How to cure blackleg potatoes. Black leg on potatoes: control measures (photo)

Introductory explanations.

Diseases such as cancer, late blight, black tuber scab, macrosporiosis and others cause great damage to potato growing. The causative agents of these dangerous potato diseases are fungi. In addition to fungi, potatoes are affected by actinomycetes, bacteria and viruses. The harmfulness of potato diseases manifests itself not only in a decrease in crop yield, but also in a decrease commodity value tubers (deterioration taste qualities, increased waste of ware potatoes, decreased keeping quality of tubers).

Black potato leg - bacterial disease. Pathogen – Pectobacterium phytophtorum.

Blackleg appears on both tubers and plants in the field. Affected plants rot and blacken the base of the stem. The leaves on such stems first become chlorotic, then turn yellow and dry out. Affected stems are easily separated from the mother tubers and pulled out of the soil. The disease appears early, sometimes soon after germination.

On tubers, blackleg manifests itself as rotting of the core, which almost always begins at the point where the tuber attaches to the stolon.

Sick bushes differ from healthy ones: they form a small number of stems (2-3 pieces). The leaves of diseased plants become slimy in humid weather, brown spots and cracks appear on them, and if you make a cross section of the stem, the blackening of the blood vessels is clearly visible, because bacteria clog the plant's vascular system.

The bacteria that causes blackleg persist and spread primarily from planting material. In the field, the infection persists only until the plant residues rot, and bacteria that enter directly into the soil are quickly suppressed by other soil organisms. Air temperature 15–18 0 C and increased soil moisture contribute to the development of the disease.

The disease is spread by soil insects: larvae of lamellar beetles, rot flies and gnawing cutworms.

Control measures: healthy tubers weighing no more than 50 g are selected for planting; Before planting, potatoes are sprouted and tubers with weak sprouts are discarded; carry out phytosanitary cleaning of potato plantings; when harvesting potatoes, they try to prevent contact of tops with tubers and mechanical damage to tubers; use fungicides permitted by the “List...”.

Ring rot - a bacterial disease caused by Corynebacterium sepedonicum.

The disease manifests itself in plants during the growing season in the form of wilting, which appears in the middle or in the second half of the growing season. Most often, the leaves turn yellow and wither not on the entire plant, but on individual stems of the bush. A section made through the affected stem reveals darkening of the vascular system of the stem. When pressed, viscous yellowish mucus emerges from the infected vessels - an accumulation of bacteria.

On tubers, the disease manifests itself in two forms: the first is ring rot of tubers and the second is pitted rot of tubers. In the first form, the manifestation of the disease is marked by the formation of a continuous or intermittent brown ring, found on a cut made through the tuber. The vascular tissue affected by bacteria softens, and when pressed, droplets of a mucous whitish mass protrude from it.

Pit rot is characterized by the formation of yellowish, initially oily, round spots under the skin of the tuber. Spots of pitting rot are revealed only when the tuber peel is removed.

The infection persists in the seed material. When planting, diseased sprouts appear from diseased tubers, and when cutting the stems, a cluster of bacteria along the vascular ring is visible. Nutrients and water do not reach the plants. Therefore, the leaves of diseased bushes dry out and wither, and the number of stems increases to 2-3.

Control measures: removal during phytocleaning of diseased plants. Timely harvesting (when the tubers have ripened and the peel has become rough), if possible in dry weather. Rejection of diseased tubers when cutting planting material. Fungicides approved by the “List...” are used.

Wet rot of potatoes. Causal bacteria - Pseudomonas, Bacillus, Pectobacterium and etc.

The disease manifests itself on tubers, which are light at first and later become dark brown. With further development of the disease, the tubers become soft and wet, and their pulp turns into a pasty mass with an unpleasant odor. The affected areas become covered with yellow-brown mucus, but the skin often remains intact.

Control measures: mowing the tops 7-14 days before harvesting; preventing mechanical damage to tubers; drying tubers after harvesting and creating optimal conditions for storage; the use of fungicides permitted by the “List...”.

Dry rot of potatoes. The causative agents of the disease are fungi from the genus Fusarium (Fuzarium coeruleum saac., F. Sambucinum Fuck., F. solani App. et Wr. , and other species), which belong to the class Deuteromycetes order Hyphales.

The disease is detected on tubers approximately in the middle of storage. The tissue affected by the fungus becomes dry and rotten, the skin on the tubers in the affected areas wrinkles and acquires characteristic folding. Subsequently, rot covers the entire tuber, it dries out and becomes hard. The surface of the tuber is covered with a coating of mycelium and conidial fungal sporulation pads, which can be white, yellow or pink. The infection persists in the soil.

Control measures: prevention of mechanical damage, hypothermia or self-heating of tubers during harvesting and transportation; thorough and early (1.5-2 months in advance) cleaning and disinfection of the storage facility; light hardening of seed potatoes before storage; storing healthy tubers; application of fungicides, according to the “List...”; compliance with the storage regime.

Fomoz, or button rot of tubers. Pathogens: Phoma exigua Desm. ( Class Deuteromycetes, order Sphaeropsidales) , Ophiobolus porphyrogonus Sass. (Class Ascomycetes, subclass Loculoascomycetidae, order Pleosporales) .

The disease manifests itself in the formation of round, somewhat depressed spots on the tubers. When cut, the tissue under the stain is brown, almost black at the edges. The affected tissue wrinkles and cracks over time. Pycnidia protrude to the surface through the tuber skin. On the stems during flowering, blurry spots elongated to 8 cm are visible near the petioles, on which many light or dark brown pycnidia are subsequently formed. Sometimes the spots take on the character of ulcers, their edges are distinguished by a darker color. The stems are stunted and wither, and if severely damaged, they break. Tuber infection can occur again in the field during storage.

Control measures: implementation of quarantine measures; compliance with crop rotation; planting healthy tubers; pre-harvest mowing of tops; creating optimal conditions for storing tubers; application of fungicides according to the “List...”.

Potato late blight. Pathogen: Phytophthora infestans(Class Oomycetes, order Peronosporales) .

Late blight is one of the most common and harmful potato diseases. For the development of the fungus, it is necessary to have drops of water that remain after dew or rain on the potato leaves, and an air temperature of 19-24 C. The development and spread of the disease increases if the temperature at night drops to 10-13 C.

The disease appears in masses before flowering. Vague dark brown weeping spots appear on the edge of the leaf blade. On the underside of the leaves, at the border between the affected and healthy tissues, a white coating forms, clearly visible in rainy weather or in the morning before the dew dries. Elongated brown stripes form on the stems and petioles, and slightly depressed, sharply defined brown hard spots appear on the tubers. On a cut of a tuber, a rusty coloration of the pulp is visible, distributed in depth in the form of separate sections, the so-called tongues.

Tubers are mainly infected by fungal spores washed off the leaves by rain or dew and penetrating through the top layer of soil. Many tubers are affected during harvesting when they come into contact with diseased tops.

The infection persists as mycelium on tubers, and also as oospores on plant debris or in the soil.

When planting diseased tubers, brown sprouts appear, which often die. From these isolated foci of infection, the fungus spreads by rain or wind to neighboring plants. In addition, fungus sporulation forms on the affected tubers that enter the soil during planting and, as a result, the soil around the tubers becomes infectious. Sprouts emerging from healthy tubers planted next to diseased ones become infected upon contact with infected soil.

Control measures: mowing the tops 1.5-2 weeks before harvesting, selecting healthy tubers for planting, timely high hilling, applying fertilizers, harvesting in dry weather and laying for a period of 3-4 weeks for temporary storage, and then harvesting the sorted potatoes for permanent storage , light hardening of seed potatoes (solanine formed in tubers in the light protects them from rot), the use of fungicides, according to the “List...”.

Potato macrosporiosis . Pathogen: Macrosporium solani(Class Deuteromycetes, order Hyphales) .

Macrosporiosis, or early spotting, manifests itself as dry, brown, zonal spots on leaves and stems before budding. A black coating forms in the form of concentric circles on the underside of the spots. Plaque is conidial sporulation. Gradually, the affected leaves turn yellow and dry out. The spots on the stems are the same, but dark brown in color and also with concentric circles. The infection persists as mycelium on plant debris. The harmfulness of the disease is especially great in hot summers with light (short-term) rains or night dews.

Control measures: deep plowing of plant residues, compliance with crop rotation, application of fertilizers. Spraying potatoes during budding or when the first signs of macrosporiosis appear with fungicides permitted by the “List...”.

Rhizoctoniosis, or black potato scab - pathogen Rhizoctonia solani, Class Deuteromycetes, order Mycelia sterilia.

On tubers, the disease manifests itself in the form of small, mostly flat sclerotia of the fungus adhering to the surface of the tuber, resembling lumps of dirt. For seed potatoes, rhizoctonia is the most dangerous looking scab. On tubers planted in the soil, sclerotia germinate into mycelium, which causes infection of the sprouts. Dark depressed spots form on them, often merging and enveloping the sprouts in a ring. Sick sprouts sometimes die before they reach the surface. This form develops especially strongly when tubers are planted early and deeply in damp and insufficiently warmed soil, during a cold and prolonged spring. On adult plants, rhizoctonia appears in the form of a so-called white leg. The lower part of the stem is covered with a whitish-gray film formed by the basidial stage of the fungus. Basidiospores from the stem can be washed into the soil by rain and infect young tubers. Mass infection of a new crop also occurs due to sclerotia in the soil.

Control measures: compliance with crop rotation; optimal timing for planting tubers with embedding to a depth of 6-8 cm on heavy soils and 12-15 cm on light soils; when a crust forms on heavy floating soils, harrowing is carried out 4-5 days after planting and after seedlings; destruction of weeds (sow thistle, quinoa, etc.); use of fungicides permitted by the “List...”.

Potato cancer. Pathogen: Synchitrium endobioticum(Class Chytridiomycetes, order Chytridiales) .

The disease manifests itself on tubers in the form of growths of various shapes and sizes. Very rarely there are growths on the lower part of the stems. With severe damage, the entire tuber becomes covered with growths and loses its marketable value. The growths are destroyed over time and transformed under the influence of bacteria into a slimy, unpleasant-smelling mass. On a section through the growth, resting spores or cysts, characteristic of the causative agent of cancer, are found mainly along the periphery of the growth - rather large, oval with a thick thickened shell. Cysts are the dormant stage of the fungus in which it remains in the soil. Cysts can persist in the soil for up to 10-13 years or more. The cysts germinate into the sorus of the zoosporangium with zoospores and cause repeated infection in the same summer.

Control measures: cultivation of cancer-resistant varieties, in the hotbed of potato cancer, plants not affected by this disease are cultivated and the soil is cleared of infection (cabbage, carrots, cucumbers), compliance with quarantine measures, pre-sowing treatment of tubers with preparations permitted by the “List...”.

Common potato scab. The causative agents of the disease are different kinds actinomycetes: Actinonomics scabies, Actinonomicestricolor, Actinonomics cretaceus.

Round, flat or slightly convex warts that crack in a star shape form on the surface of the tubers. Sometimes cracking ulcers pressed into the tuber form on the surface of the tubers. Warts and ulcers often merge, covering the entire tuber with scabs. A white cobwebby coating of mycelium is noticeable on the dug up tubers; when the tuber dries, the coating quickly dries and disappears.

When plants are damaged, there is a decrease in the marketable value of tubers, a deterioration in taste (starch content decreases by 5-30%), an increase in waste of food potatoes, and a decrease in the keeping quality of tubers. The infection accumulates mainly in the soil on plant debris after harvesting. Under normal storage conditions, the infection persists in small quantities.

Control measures: compliance with crop rotation; cultivation of resistant or slightly susceptible varieties; It is not recommended to place potatoes on heavily limed soils; on alkaline soils it is not recommended to apply physiologically acidic fertilizers (superphosphate, etc.); pre-sowing treatment of tubers is carried out with preparations permitted by the “List...”.

Iron spot or tuber rust .

This is a non-infectious disease of tubers, detectable only on a cut: rusty spots of various sizes and shapes form in the pulp of the tuber.

The manifestation of glandular spot may be associated with excessive accumulation of iron and aluminum in the plant with a lack of calcium, with increased activity of oxidative enzymes in the tuber and insufficient phosphorus nutrition of the plant. Overheating of the soil increases the manifestation of the disease.

Control measures: depending on the cause of the disease, protective measures are taken. In some cases, this is the application of optimal doses of phosphorus fertilizers, in others - nitrogen fertilizers, and liming is carried out on acidic soils. Normal humidity has a positive effect.

1. Study the symptoms of potato diseases.

2. Consider herbarium and collection material, identify diseases, record the progress of the determination in Table 10 and sketch the external signs of potato diseases.

Table 10 - Characteristics of pathogens of potato diseases.

3. Prepare preparations, examine and sketch the causative agents of dry and wet rot of potatoes, late blight of potatoes, resting spores (cysts) of the causative agent of potato cancer.

4. Prepare and examine under a microscope the plaque from potato organs affected by macrosporiosis, sketch the conidiophores with conidia.

5. Prepare a preparation and examine the sclerotium from a potato tuber affected by rhizoctonia under a microscope.

Control questions:

1. What potato diseases are caused by fungi? What potato diseases are caused by bacteria? What potato diseases are caused by actinomycetes? What potato diseases are caused by viruses?

2. Black leg of potatoes and measures to combat the pathogen.

3. Potato late blight and measures to combat the pathogen.

4. Ring rot of potatoes and measures to combat the pathogen.

5. Potato cancer and measures to combat the pathogen.

6. Dry rot of potatoes and measures to combat the pathogen.

7. Wet rot of potatoes and measures to combat the pathogen.

8. Common potato scab and measures to combat the pathogen.

10. Potato macrosporosis and measures to combat the pathogen.

Fighting black leg in potatoes. Growing potatoes is one of the important industries of any Agriculture. After planting tubers, an agronomist may encounter such a nuisance as black leg in potatoes. This is a fungal disease called Erwinia carotovora.

🥔 Symptoms and causative agent of Black leg in potatoes

It is not always possible to detect symptoms of the disease immediately. Most often they appear 2 weeks before flowering begins. Affected bushes have a depressed appearance, the tops turn yellow and curl. The entire bush or individual shoots may be infected.

The main sign of the disease is blackening of the stem and rotting of the root system. An infected bush can be easily pulled out; tubers will not form on it. If you carefully examine the infected fruit, you will notice darkened spots that turn the potato into a viscous, unpleasant mass.

💡 Advice! If the tops look unhealthy, but you are not sure that the crop is definitely infected with Blackleg, you need to put the darkened stem in a glass with clean water. An infected plant will cause the water to become cloudy.

• remains of vegetation;
• diseased tubers;
• weed grass.

Bacteria multiply at temperatures from +2C to +27C and high humidity. One diseased tuber can become a source of infection for the entire potato.

🥔 Measures to combat black leg in potatoes

1. Observe crop rotation; you cannot plant potatoes for 4 years in an area where nightshade crops, including potatoes themselves, had previously sprouted. The best predecessors - legumes.
2. If infected bushes are found, loosen the soil around them, dry them and powder them with wood ash. You can use charcoal crushed into dust.
3. It is important to promptly clear the plantings of weeds, at least 3 times per season:
- when the first shoots appear;
- during the flowering period;
- 2 weeks before harvest.
4. Eliminate all infected crops from the site, and treat the soil with a solution of 1 tablespoon of copper sulfate per glass of wood ash.
5. After harvesting, collect all infected leaves and stems and burn them outside the site. Dry the tubers well and sort out the sick ones.

🥔 Prevention

It is easier to prevent a disease than to fight it later. Therefore, prevention in this case is simply necessary.

1. The storage room for potatoes must be dry and at a certain temperature and humidity.
2. Use varieties that are more resistant to bacteria for planting (Skorospelka 1, Viliya, Borodyansky).
3. Plant potatoes in well-dried soil.
4. Before plowing, remove all last year’s tops and rotten tubers from the site.
5. When planting, use dolomite flour, which neutralizes the soil and prevents the appearance of bacteria.

6. Do not use infected weeds as compost. When digging, place wood ash to a depth of 15 cm, which prevents the spread of bacteria.
7. Dry the harvested crop well before storing. Reject tubers with mechanical damage, as they are more susceptible to Blackleg bacteria.
8. Treat the soil with a manganese solution.

Tip: the soil around the plant should not be covered with a layer of mulch. In this case, it only contributes to the further spread of the disease.

🥔 Folk methods of struggle

Not every gardener wants to use it on their plot chemical compositions, in this case you can resort to traditional methods fight against the Black Leg.

1. Milk. Dilute any of the following in equal proportions milk product with water. Using a spray bottle, spray all bushes and stems with the resulting mixture.
2. Garlic. Garlic passed through a press is diluted with a small amount of water and left for 2 days. The strained mass is poured into a bucket of water and the area is treated, covering the entire area.

3. Iodine and milk. It is necessary to add 15 drops of iodine to a liter of milk. Treat the potato tops with the resulting solution.
4. Superphosphate. Prepare 1 liter of a weak superphosphate solution, adding 1 tablet of trichopolum to it. Treat the plants.

Advice: it is important to promptly remove pests from plantings, in particular the Colorado potato beetle, as they are the main sources of spread of the Blackleg.

🥔 Using chemicals against Blackleg

In case of severe infection, folk remedies may not help, then it is worth treating the area with chemicals.

1. The drug "Fitosporin - M". For preventive purposes, dilute 10 - 15 drops of the drug in a liter of water. Treat the tubers with the resulting mixture before planting. For treatment, add 10 ml of the drug to a 10 liter bucket. Treat all healthy plants with the resulting solution, disposing of disease-damaged shoots and bushes in advance.

2. Water the soil not only with a solution of potassium permanganate, but also with chemicals such as “Topsin-M” or “Vitaros”. For treatment you will need 2 grams of the drug per liter of water.

3. In preventive measures, the drug “Effektona” is effective. For 10 liters of heated water, take 3 tablespoons of the drug. Processed by irrigation method.

4. The drug "Energen". For 10 liters of water you will need 5 ml of the drug. Treat the crop with the resulting solution by watering.

5. The drug "Hom". Add 4 grams of the drug per liter of water. Use the resulting mixture to treat all plantings susceptible to the disease.

6. Immediately before storing potatoes in the cellar for storage, they are treated with the “Maxim” preparation.

! Conclusions

If measures are not taken in time when the disease is detected, Blackleg pathogens can destroy most of the crop.

📽 How to deal with blackleg video

Ring rot, pit rot, wet bacterial rot, tracheobacterial wilt, potato blackleg are bacterial diseases of potatoes caused by bacteria (Pseudomonas solanacearum, Corynebacterium sepedonicum).

Potato plants affected by these diseases quickly wither, the leaves turn yellow, wrinkle, the stems and leaf petioles droop. The tubers darken, soften, then turn brown and are easily pressed with a finger.

Signs of tracheobacterial wilt can be found at the end of potato flowering. The leaves suddenly turn yellow, the leaf segments curl along the main vein, the stems droop lifelessly and dry up. Signs of the disease are especially noticeable in hot, dry summers.

Rice. 1 Bacterial rot of potatoes

Ring rot: 1 - affected tuber in section;

Wet bacterial rot: 2 and 3 - affected tubers;

Black leg: 4 - affected plant, 5 - affected tuber in section;

Tracheobacteriosis wilt: 6 - affected plant, 7 - affected tuber in a section.

Ring rot causes great damage to potato crops. The disease manifests itself in the form of wilting of individual bushes or leaves. Ring rot, caused by sepedonicum bacteria, gradually moves deeper into the tuber. On a section of a diseased tuber, and sometimes even a stem, the affected area is visible vascular system, which is light cream or brown in color and has a smooth, oily consistency. When pressed, a light yellow viscous liquid emerges from the affected area on the tuber.

Ring rot develops strongly when potatoes are stored in relatively dry conditions. Carrier ring rot are infected planting tubers.

The same sepedonicum bacteria can cause pitting rot of tubers, which is detected only at the end of March. When peeling potato tubers, small, pinhead-sized, rounded spots of rotting pulp, creamy or yellowish in color, are noticeable on the peel. Around these spots, a more transparent, but still hard, pulp forms. Later, the pitted rot deepens, expands, the tuber peel bursts above the rot, and a depressed pit is formed. At room temperature +18+20 o C, the development of pit rot intensifies.

Wet bacterial rot of potato tubers can develop both on waterlogged land plots, and during storage of potatoes in the cellar. Affected tubers become dark brown, wet, and soft to the touch. Gradually, the entire tuber turns into a slimy, mushy, viscous mass with an unpleasant odor.

First, brownish-gray spots appear on the surface of the tuber, then they cover the entire tuber. Ultimately, the tuber shrinks, dries out, and the entire contents of the tuber turn into a dry yellowish mass.

The causative agents of wet rot are bacteria that penetrate tubers through various damage; there are a lot of them in areas affected by late blight, scab and other diseases.

Wet bacterial rot of potato tubers spreads more strongly in rainy weather. Wet bacterial rot of potatoes develops very quickly in places where potatoes are stored with sharp fluctuations in temperature and high humidity.

The following measures are effective in the fight against bacterial rot of potatoes: careful selection of healthy tubers for planting; planting with uncut tubers. In some cases, it is allowed to cut potato tubers 7-10 days before planting with mandatory treatment with a 1% solution of boric acid or borax.

Compliance with crop rotation, in which the return of potatoes to the same place is provided no earlier than after 4 years. If bacterial rot is widespread, it is recommended to increase the recommended doses of potassium by 10-15%.

In the fight against bacterial rot, you can treat the tubers before planting, as well as sowing potatoes with a 1% solution of Bordeaux mixture or copper sulfate.

It is necessary to observe agrotechnical measures when growing potatoes, such as applying organic fertilizers, constantly loosening the soil, applying nitrogen fertilizers only in the recommended amount. Excess nitrogen fertilizers can also provoke the appearance of bacterial rot of potatoes.

Cleaning potato crops from weeds and diseased plants. Potato tops in contaminated areas are burned. After digging, the tubers are thoroughly ventilated, dried, and any loose soil is removed.

Thorough treatment of the premises before storing potatoes, maintaining temperature and humidity in the cellar during potato storage.

Image source: http://www.potatogrower.com, http://agromage.com

Pathogen: Pectobacterium carotovorum subsp. atrosepticum (van Hall) Hauben.

Maliciousness. Potato blackleg is common throughout growing areas cabbage. Affected young plants rot at the bottom of the stem, and wet tuber rot forms on their tubers. As a result of the development of the black leg of potatoes, plantings become thinned out, productivity decreases, and seed and commercial qualities deteriorate during storage. Yield losses depend on the aggressiveness of the pathogen and weather conditions and range from 1-2 to 50-75%. For example, if during the growing season 5% of the plants are affected by the black leg of potatoes, then the losses will be 20% or even more during storage.

Symptoms of potato black leg

As a result of the early development of the disease, the lower leaves of the seedlings turn yellow, the leaves become stiff and curl into a boat. The growth of the upper leaves occurs at an acute angle, later they also turn yellow. The base of the stem becomes soft, rots, and when pulled out of the soil, easily breaks off in the area of ​​the root collar.

Tubers are affected starting from the second half of the growing season. The affected tubers soften at the point of attachment to the stolon. At first, the softening is light yellow or colorless, later the core of the tuber rots, starting from the stolon part. As a result, the tissue darkens, becomes soft, slimy, and acquires an unpleasant odor. During storage, affected tubers with potato blackleg become a source of wet rot.

Black potato leg photo:

Biology of potato blackleg

Potato blackleg bacteria produce pectolytic enzymes that cause wet rot, maceration and mucus. Penetration of bacteria into tubers occurs through damaged tissue, stolons and lentils. The disease is spread by insects. The greatest harmfulness of potato blackleg is observed at high humidity on heavy soils. However, there were cases when potato black leg and wet rot developed well in sandy loam soils in wet weather conditions.

Sources of infection. The source of infection can be planting material and plant residues until they are completely rotted.

Protective measures against potato blackleg

It is important to observe crop rotation and thoroughly incorporate plant residues. Potatoes must be carefully sorted before storing in storage in the fall and before planting in the spring. If a disease occurs, in the following years grow only resistant varieties such as: Gatchinsky, Priekulsky early, Borodyansky, Volzhanin, Iskra and others.

Biological agents. To reduce the contamination of tubers with wet rot, seed material before planting must be treated with a working solution of the drug Fitosporin-M with a consumption of 0.4-0.5 kg, having previously dissolved it in 30 liters of water, spraying is carried out with mixing of the tubers.

Chemicals. Treating seed tubers before planting with TMTD, VSK. The working solution is prepared in this way: 4-5 liters of the drug are dissolved in 65-70 liters of water and 1 ton of tubers are treated. It is possible to use other drugs in this group.

Before storing seed potato tubers for storage, they are treated with the drug Maxim. Preparation of the working solution: 0.2 liters of the drug is dissolved in 2 liters of water and sprayed onto the tubers, stirring them from time to time.

based on materials from the St. Petersburg Farmers Assistance Service

Black potato leg

Symptoms of damage: Affected plants are mostly noticeable in early to mid-July due to curling of the upper leaves, yellowing and wilting. With early damage, plants are stunted and then die. Affected shoots can be easily pulled out of the soil. The stem is slightly rotten at the base with varying color from dark brown to black. After a late infection, individual shoots become sick and die. In recent years, other symptoms of damage have been detected in some places: In some plants, the leaves of the leaves wither and die from the bottom up. At first, the stem of the affected shoot feels still strong, but inside it has already decomposed to a slimy state. Nothing is visible externally at the base of the stem.

Defeat conditions: Use of affected planting material, early planting, cold weather at the beginning of the growing season. Cleaning at unfavorable conditions with numerous injuries and damp storage.

Control measures: Cultivation of healthy and perfect planting material, because the pathogen, various types of bacteria, are carried only with planting material. Planting too early and deep is not allowed, because the affected mother tuber rots, bacteria enter the stem or penetrate into young tubers. Reducing damage during harvesting and harvesting, and proper storage of potatoes reduces blackleg damage because bacteria can penetrate all damage. Chemical control measures are not possible.

Wet rot of potatoes

Meaning: A very dangerous disease that in a short time during winter storage or transportation forms rotten nests and can destroy an entire batch of potatoes.

Symptoms of damage: The tuber tissue becomes a soft, mushy mass, which is demarcated from healthy tissue by a black line. Without external pressure, the peel does not allow the tuber to fall apart. After cutting, the rotten pulp emits a not very strong basement smell of mold. The colorless pulp darkens when air enters and eventually becomes black -brown.

Defeat conditions: Seed tubers are carriers of bacteria that cause wet rot. When the mother tuber disintegrates, bacteria enter through the lentils, stolons or eyes into the young tubers. Rot does not appear immediately, but only with a lack of oxygen and high humidity during storage; in this case, bacteria are activated. The disease progresses very quickly when the pathogen penetrates the tuber through damage during harvesting and storage. The exposed tissue of unhealed tubers and the presence of moisture on the surface are favorable for the rapid onset of the disease.

Control measures: Minor damage to tubers due to harvesting at soil temperatures above 10 degrees and slow conveyor speed. Drying potatoes immediately after storing them. Tubers should not sweat in the bins. When unloading, it is necessary to take into account the height of the fall. Select rotten tubers in advance. Careful hygiene in the household! Chemical control methods are impossible.