Alternaria is a widespread disease of solanaceous crops (mainly potatoes and tomatoes), protruded by imperfect mushrooms Alternaria alternat Keissler and Alternaria solani. Every year in Russia, due to Alternaria, about 5% of the potato crop is lost. In obedient years in the Baikal and Far East losses are 40-50%.
Features Often alternarioz appears closer to the middle of June before flowering bushes and develops all summer. At risk, mid-season and mid-late potato varieties. The disease affects the leaves and stems, leading to slower growth, tubers are less likely to suffer. Young tubers become infected only during harvest when they come into contact with spores on the surface of the ground, mature ones if the peel is mechanically damaged.
Optimal conditions for the development of Alternaria - air temperature 25-27 ° C and the presence of droplet moisture for at least 2 hours (rain or dew). Recently, there has been an adaptation of the fungus to lower temperatures.
During the growing season (summer-autumn) several generations of fungi appear, the spores of which are carried by the wind, raindrops and insects, infecting new bushes. In most cases, foci of diseased potatoes are formed. The fungus of alternariosis overwinters in the form of mycelium and conidia on residues of plant origin.
Factors contributing to the development of Alternaria:
- dry hot weather and lack of moisture
- weak immune system of potato bushes,
- leaf damage by parasites
- lack of nitrogen and potassium in the soil, an excess of phosphorus,
- infection of tubers with viruses (any) until planting.
Signs of Alternaria. 15-20 days before flowering, first on the lower and then on the upper leaves dry brown spots of diameters 10-35 mm appear. The disease spreads from the center of the leaf to the edges. The spots have a rounded angular shape with conspicuous concentric rings. The affected tissue is dry and breaks easily. 3-4 weeks after the first signs, a plaque containing spores is observed. Stems are similarly affected. On infected tubers, small in-depth spots appear with spore deposits.Close-up Noticeable manifestation on the sheet Struck stalk Manifestation on the tuber
Treatment of Alternaria Potato
The following chemicals are suitable for fighting the disease by spraying: Mancozeb, Novozri, Profit, Thanos, Utan, Kuproksat, Penkozeb, Kuprikol, Metaxil, Yunomil MC, Abiga-Peak, HOM, Metamil, Acrobat MC, Ridomil Gold MC, Ordan, Tsikhom , Bravo, Sectin phenomenon, Pilon, Polam, Volman, etc. Their use is governed by the manufacturer's instructions.
The initial treatment is done when the first signs of the disease are detected, usually it is the time when the foliage in the rows is closed. In the future, the frequency of treatment depends on the duration of the selected drug and temperature conditions. During the season it may take up to 4 sprays.
Prevention of Alternaria
1. Cleaning and destruction of the remains of diseased plants. Deep autumn plowing contributes to the decomposition of plant residues, which prevents the accumulation of pathogenic spores in the soil.
2. Compliance with the rules of crop rotation, do not plant potatoes near tomatoes, which also suffer from Alternaria. Do not grow potatoes in one place for more than 3 years.
3. Proper use of fertilizers. The soil must contain a sufficient amount of nitrogen and potassium, without exceeding the concentration of nitrogen.
4. Growing potato varieties with increased resistance to Alternaria. For example, "Blue", "Lyubava", "Nevsky", "Victory", "Resource", "Reserve", "Master" and others. It should be remembered that while there are no varieties completely resistant to Alternaria.
5. Remove the tubers fully ripe, avoiding mechanical damage. Timely reject diseased potatoes.
6. To process seed tubers before planting with special biological products: Baktofit, Integral, Planriz, Agat-25.
The most common infection is late blight. Yield losses during infection with them can reach 60% or more. External manifestations of late blight begin to appear in the flowering phase. The lower leaves of the potato become covered with brown spots that grow over time, which over time covers the entire nest. In rainy weather, white bloom appears on the underside of the diseased leaves - spore-bearing tissue of the fungus Phytophthora infestans. Tubers infected with blight, covered with dark spots. Fabrics remain dry and hard.
With the appearance of diseased plants, it is important to practice potato crop rotation, because the spores of phytophthora are stored in the soil, on the remains of the leaves, and in the tubers.
Tubers infected with late blight are not recommended to be deposited, as in this case there is a risk of losing the entire crop, including vegetables, which are in the same room with sick potatoes.
Another dangerous infection is potato cancer. In areas where they record cases of potato infection, the quarantine regime is introduced. This fungal disease affects the tubers and stolons of plants, leaf blades and stems. On the tubers in the immediate vicinity of the eyes appear growths that increase in size. Despite the absence of overt rot, cancer-bearing tubers cannot be stored.
To avoid the appearance of the disease, it is important to choose resistant varieties. When potato cancer appears, it is necessary to destroy the infected tubers. The field on which the foci of the disease are found cannot be sown with potatoes for at least 3 years.
This disease can destroy the entire plant, including the stems and tubers. Most often, its victims are middle-late and late varieties. The first signs of infection can be recognized by the appearance of brown spots on the leaves that appear before the flowering of the plant. Over time, the diseased leaves turn yellow and die. The foci of infection in the tubers are also easily recognized by their brown color and irregular shape. If potato alternaria affects a large part of the tuber, the surface of these spots may look wrinkled.
Similarly to this disease, potato fomoz manifests itself, with the only difference that the spots on the tubers acquire a grayish tint, and their size does not exceed 2-5 cm in diameter. Another significant difference is the timing of infection. If Alternaria penetrates the young stalks of the plant, then fomoz affects the stalks in the second half of the growing season. The spores that have ripened on them, along with rainwater, enter the soil where the tubers are infected.
Before planting the storage of planting material from the site where plants infected with fomozy and Alternaria were seen, it is important to pickle the tubers. Infection can be contained by observing the temperature in the basement.
Large crop losses can also be sustained if they are affected by various types of scab: ordinary, powdery, or silver. The common scab develops only at high soil temperatures and low humidity. Sick tubers are covered with dry, slightly protruding dark-colored spots above the surface of the skin. The stems of this type of scab are not striking.
In the same way acts on plants and powdery scab of potatoes. It affects only the underground part of the plant. At the initial stage they appear round spots with a diameter of 6-7 cm, covered with white bloom. Over time, these areas are destroyed, and in their place remain red sores. Unlike ordinary scab, powdery shows activity only at high humidity.
Silver scab infects tubers exclusively during storage. As a result of infection, they lose a large amount of moisture, causing them to become light and excessively dry. For planting such potatoes are not suitable. An outbreak of the disease provokes increased humidity (more than 90%) and temperatures above 3 degrees.
To avoid mass infection of tubers with any kind of scab, it is important to observe potato crop rotation. It is important to pay attention to the preparation of planting material: dressing before putting it into storage will prevent re-infection of tubers and soil.
Black Leg Potato
The disease develops as a result of the destruction of the plant by the bacteria Pectobakterium. The source of infection is diseased potato tubers, plant residues in the soil. Often distributed by insect larvae. It affects almost all parts of the plant in all phases of development. Chronic character gets in dry conditions. Potato bushes begin to hurt immediately after germination. At first the leaves turn yellow, then they curl up and dry out. The bush quickly fades, the stem becomes soft and easily pulled out of the ground. On the tubers, the black leg of the potato appears as dark rot in a part of the stolon.
Another potato disease in which crop losses can reach 50% is fusarium wilt. Most often it develops in conditions of elevated temperatures and humidity. At first, Fusarium can be mistaken for a disease of potato tops, the photos of which often appear in specialized publications. The infection infects the leaves of the plant: the upper ones become light, and the edges of the lower ones acquire an anthocyanin hue. Over time, they lose their elasticity and fade. On the bottom of the stems, spots appear, covered with a bloom of orange or pink color. Getting into the soil, the infection infects the tubers, causing them to rot.
To avoid the death of the crop from Fusarium, it is enough to mow infected tops and remove all plant residues from the site. Only after that you can start harvesting potatoes.
How to treat potatoes for fungal infections?
It is necessary to fight potato fungal diseases even at the stage of planting material preparation. Before processing potatoes with a solution of boric acid or copper sulfate, it is important to select tubers intact. During the growing season it is necessary to constantly monitor the condition of the tops. At the first signs of disease, it is necessary to remove the affected plants, and then treat the plantings with a 2% solution of copper sulfate, Hom or Maxim.
Fungal infections often get into the soil with not completely rotted plant debris and manure. It is important to exclude such phenomena, as this will reduce labor costs for processing crops with special means and increase the amount of the crop. To avoid infection of tubers during the harvest, it is necessary to mow the tops in advance and remove plant residues from the site. Tubers damaged during transport and storage should be eaten first, since they are most often affected by infections.
Equally important is the crop rotation of potatoes. Most fungal diseases exist in the soil for 2-3 years. In the absence of cultures in this area that can become carriers of the infection, it spontaneously disappears.
Adding an article to a new collection
The disease is caused by fungi of the genus Alternaria. These pathogens infect many garden, garden and flower crops. To save their green pets, you need to know how to treat Alternaria.
But the first thing you need to learn to distinguish this fungal disease from a number of other ailments, which also appear on plants in the form of mold and stains. Depending on the particular culture, the signs of Alternaria can vary slightly, but the disease control measures are identical for all plants.
Alternariosis is dangerous because its spores are quickly transferred by wind, raindrops and insects to healthy plants. The disease can destroy about 50% of the crop of fruits and vegetables in a season.
Alternaria disease of tomatoes
In tomatoes, this disease is often referred to as dry, or zonal, spotting. The disease is dangerous for all nightshade as well as late blight, but it begins to manifest itself much earlier: immediately after the transplanting of tomatoes into open ground or greenhouse.
The fungus infects the entire aboveground part of the plant: stalks, leaves, fruits. The main symptom of the disease is the appearance of dry, well-defined rounded spots (ranging in size from a few millimeters to a few centimeters) of gray-brown color. The affected leaves turn yellow and die prematurely. If fairly deep spots are formed, the plant dies. Fruits become ugly and tasteless.
Hot and dry weather with night dew and intermittent rains is especially favorable for the development of Alternaria. Unfortunately, there are no varieties and hybrids of tomatoes that are completely resistant to Alternaria. Only a few of them are ill to a lesser extent (for example, Firebird F1).
The first symptoms of the disease appear in May. Affected leaves and shoots of grapes are covered with light yellow and silver spots, which are easily confused with traces of oidium. Over time, the spots darken and become brown. With a strong defeat the leaves turn black and dry.
On berries, the disease manifests itself in the form of a bright metallic luster on the skin; a dark gray fungal plaque gradually develops. Berries shrink and get unpleasant taste.
Alternaria apple tree
In late spring and early summer (usually a month after flowering), small roundish brown spots with a violet edging appear on the leaves of the apple tree. Over time, spots increase in size, sometimes merge. Affected leaves fall prematurely. Alternariosis affects the fruits: they appear small bright spots with a dark border.
Alternaria cabbage, or black spot
The disease affects both adults and young plants of different types of cabbage. On the seedlings (cotyledons and subnuclear knees) black necrotic stripes and spots are formed, as a result of which the plant fades. In adult cabbage, on the upper leaves of the head of the head dark spots are formed, covered with a friable deposit of soot color. At the same time spots often have a yellow edging.
When Alternaria appears on the cauliflower, brown rot begins to develop on its inflorescences, as a result of which the plant becomes unfit for human consumption.
On the leaves of the onion, first form small watery spots with a white center. Then they increase in size, darken and become brownish-maroon. Over time, the spots merge, after which the sheet breaks and dies. Under the condition of high humidity on the spots appears gray-black bloom.
The bulbs are also sensitive to Alternaria. The affected tissues are initially watery, then gradually become yellowish or terracotta, a brownish coating appears between the scales.
Alternaria can also occur on carrots, cucumbers, peas, barley, wheat, pear, gooseberry, sunflower, rape, tobacco. And from flower cultures, the disease affects zinnia, dragon-seed, orchid.
Measures to combat Alternaria
When the first symptoms of the disease appear, the plants are treated with a solution of copper sulphate (20 g of the drug and 200 g of soap chips per 10 l of water) or other fungicides (with the preparations Abiga-Pik, Bravo, Ridomil Gold MC, Acrobat MI, Poliram, Ordan, Quadris). Spraying is carried out with an interval of 10-14 days until the disappearance of signs of the disease.
Opponents of the "chemistry" recommend the treatment of Alternaria with a biological product such as Trichodermin. He also leaves and stalks of plants sprayed in April-May to prevent the disease.
Consider: the damaged tops of garden crops are destroyed no later than a week before the harvest, so that the fungus does not have time to get over the fruit.
The fight against Alternaria is not always effective, so you should not forget about preventive measures. To prevent disease, planting material and planting material are soiled with fungicides. To improve the immunity of plants, planting is treated several times per season with Immunocyte: 1 tablet is dissolved in 1 tbsp. water and add to 2 liters of water. The solution is enough for 50 sq.m.
It is important to fight insects in time, in particular, with aphids, as they are capable of transferring fungal spores to healthy plants. As well as remove and burn all plant residues of infected crops, dig deep soil in the fall and strictly observe crop rotation.
For garden crops dangerous not only alternarioz. Read about other common diseases in the article The most dangerous diseases of vegetables - photos, descriptions and control measures in the tables.
General description of the disease
Alternaria - a disease that occurs under the action of mold fungi Alternaria. The optimal conditions for the development of this microorganism are the air temperature within + 22-26 degrees and the presence of droplet moisture for at least 2 hours.
Alternaria disease is widespread in Belarus and Russia, especially in the Far East, in the western and central regions of the European part of the country.
The fungus is active at a temperature within + 7-12 degrees, dies at temperatures below -30 degrees. Pathogenic fungus overwinters in the soil at a depth of no more than 5 cm on infected plant debris. Продолжительность жизнеспособности этого микроорганизма зависит от температуры, а также показателя влажности окружающей среды.
Болезнь особенно активно проявляется на нижних и средних листьях стебля в начале июля. Обычно грибок поражает стебли и листья, иногда распространяется на клубни.
Альтернариоз также называют сухой пятнистостью. Most often, this disease affects early ripe potato varieties, while medium and late ripe varieties suffer from fungus much less often. At the same time, the decrease in yield in the early varieties is much less pronounced.
Currently there is no variety that has full resistance to Alternaria, but there are known types of potatoes that have an increased resistance to it. These are Adretta, Master, Twinkle, Lyubava, Filatovsky, Gala, Lugovskoy, Lasok, Svitanok, Bryansk delicacy, Fairy tale, Lazurit and some others.
This disease is not peculiar to potatoes: the disease affects other plants, including those belonging to the family of nightshade. In addition to potatoes, Alternaria also affects cabbage, tomatoes, eggplants, zucchini, carrots, onions, sunflowers and peppers.
Most scientists believe that Alternaria affects mainly weakened plants, but this pathogenic fungus is also found in cultures that appear to be completely healthy.
Ways of infection risk factors
The main reason for the spread of dry potato blotch is the penetration of mycelium and Alternaria fungus cells on tubers. This can occur during the planting period, when the mycelium preserved on the remains of plants and old tubers enters the tuber.
Sources of infection: tubers, plant debris, soil that contains fungal mycelium.
Spores of fungi are transferred throughout the summer and autumn period. They fall on the potatoes with the wind, raindrops. The vectors are also some insects.
Infection occurs as follows:
- the pathogen, falling on the surface of the plant, grows into it, penetrating through the stomata and the damaged epidermis,
- a mycelium is formed in the intercellular spaces, which, as it grows, produces acid, which has a destructive effect on the tissue of the aerial part of the potato bush,
- the destructive process reaches the tubers, the lesion expands.
The pathogenic fungus Alternaria causes necrosis of the leaf apparatus, which leads to the premature death of the entire plant. Over the entire period of potato development, the appearance of several generations of a pathogenic fungus is possible. The infected plant has impaired respiratory and nutritional functions.
Factors that increase the risk of developing the disease are:
- soil deficiency of minerals - nitrogen and potassium,
- excess phosphorus,
- insufficient moisture level
- high air temperature
- improper preparation of seed for planting,
- water stagnation for more than 2-3 hours during irrigation, natural irrigation (rain),
- infection of tubers with viruses even before they land on the soil,
- weakened plant immunity,
- growing potatoes with other Solanaceae crops infected with Alternaria (mainly tomatoes),
- exposure to parasites.
The symptoms of this fungal disease are most clearly manifested in hot weather, which alternates with abundant morning dews and rains.
The incubation period of potato alternaria is on average 3-8 days. If the weather conditions are favorable for the development of the disease, then the symptoms appear within 3-4 days. The first symptoms are usually found on relatively young plants, the height of the bush which reaches 15-20 cm.
Signs of potato alternaria
The first manifestations of the fungal disease can be considered when the bush grows 20 cm in height.
The lesion of the fungus is expressed in the following symptoms:
- The formation of small black spots on the leaves. Their peculiarity is the presence of concentric circles and a weak black deposit on the underside of the leaves. Spots usually appear 3 days after infection. Over time, the diameter of the spots increases. On the surface of these lesions there is an velvety olive plaque. As the disease progresses, the spots merge and can soon cover the entire surface of the leaf.
- The fragility of the leaves, as a result of which they die.
- The formation of dark spots on tubers. Potatoes are rarely affected by Alternaria.
- The presence of areas of rot in a tuber cut in half.
- The appearance of deep wrinkles in areas covered with dark spots.
On the stems and petioles, the fungal disease manifests itself in the form of strokes, which merge and form solid spots. They are extended in length by 3-5 cm, slightly immersed in the tissue of the stem.
Alternaria on the seeds appears as a black mold. The disease adversely affects the germination of seed.
If infection by alternariosis occurred during harvesting against the background of contact with infected root crops, the symptoms of fungal disease manifest no earlier than 2 weeks later.
Ways to combat the disease
To combat Alternaria, various chemicals that fight the causative agent of fungal disease are used.
In case of this potato disease, such solutions of chemical preparations (0.2-0.3%) are effective:
Each of the drugs should be used in a strictly defined dosage. The method of application is also different. For example, Acrobat MC is sprayed onto bushes up to three times during the growing season of potatoes, and Albit is sprayed twice a season, during the period when the bushes close. The exact dosage is indicated in the instructions to the tool.
You can also treat plants that are sick with a fungal disease with the help of copper oxychloride at the rate of 24-32 g per hundred.
Chemicals are very toxic, so you should take precautions when handling them. It is important to follow the recommendations specified in the instructions, use personal protective equipment, after working with the drug, change clothes and wash. During the spraying can not smoke, eat, drink.
To avoid the effect of addiction, you need to alternate preparations for the treatment of diseased plants.
It is necessary to treat the fungal disease, since in the absence of measures one can lose a significant part of the potato harvest.
To prevent the development of this disease, you must:
- be sure to remove from the site, and then destroy the remnants of sick potatoes,
- deep plowing the land - it contributes to the decomposition of infected plant debris,
- observe crop rotation: this means that a certain variety of potatoes should be returned to the original landing site after 3-4 years,
- plant only healthy potatoes, inspect each tuber before planting,
- in the autumn period to carry out deep plowing of the soil - not less than 50 cm,
- before planting, treat tubers with special formulations that hinder the development of Alternaria: the most popular are Integral, Scor, Acrobat, Baktofit, Agat-25,
- to carry out the first spraying of bushes with antifungal agent at the stage of closing the foliage in rows,
- before digging potatoes, mow the tops to prevent spores of the pathogen from entering the tubers,
- planting potato varieties that are resistant to Alternaria: Resource, Victory, Master, Blue, Adretta, Bronnitsky,
- to fight carriers of the fungus, in the role of which are aphids and other insects,
- to separate sick potatoes from healthy ones, to prevent their joint storage,
- Do not plant potatoes next to tomatoes, affected by Alternaria.
During the entire growing season, it is necessary to monitor the state of the potato and take measures at the very first symptoms of a bush lesion with a fungus. The sooner you take action, the more likely you are to retain the harvest.
Alternaria - a disease that spreads to solanaceous crops. It affects not only the aboveground part, but also the tubers. To prevent the development of the disease, you need to process potatoes with special preparations. If it has already spread to the plant, it should be treated as soon as possible with special chemicals.
Causes and pathogen
Alternaria potato, or dry spotting, has a fungal origin: the causative agents are Alternaria solani and Alternaria alternate Keissler, affecting not only potatoes but also other solanaceous crops.
Sources of the disease are mycelium and conidia, preserved in plant residues. Under the influence of the wind, they fall on the surface of the bushes and infect them. How does this happen:
- Conidia germinate, penetrating inside the plant through the stomata and damaged epidermis.
- A mycelium develops in the intercellular spaces, releasing alternaria acid during the growth process, under the influence of which the tissues of the aerial part of the bush die.
- Failure to take timely measures leads to infection of the tubers with the expansion of the lesion.
Some mistakenly call the disease "potato macrosis", although scientists still cannot unanimously decide whether the causative agents of Macrosporium solani and Alternaria solani belong to the same species. External manifestations are similar. However, for germination and active development of spores of alternaria, the temperature above 22 ° C in combination with high humidity (about 90%) or the presence of droplet moisture is optimal, while macroporiosis fungus begins to act at 18 ° C.
The risk of developing the disease increases if the plant is difficult to resist due to low immunity. This can happen:
- with improper soil mineralization (lack of potassium, nitrogen, excess phosphorus),
- high air temperature and lack of moisture,
- viral infections
- exposure to pests.
Signs of tuber disease
The main risk group is mid-ripening and late varieties, since the fungus first infects leaves, tops and tubers of young plants. Early potatoes at the time of occurrence of favorable conditions for the development of the disease is already beginning to ripen, and its tops - to fade.
The diagnosis of potato alternaria can be diagnosed if:
- 2-3 weeks before flowering, foliage has specks of dark brown color, gradually expanding in the direction from the center of the leaf to the edges,
- as the degree of damage increases, they merge into a single large formation of dry tissue that breaks easily when pressed,
- elongated spots on the affected stems and petioles.
Determine the disease of the tuber affected in the soil, you can visually during harvest:
- there are dents of different shapes and a darker shade than the skin,
- gradually they grow and become covered with a net of wrinkles, which are parallel to each other along the edge of a rotting circle.
Considering the affected tuber in the section, you can see areas with dead tissue: thick, dry and brownish-black.
If the infection occurred during harvesting in contact with diseased roots or soil, then it is impossible to immediately determine the disease. It will appear no sooner than 2 weeks. To remove such potatoes for storage means to form new foci of infection. Therefore, it is necessary to send tubers to the cellar after a thorough inspection 2-3 weeks after harvesting.
Breeders have not yet brought a variety that has full immunity to Alternaria. Therefore, where it is a common disease, it makes sense to grow potatoes with increased resistance to the fungus. These are varieties such as:
- Lyubava and others.
How to deal with Alternaria
Alternaria can be avoided with proper agrotechnology. If you still have the first signs of the disease, it is necessary to take urgent measures. It will be difficult to fight a fast-growing enemy, but you can defeat him. The main thing - to begin work on the destruction as soon as possible.
One of the most effective and popular drugs is the Bordeaux mixture (1%). Properly prepared liquid should be blue in color and have a uniform consistency. It is treated with the first unfolded leaves affected by Alternaria, at least four times a day. The procedure is repeated for 7 days.
There are other fungicides that are used in the formation of alterotic spots on the tops of trees, defeat the pulp of the tuber. Even with the complete destruction of the fungus after harvesting you need to get rid of the nursery of infection - plant debris. Otherwise, this attack will return next year.
Protect potatoes from Alternaria can even during planting tubers. For their spraying use solutions of protective drugs: Agat-25, Baktofid or Integral.
When choosing fungicides to combat pathology, you should pay attention to Planriz, which is used during the flowering period of potatoes.
The microbiological preparation Fitosporin-M, which can be used in conjunction with fertilizers and growth regulators, will also help to resist late blight or Alternaria.
If biological products do not act as effectively as we would like, and the area of the disease increases, you can resort to solutions (0.2–0.3%) of chemical agents:
A 0.4–0.5% solution of such agents as Acrobat MC, Cupricol, Metaxil, and HOM are also used. To prevent disease during storage, prior to laying it is possible to spray Maxim (200 ml per 1 ton of root crops).
The use of any chemicals is very dangerous (they are very toxic). To reduce the risk of poisoning, you must:
- Act strictly according to the instructions.
- Wear protective equipment: gloves, suit, goggles, mask or respirator.
- After work, change clothes, wash well.
- Thoroughly rinse the sprayer with detergent.
What is a vegetable pathology?
Dry blotch potatoes are called alternarioz. The disease is widespread among plants of the Bean family. Potatoes and tomatoes suffer most from the infection. Taking into account the fact that the fungus is activated during hot weather, mid-ripening and middle-late vegetable varieties fall under the infection.
To understand the danger of a fungal infection, you need to know its description. Spores, leaves of a potato are affected by spores. The fungus penetrates the tubers if the fruit is damaged during the harvest. Often, potato tubers also become infected through contaminated land.
The fungus is characterized by vitality, and its spores are carried by rain, wind, infecting other plants.This is how the infection centers are formed. After overwintering in plant waste, pathogenic microorganisms begin to be colonized in a plant planted in the spring.
Causes of infection
At the heart of the disease is infection with conidia and mycelium, preserved on the plant leaves and tubers of the old crop that had lain under the snow. As soon as hot weather sets in with some rains, the fungi of the species Alternaria begin to intensify. Extracting acid, they provoke necrosis of leaves, potato stalks. The description of the mycelium of this species is as follows:
- interlaced fibers
- branched and fine structure
- no color threads.
Factors contributing to the development of fungal pathology include:
- hot weather
- weakness of the protective functions of plants,
- soil depletion of potassium and nitrogen
- excess phosphorus in the soil,
- defeat potato pests
- infected planting material.
Interestingly, the fungus has adapted to harsh conditions. It can be active at low temperatures.
Symptoms of vegetable disease
It is possible to detect potato alternaria by strongly pronounced features:
- Two weeks before flowering, on the lower leaves dry brown spots are found with a diameter of 1-3 cm. They appear in the middle of the sheet plate, spreading to the edges. In a form remind concentric rings.
- Round-oblong spots spread, leading to complete drying of the leaves.
- The leaves are dry and easily broken.
- One month after the infection with the fungus, a patina with fungal spores is visible on the green parts of the potato.
- If a potato tuber is infected, it can be determined by the presence of dark spots. At the same time, the affected part of the potato is covered with a network of brown wrinkles, concentrically arranged in a circle.
- Inside the cut potatoes are areas of dry rot, representing a dark dense mass.
If the disease is identified in time, then the plant can be saved by selecting the appropriate treatment.
Ways to eliminate Alternaria
During the growing season of potatoes, it is necessary to fight against fungal infection with the help of chemicals. Suitable treatment of diseased plants with drugs:
Profit Gold, containing toxic substances, acts both internally and externally on the infected plant. After treatment with a means, a protective film is formed on the leaves and stems, which is indestructible by precipitation. Fungi and spores die, and within two weeks the potato becomes healthy.
Fungicide Thanos is considered a safe remedy for humans, pets. The components of the drug penetrate into the tissues of the plant, killing the fungus.
Bravo refers to prophylactic drugs. The product contains chlorine, which has a detrimental effect on the fungus, does not allow it to multiply.
Use chemicals in accordance with the instructions. Be sure to protect your hands before spraying with rubber gloves, eyes - with special glasses, and the mucous membranes of the nose and mouth - with masks.
In the control measures include biological means, which are treated tubers before planting. The seed of the vegetable will be protected from Alternaria by the drug Planriz. The basis of the means of soil bacteria that are active against fungi. In addition, microorganisms enhance the growth of potatoes. Обработку препаратом можно проводить, опрыскивая всходы картофеля.
К фунгицидам биологического типа относят Бактофит. Обрабатывают им клубни перед посадкой. Можно опрыскивать посадки овоща трижды в период вегетации.
Before laying the vegetable seeds are pickled with Maxim. The working solution is prepared from ten milliliters of money, diluting them in five liters of water. Per kilogram of potatoes usually spend one liter of the finished product. Prepare the solution before processing, since it can only be stored for a day.
How to prevent the appearance of the disease?
The prevention of Alternaria in solanaceous crops includes:
- destruction of residual tops after harvesting a vegetable,
- following the rules of crop rotation,
- timely fertilization with a sufficient amount of potassium, nitrogen,
- careful digging of tubers without damaging them,
- seedbed preparation,
- spraying a potato field with preparations against fungal infections three to four times a season.
Cultivation of potatoes is not difficult. But you need to know that you can not plant a plant in one place for more than three years. Nearby you should not put the beds with tomato and other nightshade.
Potato varieties resistant to Alternaria
You can plant on the site such varieties of vegetables that are resistant to fungal infections:
- The early ripe potato Lyubava has white color of tubers. In the process of cooking the potatoes are not boiled soft, retains the white of the pulp. During the growing season, the plant rarely becomes infected with Alternaria fungi.
- The variety Bronnitsky has increased resistance not only to Alternaria, but also to scab, blackleg, late blight.
- Andretta with yellow skin refers to the early ripe type of vegetable culture. After sixty days you can harvest tubers. The popularity of the variety in the excellent taste of yellowish flesh, resistance to low temperatures, alternariosis.
- In Nevsky potato, the growing season is 90 days. The advantages of cultivating a variety include its immunity to scab, alternariosis, blight.
- 45 days after planting, Dolphin tubers are being dug up. Appreciate the vegetable for high yield, excellent taste of small fruits. Differs plant resistant to scab, late blight and Alternaria.
- Late-ripen pace is considered resistant to bacterial and fungal infections. It is adapted to temperature extremes, enduring drought.
Properly selected seed is also important in the prevention of fungal disease.