territory of our country it was tested and approved by the Association of Producers of Fruits, Berries and Planting Material (APPPM). It is mainly effective against tobacco (54.58%) and cucumber mosaic viruses (71.20%).

The drug enters cells infected with the virus and promotes crystallization and blocking of the virus. As a result, the plant is restored and returns to normal (or close to normal) life. Spraying is best done for prophylaxis (before signs appear).

Processing is carried out four times: the first - 15 days after sowing or emergence of shoots, then - every 10 days. Treatment of a plant with symptoms of the virus is carried out according to a special scheme (available in the instructions for the preparation). Florists note 50% effectiveness of the drug on petunias and 100% effectiveness on pelargoniums.

"Enzyme Phyto" (Enzyme-phyto). This drug is the know-how of Novosibirsk scientists, developed at the Novosibirsk State Agrarian University. Enzyme-Fito is a biological multi-enzyme complex with antiviral activity. In addition, it is effective against powdery mildew and bacterial spot. The main advantage is absolute harmlessness to humans (processing is carried out without protective agents) and pollinating insects (bumblebees, bees). Moreover, he even has a positive effect on the latter.

The solution is applied four times. In this case, after the first treatment, signs of the disease may first appear or intensify. But after the second treatment, young shoots grow back without signs of a virus. After the third treatment, the plant begins to actively grow.

There is also information that certain viruses are inactivated as a result of prolonged exposure to plant tissues at rather high temperatures. And there is such a method of treatment as to sustain seedlings or a collection of plants for 20 to 30 days at a temperature of +38 ° C.

For the prevention of viral diseases of seedlings, timely treatment from pests must be carried out
For the prevention of viral diseases of seedlings, timely treatment from pests must be carried out

Prevention of viral diseases of seedlings

All sowing and planting containers (even new ones) must be disinfected twice with bleach before the new season. Small containers can be boiled if possible. Other disinfection methods will not kill the virus.

All pruning (pinching) tools must be disinfected (eg with pharmaco) after each seedling. When propagating small assortments, it is best to use disposable blades for each plant.

It is necessary to carry out timely processing of seedlings from pests. Regularly carefully inspect plants for the presence of harmful insects and mites.

Do not use used soil for growing seedlings. The virus can be stored in dead plant tissue for up to 50 years, while it overwinters well in the ground.

If possible, you need to isolate the seedlings from indoor flowers as much as possible. Unfortunately, many indoor flowers can be hidden carriers of the virus. In particular, some of the older varieties of orchids originated precisely under the influence of the virus and were mistaken for mutations. The virus can be transmitted to seedlings even from a bouquet of flowers.

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