Why does potato rot during storage, and how to avoid it?


Despite the fact that potatoes are sold on the markets all year round, I want my own - incredibly tasty, boiled and environmentally friendly potatoes. But often home-grown potatoes can not be stored until spring. After the New Year holidays, intensified "spoilage" of tubers begins, an unpleasant smell and even (as the newspapers write) an explosive atmosphere when gas is accumulated indoors begins to appear in the storehouse. What causes rotting of tubers, and how to avoid it? Let's understand the reasons and develop a scheme for preserving the harvest of our favorite potatoes.

Why does potato rot during storage, and how to avoid it?

Fungal diseases of potato tubers during storage

Potatoes are affected during the growing season and when stored by fungal and bacterial diseases. Of the fungal infections, late blight, fusariosis, and alternariosis cause the most harm.

Late blight

Late blight is one of the most dangerous fungal diseases. The fungus infects the crop during the growing season (it can destroy up to 70% of the crop in a short period) and is transferred to the storage places with tubers.

Solid gray spots appear on the surface of the tubers, clearly visible on the pulp when the potato is cut. With the growth of mycelium, rotting of the tuber begins.

Protection and control measures

When plants are affected during the growing season, it is necessary to spray potatoes with a 2% raster Bordeaux liquid. If a complex lesion is suspected (that is, several types of fungal diseases), the biofungicides Fitokhit, Fitosporin-M, Planriz, etc. are used.

Optimal storage conditions - good ventilation, lack of light, air humidity within 80-90%, air temperature not higher than + 2 ... + 3 ° С. For the development of late blight, a high temperature is required (+ 20 ... + 24 ° C). Therefore, it is not recommended to store potatoes in high-temperature residential areas.

The best varieties of potato resistant to late blight are: “Lasunok”, “Temp”, “Scarlet”, “Aspia”, “Bulletin”, “Golubizna”, “Lugovskaya”, “Resource”, etc.

Fusarium (dry rot)

Like late blight, it affects the tops and tubers during the growing season. Excessive soil moisture (prolonged rains) at high temperature contributes to the rapid spread of the disease.

During the growing season, external signs appear as gray spots on the leaf surface, general withering and drying of the plants. The affected plant withers literally in one day. A striking feature of the defeat of culture by Fusarium is the blue-black ring on the section of the stem (vessels clogged with hyphae of the fungus).

Tubers laid for storage are covered with a whitish coating, or the skin in the places of formation of gray-brown spots shrinks and becomes dry (without obvious reasons for violation of the rules for storage of products). In the section, dark voids filled with mycelium are visible.

Protection and control measures

The degree of harmfulness is very high. Mycotoxins of this disease are stored not only on the crop, but also on processed products. They affect the human nervous system, cause the death of birds and animals. Tubers (like other products - flour, juices, preserves, animal feed) affected by Fusarium cannot be used as food.

During the growing season, plants are sprayed with a 1-2% solution of Bordeaux fluid, solutions of biofungicides (Fitosporin-M, Fitokhit, Bactofit, Integral, Planriz).

The optimal conditions for storage are the same as those for protection against late blight. It is recommended to process tubers with Fitosporin when laying for storage (biofungicide does not affect human and animal health). Systematically sort the potatoes (carefully so as not to disturb the outer skin, as the infection quickly transfers to neighboring tubers).

The best varieties resistant to this disease are: "Detskoselsky", "Priekulsky early", "Berlichingen", "Nevsky", "Skarb" and others.

Late blight of potato tubers. Fusarium (dry rot). Alternariosis (dry spotting of potatoes).

Alternariosis (dry spotting potatoes)

In terms of damage to potato yields, this disease is similar to late blight. It affects all parts of the plant (stems, leaves, tubers). Most often, it is middle and late potato varieties that are recommended for laying for winter storage.

Damage during the growing season appears on leaves and stems in the form of large concentric spots. The spots gradually become brown or dark brown with a brown tint. Indented spots appear on the surface of the tubers, which gradually wrinkle. In the section of the tuber, the affected areas are necrosized; they differ from healthy tissue in solid, dense flesh of black-brown color.

Protection and control measures

When preparing for planting, treat the tubers with the biological preparations Planriz, Bactofit, Integral, Fitosporin-M and others from the recommended list. During the growing season, carry out the same treatments as with previous diseases.

The optimal conditions for storing potatoes are the same as when protecting against the previously listed diseases.

The best potato varieties resistant to this disease are: Gatchinsky, Ogonyok, Zarevo, Lyubava, Bronnitsky, Sibiryak, Severyanin, Russian Souvenir, Effect, etc.

The above-described diseases (late blight, fusarium infection, alternariosis), as well as rhizoctonia, common scab, fomosis, anthracnosis are distributed mainly through the seed material. Therefore, the planting and cultivation of disease-resistant varieties zoned to external conditions is the key basis for the preservation of tubers during winter storage until a new crop.

Bacterial diseases of potato during storage - rot

In addition to fungal, potatoes are susceptible to bacterial diseases. The source of damage is putrefactive bacteria, capable of turning tubers into a gray decaying mass with a sharp unpleasant odor in 2-3 months.

Bacterial infections develop in violation of the storage conditions of products (poor ventilation, high temperature and humidity). Pathogenic bacteria penetrate into the tuber through external damage (cracks, cuts when digging potatoes, etc.).

A bacterial infection is transmitted mainly through seed material, but during the growing season it affects not only tubers, but also vegetative organs (stems, leaves, roots, stolons).

In the years of epiphytotism from bacterioses, up to 50% of the crop in the field dies and up to 100% - during storage. Most healthy tubers become infected with phytopathogenic bacteria during preparation for planting, inaccurate harvesting (with various kinds of mechanical damage) and sorting before storage.

Of bacterial diseases, most often, potatoes are affected by wet bacterial rot, button rot, ring rot, black leg.


Crop losses can range from 1-2% to 50-70%. Bacteriosis affects the vegetative parts of the plant and tubers. It is difficult to get rid of a bacterial infection, due to the fact that there are still no cultivars resistant to this disease.

When planting infected material, many seedlings of potatoes fall out or seedlings are weak, poorly developed. With age, the lower part of the stem blackens (hence the name of the disease is "black leg"), the leaves turn yellow, become brittle, hard. The leaf blades are twisted by a boat, the leaf itself grows at an acute angle to the stem. When excavating, the mother tuber is rotten, slimy.

Ring rot

Bacterial infection affects all parts of potato plants. The external manifestation of the disease during the growing season, like that of the black leg, is the withering of the aerial part and the decay of the mother tuber.

A distinctive feature is leaf mosaic in pale yellow tones and swelling of leaf nodes. 1-2 weak stems develop from the mother tuber. On harvested tubers, pitting rot is visible during harvesting; when cut, diseased tuber tissue has a ring lesion of vascular tissue or yellow subcutaneous spotting.

Brown rot

Mucosal bacteriosis is one of the most malignant bacterial diseases. It differs by the rapid course of the disease. It affects about 200 species of plants, including potatoes.

Distributed mainly in regions with a warm climate. The source of infection is diseased tubers and soil, weeds, irrigation water. The causative agent of the disease penetrates into the tubers of the new crop through mechanical damage, stomata, fills the vessels of the stems, stolons, roots with mucous mass, which causes the plant to wilt and die.

Symptoms of the disease externally appear in the flowering phase in the form of wilting leaves at the ends of the shoots. Green leaf blades acquire a brownish tint, curl into a half-tube and hang. The basal part of the stems softens. The bacterial mucus accumulated inside (in the vascular ring) is secreted through the breaks of half-rotten stolons, stems, rotted tubers.

Potato stricken with a black leg. Potato ring rot. Brown rot of potato.

Measures for the protection and control of bacterioses (rot)

All bacterial rot (as shown in the above diseases) are distinguished by the general withering of underdeveloped potato bushes during the growing season and the rapid decomposition of tubers to the mucous mass during storage. A significant part of the rot is soil pathogens and is able to persist in the soil for a long time, affecting planted healthy material.

Therefore, the main measures to protect the culture from bacteriosis are the use of zoned, resistant to damage potato varieties, mandatory autumn-spring disinfection of the soil before planting, processing of planting material to suppress soil infection during tuber germination, preparation of storages, sorting of tubers before laying them for storage.

The best varieties are resistant to this complex of diseases: "Scarb", "Nevsky", "Rosinka", "Early Lapis lazuli", "Bronnitsky". Resistant to bacterial rot and mid-season varieties "Rodnik", "Resource", "Bulletin", "Blue" and others.

How to protect potatoes from rotting?

Based on the foregoing, it is clear that the poor preservation of tubers in the cold period begins with a violation of the technology for growing and harvesting this crop. The following significant reasons are the unpreparedness of the storage (cellar, basement, vegetable pit, balcony, loggia, etc.) for the storage of products, improper selection of potato varieties, and violations of its storage technology.

It is these reasons that cause the defeat of tubers by various fungal, mold and bacterial diseases; contribute to their rapid spread and loss of yield not only during cultivation, but also during storage.

To protect potatoes from rotting during storage, it is necessary to properly prepare a site for this crop. Fertilize, fertilize, and treat diseases and pests only in accordance with technology and recommendations.

Read our detailed materials. Features of growing potatoes: preparation and planting and Features of growing potatoes: agricultural technology.

For planting (for the purpose of long-term storage of tubers in the cold period), it is necessary to use only zoned, middle and late varieties (in terms of ripening) that are resistant to fungal and other diseases. Before planting the seed material must be processed.

Read our material Proper potato processing before planting.

During the growing season, the treatment of plants must be carried out at the very beginning of the disease, and not wait for a mass lesion. It is more practical to carry out preventive treatments according to a previously worked out scheme.

Only absolutely healthy, intact tubers should be stored in prepared storage.

Read also our detailed material: When and how to dig potatoes?

Fulfillment of the basic requirements for the preparation of tubers, their planting, care and harvesting will minimize crop damage during winter storage.

When planting on a site of several varieties, each is harvested separately

Rules for protecting potato tubers from decay during storage

  1. When planting on a site of several varieties, each is cleaned separately.
  2. Only mid-season, mid-late and late potato varieties are laid for storage. Early varieties after December are no longer suitable for use in food and remain as planting material, or are used for animal feed.
  3. To tubers ripen well, potato tops are mowed 10-15 days before harvesting.
  4. Digging potatoes is carried out in dry sunny weather. If the weather is rainy, the potatoes are slightly dried and manually cleaned of adhering dirt (to avoid mechanical damage through which fungal or bacterial infections can enter the tuber).
  5. Mechanically damaged and diseased tubers are immediately laid in a separate pile.
  6. Healthy, undamaged potatoes are transferred under a canopy (covered from the sun) or in a dark room with good ventilation for 5-7 days to ripen (coarsen) the upper skin. Light protection is necessary so that the potatoes do not turn green. Solanine is formed in the light, and such tubers cannot be used as food.
  7. Before laying for storage, the storage is disinfected and dried.
  8. Dried and peeled tubers, to protect against rot during storage, can be treated with biological products "Fitosporin" and "Anti-rot", which will reduce the infectious background. They are harmless to humans and animals.
  9. If the potatoes are stored in bulk, it is advisable to lay 1-2 rows of beets on top. It will absorb excess moisture, which will protect the potato tubers from decay. Beets will not be affected.
  10. It is more expedient to store potatoes in boxes (each grade separately).
  11. Once a month, the tubers are reassembled, removing the sick.
  12. Good ventilation will protect stored products from infection and rot.
  13. The air temperature in the storage must be maintained at + 2 ... + 4 ° C, and humidity 80-91%. With increased humidity in the room, you can place, in addition to ventilation, a container with quicklime and change the filler if necessary. With the advent of spring, the temperature can rise in the store. It will help reduce frozen water in plastic bottles with a capacity of 3-5 liters. Ice tanks are placed in different places. Ice in closed containers will gradually melt and cool the room.

Read also our detailed material: How to store potatoes?

Dear ReadersIf you still have questions after reading the article, we invite you to a discussion on the forum or in the comments on this material. Many experienced gardeners have their own secrets to effectively protect potatoes from fungal and bacterial infections. Your advice would be greatly appreciated.