Some gardeners, in order to avoid crop losses from potatoes, plant using innovative technologies in barrels, bags and under hay. But they soon become convinced that this does not save the tubers from bacteria, fungi and viruses that provoke a variety of ailments. They mercilessly attack healthy plants and their fruits in the open ground, and even in the cellar. Others often act as carriers of pathogens. Let's take a closer look at what potato diseases there are and measures to combat them.
Important! It is almost impossible to instantly cure planted tubers from diseases of any nature. This is due to the fact that most pathogens infect soil or seed. As a result, the fight against them should begin with processing and treating the fruits, as well as carefully preparing the bed for planting.
Bacterial diseases of potatoes
Bacterial diseases of potatoes are provoked by various kinds of microbes, which gradually spread from the tubers along the stems, infecting everything. It is extremely difficult to fight them, since the soil in which the root crop grows also needs disinfection. 
To cope with such a task, timely and competent sowing changes are necessary. Sometimes this will take years with alternate sowing of microorganism-resistant crops, such as wheat, corn, barley, in the infected area.
Brown bacterial rot
The disease occurs due to the activity of microorganisms Ralstonia solanacearum on potatoes. Its first manifestations are noticeable during the flowering period of the crop, when root crops begin to form. At this time, yellowing and wilting of the foliage is observed, it becomes wrinkled and lifeless, and the stems droop down and turn brown over time.
As pathogenic bacteria multiply, softening and putrefactive processes are observed in the lower root part of the stem. Splitting is clearly visible along the sprouts, and the infected veins acquire a brown, putrid color. 
If you cut the stem of a diseased plant, you will see dark brown fibers on the cut ring. When such a sprout is squeezed, a gray-white cloudy mucus will be released from it.
Botanists classify brown rot as a vascular disease of potato and note the death of bushes as a result of clogging of xylem veins with a dense gumy mass. There are cases when the disease manifests itself only as verticillium wilt and ring rot, in which there is no splitting of the shoots and mucous discharge is observed. 
The disease on tubers is expressed by a softened vascular ring and the appearance of brown putrefactive elements on the core. Often, decay processes begin already in storage facilities. They are accompanied by mucous discharge and an unpleasant odor. Such potatoes infect all neighboring tubers and completely rot.
Did you know? According to the International Finance Corporation, Ukrainians annually consume about 4 million tons of potatoes, despite the fact that the average annual yield of root crops is approximately 18 -19 million tons.
The country's leading agronomists draw the attention of farmers and landowners to the fact that the fight against bacterial diseases of potatoes should be aimed at comprehensive protection against the pathogens described above. At the heart of all such measures is the management of relations between internal and external populations.
This means that the plant must be protected throughout the entire growing period using different methods, including seed production and organizational and economic nuances, as well as the principles of combining crops.
When brown rot appears, crop rotation and the application of optimal fertilizers are key in the fight against it. It will be possible to plant potatoes on infected soil only after 5 years. Seed tubers must be carefully sorted and heated for 20 to 30 days. This will help to accurately detect unsuitable material. It will also be indicated by a 0.002% solution of succinic acid, which is used to treat the fruits for half an hour. 
If during planting it becomes necessary to cut root crops, the knife must be disinfected with formaldehyde or potassium permanganate. Healthy, for preventive purposes, before planting, they are treated with chemicals such as: “TMTD”, “Rizoplan”, “Baktofit”, “Polycarbocin”, repeating the treatment twice on seedlings until budding begins.
Varieties with increased resistance to microbes are well cultivated: “Resource”, “Ulyanovsky”, “Udacha”, “”. Control of bacterial diseases of potatoes includes regular inspection and removal of diseased plants.
Experts advise carrying out the first cleaning after the stems reach a height of 25 centimeters, the second during flowering, and the third several weeks before harvest. It is important to completely mow the tops during this period so that they have time to dry before harvesting the fruits. The entire crop should be thoroughly dried before storing in the cellar. Preparatory work is also needed in the storage facility.
For this purpose, remove all the remaining last year's and, disinfect with a 2% aqueous solution and treat the walls with extinguished. When entering the room, place a mat soaked in a 5% solution of copper sulfate.
Important! To safely preserve potato tubers in the cellar, for the first 20 days the room temperature should not be lower than +13 °C, and the air humidity should be kept at 90%. In the future, gradual cooling to 2 degrees is necessary.
Ring rot
Signs of ring rot are quite noticeable on potato tubers and biomass. They appear after flowering in the form of yellowing of thin shoots and curling of leaves. Affected specimens are difficult to pull out, even with general cell death. This happens due to the destruction of the stringy structure of roots and shoots. 
The disease begins from the roots, but its first symptoms can be noticed on the fruits only when they are cut. Yellow or brown rings on the edges of the core indicate the further development of putrefactive processes that will eventually destroy the entire fruit. When pressed, gray-yellow mucus flows from the affected areas.
If, when examining the seeds, you did not notice signs of rot and planted such a root crop, dwarf, poorly developed, thin shoots with small deformed leaves will grow from it. You should not expect a large harvest from such bushes. 
In most cases, bacterial diseases arise due to poor-quality planting material, or due to mechanical damage during harvesting root crops, transporting tubers in contaminated containers, as well as when storage rules are violated. Today there are no special pesticides against putrefactive diseases of nightshade crops. 
They are fought with quarantine methods, which, in addition to proper preparation of planting material and harvesting, include sowing changes for 3 years, selection of resistant varieties, potato fields with potassium preparations and systematic removal of diseased plants at the first signs of rot.
Did you know? Potato diseases destroy from 30 to 65% of the crop.
Wet rot
The disease begins from the core of the tubers and is often difficult to detect in the initial stages of development. Its root cause is bacteria or fungal pathogens that enter the root crop due to mechanical damage or are carried by pests. Based on these factors, it becomes clear why potatoes quickly rot from the inside. 
This process is expressed in the softening of the tubers and the spread of a strong stench. Rotten tissues are initially white, but later they turn brown, acquiring darker shades. By the way, the skin is affected when the inside is completely rotten. It happens that the surface of root vegetables becomes covered with dark dents, from which, when squeezed, a whitish starchy substance flows out.
If a root crop is exposed to cold conditions, its eyelids die and the process of rotting begins. Therefore, such tubers should not be protected; it is better to use them immediately, otherwise they will ruin the entire harvest. Farmers note that very often potatoes are affected by this disease in the cellar, especially when the product freezes or, conversely, is piled in a compartment and stored at temperatures above +4°C. 
The appearance is also accompanied by high indoor humidity and poor ventilation. This is explained by a lack of oxygen, which entails a decrease in the immunity of potato fruits. You can, again, get rid of the problem through comprehensive measures. To do this, it is important to ensure that the soil in which the crop grows is not waterlogged and is well loosened. When storing in storage, select healthy tubers and dry them thoroughly. 
It is advisable to treat seed potatoes with the chemical “Maxim” before placing them in the cellar. And also protect the crop from various kinds of abrasions and cuts, take timely measures to combat pests. For the winter, place root vegetables, regardless of their purpose, in boxes or vegetable nets. In cases where you find foci of putrefaction, remove all tubers from the infected area and try to use them as soon as possible. Also strictly follow the rules for storing potatoes (we mentioned them above).
Did you know? Every year, Europeans collect about 35 tons of potatoes from 1 hectare, while Ukrainians collect only 15 tons. This difference arises as a result of the fact that 95% of the product is cultivated in small farms, which, of course, affects the quality of the tubers.
Mixed internal rot
This disease of potato tubers, like previous types of bacteriosis, occurs when root crops are wintered improperly and as a result of mechanical abrasions, blows, and cuts. Symptoms depend on the type of pathogens that have entered the tissue membranes of tubers. You can observe the signs of wet or ring rot, as well as dry rot, that we have already described. A gray, pink or brown slippery coating will certainly appear on the affected areas. 
The methods of combating these microbes are no different from those mentioned above. Your main task is to protect the crop from mechanical damage and provide the right conditions for its conservation. It is important to disinfect seed material before planting with any antibacterial and antifungal chemicals. Experienced summer residents recommend the drugs “Fludioxonil” and “Maxim”.
Blackleg
The disease begins to manifest itself as soon as favorable conditions arrive: increased dampness or prolonged hot weather. During drought, the course of the disease is sluggish and becomes chronic. The black leg is noticeable on both the underground and above-ground parts of the potato: the stem below turns black, the leaves turn yellow, the bush gradually fades, and the root crops begin to rot.
In the heat, within a week, the sprouts will begin to soften in the root zone, which usually fall due to their own weight. Infected specimens are easily pulled out, and mucous discharge is visible on stem sections. Tubers rot from the stolon areas, becoming covered with dark spots. A sure sign of the disease are putrefactive spots on the potatoes, darkened skin, cracks from which a stinking, pulling liquid is released. Such root vegetables are very light, which indicates the complete destruction of their insides by bacteria. 
Blackleg can be overcome by strictly following the rules of agricultural technology for growing potatoes, harvesting and storing them. In this aspect, crop rotation, planting high-quality seeds, timely loosening of the soil, phyto-cleaning and weed elimination, and disinfection of work equipment are important. Before planting, it is advisable to treat the tubers with preparations such as: “Maxim”, “Prestige”, “TMTD”.
Important! In order for seed potatoes to be well preserved until spring, they need to be greened in the fall.
Fungal diseases of potatoes
Botanists describe this group of potato diseases as the most serious and dangerous. The appearance of various fungi on the bushes or in the roots of potatoes necessarily entails disease.
They are often carried by harmful insects or caused by improper conditions for cultivating root crops. Let's look at brief characteristics of the most common fungal diseases and methods of combating them.
Common scab
The disease appears as a result of the activity of radiant fungi of the genus Streptomycetes. The precursors to their occurrence are low levels, limestones, sandy, sandy loam substrates and hot weather conditions. The pathogen enters the tubers through the stem. Infected fruits lose their taste and presentation. Small brown asymmetrical spots appear on the potatoes, which “cork” over time. 
As they develop, the sores merge together, and a coating is barely noticeable on freshly dug fruits. In the sun it quickly dries out and loses its mark. The core of such root vegetables, despite the ulcerative crust formed on the outside, does not change. For preventive and therapeutic measures, Candidate of Biological Sciences, Professor of NUBiP of Ukraine Ivan Markov advises observing crop rotation and rules for fertilizing potatoes.
According to the scientist, fresh, overdose and contribute to the development of pathogens. Therefore, it is important to introduce physiologically acidic substances at the rate of 60 kg per 1 ha, which are manganese sulfate and ammonium sulfate. Nitrogen stabilizers are also desirable. 
The harmfulness of scab is significantly reduced with proper dosage of calcium chloride, manganese, boron, copper, and cobalt. The required amount of the listed chemicals for a specific field can be calculated based on its agrochemical examination, which can only be done by a specialist.
If there is no possibility or means for laboratory tests, you can use the cheapest way to combat scab, focusing on disease-resistant potato varieties. Do not be afraid of fungal diseases “Bozhedar”, “Kosen 95”, “Chernigovskaya 98”, “Lugovskaya”, “Borodyanskaya pink”, “Vesta”, “Symphony”, “Vodograi”, “Velox”, “Gatchinskaya”, “Volovetskaya” ", "Zarevo", "Lybid", "Drevlyanka", "Serpanok", "Poran", "Rozara" and other varieties with thin skin of reddish tones. 
Also, each owner of a land plot should take care of the condition. To enrich it with useful elements, it makes sense to organize the plowing of green manure: lupine, clover or. Before burying, high-quality root crops selected for planting are treated with the preparations “Maxim”, “” and the growth regulator “Agat-25K”. After buds begin to form on the seedlings, the soil must be irrigated for 4 weeks, maintaining humidity at 75%.
Powdery scab
You can save potatoes from slime mold by regular sowing changes, planting high-quality seed, which should first be treated with fungicides (Maxim). The collection of root crops should be organized in dry, warm weather, observing the above rules for harvesting and storing tubers. In heavily contaminated areas, re-cultivation of the plant is possible only after 7 years.
Did you know? According to the Main State Plant Protection Inspectorate of Ukraine, in 1996 all potato plantings in household plots and agricultural enterprises in the Lviv region were affected by scab. This was a burst of intense fungal development. The latest data on tuber infestation is 17 – 24%.
Silver scab
By spring, they will show clear dents and a silvery sheen, which occurs as a result of complex processes of tissue exfoliation and access of oxygen to the formed cavities. In cases where mass infection occurs, the upper shells of the fruit are severely deformed, losing moisture. 
Comfortable conditions for the development of silver scab on potatoes are dampness in storage and too high a temperature. For example, 1 hour at +15 °C is enough for the formation of pathogenic spores. At +3 °C, mushrooms are not produced.
Methods of combating silver scab are traditional, as in previous cases of bacterial and fungal diseases. They differ only in the means for disinfecting seed potatoes. Agronomists advise using the following drugs: “Vivatak 200”, “”, “Maxim”, “Bontan”, “Titusim”, “Nitrafen”, “Tekto 45”. Dressing should be carried out immediately after harvesting root crops.
Black scab (rhizoctoniosis)
Compared to silver and common scab, rhizoctonia affects not only tubers, but the entire plant. The disease appears from substrates infected with pathogens, especially in the cold season. This distinguishes black scab from other species and poses a great threat to tubers planted in unheated soil. 
Young shoots of diseased crops are very sparse and depressed. Black, warty dots are noticeable on root vegetables, which peel off easily and can merge together.
On the stems, the disease manifests itself as brown sores, which in the root part are covered with a felt-like whitish coating, and on the roots - with rough spots. The massive spread of fungal spores can significantly reduce the yield and completely destroy it in the cellar. 
Its development is favored by cold and dampness. Therefore, for prevention, do not rush to plant potatoes, give the soil a chance to heat up and lose excess moisture. Take a good look at the seed roots, discarding contaminated samples.
Before planting, it is important to treat healthy tubers with Fundazol, Prestige or Maxim. Timely rotation of crops in the garden, elimination of tops before harvesting and plant residues after harvest, and fertilizing the soil exclusively with rotted organic matter are also important. 
Important! To increase productivity, potatoes should be renewed every 4 years, giving preference to elite, uninfected varieties of Dutch selection.
It is also important to germinate seed tubers in the sun, since sprouts that appear in the dark are the first to be affected by black scab. Agrochemists advise treating diseased bushes with potent drugs: Ditan M-45, Colfugo, Mancozeb, Fenoram Super.
Important! To save healthy potatoes from the scourge of black scab, it is recommended to organize early harvesting of the fruit.
Alternaria (dry spotting)
Alternaria potato blight is caused by fungi of the genus Alternaria, which become more active in dry and hot weather. You can notice traces of their vital activity starting from the flowering period of the plant. Symptoms are clearly expressed until the root crops are harvested. The disease manifests itself on leaves and sprouts; rarely, fungi infect tubers. You should be alerted by brown round or triangular spots that appear on the foliage or stems. 
Myceliums are easily transported by the wind, infecting new areas of the garden. This is the danger of Alternaria leaf disease on potato leaves. The fact of focal spraying of spores becomes clear. Their formation is facilitated by frequent changes in wet and dry weather, lack of moisture, unfavorable soil conditions, lack of potassium and nitrogen, and excess phosphorus.
Young fruits become infected with the fungus when they come into contact with the soil when dug up, while mature fruits become infected in the presence of abrasions and other mechanical damage. To destroy the fungi that cause dry spotting, the first step is to eliminate the primary sources in the soil. This is done by autumn plowing. In the future, beds with potatoes should be placed as far as possible from tomatoes, since Alternaria blight is dangerous for all nightshades. 
Seed tubers should be carefully examined, discarding specimens with a black or brown surface and slightly concave spots with uneven but clear edges. It is important to fertilize grown seedlings on time. As soon as you notice the first signs of the disease, immediately spray the planting with any fungicide. It is advisable to re-treat depending on the degree of infection and the long-term effect of the drug used. 
It is better to carry out disinfection in cool and damp, possibly rainy, weather. The percentage of the harvest you save depends on following the harvesting rules and storing it in the cellar. We have already mentioned above how to do this correctly. 
Some summer residents share their experience of planting varieties resistant to Alternaria. For example: “Lina”, “Nevskaya”, “Victory”, “Fairy Tale”, “Reserve”, “Lyubava”, “Skoroplodnaya”, “Volzhanka”, “Master”.
Did you know? Spanish farmers flatly refused to cultivate potatoes only because the root crops frightened superstitions with their human-like shapes.
Potato cancer
This is a fungal quarantine disease provoked by microbes, due to the activity of which damaged tubers are prohibited from being transported from their places of growth. Pathogenic microorganisms spread to root crops and the root system of the plant. The cancer appears as growths with a wavy structure that resembles cauliflower. 
Over time, these formations increase in size, change color, and move to the root zone of the stems and stems. At the final stage of development, they become black with a slippery, putrefactive surface. The spores are easily transferred to healthy fruits, especially during times of high soil moisture. They get into the ground with the help of working equipment, animals and manure, and remain viable for 4 years.
To get rid of the problem, pour kerosene, bleach or formaldehyde on infected fruits and tops and bury them to a depth of at least 1 meter. As an alternative, some gardeners suggest burning all affected plants, although surviving potatoes are not suitable for seed, as they are a potential carrier of pathogens. It is better to use such tubers for food purposes. 
Of course, the purchase of seed material is carried out exclusively in specialized centers. Before planting, inspect the tubers - cancerous spores may be hiding under the soil stuck to their surface. Organic and mineral fertilizers help free soils from infectious microbes. But it is important to ensure that the manure is thoroughly rotted. Chemical methods of combating cancer are only available under the supervision of a plant quarantine inspector. 
Important!Tubers that have grown in cancer-affected areas can be disinfected before sowing using a 1% Fundazol suspension.
Dry rot (fusarium)
The reasons why dry rot appears on potatoes are considered to be gross errors in agricultural technology and unfavorable soils, as well as mechanical damage and improper storage of tubers in winter. The symptoms of the disease clearly appear on the tubers in the form of dark swamp-brown spots, which over time transform into shallow dents. The skin on the affected areas is wrinkled, and a pubescent coating is noticeable. A similar picture occurs inside the fruit. 
With the development of fusarium, the bushes of the plant begin to wither, droop the stems and lose viability. If you cut off a diseased sprout, you can see a dark ring where the blade passes.
In order to destroy pathogenic dry rot fungi, it is recommended to strictly follow the rules of agricultural technology and storage of the harvested crop, plant only high-quality material, protect potatoes from blows and cuts when harvesting, and annually carry out pre-sowing treatment of tubers with fungicidal preparations (for example, “Maxim”, “Prestige”). 
Late blight
A fungal potato disease called late blight is considered the most insidious of the entire list of ailments. It affects the entire plant, but appears primarily on the foliage during budding of the bushes. You can recognize the appearance of late blight by the brown felt spots that form on the underside of the leaves and, growing, cover the plant with a solid brown carpet with a light white coating. On the stems, the disease is revealed by long dark stripes. Such a plant is not able to fully develop; rotting processes begin in it. 
Favorable conditions for the occurrence of late blight are high humidity after prolonged rains, warm weather and lack of good ventilation. When the weather returns and the soil dries out, the mushrooms stop functioning. But this does not mean your victory over the disease, since after the first rain the disease will begin to progress. 
To cure a crop, in addition to traditional methods, proper cultivation and storage of root crops, be sure to spray the bushes with a boron mixture, “Oxychom” or “Polychom” at the initial signs of late blight. Some summer residents resort to folk technologies for prevention, treating the foliage with garlic tincture six times. This process begins at the beginning of flowering and is repeated every 14 days.
The preparation of seed material is also important. In addition to germination and discarding everything unsuitable, the tubers should be treated with Fitosprorin, boric acid or copper sulfate. The soil in contaminated areas in spring and autumn is also treated with the above-mentioned preparations. 
Did you know? In the 17th century, the French introduced the fashion of decorating costumes and wigs with bouquets of potato flowers. In this country, the plant has long been cultivated as an ornamental.
Potato blight
Phoma pathogens penetrate the root crops, stems and sides of potatoes, having a detrimental effect on them. The sore appears as elongated, shapeless spots covered with brown dots. 
As they develop, fungal spores ring the shoots and prevent the culture from developing. Affected bushes differ from healthy ones by loss of foliage color saturation and lifelessness. If no measures are taken, the plant will die. On tubers, signs of phomosis are expressed in the form of ulcers that spread up to 6 cm. Over time, deep cavities appear in the affected areas. Such specimens stored in the cellar contribute to the proliferation of mycelium. They are also accompanied by post-harvest residues and weeds abandoned in the garden. 
Viral diseases of potatoes
Dangerous pathogens of potato viral diseases cause damage to yields gradually, resembling a time bomb. In the first years, their vital activity is almost unnoticeable, but later they destroy up to 50% of the fruits. Carriers of such diseases are Colorado potato beetles, aphids, cicadas and other pests. Infection during processing of root crops is also possible. Let's look at the most common potato diseases caused by viruses.
Ordinary mosaic
It is caused by several viruses at the same time. Favorable conditions for this are mechanical processing and the presence of harmful insects in the garden bed. Appears on young leaves as barely noticeable light green dots of asymmetrical shape. Over time, this mottling darkens and spreads to the entire bush. 
Wrinkled mosaic
When infected, the leaf tissues of the plant swell greatly, forming peculiar folds. They arise as a result of poor outflow of assimilated products. 3 years after cultivating infected potatoes, you will notice how the plants degenerate into dwarf plants with corrugated, underdeveloped foliage and very fragile stems. Such a bush is not able to set buds and bear fruit. He will finish his own a month earlier than healthy specimens.
Striped mosaic
For banded, the characteristic features are mosaic specks, which, first of all, appear on the lower and middle leaf blades. Later, black stripes and veins form on the affected areas. The leaves break easily, die quickly, and often hang lifelessly, exposing the stem before budding begins. The pathogen overwinters in root crops.
Gothic potato tubers
The disease occurs through the ingestion of the spindle veroid virus (VVVV), which is why it is also called “spinoid virus.” The harmful microbe manifests itself by deforming the tubers, deteriorating their taste and presentation. The foliage of diseased bushes is too elongated, very small, and does not develop properly. The edges of these leaves have an anthocyanin tint. Diseased plants grow poorly, are stunted, and the color of the tubers of red-skinned varieties is lost. At the same time, the root crops grow small in size with a spindle-shaped shape. 
Did you know? The most dangerous and widespread viruses are the PLPV and PVY viruses, which reduce the weight, quantity and starchiness of tubers, killing up to 80% of the crop.
Necrosis of potato tubers
The development of necrosis on potatoes begins with the entry of the Tobacco rattle virus into the soil and tubers, which reduces the starch content and leads to necrosis of the fruit. Characteristic features of the disease are small light specks that cover the leaves, deformation of inflorescences, dark necrotic spots on root crops, which often bend into bizarre stripes, arcs or rings. 
A very high prevalence of this virus is observed in sandy and swampy areas. Today there is no drug for viral potato diseases that would immediately solve the problem. However, in order not to lose the entire harvest, if symptoms of any of the listed viral infections are detected, immediately organize phytocleaning, repeating it periodically until all affected plants are removed.
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Black leg on potatoes is often a sign of disease. You can easily distinguish traces of overwatering from plant disease simply by looking closely at it.
If the stem falls off on its own or the plant is easily pulled out, and there are no visible signs of moisture, then most likely there is an infection with black stem.
Primary diagnosis can be carried out in a very simple way: take a darkened stem of a plant and dip it in water, it will become cloudy. Such a simple check can help determine the cause of plant damage.
Previously, it was believed that blackleg disease was caused by three types of bacteria. Currently, they are all combined into one species called Erwinia carotovora. This species has two varieties: subsp.atroseptica (Eca) and subsp.ceretovora (Ecc).
Under a microscope you can see the microorganisms E. Carotovora. The bacterium has short rods, straight, with rounded edges. The average size is 0.6 - 1.8 x 1.7 - 5.1 microns. They can be single, connected in pairs or in short chains. The bacterium is characterized by mobility and does not form capsules or spores. They are classified as gram-negative, facultative anaerobes.
Diagnosis and prevention of the disease can be done at the stage of planting the crop. To do this, let's move on to the symptoms and causative agents of the disease.
Symptoms and causative agent of the disease
The disease does not always manifest itself immediately. Most often, its signs are visible in the first half of summer, usually two weeks before flowering.
Affected plants look much worse than their healthy counterparts: they look depressed, the color of the foliage changes, the leaves may be stunted yellow and curled.
Individual shoots in a bush may be infected, but the entire course may wither at once.
A clear sign of the disease is rotting of the plant roots and blackening of the stem. Due to this, additional roots stop developing.
If you try to pull an infected plant out of the ground, even a child can easily do it, since it is extremely easy to pull out a plant.
As a rule, infected plants do not develop and remain single-stemmed and do not form tubers.
If infected at later stages (before flowering), the plant produces a harvest, but it will be minimal.
Externally, you can examine the tubers and notice small dark spots; this darkening spreads inward. The affected fruit darkens and turns into an unpleasant slimy mass. Rot is present on the outside of the tuber and inside the fruit. Externally - rot and a slimy mass, inside - weeping black and jagged edges.
Diagnosis of infection
Having examined the stolon part, you can even notice changes with the naked eye. The bacteria spread, moving from the stems to the daughter tubers and, spreading to the middle, transform the stolon into a rotting soft mass with an unpleasant odor. The color of these parts of the tuber also changes: from light it becomes quite dark.
Another feature of affected tubers is an unpleasant-smelling liquid flowing from cracks. Cavities form inside the tuber, and cracks and dark skin appear externally.
In dry conditions, infection occurs in a chronic form.
Diseased plants are detected after germination. The leaves immediately lose melatonin, turn yellow, curl up and dry out; the stem turns yellow and withers.
Rapid development of the disease. Period - from 4 to 6 days. Wednesday - high humidity, hot weather. Plant changes: the stem breaks under its own weight. The leg turns black and rots.
The difference from Rhizoctonia is that plants are easily pulled out of the soil. Additionally, on transverse sections there is browning of the vascular bundles.
Causes of infection
Biology of blackleg
Blackleg affects not only potatoes. It can also occur in other cultures. Lettuce, cabbage, radishes and garden crops are at risk. The signs of infection in these plants are exactly the same: the stem rots, the plant withers and the leaves change color.
The reason is all in the same Carotovora bacteria. Sources of infection: soil, planting material, vectors of infection.
Sick plants can tolerate diseases in different ways: from developmental delays to complete wilting.
Fighting methods
Preventive measures against blackleg. Biological agents
Preventive measures to protect against Blackleg. Chemicals
- Before planting, tubers are sprayed with TMTD or Fitosporin-M preparations.
- The earth can be watered not only with a solution of manganese, but also with chemicals that are applicable to combat fusarium. For example: foundationazol, vitaros, topsin-M, benthal or previkur in the proportion of 2 grams of the drug per 1 liter of water.
- For prevention, watering with the addition of “Effecton” is used in the proportion of 3 tablespoons per 10 liters of water. Consumption per plant is half a liter of water. The solution must be heated to twenty-five degrees.
- Before storing potatoes, they are treated with the drug “Maxim”.
Review
Anastasia
We decided to grow potatoes where they grew last year. We thought it was all nonsense and there would be no problems. This was not the case: even as the potatoes were sprouting, they began to turn into something unknown. It was getting blacker and darker, we already thought we couldn’t save it, but a neighbor suggested a good drug called Energen, we treated it and everything seemed to go away.
Blackleg
When the disease progresses slowly (in dry conditions), it is chronic. Diseased plants are detected soon after germination. The leaves turn yellow, curl up and dry out. The stem also turns yellow and withers. With the rapid development of the disease (observed in hot weather with high humidity), already 4-6 days after the lesion, the blackened part of the diseased stem softens, it breaks, unable to withstand its own weight. Plants affected by blackleg are easily pulled out of the soil - this distinguishes “Blackleg” from Rhizoctonia. On transverse sections of the stems, browning of the vascular bundles is noticeable. When the end of the stem is placed in water, mucilage is noticeable. Sometimes plants have one or more stems affected.
On affected tubers, symptoms of the disease appear in the form of dark rot, usually starting in the stolon part. Penetrating from the stems through the stolons into the daughter tubers, the bacteria spread to the middle and turn it into a soft rotting mass. The color of the affected parts of the tuber is initially light, then darkens. A distinctive feature of diseased tubers is darkened skin, the presence of cracks, and lightness. An unpleasant-smelling liquid leaks from the cracks. Cavities may form inside the tuber.
There are no varieties that are absolutely resistant to the disease.
To combat blackleg(1) do not plant potatoes on affected soils, (2) plant healthy seed tubers, (3) destroy weeds, (4) be careful when cutting potatoes - the knife should be sterilized after cutting each tuber, (5) treat the tubers with disinfectants before planting ( for example, TMTD - 4-5 kg/t), (6) destroy the tops before harvesting, (7) observe crop rotation, the best predecessors are wheat, perennial grasses, legumes, vetch-oat mixture, beets, bad predecessors are cabbage, carrots, tomatoes, onions, (8) harvest fully ripened potatoes, dry them, (9) seed tubers are good to green in the fall, (10) grow resistant varieties.
The disease appears in the first half of summer, 2 weeks before flowering. Sick plants stand out from healthy ones by their depressed appearance and chlorotic coloration of the tops; The leaves of such plants are yellow and curled. Severely affected plants wilt; In clones, individual shoots are often infected.
The most characteristic sign of blackleg is blackening and rotting of the root collar, as a result of which lateral and additional roots do not develop. Very often, affected plants remain single-stemmed and are easily pulled out of the ground. Since young plants are usually infected, tubers often do not form on them at all; in case of later infection (before flowering), diseased plants produce a harvest, but it is very low. The tubers are small and mostly infected; a small dark spot is visible on the surface of the tubers at the end, from here the darkening spreads inward. The damaged tissue softens and turns into a mucous mass. Cavities with black, uneven, wet edges form inside the tuber. Rot can also develop from the surface of the tuber, which is often observed during potato storage.
The causative agent of blackleg is the bacterium Erwinia phytophthora Berg. During winter, the bacteria persist in infected tubers. In unrotted remains (stems), bacteria can overwinter, but directly in the soil they quickly die. Consequently, the main source of the disease is planting material.
When planting infected tubers, bacteria enter the soil. They penetrate the underground parts of the plant through various damage - mechanical, damage by soil insects, nematodes. But most often, bacteria penetrate the stem from an infected mother tuber. If bacteria are introduced with infected tubers into storage or piles during the winter period, mass rotting of potatoes is possible.
The development of blackleg depends largely on soil and meteorological conditions. Blackleg is especially noticeable on clayey, moist soils; humid and moderately warm weather also favors the development of the disease.
Blackleg is widespread, especially in the non-chernozem zone, in the BSSR, in Western and Eastern Siberia and in other areas.
Control measures
1. Selection of healthy planting material; disinfection of tubers before vernalization (see black scab).
2. Cleaning potato plantings three times, i.e. removing diseased plants. The first cleaning is carried out in the spring after seedlings, the second - during flowering and the third - before harvesting. This activity is necessary in seed plots to obtain healthy planting material.
3. Drying of tubers in the field and, if necessary, additional drying before storing them. Drying and light-hardening are especially important for seed potatoes.
4. Compliance with the rules for storing potatoes (see late blight).
5. Use of resistant varieties. Relatively stable: Pirmunes, Viliya, Detskoselsky, Skorospelka 1, Kameraz 1, Slev, Ulyanovsky, Agronomichesky, Veselovsky 2-4, Karnea, Borodyansky.
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Potatoes are affected by this type of bacteria during the growing season and during storage.. Blackleg disease is characterized by general plant oppression. The leaves turn yellow, become hard and curl, especially the upper ones; In addition, the plants develop poorly.
When affected by blackleg, very often the affected plant remains single-stemmed. Characteristic signs of the disease are blackening and rotting of the base of the stem, which can spread up the stem 10 cm or more. Hence the disease got the name blackleg ( table 33).
The disease intensifies noticeably during the flowering phase. Sick plants are stunted, their leaves turn yellow and curl. The plant dies slowly and is easily pulled out of the soil.
Table 33. Black potato leg:
1
- affected plant;
2
- a cork layer formed in the tuber pulp after the penetration of soil bacteria and fungi;
3
- cracking of the tuber skin;
4
- affected tuber in section
The disease spreads from the stem to the tuber and causes rotting of the core and the formation of small subcutaneous brown spots. On the cut surface of the tuber, rotting tissue is clearly visible.
Rotting often begins from the place where the tuber is attached to the stolon and goes inside the core, turning it into a dark mushy mass with the formation of a rotting void in the center.
In case of illness plants at an early age (before flowering) tubers, as a rule, do not form at all; with a later disease, tubers are formed, but are affected by blackleg.
In such tubers rotting continues during storage. During winter, bacteria persist in infected tubers or on the surface of healthy tubers. Bacteria do not survive in soil for long.
The disease can be transmitted by cutting planting material. During the growing season, bacteria enter potato plants through lesions and damage caused by soil insects, rot flies, nematodes, and cultivation tools when caring for crops.
The development of the disease is favored high humidity and moderate temperature. High temperatures and drought delay the development of the pathogen. It was noted that the disease is more pronounced on clayey, heavy, damp soils, and less so on light sandy loam.
Black leg calls plant losses, decreased tuber formation and, as a result, leads to a significant crop shortage. In addition, infected tubers that end up in storage create foci of infection.
Ways to combat black leg on potatoes
1)
use of healthy planting material;
2)
growing strong, healthy plants;
3)
three times cleaning (removal) of diseased bushes: the first cleaning is carried out soon after germination; the second - during flowering and the third - shortly before harvesting;
4)
control of insects that damage tubers and are carriers of the disease;
5)
drying and light-hardening of potato tubers: drying is carried out before storing the tubers for storage, and light-hardening is only for seed potatoes for 3-7 days;
6)
storage in dry and cool rooms;
7)
the use of varieties with increased resistance: early ripening - Khibinsky early; mid-late - Berlichingen, Ideal, Loshitsky; late ripening - Olev.