Fighting potato rotting in the ground, immediately after harvesting and in the basement. Fungal and bacterial rots of potatoes Root rot of potatoes

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.

Potato diseases: photos, descriptions and treatment methods

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 absolutely 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.

This article contains fungal diseases of potatoes. Many of us are already familiar with late blight, as it is found everywhere. But there are other, no less dangerous potato diseases.

Late blight, or potato rot

Signs of late blight on potatoes

During potato flowering, first the lower leaves begin to wither, turn black and dry out, then the upper leaves are also affected, and small but quickly growing dark brown spots appear on the stems. If the weather is rainy, the potato stems and leaves may rot. On the underside of wilting, blackening leaves, a faint whitish cobwebby coating forms around the black spots at the border with healthy tissue in damp weather.

Fig.1. Potato late blight: 1 and 2 - leaf damage from above and below; 3 — potato tuber affected by late blight; 4 - affected tuber in section.

With raindrops, the mycelium of the disease falls on potato tubers. Sharply outlined grayish and then brown depressed hard spots of varying sizes appear on the affected potato tubers.

Pathogen late blight is a mushroom (Phytophthora infestans). The incubation (latent) period depends on the air temperature and is about two weeks. Phytophthora fungi are capable of developing at positive air temperatures from + 1 to + 30 ° C.

Further infection of tubers occurs from contact with infected tops and soil. Mechanical damage to tubers during soil cultivation and harvesting also contributes to the penetration of late blight fungus. After harvesting the potatoes, the tubers should be dried; those affected by late blight should be immediately destroyed, since the mycelium of the disease overwinters on the tubers and the first signs of late blight are observed already on the first potato shoots.

During storage of potatoes, late blight does not spread, but other microorganisms often settle in places of late blight lesions, which cause rotting of tubers in storage.

Measures to combat late blight

To increase the resistance of potatoes to late blight, before planting or during planting tubers, it is recommended to add copper sulfate to the soil along with mineral fertilizers.

Plant varieties that are relatively resistant to late blight: Sadko, Temp, Stolovy 19, Moskovsky, Komsomolets and others.

After the emergence of seedlings, the potato plantings are sprayed with a solution of copper sulfate at the rate of 10 g per 10 liters of water.

When individual affected plants appear, they can be pollinated with copper oxychloride (2 g per 1 m2). Sometimes spraying with a 1% solution of Bordeaux mixture is also used. In case of massive late blight infestation, an aqueous solution of copper oxychloride is used.

Potato varieties such as Ogonyok, Zarevo, Filatovsky, Borodyansky and others have increased resistance to macrosporiosis.

Fig.2. Alternaria blight: 1 - affected leaf; 2 - spot at the site of the lesion; 3.4 - affected tuber.

Early dry spot, or macrosporiosis: 5 - affected leaf.

Alternaria blight

Alternaria blight affects leaves and stems, and sometimes potato tubers. On the edges of the leaves, small dark brown spots with an olive velvety coating appear. In warm, dry weather, the edges of potato leaves heavily affected by Alternaria, curled upward, resemble a boat.

The petioles of the leaves and stems of the potato are covered with black spots, but without noticeable concentricity, as happens with early dry spotting. On tubers affected by Alternaria, round, slightly depressed spots appear, sometimes covered with a black coating.

The causative agent of Alternaria blight is the fungus (Alternaria solani). Infection of the plant occurs under optimal conditions for the development of mycelium - warmth (temperature +22 +26°C) and high air humidity.

The fungus overwinters on plant debris left after harvesting and can also survive on tubers. Alternaria can also affect other plants of the nightshade family.

Measures to combat Alternaria

If measures were taken to combat late blight, the degree of damage to potatoes by Alternaria blight is significantly reduced. In addition, it is necessary to observe crop rotation, weed control, fertilizing, and removing plant residues after harvesting. Only healthy tubers should be selected for storage; the storage should be ventilated and disinfected in advance.

Verticillium wilt of potato

Verticillium wilt of potatoes begins to appear at the beginning of flowering. The leaves wither, lose turgor, the edges of individual leaf segments begin to turn yellow. Further development of the disease provokes the appearance of light brown spots on the leaves, bordered by a bright yellow stripe. In dry weather, potato leaves dry out and fall off; in wet weather, they hang along the stem.

If wet weather lasts for a long time, then a grayish-dirty coating consisting of mycelium (Verticillium albo-atrum) appears on the petioles and main vein of wilted leaves. With Verticillium wilt, potato stems also die, but remain standing until harvested. Verticillium wilt affects vascular fibers, which leads to disruption of water supply to the above-ground parts of plants, their wilting and death.

During storage of potatoes, the fungus penetrates the eyes of the tubers, and as a result, depressions form in place of the eyes. At high humidity in the storage, the tubers rot, become covered with a gray dusty mass, turning into a source of infection.

The source of further infection is infected tubers, plant debris overwintering in the garden, and soil.

Verticillium wilt can occur in tomatoes, eggplants, and peppers.

Measures to combat verticillium wilt the same as for late blight. If several plants are affected, then they are selectively removed from the site; if all potato plantings are affected by verticillium wilt, then the above-ground part of the plants must be mowed and removed from the site. Maintaining crop rotation, using healthy planting material, cultivating soil and plants during the growing season, harvesting and disinfecting plant residues also reduce the risk of verticillium wilt of potatoes.

Rice. 3. Fusarium wilt of potato (Fusarium oxysporum): 1 - affected plant;

Dry rot of tubers (Fusarium solani): 2 - affected tuber;

Verticillium wilt of potato (Verticillium albo-atrum): 3 - affected tuber; 4 - affected stem.

Fusarium wilt of potatoes

With Fusarium infectious wilt, the leaves also begin to wilt and turn pale green. By all indications, the plant is withering as if from a lack of moisture, and if it is watered thoroughly, then overnight the turgor of the leaves is restored for a short time, but then the top of the stem turns completely yellow, curls, and the whole plant dries out. In this case, not only the above-ground part of the plants dies, but the underground stem, lateral roots, and stolons turn brown and are destroyed. Sometimes it is very difficult to distinguish verticillium and fusarium wilt by external signs, and only an analysis carried out by the quarantine inspection can give an accurate answer.

Fusarium wilt is caused by a fungus (Fusarium oxysporum). It penetrates the plant through root hairs, moves higher along the stem and clogs the vessels, causing them to die.

Control measures the same as for verticillium wilt.

Dry rot of potato tubers

Dry rot usually appears on potato tubers during storage. Initially, grayish-brown spots of various shapes appear on the surface of the tubers, slightly pressed into the pulp. Later these spots increase in size. The affected tuber tissues shrink and small convex grayish-white mold pads appear on them.

If the storage is dry enough, the tuber affected by dry rot gradually dries out, and its skin at the border between the affected and healthy tissue wrinkles in the form of folds. The tuber pulp turns brown, dries out, and becomes rotten. If the storage is damp, then potatoes affected by dry rot become wet, but do not turn into a slimy mass with an unpleasant odor, as with bacterial rot.

Dry rot is caused by fungi (Fusarium solani). The optimal conditions for their development are air temperature +17 +25°C, air humidity 70% and dense, compacted soil.

The fungus penetrates inside the tuber through mechanical damage. The causative agents of potato dry rot persist on tubers, overwintering plant debris and in the soil.

Measures to combat dry rot of potatoes

Firstly, the ground must be soft. If it is heavy and clayey, then in the fall you need to add rotted manure to the site and dig it up thoroughly. In spring, humus is added under the potatoes. It not only serves as a fertilizer, but also prevents caking of the top layer of soil, that is, it makes the soil more permeable to air.

Image source: http://agromage.com, potatoes.ahdb.org.uk, fyi.uwex.edu, www.potatogrower.com, www.longislandhort.cornell.edu, https://www.flickr.com European Crop Protection Association, extension.umaine.edu, usablight.org, www.agric.wa.gov.au, glennamalcolm.wordpress.com, eplantdisease.blogspot.com, en.wikipedia.org, http://www.ipmimages.org , www.omafra.gov.on.ca, www.southyardleyallotments.btck.co.uk, labs.russell.wisc.edu, potatoes.ahdb.org.uk, www.ars.usda.gov, www.agric.wa .gov.au, potatoes.ahdb.org.uk, http://www.unece.org, www.entofito.com, web2.mendelu.cz, gd.eppo.int

Wet rot is caused by a number of bacteria that penetrate the tubers due to mechanical and fungal irritation of external tissues. This disease begins to develop on tubers even before or during harvest, but it develops most during storage. If stored improperly, bacteria quickly spread to healthy tubers. Thus, you can lose a significant part of the harvest. In this case, all healthy potatoes will be wet and covered with the remains of infected potatoes. Therefore, it is very important to know how to properly deal with wet rot of potatoes.

Symptoms of the disease

Wet rot at the final stage is difficult to confuse with another disease, since it has extremely pronounced symptoms. The main symptoms of this disease include:

The internal tissues of the tubers become soft and have an unpleasant odor. At first the rot is white, but over time it darkens and becomes dark brown. The peel may be intact in the initial stages.
Soft areas may appear on the surface; if you press on them, a light-colored liquid starch mass will be released. In this case, rounded areas of hard tuber tissue will be clearly visible.
At temperatures close to 0, the skin of the tubers becomes soft and moist, and the eyes die off. Potatoes that have been over-cold cannot be stored because after some time they will begin to rot and thus infect healthy tubers with wet rot.

Conditions of infection

Potatoes can become infected with wet rot in the garden or in storage. This requires special conditions:

Bacteria that cause wet rot usually enter tubers due to mechanical irritation of the skin by pests and other diseases. Ring rot and blackleg are most often the precursors of wet rot. Potatoes are also often infected as a result of irritation of the tubers by wireworms.
Wet rot develops best at storage temperatures above 5 degrees Celsius. If the potatoes are poured in large piles and in places where there is high humidity and air temperature, then the disease will spread very quickly throughout the entire potato. In places where there is an outbreak of the disease, the temperature, due to the activity of bacteria, can rise to 50 degrees Celsius. In such places, potatoes quickly rot.
When tubers are smothered, outbreaks of wet rot often occur. The tubers lack oxygen, and the high carbon dioxide content weakens the immune system. Therefore, in storage, potatoes should not be placed in large piles and reliable ventilation in the room should be ensured. Suffocation can also occur in the soil if the soil is wet and very dense.
Wet rot develops better in potatoes that have been supercooled at temperatures close to zero. Potatoes that have been stored at temperatures below 0 degrees cannot be stored; they must be isolated and used as soon as possible.

Fighting methods

The main methods of combating wet rot of potatoes include:

Only healthy and mechanically undamaged tubers should be stored. All potatoes should be dry and free of adhering soil.
The storage must be well dried, with good ventilation and must be disinfected with a 3% lime solution or a 5% copper sulfate solution.
Potatoes should be stored at a temperature of 1-2 degrees Celsius.
Harvesting and transporting potatoes should be done with the utmost care. so that there are not a large number of damaged tubers that can no longer be stored. It is better to store potatoes in boxes or in vegetable bags, rather than in bulk.
In places where outbreaks of the disease have occurred, there is no need to sort through the potatoes, you just need to take all the potatoes from the infected area. After this, in another place, the potatoes need to be sorted and used in the near future. All potatoes that have been in contact with an infected person at a distance of 20-30 centimeters must be taken away. This is the only way to reduce losses and prevent further infection.
Seed potatoes must be treated with antifungal and antibacterial drugs before storing.

Potatoes are one of the most popular crops in Russians' garden plots. But for some reason, many people think that they can simply throw the tubers into the ground and forget about them until the fall. Often with such “care” most of the crop is lost, because potatoes often suffer from various diseases. Therefore, the bushes need to be regularly inspected for the presence of suspicious symptoms, and if they are detected, appropriate measures must be taken immediately. Prevention is also important - after all, preventing a problem is much easier than fighting it later.

How to deal with fungal diseases of potatoes

Potato diseases caused by fungi are the most common. Their spread is facilitated by long-term cultivation of crops in one place, thickening of plantings, unsuitable soil, and poor-quality seed material. Also, do not plant potatoes next to other Solanaceae. They suffer from the same diseases, the pathogens of which are transferred from plant to plant by insects.

Late blight (brown rot)

One of the most common potato diseases, the spread of which is facilitated by heavy rainfall combined with heat. As a rule, it appears in early summer, about a month after the appearance of the first shoots.

Dark, rapidly growing spots appear on leaves and stems. The underside of the sheet is covered with a thick layer of pale gray “lint”. If nothing is done, the fungus spreads to the developing tubers. They become covered with the same spots, the flesh in these places darkens, then rots.

Often the gardener himself is to blame for the appearance of the disease, using already infected tubers from the previous harvest for planting. Seed potatoes need to be very carefully selected in the fall and examined again in the spring.

Experienced gardeners, in order to protect the planting material, advise 10–12 days before the expected harvest to mow down all the tops, leaving only stems 7–10 cm high, and if this was not done, immediately remove from the garden the plant debris generated when harvesting potatoes. Tubers, which may well be healthy, quickly “pick up” the fungus from infected leaves.

It is useful to water the potato bed in the spring with Thanos or Ridomil solution to destroy fungal spores that may have overwintered in the soil. Planting material is sprayed with Agat-25, Planriz, and Zircon 7–10 days before planting.

When the first signs of late blight are detected, potatoes are sprayed with any fungicides. The most common of them are Bordeaux mixture and copper sulfate (5–10 g per 10 l), as well as Cuprozan, Oleocuprit, Kuproxat. If preparations of biological origin are used (Baktofit, Alirin-B, Binal, Praline), they can be used up to 4-5 times per season. Mandatory - before hilling, before the tops close into a continuous carpet and as soon as the buds form.

There are also folk remedies. It is more advisable to use them for prevention, repeating the treatment at intervals of 10–12 days, starting from the moment of germination:

Milk or whey. Diluted with water in a 1:1 ratio.
Wood ash. You can simply dust the leaves or prepare an infusion (a liter jar with 10 liters of boiling water). It's ready in a day. To make the product “stick” to the leaves better, add a little small shavings of laundry or green potassium soap.
Garlic infusion. Both cloves and “arrows” are suitable for cooking. 150 g of crushed raw materials are poured into 200 ml of warm water. Leave for 2-3 days, filter before use, add another 10 liters of water and 0.5 g of potassium permanganate.
Horsetail infusion. Crushed leaves and rhizomes (1.5–2 kg) are poured into 10 liters of water, infused for 3–5 days, and filtered before use.
Iodine solution. 15 drops and a liter of milk per 10 liters of water.
Trichopolum. Tablet per liter of water. The frequency of processing is once every 15–20 days.
Compost. About 1 kg of raw material is poured into 10 liters of water and left for 4–6 days. Before use, add 15–20 g of any nitrogen-containing fertilizer.

Video: potato late blight and the fight against it

Rhizoctoniosis (black scab)

The disease often manifests itself already at the stage of tuber germination. Some of them do not sprout at all, on others they look more like a spiral. This is due to the fact that tubers were selected for planting, covered with small black spots, as if stuck to soil particles. Since they can easily be scraped off with a fingernail, the defect was considered minor, and completely in vain. Bushes from such potatoes turn out to be low-growing, with small leaves and thickened stems.

In general, the symptoms typical for rhizoctoniasis largely depend on the weather during the summer. In extreme heat and drought, the tubers become covered with deep cracks; if, on the contrary, it is damp and cold, they become covered with “ulcers” that gradually grow deeper. On bushes, the disease manifests itself in the form of a whitish coating similar to poplar fluff on the underside of the lower leaves and dry rot of the stems. Their base becomes thinner and darker, and the shoots are effortlessly pulled out of the soil.

To prevent rhizoctonia, when growing potatoes in the same place for three years or more, the garden bed is watered with Quadris solution in the spring. Tubers are sprayed with Baktofit, Integral, Maxim 7–12 days before planting or soaked in the solution for 10–15 minutes, reducing the concentration by half compared to that recommended by the manufacturer.

If the disease is detected during the summer, Ditan M45, Fenoram, Mancozeb, Colfuto are used. During the season, no more than three treatments are allowed with an interval of 12–15 days. The last time - no later than 20 days before the expected harvest.

Alternaria (dry spotting)

Most often, the source of the disease is plant debris left in the garden since last year. Moist, warm weather promotes its spread.

Large brown-brown spots on the leaves are most typical of Alternaria blight. They quickly increase in size, and after 3–4 days their surface is covered with small gray-black dots. The leaves dry out and die, then similar spots appear on the stems. Alternaria blight affects tubers. They form depressed black-brown spots with a “wrinkled” surface. The pulp in these places dries and turns into beige dust.

In order to identify infected tubers in advance, it is recommended to keep them for 3–5 days at a temperature of 16–20ºС before planting. When tiny dark spots appear on the skin, they are immediately rejected. An alternative is pre-planting treatment with Reglon, VR.

During the summer, if suspicious symptoms are detected, Profit, Abiga-Pik, Polyram, Acrobat MC are used. For prevention, the first spraying can be carried out when the leaves are closing into a solid green carpet. No more than four treatments are allowed per season.

There are no varieties that are completely resistant to Alternaria yet, but Nevsky, Sineva, Lyubava, Master, and Resurs have increased resistance.

Fusarium wilt

The disease develops rapidly; seemingly healthy bushes wither in 3–5 days. The spread of the fungus is promoted by moderate heat (22–25ºС). The fungus penetrates the plant tissue through the roots, but first attacks the upper leaves. They turn yellow, curl along the central vein, then wither and fall off. After this, the stems become covered with a pinkish-orange coating, and rot quickly spreads from these areas. The shoots are effortlessly removed from the ground; when cut, they are brown.

It is impossible to combat fusarium due to the rapidity of development of the disease. For prevention, potatoes must be greened before storing or planting by keeping them in the light for 15–20 days. 7–10 days before planting, it is treated with a solution of copper sulfate (1–2 g/l) or boric acid (0.5 g/l). An alternative is soaking in a solution of fungicides (Maxim, Colfugo Super Color, Fitosporin-M).

Do not get carried away with nitrogen-containing fertilizers. Excess in the soil reduces plant resistance to this disease. But potassium supplements have the opposite effect, increasing immunity.

The varieties Detskoselsky, Priekulsky early, and Berlichingen are resistant to fusarium. But it is still not absolute.

Verticillium

Most often, verticillium wilt begins to develop during potato flowering. Individual “lobes” of the lower leaves wither slightly and turn yellow at the edges. Then they become covered with light beige spots with a brighter yellow border. In hot, humid weather, the underside becomes covered with a pinkish-gray coating. Next, the disease spreads to the stems, “striking” them with thin dark brown strokes. Gradually the plant dries out and the above-ground part dies off.

Potato varieties Lorch and Ermak have good resistance to verticillium. The fight against the disease consists mainly of competent prevention, similar to that carried out to prevent the development of fusarium.

It is also a good idea to feed the bushes 3-4 times during the season with phosphorus and potassium fertilizers or an infusion of wood ash to increase their immunity. To spray the leaves, use a solution of potassium permanganate (10 g), boric acid (3 g), copper sulfate and zinc sulfate (2 g each) in 10 liters of water.

Having discovered the first alarming signs, treat the bush with a solution of Previkur, Topsin-M, Trichodermin. But these drugs do not provide a 100% guarantee of victory over the fungus.

Powdery mildew

Most often, potatoes planted in warm southern regions suffer from powdery mildew. Heat and high humidity are a necessary condition for the development of this disease. It is easy to identify by its dark brown spots of round or oval shape. They appear on the surface of the sheet, but are also clearly visible from the inside. The spots gradually increase in size, spreading to the stems. Then their surface is covered with a thick layer of off-white powdery plaque, the tissue underneath turns gray and dies.

The only way to combat powdery mildew when the disease has progressed is to dig up and burn diseased bushes. Having discovered the first signs, the leaves are sprayed with Azocene, Bayleton, Thiovit or a solution of soda ash (3–5 g/l). For prevention, newly emerged seedlings are dusted with colloidal sulfur or treated with a solution of any preparation containing this microelement. During the summer, the procedure can be repeated 2-3 more times with an interval of 12-15 days.

Scab

Scab affects potato tubers, which as a result greatly lose their taste, their shelf life sharply decreases, as does the content of starch and other nutrients. You can eat such potatoes if you first cut off the infected part.

The scab that affects the planting material spreads to the future harvest. Such tubers germinate very reluctantly.

Scab is divided into several types:

Ordinary. The tubers are covered with dark brown “scabs” or raised small brick-colored “warts.” In particularly severe cases, deep reddish-purple “ulcers” appear. Most often, early potatoes with red skin suffer from it.
Powdery. Characteristic are small light beige “warts” on the skin. Over time, they dry out, and two deep intersecting cracks appear on the surface. Gradually the tuber dries out and “mummifies.”
Tuberous. Small swellings and tubercles that do not differ in color from the skin. When affected by this type of scab, the percentage of starch in tubers decreases sharply.
Silver. The skin becomes covered with raised spots resembling pimples - a black dot on a whitish surface. Gradually they turn into slightly depressed silvery-beige “ulcers”.

Photo gallery: types of potato scab

Most often, early potatoes are infected with lumpy scab - they have thinner skin
Tubers affected by powdery scab eventually turn into “mummies”
Tubers infected with tuberous scab greatly lose their taste due to a decrease in starch content
Silver scab is very easy to recognize

Fighting scab is problematic, since it does not manifest itself in any way on the plants themselves. To prevent the development of scab, tubers are sprayed with Polycarbacin before storing. For seed potatoes, repeat the procedure 7–10 days before planting. It must be landscaped.

The fungus feels most comfortable in alkaline soil. To “acidify” it, ammonium sulfate is used (40–50 g per 10 liters of water). It is necessary to refuse to fertilize the beds with fresh manure, it is advisable to replace it with green manure (soybeans, leaf mustard, clover, lupine).

Video: how to deal with fungal diseases of potatoes

Diseases caused by bacteria

It is almost impossible to fight bacterial diseases. Moreover, they are very dangerous and can destroy almost the entire potato crop. Therefore, infected bushes must be immediately dug up and burned.

Ring rot

Its development is facilitated by the degeneration of planting material during potato propagation by vegetative means. At the same time, the disease may not manifest itself for a long time, being passed on from generation to generation, waiting for suitable conditions - heat and low humidity.

Nothing is noticeable on the tubers from the outside. Only if you cut them, you can find a ring of yellowish-brown spots almost under the skin. In conditions of high humidity, the pulp turns into a translucent slimy mass. Symptoms do not always appear on bushes. In some cases, the stems become thinner and turn yellow, the leaves become smaller and curl, and the bush seems to be “falling apart.”

There are no special means to combat ring rot. To identify infected potatoes, planting material is heated for 2–3 weeks at a temperature of about 20ºC. Those tubers that have shallow black “pits” with softened pulp underneath are immediately thrown away. In case of mass damage, it is recommended to replace all planting material.

"Blackleg"

The disease affects not only potatoes, but also most vegetable crops. Cool, rainy weather promotes its development. Symptoms are noticeable within 2–3 weeks after the first shoots appear. The leaves turn yellow, curl into a tube, dry out, the stems below turn black and begin to rot. It is very easy to pull them out of the soil. If nothing is done, the “black leg” will spread to the tubers, and their flesh will begin to rot.

The bacterium that causes the disease is carried by many insect pests of potatoes - the Colorado potato beetle, aphids, wireworms, and leafhoppers. Therefore, it is necessary to fight them too. It is worth paying attention to the most disease-resistant varieties - Ukrainian pink, Volzhanin, Iskra, Volshebnitsa.

Pre-planting prevention consists of treating tubers with Maxim, Integral, Baktofit. When preparing the bed, dolomite flour and colloidal sulfur are added to the soil.

When the first signs are detected, the bushes are watered with a bright pink solution of potassium permanganate and dusted with sifted wood ash. This will not destroy the bacteria, but will reduce the rate of development of the disease. The holes formed at the site of the dug bushes are watered with a 2% solution of Bordeaux mixture or filled with a mixture of wood ash (a liter jar) and copper sulfate (15–20 g).

Bacterial wilt

The disease is widespread mainly in the southern regions of Russia. The leaves turn yellow and the stems droop in just a few days. Brown “striations”—affected vessels—are clearly visible on them. Then the tops turn brown, the bases of the stems soften and rot. If you make a cut, it will release a cloudy yellowish-cream liquid.

For prevention, planting material is etched with a solution of Ditan M45, Rovral, Griffon 5–7 days before planting. The processed potatoes are dried and kept under plastic film at a temperature of 20–22ºС until planting.

Bacterial cancer

Potato cancer is a very dangerous disease, in Russia it occurs mainly in the North-Western region and much less often in the middle zone. The varieties Nevsky, Zhukovsky early, and Pushkinets have good immunity to it. Tubers, roots and stem bases become covered with ugly growths. At first small, they quickly increase in size and change color from greenish-beige to black-brown.

The detection of potato canker should be immediately reported to the plant protection inspectorate. Eating such tubers for food and feeding them to animals is strictly prohibited. There are no effective treatments for the disease, so a quarantine will most likely be declared.

You can minimize the risk of disease by observing crop rotation and placing potato beds away from other Solanaceae. Also, you should not purchase planting material whose quality cannot be vouched for.

Viruses dangerous to crops

Viral diseases are the most dangerous for potatoes. Effective measures against them, as well as against bacterial ones, do not yet exist. Infection occurs through direct contact of diseased plants with healthy ones. Or viruses are spread by insects, primarily aphids and leafhoppers.

Mosaic virus

Hot, dry weather contributes to the spread of the mosaic virus. If it appears, you can lose up to a third of the future harvest. This disease is divided into several types:

Striped mosaic. Most often it appears during budding. The front side of the leaf is covered with yellowish-green stripes, the back side is covered with brownish spots. The stems become thinner and often break under their own weight. For prevention, potatoes are sprayed with Bravo and Shirlan fungicides.
Wrinkled mosaic. The leaf tissues between the veins become wrinkled. Gradually they droop and dry out, but do not fall off, acquiring an unnatural bronze hue. Ditan and Ridomil are used for prevention.
Speckled mosaic. The leaves are covered with chaotically located pale green spots of different shapes. The most dangerous of all types of mosaics, crop losses reach 50% or more. Preparations for prevention - Quadris, Revus.

Photo gallery: various types of potato mosaics

Banded mosaic most often appears during the formation of buds
As the wrinkled mosaic develops, the leaves gradually turn bronze
Speckled mosaic - the most dangerous of all

The first time potato seedlings are sprayed 7–10 days after they appear. Treatment during budding is also required. During the season, you can carry out 1-2 more procedures with an interval of 12-18 days.

Curling leaves

The virus that causes potato leaf curl is transmitted through the soil and is also carried by the wind. Its spread is favored by dry, hot weather. The leaves curl into a “boat” or “tube”, acquire an unnatural yellowish or pinkish tint, and break with a crunch at the slightest touch.

Not only plants suffer from it, but also tubers. When you try to germinate them next spring, the sprouts will either not appear at all or will be very thin, thread-like.

Infected plants must be destroyed as soon as possible. Particular attention will have to be paid to the quality of planting material, immediately discarding tubers with long thin shoots.

Tuber necrosis

The damage caused by the virus is practically invisible from the outside. Sometimes small yellowish dots may appear on the leaves, and individual flowers may become deformed, but this is not a necessary sign. Only if you cut the potato, dark spots and stripes in the pulp become visible. They rot along the edges, if the development of the disease has progressed far, mucus oozes from the cut site. You can't eat such tubers.

Yield losses in the event of tuber necrosis development can be 25–50%. No chemicals will help protect the crop. The only effective preventive measure is careful selection of planting material and regular crop rotation. Most often, potatoes grown in unsuitable soil suffer from the virus - either too light, sandy, or swampy or muddy.

Gothic tubers

Tubers affected by this virus greatly lose their presentability, although this does not particularly affect their taste. The starch content in them is reduced by 15–20%.

The potatoes become smaller, elongate greatly, becoming like a spindle. The number of “eyes” increases and they are located in small recesses. Yield loss is within 20%. Sometimes gothic can be identified by the leaves - they become smaller, acquire an uncharacteristic inky tint, and the skin of the tubers is painted the same color.

The virus from diseased tubers is transmitted to the future harvest, so it is not worth planting deformed potatoes. It is also transmitted by direct contact in the presence of mechanical damage to the skin; it is carried by aphids, Colorado potato beetles, grasshoppers, and bedbugs.

There are no potato varieties that are immune to the virus. The best prevention is regular crop rotation, the use of green manure plants and disinfection of garden tools. We must not forget about the fight against harmful insects. If there are a lot of diseased tubers, it is better to store them separately from healthy ones.

What can happen to potatoes during storage?

No less important than growing a potato crop is being able to preserve it until next spring. To do this, you need to create an optimal microclimate. A dark, well-ventilated room in which a constant temperature is maintained at 2–4ºС and humidity within 75–80% is best suited.

Even with a slight deviation from these parameters, a significant part of the crop can be destroyed by diseases, primarily fungal ones. Therefore, potatoes in storage should be inspected regularly, and if there are any suspicious signs, they should be thrown away immediately.

Most often, the harvested crop in the cellar suffers from the following diseases:

Late blight. Gray-brown “dents” appear on the skin of the tubers, and thin brownish “veins” appear in the pulp. Potatoes affected by the fungus quickly rot. It penetrates into the tubers through the smallest cracks in the skin, not to mention mechanical damage received during the harvesting process. To prevent the development of late blight, potatoes are sprayed with any fungicide and dried a day or two before storage.
Rhizoctoniosis. Most often it develops during storage if the potatoes were harvested too late. Small growths on tubers, similar to stuck earth, turn into black-gray “moss” under conditions of elevated temperature and humidity. The pulp under these “ulcers” dries out, turning into beige dust. For prevention, potatoes intended for storage are sprayed with a solution of Planriz, Agata-25.
Dry fusarium rot. Most often it develops towards the end of winter. The tubers become covered with dull gray spots of irregular shape, then dents form in these places. The pulp underneath dries out, and the resulting voids are filled with yellow-gray “dust.” The fungus is transmitted from diseased tubers to healthy ones through direct contact, especially if there are mechanical damage or droplets of moisture on the latter. The best prevention is to ensure optimal storage conditions.
Wet bacterial rot. Of all the diseases, it develops the fastest; the tuber completely rots in 10–12 days. It appears quite quickly, already in the first 4–5 weeks of storage. The skin darkens and oozes mucus, the flesh softens, turning into a grayish-brown pulp that emits an unpleasant odor. The development of the disease can be prevented by maintaining the required temperature and humidity in the storage facility and regularly ventilating it.
Phoma rot. The only way to “catch” the disease is through mechanical damage to the skin. Its source can be soil or tops. Round spots appear on the tubers with the skin as if tightly stretched over them. Then their surface cracks and becomes overgrown with a grayish-beige coating. The pulp turns brown and dries. Phomasis develops only at elevated temperatures (10ºC or more), so this indicator must be carefully monitored.

Photo gallery: potato diseases during storage

Good prevention of late blight of tubers - any fungicides
Defects on tubers caused by rhizoctonia may seem insignificant, but this is by no means the case.
Fusarium dry rot most often develops in late winter or early winter.
Wet bacterial rot destroys stored potato tubers most quickly
Phoma rot spreads only through mechanical damage to the skin