The main problem of all gardeners is plant diseases, which not only spoil their appearance, but also reduce productivity. Potatoes are a very productive crop, but diseases and pests can reduce all work to zero.

What are potato diseases?

Potato diseases spread quite quickly as pathogens move from stems to tubers, causing crop loss. To prevent this, it is necessary not only to carry out pre-sowing treatment of planting material, but also to carefully monitor the vegetables during the growing process. When the first signs of disease are detected, treatment is carried out with special means.

Causes

The main causes of pathologies include improper selection of planting material, violations of crop rotation and improper care of plants. Most modern hybrid varieties are disease resistant. However, when growing varieties unsuitable for a certain climate, this property is lost. Therefore, it is recommended to grow local varieties adapted to climatic and soil conditions. Crop rotation also plays an important role. Pathogens often linger in the soil, and if crop rotation is disrupted, they affect crops at the very beginning of cultivation or at the stage of tuber ripening.

Improper care can also cause the development of diseases. For example, excessive watering can provoke late blight, and elevated temperatures can cause fungal diseases.

Symptoms

Most gardeners notice symptoms of potato diseases already at the harvest stage. However, with certain knowledge, signs of diseases can be seen earlier. Thus, late blight damages not only tubers, but also causes blackening of leaves and stems.

The presence of aphids will also help determine that plants may be infected. These insects are carriers of many diseases, so it is important to remove weeds in a timely manner and spray against pests.

But the main sign of crop damage is the general condition of the above-ground parts of the plants. If they begin to turn yellow prematurely, wilt or be stunted, it makes sense to inspect the root part and tubers. This will help diagnose pathology and choose a product for spraying.

Kinds

There are several types of potato diseases. They differ in the type of pathogen that causes the disease.

There are these types of potato diseases:(picture 1):

• Bacterial transmitted through tubers intended for planting or soil. The pathogens of this group can remain in the soil for a long time and do not die at low temperatures. Bacterial diseases include rot and blackleg.
• Viral provoke changes in the structure and color of leaves, stems and tops. As a result, the plant becomes weak and cannot produce enough tubers. Viral diseases include different types of mosaics.
• Mushroom diseases can damage all parts of plants: tubers, leaves and stems. The most famous example of fungal infections is late blight, which, if massively infected, can lead to the loss of most of the crop. The danger of fungal diseases is that they not only damage the tubers, but also make the crop vulnerable to other diseases.

Figure 1. Main types of potato diseases

Each type of disease requires specific treatment and prevention. Therefore, before starting field work, it is recommended to treat the tubers with special preparations.

From the video you will learn all about common potato diseases and methods of combating them.

Peculiarities

The main feature of potato diseases is that they damage mainly tubers. As a result, not only the crop intended for food consumption is lost, but the quality of the seed material deteriorates.

In addition, the features of potato diseases can be considered their hidden course. Most pathologies are almost impossible to diagnose by external examination, and symptoms begin to appear only at harvest or mass damage (when plants are significantly stunted in growth). That is why pre-sowing treatment of tubers plays an important role.

Bacterial diseases of potatoes (causes, symptoms and treatment)

Infection with bacteria occurs directly from the soil in which the pathogens are located. However, the spread of diseases can also occur directly through tubers if they are not inspected and treated before planting.

The danger of bacterial diseases of potatoes is that they damage the stems and lead to the death of the crop. Most often, pathogens infect tubers. They begin to rot and become unfit for food.

Ring rot: photo, description and treatment

Potato ring rot is dangerous because it causes serious damage to the crop and spreads quickly.

Note: With massive ring rot infection, crop losses can reach 45%.

The disease affects stems, leaves and tubers. Their blood vessels are damaged and the sprouts gradually die. If you cut the stem and press on it, a yellow slimy liquid will begin to secrete (Figure 2).

Figure 2. Signs of ring rot

There are two types of ring rot of tubers. Pitted causes the formation of yellow oily spots directly under the skin. With the ring type, necrosis of the vascular ring begins, it first becomes yellow and then brown.

Brown bacterial rot

The disease affects only tubers. Bacterial brown rot of potatoes intended for planting can cause stunted plant growth and stunted development. With severe damage, seedlings wither at an early stage of cultivation.

Note: It is difficult to identify bacterial brown rot, since its symptoms begin to appear clearly only in the second year.

Figure 3. Symptoms of brown bacterial rot of potato tubers

You can notice signs of the disease even at the flowering stage (Figure 3). Affected plants wilt, leaves turn yellow and begin to wrinkle. To prevent crop loss, you need to strictly observe crop rotation and carefully select planting material. In addition, it is recommended to select varieties that are resistant to bacterial brown rot.

Mixed internal rot

Mixed internal rot appears on tubers with mechanical damage. Fungi and bacteria penetrate inside, and the vegetable begins to rot from the inside.

Very often, the disease appears not during the growing process, but during storage. To prevent crop loss, the storage facility is treated with copper sulfate and thoroughly cleaned of plant residues. Tubers must be inspected before storing.

Wet rot

Wet rot on potatoes appears with excessive watering and high soil density. This causes massive rotting of tubers right in the soil (Figure 4).

The disease can also appear during storage. If the room is too humid and the temperature is above 5 degrees, wet rot can destroy almost the entire crop. In this case, the tubers rot from the inside, while remaining completely normal on the outside.

Figure 4. Wet rot on potatoes

For prevention, you need to carefully select planting material, and if wet rot is detected, destroy all tubers from the bush and those located nearby. In addition, it is necessary to strictly adhere to storage technology, avoiding an increase in humidity and temperature in the room.

Blackleg

This is a bacterial disease that often occurs when potatoes are planted in an area where cabbage was previously grown. When damaged, the lower part of the stems begins to rot, and the tubers become wet (Figure 5). As a result, the quality and quantity of the crop decreases, including during storage.

Note: Blackleg is very dangerous, since if it is massively affected, it can cause the death of 60-70% of the crop.

Figure 5. Signs of black leg on potato stems and tubers

In the early stages of development, the black leg provokes yellowing and wilting of the lower leaves. The stem becomes thin and is easily pulled out of the soil. The tubers become soft, begin to rot and gradually acquire an unpleasant odor. To prevent disease, you need to carefully check the planting material and remove all plant debris after harvesting. In addition, it is necessary to carefully observe crop rotation, treat tubers before planting and choose disease-resistant varieties.

Viral diseases of potatoes

Viral diseases include mosaics of various types. The disease gets its name from characteristic changes in the color and structure of leaves, stems and bushes in general.

Virus mosaic vulgaris

An ordinary viral mosaic in the early stages is manifested by the appearance of yellow spots of various shapes and sizes on the leaves. The same symptoms are characteristic of iron deficiency, so to clarify the diagnosis you need to carefully monitor the bush.

If, after yellowing, the spots turn brown or brown, it means that the plant has been infected with viral mosaic. The bush needs to be dug up and burned. In addition, it is necessary to carefully examine neighboring plants and carry out preventive spraying with antiviral drugs.

Striped mosaic

A common viral disease with many strains. Symptoms of banded mosaic differ depending on the type of pathogen, but in general this disease has common characteristic symptoms (Figure 6):

• The stems become brittle and break easily;
• Pronounced spots and stripes appear on the leaves and stems;
• The veins on the lower parts of the leaves become covered with dark brown spots.

Figure 6. Symptoms of banded mosaic

Striped mosaic spreads quickly, so when the first signs are detected, the plant must be destroyed.

Wrinkled mosaic

Wrinkled mosaic can cause serious damage to crops. However, the disease manifests itself only in certain years and in the presence of suitable climatic conditions. The virus develops especially actively in hot, dry years.

Figure 7. Potato bushes affected by wrinkled mosaic

Plants affected by wrinkled mosaic are severely stunted and do not bloom (Figure 7). A shortening of the growing season leads to crop loss (in case of massive damage, the shortfall can reach 30%).

A characteristic sign of the disease is leaf curling. They lighten, wrinkle and gradually die off. In this case, the leaves remain on the bush, but the plant itself completely stops growing and does not bear fruit.

Fungal diseases

Fungi that cause damage to tubers and bushes quickly spread and penetrate into the plant through mechanical damage. This process can additionally cause bacterial or viral damage.

There are many fungal diseases, so to correctly identify the disease and fight it, you need to know exactly what a particular disease looks like.

Late blight

Potato late blight is the most dangerous disease of this crop. If it is not identified in time and appropriate measures are not taken, crop losses can reach 70%. Late blight destroys not only tubers, but also affects stems and leaves, slowing down plant growth.

Figure 8. Symptoms of late blight on potatoes

The main symptom of late blight is brown spots on the leaves, which appear mainly during the flowering period (Figure 8). With high air humidity, they become covered with a characteristic white coating.

Further development of late blight provokes damage to the tubers. Hard dark gray spots appear on their surface. The causative agent of the disease persists in tubers and soil, so before planting it is necessary to treat the tubers, and during the growing process carry out preventive spraying.

Black scab

The viral disease affects all parts of the plant, and if infection occurs in the early stages, all young shoots may die.

Figure 9. Black scab on potato tubers

Black scab of potatoes is dangerous not only during cultivation, but also during storage of the crop. Mature tubers become covered with brown spots and gradually rot (Figure 9). The development of the disease is promoted by elevated temperature and humidity. The pathogen remains viable on tubers and in soil.

Prevention of black scab includes compliance with crop rotation standards and planting disease-resistant varieties. In addition, tubers can be sprayed before planting using Maxim, Fenofram Super or Colfugo.

Silver scab

Identifying silver potato scab is very easy. To do this, just hold the tuber in your hand. Light potatoes are infected as the disease causes moisture loss. Such vegetables are not suitable for planting or eating (Figure 10).

Figure 10. Signs of silver scab on potatoes

Silver scab appears on planting material closer to spring. The potato skin acquires a characteristic silvery sheen and is slightly pressed inward.

Note: Silver scab will actively develop if potatoes are stored in a room with a humidity of more than 90% and at temperatures above +3 degrees.

To prevent infection, all tubers must be dried after harvesting. It is necessary to maintain stable temperature and humidity in the storage, and observe crop rotation when planting. It is also possible to carry out pre-sowing treatment of tubers with fungicides.

Powdery scab

The disease actively develops in rainy years. Powdery scab symptoms appear on the lower parts of stems, roots and tubers (Figure 11).

Note: If you send potatoes infected with powdery scab for storage, you may lose part of the harvest. This is explained by the fact that rot can penetrate through the sores formed on the tubers.

Figure 11. Signs of powdery scab

During the growing process, powdery scab can be identified by the characteristic white growths on the roots and stems. Later they darken and collapse, forming red ulcers on the surface. The causative agent of the disease remains viable not only in tubers, but also in soil and manure.

When potato cancer is detected, a quarantine is declared on the farm, as this disease is considered one of the most dangerous. The main symptom of cancer is the formation of tubercles on tubers. Gradually they increase in size, and their surface becomes uneven and rough (Figure 12).

Figure 12. Signs of potato cancer

If a disease is detected, the affected plants are destroyed, and the remaining bushes are sprayed with special preparations. After this, potatoes cannot be grown in the ground for another 3-4 years.

Dry rot

Potato dry rot is also called fusarium wilt. They can affect plants at all stages of development, but most often the crop is vulnerable during the flowering period.

Note: In hot weather, dry rot develops especially actively. In this case, crop losses can reach 40%.

A symptom of Fusarium wilt is a change in color of the upper leaves (Figure 13). They brighten and gradually begin to fade. Brown spots appear at the bottom of the stem, and if the weather is humid, these areas become covered with plaque and begin to rot.

Figure 13. Symptoms of dry rot

Dry rot can be identified by cutting the stem. It has clearly visible brown vessels. Affected plants should be removed from the soil and burned, as the disease can quickly spread to neighboring bushes.

Methods to combat dry rot include regular inspection of plantings. It is also necessary to observe crop rotation standards, select only high-quality planting material and process it before planting in the ground.

Prevention of potato diseases

Most potato diseases can significantly reduce the yield. To prevent this, you need to follow certain preventive measures:

• Select potato varieties that are resistant to diseases and pests. It is better to give preference to local varieties that are best adapted to the climatic and soil conditions of a particular region.
• Carry out pre-sowing treatment of tubers with special preparations. They strengthen the planting material and significantly reduce the risk of tubers becoming infected with bacteria and viruses.
• Observe crop rotation - without this condition, tubers can be affected by diseases of other crops, which also pose a danger to potatoes.

Figure 14. Preparations for treating potato tubers before planting

After harvesting, be sure to remove all tops and plant debris. In addition, during the growing process it is necessary to regularly remove weeds, and when the first signs of diseases are detected, preventive spraying should be carried out.

How to treat potatoes before planting against diseases

There are many drugs designed to treat tubers and adult plants against diseases. The most common means include a solution of copper sulfate (concentration: a teaspoon of the product per 3 liters of water). In this case, the tubers are not sprayed, but immersed in liquid for about two minutes, then dried and planted in the ground. Examples of preparations for treating crops are shown in Figure 14.

To protect against fungal diseases, use the drug Fitosporin-M. The working solution is prepared according to the instructions indicated on the package, and the tubers are dipped in the liquid for 15 minutes, after which they are dried and planted.

The drugs Maxim, Prestige, Quadris and Confugo are considered effective remedies against diseases.

The author of the video will talk about pre-sowing treatment of tubers to protect the potato crop from diseases.

Potato diseases bring a lot of trouble to gardeners. Photos, descriptions and treatment of scab (rhizoctoniosis), dry rot are the subject of our conversation. After all, potatoes are a staple food in many countries. It is easy to grow in the garden, which makes it popular among gardeners. But potatoes are susceptible to many diseases. The main pathogens are various fungi, bacteria, viruses. Prevention is almost the only means of protection. Many diseases can be prevented if preventive measures are taken in time or treatment is started at the initial stage.

Scab or rhizoctonia is a common potato disease.

Rhizoctoniosis is one of the common fungal diseases of potatoes in household plots, called black leg or black scab. It causes especially great damage under conditions favorable for the development of pathogens.

Photo of a stem infected with blackleg

Rhizoctoniosis - manifests itself in the form of black scab, rotting of eyes, sprouts, death of roots, as well as “black leg” of stems in wet weather. At the beginning of the development of the disease, lesions on stolons, roots, and stems are reddish-brown. When they mature, they turn into rough, cracked sores. If the cankers are significant, they can encircle the stem, interfering with the normal movement of juices and carbohydrates throughout the plant. Thus, symptoms of the disease can be seen on the above-ground part and on the tuber.

Sunken brown cankers of varying sizes and shapes can be seen on infected stolons or stems above or below the soil surface. These ulcers can be girdling in nature - in this case the plant dies sooner or later. Young nodules cannot arise or develop on such stolons.

Black plaque is the most noticeable sign of the disease. During this phase of the disease, the fungus Rhizoctonia Solani produces dark brown to black growths, as if potatoes were stained in the soil. But this is not the earth, these are the so-called sclerotia located on the surface. They are irregular in shape, ranging from small flat spots to large raised spots. Although these structures fit tightly to the surface of the tuber, they do not penetrate inside and do not spoil the taste of the potato.

However, if such potatoes are used as seed material, then the sclerotia will inhibit the development of the planted potatoes and may even destroy them. This happens because during the growing season the fungus Rhizoctonia Solani attacks the root system and the base of the plant stems. The movement of nutrients from the leaves to the young tubers is disrupted. The upper leaves curl along the main vein. It appears that they are infested with aphids.

The main source of infection is seed material. Sometimes heavily infected potatoes are unable to even form stems. This symptom is called "no top" and can be confused with the same symptoms as growing from physiologically old seeds.

Potato scab, photo, description and treatment

Treatment of rhizoctoniosis and black scab requires an integrated approach, knowledge of each stage of the disease. One of the most important means of combating the disease is to purchase and plant only high quality seed material that is not contaminated with pathogenic fungi.

An effective way to combat diseases is prevention - pre-sowing light germination of tubers. The application of rotted manure, superphosphate, and potassium fertilizers reduces the negative effect of the pathogen.

Potatoes are best planted after corn, beets, beans, and peas. Weak plants are most susceptible to the disease, but it practically does not affect the sprouts of sprouted tubers. Therefore, it is very important to germinate potatoes before planting, so that potatoes infected with rhizoctonia can be discarded before planting. It is equally important to loosen the soil after rain to prevent a crust from forming. In this case, favorable conditions are not created for the fungus that causes the disease.

Treating potatoes before planting with a 1.5% boric acid solution also protects them from infection with rhizoctonia. The volume of solution should be prepared at the rate of 50 ml per 1 kg of tubers.

The disease is most severe during cold and wet seasons. Microspores persist in potatoes or plant residues for up to two years. When cutting seed material if there are infected tubers among it, for example, when growing potatoes from eyes, infection of healthy ones is possible. Therefore, do not forget to remove diseased bushes from your area. Cut off the tops before digging up the crop so that rhizoctonia bacteria do not have time to get from the leaves to the tubers. Be sure to germinate the seed material in order to remove diseased potatoes in time. Be sure to warm the seed material in the sun, dry it, and green it before putting it away for storage.

Dry rot, fungal disease of potatoes

Dry rot

Dry rot of potatoes, photo, description

Dry rot is caused by several species of fungi of the genus Fusarium, hence the name fusarium dry rot. If, while periodically inspecting the potatoes in the basement, you find dry, depressed spots on the skin, this indicates that they are affected by Fusarium dry rot. These spots are the first symptoms of the disease. As a rule, they appear on the surface of the tuber. Gradually, the pulp under the stain dries out and becomes rotten. At the same time, the skin wrinkles and breaks. In the resulting voids, mycelium grows, that is, mycelium with ripening spores.

Section of a tuber with dry rot

Several species of Fusarium fungi cause dry rot. Depending on the species, the spores look like grayish-white, yellowish or pink convex pads.

Where could this potato disease come from? This can be told by the location of the spots.

If dry rot appears on the tubers only at the stolon end (a small indentation on the potato where the stolon was attached), then all the soil in your garden is contaminated with this fungus. Let us explain: a stolon is a lateral underground shoot, at the end of which a potato tuber ripens. This is a potato “umbilical cord” through which the growing tuber receives nutrients from the bush.

And if the potatoes are affected from different sides, then the reason is improper harvesting and poor storage. Most often, the disease begins to rage where there were injuries, cuts, late blight or scab.

Your basement may be too warm. At elevated storage temperatures, dry rot quickly develops and spreads. As you know, the optimal storage temperature for potatoes is 1-3 degrees above zero.

Dry rot on potatoes, methods of control, prevention

Most methods for controlling this potato disease are aimed at preventing injury to tubers during harvesting or storage. Preventing damage to the surface of the potatoes will greatly help prevent infection.

If the soil on your site is contaminated, you should not plant potatoes there for at least five or six years. Green manure or grain crops sown in such a field will eliminate the fungus from the ground, but this may take several years. Therefore, the main thing is to prevent soil contamination. And this can only be achieved by careful selection of seed material.

Is it possible to eat contaminated potatoes?

Is it possible to eat potatoes infected with scab? Or should they be thrown away? Not at all. Select them, remove the damaged parts. Feel free to fry potatoes or make mashed potatoes for dinner.

On the contrary, it is not recommended to eat potatoes affected by dry rot. Even if you have a tuber affected only on one side, you should not eat the supposedly healthy other half. Throw away the entire tuber without any mercy.

To keep your potatoes healthy, select or buy high-quality seed material for planting. Pay attention to the characteristics of the variety, resistance to a particular disease. Dig up potatoes intended for future planting earlier than for food and storage, since the longer they are in the ground, the greater the likelihood of infection. Try to maintain crop rotation.

Potatoes are affected by a wide range of diseases that cause great damage to the crop. Dry Phoma rot in some cases can be placed on a par with late blight and black scab. This disease is caused by a specific fungus that can persist in the soil for a long time and affects a large number of other cultivated plants, sometimes some weeds. In all natural and climatic zones where potatoes are grown, infected potatoes can be found. In years favorable for the pathogen, the disease can reduce the potato yield by up to 40%. Therefore, it is very important to know how to properly deal with dry Phoma rot.

Symptoms of the disease

The symptoms of this disease can often be confused with those of late blight. Still, there are certain unique signs that make it possible to accurately determine the disease and its stage of development. The main symptoms of the disease include the following:

1. First, small, slightly depressed, round spots appear on the tubers. As the disease progresses, the spots increase in area.
2. At the first stage of the disease, healthy tissue can still be separated from infected tissue. If you cut the infected tissue, it will have a light brown color.
3. In the second stage, the infected tissue becomes darker and may even turn black. In the middle of infected tubers there may be voids, which are usually covered with a gray coating - this is the mycelium of the fungus.
4. At the final stage of disease development, infected tissues dry out and fungal spores can spread to healthy tubers. In this case, the tubers can be almost empty. In the middle you can find the remains of the vital activity of the fungus and its mycelium.
5. Phomosa stem rot appears during potato flowering. Infected areas appear on the stems of leaf cuttings, on which brown pycnidia (spores) eventually appear.
6. Symptoms of the necrotic form of this disease resemble the symptoms of late blight. Small dark ulcers appear on the tubers, which can have a variety of shapes. In this case, the infected internal tissue has a yellow-pink color, and not rusty-brown, as with late blight.
7. In the ocelliform form of the disease, depressed spots form in place of the ocelli.

Conditions of infection

Infection of potatoes with dry Phoma rot depends on many factors, which include:

1. Cool and wet weather during potato harvest.
2. Mechanical damage to potatoes during harvest. Potatoes also become infected if, when harvesting, the potatoes are not yet fully ripe and the skin of the tubers is torn off with a fingernail.
3. Improper storage of potatoes.
4. Contaminated soil, organic residues in it and seed material.
5. Failure to comply with crop rotation.

Fighting methods

The disease is very difficult to overcome in its entirety, because The pathogen infects a large number of vegetable crops and weeds and persists in the soil for a long time. The main methods of combating the disease include:

1. Use only healthy potato seed.
2. Compliance with crop rotation. Potatoes should not be planted on contaminated soils. It is better to plant potatoes after grasses and grain crops, 3-4 years after growing vegetable crops in this area. But on a small plot of land this is not always possible.
3. Thorough and timely cleaning and disinfection of storage. All rooms where potatoes will be stored must be treated with a 3% solution of bleach or 5% solution of copper sulfate.
4. Disinfection of containers in which potatoes are transported and stored.
5. Storing potatoes at a humidity of no more than 80% and an air temperature of 1-3 degrees Celsius. The storage must have good ventilation.
6. Treatment of seed material with fungicide MAXIM, KS (0.4 ml/kg).

Growing potatoes would be much easier if it were not for diseases that cause great damage to the crop. But with the development of scientific and technological progress, many diseases can be easily dealt with. In this case, the most important thing is to comply with basic agrotechnical measures that minimize the likelihood of global potato contamination.

During storage, large losses of potatoes, vegetables and fruits are often observed. The reason for this is, first of all, a disruption of physiological processes in tubers, roots and fruits.

During this period, the accumulation of substances in their tissues stops, increased evaporation of water and decomposition of reserve substances (sugars, starch, etc.) occur. As a result of impaired metabolism in the tissues of stored products, resistance to microorganisms decreases.

Microorganisms - fungi and bacteria - penetrate the tissue of tubers, roots, bulbs, fruits and cause rotting. Rot develops strongly under improper storage conditions (high humidity, elevated temperature, insufficient ventilation, etc.).

Rot pathogens are brought into storage facilities mostly from the field - with contaminated products or with soil particles. Part of the infection in the form of sclerotia or mycelium, spores in contaminated residues can persist in storage from the previous year and quickly spread to new products.

The most common diseases of potatoes, vegetables and fruits during storage are considered.

Potato rot. During winter storage, tubers most often develop late blight, fusarium, or dry rot, wet bacterial rot and fomoz.

Late blight. A very common potato disease both during the growing season and during storage. Infection of tubers occurs mainly during harvesting, but signs of the disease are detected only 20-25 days after storing potatoes. Brown, weeping spots appear on infected tubers. First, the surface tissues of the tuber rot, and then the rot spreads inside the tuber in the form of streaks; the affected tissue retains a hard consistency. However, tubers affected by late blight quickly become infected with other fungi and bacteria, resulting in typical dry or wet rot of tubers.

Under normal storage conditions, late blight usually does not cause new infection of tubers in winter, and therefore does not spread in storage. This is explained by the fact that conidial sporulation of the fungus, due to which infection occurs, can form at a temperature not lower than 10°C and at high humidity. The sometimes observed large infection of tubers with late blight in November - December is the result of infection of the tubers during harvesting or during the first period of storage, when the tubers are wet and the temperature is still quite high (10-15 ° C); under such conditions, healthy tubers can become infected from sick ones.

The danger of late blight during storage lies not only in the fact that the affected tubers lose their marketable quality, but also in the possibility of the development of secondary rot (fusarium and wet bacterial rot) on such tubers, which quickly spreads in storage and causes massive rotting of the tubers.

In the fight against late blight during storage, careful grading of tubers before planting and normal storage conditions are of main importance (see measures to combat potato rot).

Fusarium, or Dry rot. It affects potatoes only during storage. It is detected no earlier than 2-3 months after harvesting. Dry rot develops especially strongly in the second half of the storage period. This rot can occur in any part of the tuber, but in most cases it is associated with wounds, bruises or late blight.

In places of infection, brown spots appear on the tubers, covered on the surface with plaque and pads of white, pink or other light colors. Subsequently, the peel wrinkles and acquires characteristic zonal folding. Rot penetrates deeply into the tuber, the rotted tissue becomes brown or even black, rotten. Inside the tuber, voids form, often lined with fluffy white mycelium. Subsequently, the rotten tuber shrinks and becomes hard. But if potatoes are stored at high humidity, then the infected tuber retains a soft consistency, but does not turn into a slimy mass.

Dry rot of potatoes is caused by various species of the genus Fusarium, which are often collectively called Fusarium solani App. et Wr. They belong to the class of imperfect fungi and are characterized by colorless sickle-shaped spores with several transverse septa. Their sporulation is light-colored pads (white, pink, etc.) formed on the affected tissue. These _ fungi are widespread in the soil, where they live saprophytically on organic debris. With soil particles, the mushrooms fall onto the tubers and are carried into storage or piles. If there is damage to the skin of the tubers, they become infected. But it is known that these fungi can also penetrate through the lentils of the tuber.

For the development of Fusarium dry rot, in addition to damage to the tuber, storage conditions are important - elevated temperature and humidity not lower than 80%.

In storage or in piles, dry rot spreads quickly; the infection (mycelium) is transmitted when tubers come into contact. Fungal spores, formed in large quantities during storage, are one of the sources of infection of tubers. This explains the increase in the percentage of rotten potatoes after sorting in winter, which contributes to the spread of infection. Dry rot is the main cause of large losses of potatoes during storage.

In the fight against Fusarium dry rot, the main importance is the quality of tubers stored for storage. Tubers with damage, bruises, and infected with late blight and phomosis (button rot) should be discarded. A necessary measure to combat dry rot is correct storage conditions.

Wet bacterial rot. The disease is caused by various types of bacteria, of which the most active are Erwinia phytophthora (App.) Berg., which causes blackleg during the growing season, and E. carotovora (Jon.) Holl., which develops mainly during storage.

Bacterial rot is detected on tubers even during harvesting, and sometimes during the growing season, and develops strongly during storage. Brown or black weeping spots first appear on an infected tuber, then the rot spreads throughout the entire tuber. The tuber tissue softens and turns into a mucous, mushy mass with an unpleasant odor. The infection is introduced into the storage with tubers.

If blackleg develops, the tubers may have an internal infection. In most cases, bacteria fall on the surface of the tubers and serve as a source of infection. Bacteria penetrate into tubers in places where the skin is damaged or into affected tissue (late blight, powdery scab, etc.); bacterial, rot usually spreads in patches.

The development of wet bacterial rot is facilitated by improper storage conditions - elevated temperature and high (close to 100%) humidity, insufficient ventilation, etc. Frozen tubers are especially quickly susceptible to infection by bacteria.

In the fight against wet bacterial rot, as well as against fusarium rot, the quality of the tubers stored and storage conditions are important.

Measures to combat potato rot during storage. Preparing storage facilities. 1.5-2 months before laying the tubers, the storage facilities are thoroughly cleaned of the remains of old tubers and disinfected with 1% formaldehyde, using 40 liters per 100-150 m2, or 2% bleach. No later than 2 weeks before receiving the harvest, the storage facility is whitened with 20% lime milk with the addition of copper sulfate (100 g per 10 l). When preparing the storage facility, attention must be paid to ensuring good natural ventilation. Forced ventilation using an electric fan and a duct system is very effective. Such active ventilation, reducing humidity and temperature in the thickness of the potato, delays or completely stops the development of rot. Storage facilities must be equipped with thermometers and psychrometers to determine humidity.

Tuber preparation. Before storing the tubers, they must be dried in the field in dry weather, and in temporary piles under straw in rainy weather. Dried potatoes from late blight areas are left for 2-3 weeks in temporary piles to identify infected tubers. After careful grading, the potatoes are stored for long-term storage. For seed potatoes, it is recommended to green the tubers before storing them. Gardening is carried out for 8-10 days in diffused light, laying potatoes in 1-2 rows. This technique increases the keeping quality of tubers, as it promotes the formation of a surface cork layer and increases the content of solanine, which is poisonous to rot pathogens.

Storage conditions. In winter, the temperature in the storage should be 2-4° C, relative humidity 85-90%. The storage facility must strictly observe sanitary conditions. Diseased tubers discovered during storage are immediately removed; Mass selection of tubers is allowed only if they are highly infected with diseases (more than 8-10%).

Checking product quality. During the storage period, the condition of the potatoes is checked at least twice - during storage and in the second half of the storage period. For analysis, a sample of 200 tubers is taken from each homogeneous batch weighing up to 16 tons in 10-15 places from the upper and lower layers. When analyzing the sample, the percentage of tubers infected with various diseases is determined. To detect internal infection of tubers, 100 tubers are cut open to detect, for example, blackleg, ring rot or late blight if the infection is weak.

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