Scab on potatoes: how to heal the earth to avoid this scourge

Good afternoon! I recently got out a dispute with one especially gifted gardener. It was useless to persuade a person.

He got scab on the potatoes. He decided that the soil was exhausted and that it was necessary to flavor it with fresh manure as much as possible.

I ordered a truck, poured onto the field, and with full confidence waited for an excellent harvest. The result is sad - the scab appeared on the tubers even more. I will tell you in this article about what to do if there is scab on potatoes, how to treat the land and what to avoid.

Heal the soil, not destroy

Gardeners complain that there is a defeat of potato scab. It seems that a separate plot has been allotted, and the varieties are selected good and proven, but there is no crop. And the tubers are very mutilated by the wireworm. What to do?

Of course, you can etch the land in the area with a solution of bleach, but then the soil will lose its ability to protect itself and maintain the balance of beneficial and pathogenic microorganisms.

Potato scab is a fungal disease that persists in the soil for 6-7 years. And since she is given food every year, growing potatoes in the same place, getting rid of her is very difficult.

Scab develops very actively on alkaline soils, and since gardeners often add ash to the soil, it alkalizes even more. With caution, nitrogen fertilizers should also be applied, since nitrates also provoke the development of the disease.

It is undesirable to add fresh manure under the potato, since decomposed plant and organic residues contribute to the development of the disease. But the high humus content is the opposite: the more fertile the soil, the worse the disease feels in it.

Well, of course, on the potato plot you must use siderates. Sow them immediately after harvesting and dig after seedlings. Siderates buried in the soil contribute to the reproduction of saprophytic fungi and bacteria - the natural enemies of scab pathogens.

Reducing the defeat of tubers is very helpful in pre-harvest mowing tops, in about a week. Without tops, tubers ripen faster, integumentary tissues become more dense and invulnerable to scab.

Together, the components of care - crop rotation, sidebreeding - can significantly reduce the number of wireworms.For 2-3 years, you can completely get rid of the pest if you dig it deep, before the onset of stable frosts.

Larvae die in the cold. But in spring, loosening is necessary, because the larvae also can’t tolerate direct sunlight, and the oviposition of beetles also perishes.

You can arrange simple traps: in April, fill small pits with half-ripened grass, moisten and close with boards. The wireworm willingly settles in such pits, and in a few days the grass with larvae can be selected and burned. And in the hole to lay a new batch of grass.

Potato without scab

First of all, you can’t plant potatoes in one place for two to three years, so that the infection does not accumulate in the soil. The land for potatoes should be prepared in advance, cleaned of scab pathogens with the help of green manure, which is used as fertilizer for the soil.

After collecting early vegetables or throughout the season - from spring to the end of summer - sow on the field where you plan to plant potatoes in the future, such green manure as lupine, peas, beans, mustard, rapeseed.

After flowering or the formation of the first fruits in legumes, bury these medicinal plants in the ground to a depth of 15-20 cm. This technique contributes to the development of saprophytic fungi and bacteria in the ground, and they are opponents of the scab pathogens. In addition, green manure improves soil quality.

Keep in mind that the harmfulness of the scab is reduced if you put well-rotted organic matter 2-3 years old (500-600 kg per hundred square meters) into the ground. Mineral fertilizers are useful in which the ratio of nitrogen to phosphorus and potassium is such a proportion - 1: 1, 2: 1, 2: 1,5.

The necessary micronutrients

To make the planted potato more resistant to scab, copper, manganese and boron are applied directly under the bushes. On one hundred square meters, it is necessary to spend 40 g of copper sulfate, 20 g of manganese sulfate and 25 g of boric acid. Water-soluble manganese is especially useful, because scab is especially rampant just when it is lacking.

Lime is the enemy of the soil

In the middle lane it is important not to overdo it with lime (to the south it is even contraindicated). Only small doses of it (5-8 kg per one hundred square meters) can be added together with organics or separately - for seedlings.

It must be remembered that when liming, manganese is less absorbed by potatoes, and the development of scab is enhanced.

Mow the tops before harvesting.

To reduce the damage to plants by scab, water the field from the moment of mass tying of tubers and until they reach 2-3 cm in diameter. At this time, the humidity of the earth in the zone of tuber formation should be at least 75-80%. Be sure to mow the tops a week before harvesting.

Thanks to this method, tubers ripen faster, their integumentary tissues become stronger, which means they will be less vulnerable to scab.

Warnings

Do not feed potatoes with fresh manure and other undecomposed organic fertilizers. Remember that the best predecessors for potatoes are corn, table beets, carrots, cabbage. If your potato is often sick, choose varieties that are more resistant to scab.

We destroy common scab

One of the common diseases is called scab. Scab is a very rare and common fungal disease of potato. It is known in all areas where they grow this vegetable.

Potato scab infects the underground organs of culture. Brown contours, cracks or bulges appear on the tubers. Cracks are the most intense form of scab. It deforms potatoes to the greatest extent.But the disease does not infect one bush, it gets from one to another, infecting the entire plantation.

The subtleties of growing potatoes

Almost everyone is engaged in growing potatoes, because the dishes from this vegetable are everyday and familiar to us. Its large-scale production also occupies one of the initial rating positions in the country. Therefore, the issue of increasing the yield involved all gardeners.

It is ironic that every year, with the advent of new technical means, processing technologies, the annual yield on the contrary decreases. Diseases and insects, getting used to and applying to new strong poisons, poisons, are becoming more stable and harmful. The fight against them is not always effective.

And even if you get at least some kind of crop, a huge percentage that it will be damaged by some kind of insects or disease. Which leads either to the complete utilization of potatoes, or to a significant decrease in its species and taste.

With a light defeat, scab potatoes can not be destroyed, but its taste and external qualities hopelessly deteriorate

Why does the disease appear and how does it develop?

The causative agent of common scab is a microorganism from the category of actinomycetes. This microorganism is in earthen soil, so it is impossible to completely get rid of it. Factors that contribute to the spread of scab determine the temperature and condition of the soil.

The temperature that will be most optimal for the development of the disease is approximately 25-30 degrees.

Average humidity also contributes to the development of scab. But nevertheless, the most located to the scab land is sandy, loose. Organic fertilizer is beneficial for the spread of the disease. Humus, if you do not let it overreact, will be the catalyst that contributed to the growth of scab on your plantations.

Even the potato variety plays a role, some of them are less susceptible to this disease. These are varieties that have long sprouted in a certain area and already have some immunity.

Detecting the scab is very easy. When you are harvesting potatoes, pay attention to the hole. On potatoes you will see something similar to a white mycelium. It will cover the fruits, but in the sun the plaque will quickly disappear.

Ways to fight

A positive fact is that the scab of potatoes is still eradicated, although it is necessary to deal with it with the application of efforts and efforts. This should be a planned, accurate and thought out set of measures and actions for the treatment of potatoes.

What do you need to do, what measures to apply to permanently get rid of the disease:

Use all these tips, and you will at least slightly improve the condition of your landings, even if you can’t completely eradicate the scab, it’s worth constantly fighting it. Healthy potatoes - good appearance, high taste, and hence a high price.

Therefore, do not spare work, it’s worthwhile to work for a good result, control measures should be regular and focused.

Prevention and treatment of potato scab

If vegetables are grown on the site, then most likely there are also potatoes on it. Large areas are allocated for this root crop, so the necessary crop rotation is not always possible to arrange.

Ill tubers do not threaten human health, they are quite suitable for use, but their nutritional value is lower than healthy ones. The starch content in the harvested crop in this case is reduced by almost half.

But these are not all the “gifts” of scab. Such potatoes are poorly stored, rot develops faster in it. A rich harvest can turn into a rich amount of waste: potatoes, which have spent so much effort on growing, are simply thrown away.

Successfully overwintered diseased tubers planted again on the site will not bring a healthy generation. The general defeat of the peel extends to the eyes, they hatch, but give weak shoots, so you can forget about a good harvest.

Such a disease can be ignored for some time, but it tends to spread rapidly, covering more and more tubers, and the spores of the disease are very viable, they can successfully be in the ground for up to 3 years.

Scab forms and signs of failure

Potato scab, like any serious illness, has several varieties. We will provide a description of each here so that you can correctly learn to identify affected tubers.

There are 3 forms of scab:

1. common scab;
2. powdery scab;
3. silver scab.

Common scab develops comfortably at high temperatures (+ 25-30 degrees) and in alkaline soil depleted in moisture. If you performed soil liming on a site, then this is also a favorable factor for the development of potato scab.

The causative agent of the disease is formed on organic residues in the soil and, if favorable conditions are created, passes to the tubers through any mechanical damage to the skin.

Visually, these are ulcers that have an irregular shape, with the growth of potatoes, these areas also grow in size and harden. Sometimes the affected areas form cracks. You can even observe the picture when the potato is completely covered with such formations.

The scab opens the way for the pathogens of rot both dry and wet in tubers. The causative agents of the disease are very viable; they can successfully exist in the soil for years. To this type of scab are the most susceptible varieties with a thin skin or having a red color.

Another type of potato scab is powdery scab, generated by a special kind of mushroom that can move independently and is a small mucous lump.

Spots can have a different shape and pronounced relief. When the potatoes are already dug up, these formations dry out so much that the peel bursts, forming ulcers. These ulcers are filled with a dusty brown substance, which includes fungal spores and the remains of potato tissue.

Similar potato “craters” have the shape of stars with the edges turned outward. On the roots of the disease manifests itself in the form of the formation of growths of irregular shape of white color. The source of such misfortune is soil contaminated with the disease, manure and damaged planting material.

Favorable conditions for powdery scab are overmoistened soil, the temperature may be relatively low - 12-18 degrees. Most often develops in heavy soils, where it retains its viability for 5 years.

The silver scab of potatoes from previous diseases differs in the main feature - the affected tuber does not rot during storage. Here the action is somewhat different. Affected tubers lose moisture, and therefore mass.

The rind is wrinkled, at the lesion sites it has a silver sheen, lesions on the red-skinned varieties are especially noticeable. The causative agent of this type of scab is a variety of fungus, it penetrates the tuber through the soil and spreads to other tubers.

During harvesting or when stored in potatoes, gray-brown spots of various sizes are formed, they can be slightly depressed, if you peel the skin, then black formations are observed under it. Lesions in early spring or on green potatoes are clearly visible. Ill tubers sprout poorly.

This disease is formed when vegetables are grown on sandy loam, as well as loamy soils, if there is an elevated temperature during tuberization. The disease spreads with high humidity - more than 90%, and a temperature higher than 3 degrees.

Methods of prevention and treatment

Each of the scab forms examined by us has different pathogens, but the result is the same - the potato deteriorates and the yield of the plot decreases.

Even if you did not find signs of the disease on the dug up tubers, this does not mean that it will not come to your garden next year, so you should know not only the treatment methods, but also take preventive measures. And you can fight potato scab in any of its manifestations.

If, however, slightly affected tubers are caught in the planting, then during the flowering period of the plants, potatoes should be abundantly watered with water. Copper, manganese and boron with application during planting significantly reduce the percentage of the disease.

Try to change the place of planting potatoes and alternate it with the planting of legumes. If the place is permanent and there is no way to change it, never add fresh manure as fertilizer.

If your soil has alkaline symptoms, it should be acidified, for this we apply a solution of ammonium sulfate - 2 tbsp. tablespoons of substance per 10 liters of water. Watering during flowering at the rate of approximately half a liter per 1 bush.

10-14 days before harvesting the potatoes, it is useful to mow the whole tops so that the potato peel is well strengthened.

After harvesting, plant an empty area with green manure. They will make a large warehouse in the improvement of the soil and saturate it with useful substances. It can be cereals (rye, wheat), legumes (lupine, peas), cruciferous (rapeseed, mustard) or mixtures of these crops.

Zircon is able to suppress the development of potato scab. Apply it during the budding period. It is a growth regulator. Even its single use gives a high positive effect, and yield simultaneously increases.

The Fito Plus drug is able to greatly reduce tuber damage. They should process planting potatoes and sprinkle the plant during the growing season. Dose for use - 1 sachet of the product in 3 liters of water.

Highly resistant varieties

If your crop improvement measures are ineffective, you should consider changing the planted variety. Just note that the varieties absolutely resistant to scab have not yet been bred, but there are the most resistant diseases.

There are also foreign analogues: Alpha, Element, Krostotr, Lady Rosetta, Mentor, Nicolas, Ostara, Patrones, Prevalent, Prosecutor, Saturn.

Do not forget about preventive measures even when using varieties that are highly resistant to potato scab, and then your harvest will only please.

Potato common scab and preventive measures

The disease is common wherever potatoes are grown. It is characterized by increased harmfulness in all soil and climatic zones.

According to the data of the Main State Plant Protection Inspectorate, the most intensive spread of the disease on potato tubers (8–37%) occurred in 1996, the maximum damage (100%) was noted in the Lviv region - both on household plots and on farms. In 2006–2010, tuber damage ranged from 1–17%, with a maximum of 10–24%.

The harmfulness of the disease mainly consists in reducing the consumer value of food potatoes: deterioration in taste, an increase in waste when peeling tubers, and a decrease in starch content by 5–30%.

The use of diseased tubers for seed purposes leads to a shortage of 15–40% of the crop. Tubers with ulcers of common scab are poorly stored, since they are more likely than healthy ones to be affected by pathogens of dry and wet rot.

The causative agents of the disease are various types of actinomycetes (radiant mushrooms), among which the main place is Streptomyces scabies Waks. et Hern. On solid nutrient media, this pathogen forms yellow or yellow-brown, dense texture, tuberous or folded colonies.

Hyphae have no transverse partitions; they are usually thin (0.7–0.8 μm), gram-positive. The pathogen propagates by small cylindrically elongated spores of 1.2–1.5x0.8–1 μm in size.

Radiant mushrooms infect tubers, the lower part of the stem, stolons and the root system of potatoes. The disease initially manifests itself in the form of small scattered brown spots near lentils and respiratory pores, eventually turning into shallow, irregularly-shaped wounds ranging in size from a few millimeters to 1 cm or more, which are often located around or near lentils.

Torn wounds are star-shaped or otherwise. At the same time, most of the periderm is delimited from healthy tissues located below by a layer of caked dead cells. Subsequently, typical signs of the disease appear.

There are five forms of tuber damage with common scab:

1. flat scab - appears on young tubers and affects only the skin, or the upper layer of the periderm in the form of a rusty-brown hardening of the peel or scab;
2. net scab - continuous roughness, surface rusty scab in the form of shallow grooves intersecting in different directions, resulting in a shallow surface mesh;
3. convex scab - manifests itself initially in the form of small cone-shaped recesses. Later, these depressions rise above the surface of the tuber, forming growths in the form of warts or scabs;
4. deep scab - characterized by the formation of brown ulcers up to 0.5 cm deep, surrounded by torn peels. Ulcers can have a different shape. Their inner surface remains soft and loose for a long time;
5. convex-deep scab - the combined formation of a convex and deep scab on the same tuber. In this case, more or less deep ulcers sometimes appear on warts-growths.

Each of the five forms of manifestation of common scab is characterized by the corresponding dynamics of development and the level of harmfulness.

Various forms of manifestation of scab on potato tubers are caused by both different types of actinomycetes and their various strains. Thus, 17 phytopathogenic strains are described in the radiant fungus S. scabies.

Actinomycetes infect young tubers that have not had time to develop a dense peel. This period lasts from the moment of thickening of the stolon (tying of tubers) 10-30 days, depending on external factors. The development of the disease, that is, an increase in the area of ​​the affected tissue, occurs throughout the entire period of active growth of tubers.

The pathogenicity of actinomycetes and the frequency of infection of tubers are influenced by many factors. A greater number of infections occurs at a soil temperature of 20 ° C, although the temperature limits for the growth and development of actinomycetes pathogenic for potatoes lie within 6 ... 30 ° C, with an optimum of 23 ... 24 ° C.

The optimal conditions for mass infection of tubers are created when the soil moisture content is 50–70% PPV. Scab on sandy and sandy loamy soils is largely suppressed at a moisture content of over 75% and, on the contrary, actively develops on soils where humidity decreases below 70% of PPV.

The acidity of the soil also plays an important role in the development of actinomycetes and enhancing their harmfulness. The higher the pH of the soil, the higher the degree of damage to potatoes. However, severe damage to tubers often occurs on soils with a wide range of pH values ​​(from 4.4 to 7).

This is due to the high plasticity of the causative agent of the disease, the strains of which easily adapt to the acidity of the soil, and, therefore, this factor cannot be limiting in the harmfulness of the disease.

At the same time, a short-term increase in soil acidity (for example, when applying acidic forms of mineral fertilizers) suppresses the activity of highly pathogenic strains for some time (until the pathogen adapts to new conditions).

Actinomycetes are typical aerobes, that is, they need a sufficient amount of oxygen for development. A decrease in air content in the soil inhibits the viability of actinomycetes. Often tuber damage is influenced by the depth of their occurrence in the soil. In the deeper layers, where less air penetrates, the scab develops less.

The high content of organic matter in the soil, mainly in the form of humus, suppresses the causative agents of common scab. Conversely, undecomposed plant debris, fresh organic fertilizer contribute to the development of the disease.

The viability of pathogenic species and strains of actinomycetes is significantly activated in the presence of free calcium and nitrite in the soil.Reducing the severity of the disease occurs when there is a sufficient amount of manganese, boron and some other trace elements in the soil.

In fields where other crops are grown, potato-specific actinomycetes are suppressed by other types of beneficial and harmful microflora. With subsequent planting of potatoes, their concentration increases rapidly.

Use for planting affected tubers increases the intensity of the development of the disease. Tuberous infection is of great importance when growing potatoes in virgin or fallow plots, as well as in fields where it has not been grown for a long time. There is information about the antagonism between pathogens of common scab and rhizoctoniosis (black scab) of potato when they are jointly affected by tubers.

A positive correlation is observed between the temperature of the soil during intensive tuberization and the number of affected tubers, as well as the degree of development of the disease.

Protective measures

Against common scab, a complex of preventive, agrotechnological and chemical measures is carried out. The most radical, economically viable and environmentally friendly is the cultivation of resistant varieties.

The varieties of Bozhedar, Borodyanskaya pink, Veloks, Vesta, Vodograi, Volovetskaya, Gatchinskaya, Drevlyanka, Zarevo, Kosen 95, Lugovskaya, Lybid, Poran, Rosara, Serpanok, Symphony, Chernigovskaya 98 and others are characterized by increased resistance to the disease.

On the contrary, unaffected cultures inhibit these species and strains, since microflora specific for these plants develop in their rhizosphere, often exhibiting antagonistic properties to common scab pathogens.

The harmfulness of the scab is also reduced by the turnover of the perennial grass layer after winter crops, green manure from rape, mustard, vetch, soy, winter rye. Previous crops regulate the ratio in the soil of beneficial and harmful microflora.

Stocking of green manure crops contributes to the development of saprophytic species of fungi and bacteria - antagonists of common scab pathogens, the conversion of insoluble manganese compounds into soluble, which negatively affects the accumulation of actinomycetes.

The systematic use of organic fertilizers and green manure usually causes an increase in humus in the soil, which prevents the violation of soil biocenoses that are favorable for plants (including potatoes). In addition, organic substances increase the duration of the saprophytic phase of actinomycetes, in connection with which the defeat of tuber ordinary scab is weakened.

However, this applies only to high doses of organic fertilizers. And vice versa, small doses of manure or compost on medium-rich soils, green mass of green manure (up to 25 t / ha) stimulate the development of pathogenic species of actinomycetes, especially on poor soils.

The harmfulness of scab is greatly influenced by the content of mineral nutrients in the soil. The residual amount of nitrogen, for example, as a result of its excessive introduction under the previous culture or directly under the potato, increases the number of diseased tubers and the degree of development of the disease.

In this regard, it is recommended to use ammonium forms of nitrogen fertilizers in the fight against common scab or to introduce nitrogen stabilizers into the soil. An excess of potassium and phosphorus fertilizers somewhat reduces the harmfulness of scab, especially when using potassium salt, calcium chloride and superphosphate.

It is also recommended that acidic forms of nitrogen and phosphorus fertilizers be added to the rows when planting potatoes: ammonium sulfate (1–1.5 kg / ha) and superphosphate (1 kg / ha). In this case, a slight local acidification of the soil inhibits the species and strains of actinomycetes pathogenic for potatoes, and also enhances the leaching of calcium from the arable horizon of the soil, which is necessary for the normal growth and development of common scab pathogens.

The introduction of a sufficient amount of copper, manganese, magnesium, boron, cobalt into the soil in doses calculated according to the data of the agrochemical examination of the fields helps to reduce the harmfulness of the common scab by increasing the resistance of the tubers to the disease.

This, on the one hand, is associated with the antagonism of ions. Calcium cation reduces the activity of cations of sodium, potassium, copper and other elements that increase the stability of tubers. On the other hand, excess calcium activates actinomycetes. Therefore, lime can be used directly under potatoes, but in doses not exceeding half the norm for hydrolytic acidity.

The development of common scab can be significantly reduced by irrigation of potatoes from the moment of mass setting of tubers and until they reach 2-3 cm in diameter. During this period, soil moisture in the zone of tuber formation should not be lower than 75–80% of the PPV.

Pre-harvest mowing of tops contributes to the rapid ripening of tubers, strengthening of integumentary tissues and, therefore, less infection with their actinomycetes and a decrease in the development of the disease.

For disinfecting the surface of tubers from actinomycetes, it is necessary to use Rovral Akvaflo, K.S. (0.38–0.4 l / t) or Fungazil 100 SL (150 ml / t).

Prevention and methods of dealing with potato scab

Potato scab is a fungal disease that affects mainly tubers, less often the root system and the underground part of the stem. The infected potato loses up to 30% of starch, its taste is noticeably worsened, and the shelf life is reduced. Since the tubers are in the ground, timely detection and treatment of potato scab during the growth period is not possible.

Depending on the shape, color and signs of the lesion, 4 types (types) of potato scab are distinguished: ordinary, powdery, silver and black (rhizoctonia).

Common

Appears in alkaline or calcareous, poor in moisture soil at an air temperature of 25-30 ° C. Pathogens are found on tubers, in soil and organic matter. If conditions are favorable, spores affect the tubers through mechanical damage to the skin. During storage, the potato does not become infected, since in an unfavorable environment, the fungi remain dormant but do not die.

Common scab is most susceptible to varieties with a thin or red peel.Deep sowing and high humidity (if necessary, intensive watering) during the appearance of tubers reduce the risk of disease.

Symptoms of common scab: solid ulcers of irregular shape are visible on dug up tubers, sometimes the whole root crop is covered with this defect or cracks are observed in the affected areas.

Powdery

The most common form is a mushroom in the form of a mucous lump that can move independently. The disease affects the tubers, roots and the underground part of the stem. During storage, the diseased potato dries up, but if there is an excess of moisture in the storage, it quickly rots. Often dry rot and late blight appear on infected tubers.

Symptoms of powdery scab: white growths of irregular shape appear on the roots of the bush, which subsequently turn brown. The diseased tuber is covered with a colony of warts, the spots have a different area, shape and pronounced relief.

After some time, the affected areas dry out, then burst, forming ulcers. The ulcers contain a dusty brown substance - fungal spores and the remains of potato tissue. Most tubers rot.

Silver

Often appears on sandy and loamy soils at a temperature of 6-32 ° C (optimally 18-20 ° C) and humidity 85-100%. The fungus penetrates the potatoes through the soil, then spreads to other tubers. A distinctive feature is that infected potatoes do not rot during storage, but only lose moisture (unless additionally affected by dry and wet rot).

Symptoms of the scab are silvery: the tuber surface becomes wrinkled, the lesion sites have a silver hue, this is especially noticeable on varieties with a red peel.

A potato with white skin is difficult to peel. During storage, gray-brown spots increase, may be slightly depressed. Black formations appear under the skin. Ill tubers sprout poorly and give a low yield.

Black

It develops at high humidity and air temperature around 17 ° C. One of the most dangerous diseases of potatoes can occur at any stage of growth. Rainy cold spring leads to the death of bushes. Potato losses from rhizoctonia are up to 20-25%.

Symptoms of black scab: black spots on the roots, similar to the soil, they are not washed off the peel and are difficult to scrape off, but do not harm the tuber. Affected by rhizoctonia, potato bushes wither in the afternoon, grow low with twisted leaves. In warm, humid weather, a “white leg” appears near the stem.

How to fight

Methods of treating potato scab are reduced to the prevention of disease on the site and the protection of tubers:

Scab on potatoes: types, description, control measures

Scab belongs to fungal diseases and often affects potatoes. There are several types of this disease:

• Common scab
• Black scab (rhizoctonia),
• Powdery
• Silvery.

What is common potato scab?

Potato scab affects mainly varieties that have a red or thin peel. The disease is very rarely spread on the tops, root system and leaves. It looks like small or medium-sized spots in the form of small dimples, similar to ulcers.

Favorable conditions for the development of common scab are shallow bedding of tubers, air access, insufficient capacity of boron and manganese in the ground. The prerequisites for the occurrence of potato disease are heat up to 30-350С and elevated soil temperature up to 270С. At the same time, the pH of the soil should not exceed the mark of 5.5.

Spores of common scab can live in the soil for a long time. Once on the potato, prerequisites are created for the penetration of rot spores. As a result, the potato begins to rot.

Treatment of ordinary scab of potatoes should be carried out by the following methods:

1. Etching. Before planting, it is necessary to treat the tubers with a formalin solution with water in a proportion of 50 ml. 40% formalin per 10 liters. water.
2. Immediately before planting, you need to treat the soil with a solution of superphosphate, kalimagnesia and ammonium sulfate (30 g / 1 m2 each).
3. Soil preparation is also carried out by planting green manure, in particular lupine.

The most resistant varieties to common scab: Sotka, Amber, Domodedovo, Zarechny.

Rhizoctonia

A very dangerous disease that affects a plant from tubers to leaflets along with stems and tops. Potato rhizoctonia in the early stages can inhibit the growth of the stem and destroy the entire bush at the very beginning of its growth.

Black scab appears in the form of dark spots that cover the tubers almost completely. Spots are similar to small sores, which, when spread, can merge with each other, creating entire affected areas. These are the first signs of potato rhizoctonia. Favorable conditions for development are increased humidity and soil temperature of at least 180 ° C.

There are some measures to combat potato rhizoctonia. First, crop rotation must be observed. Secondly, you need to plant potatoes treated with Prestige and Maxim in the affected soil.

For the treatment of rhizoctonia, strong drugs Kulfugo, Fenoram super, Mancozeb, Ditan M-45 are also used.

Powdery scab

This disease can affect the subsoil of the stem, tops and tubers themselves during the period of active growth. Small stains appear on the stems. It develops as a result of prolonged rain periods.

Spores of the disease can get into the nest to planting material together with organic fertilizers (manure, humus, chicken droppings). They are also capable of being transmitted by air.

The fight against powdered scab of potatoes is carried out by the timely introduction of a solution of 5% copper sulfate and 3% bleach into the soil. They are bred in 10 liters. water. You need to use about 150-300 ml. on the bush as watering.

Silver

This disease appears in the form of silver spots of large diameter. One spot can affect up to 40% of the fetus. The silver scab of potatoes is able to dry both the tops and the fruits, as a result of which they wither and become soft. Such tubers can no longer be used as planting material.

Favorable conditions for the development of the disease are a temperature of +30 or more, as well as 80-90% humidity. Spores of the disease of the plants of silver scab potato can persist in tubers and in the soil for a very long time, since they are resistant to cold.

3 days before winter storage, the best tubers are selected, which will be used as planting material. They must be treated with Maxim (you can use other similar means) and carefully dried in the sun.

Immediately before planting, potatoes are treated with a special fungicide - Quadris.