White rot. Rotting of the stem, white coating on the leaves, white slippery mass on the fruits. Signs, symptoms, treatment, prevention. White rot on cucumbers. Methods of control and prevention White rot how to fight

White rot. How to diagnose a disease and cure a plant. How to determine. How to prevent infection (10+)

The material is an explanation and addition to the article:
Plant diseases - overview
The plant is sick. How to determine the disease? Types, types, classification of plant diseases and pests. Treatment tips

Pathogen white rot is the fungus S. sclerotiorum, which has a wide specialization. It occurs so often that any gardener has dealt with it at least once in his practice. The most intense infection with this disease is observed in the CIS regions, as well as in Moldova and the Central Chernozem Zone. The first alarm bell is the fading top of the plant, rotting of the bottom of the stem. The leaves at the bottom of the plant lose color, become watery, and become covered with a white coating.

Sclerotia of the fungus are usually visible on the cut of the stem - these are large black formations. The plant becomes infected through the soil, and the fungus gradually penetrates into the lower part of the stem. The best development of the disease occurs under the following conditions: temperature changes, high humidity and a decrease in temperature to 11 degrees Celsius.

Disease prevention

Preventive measures against white rot are: strict control of air humidity, the use of fertilizing (urea, zinc sulfate, copper sulfate) to strengthen plants and prevent infection. Spores can also be carried by the wind, so it is advisable to keep indoor plants indoors. You should hide your “pets” during wet weather in the summer to prevent them from getting sick. Calcining the soil before using it is also a great way to protect yourself from fungus.

How to treat?

If white rot affects pumpkin crops, then treatment is carried out by maintaining optimal conditions in the greenhouse, sprinkling the diseased tissue with calcium carbonate (in other words, chalk) or coal, coating the tissues with a mixture of potassium permanganate and calcium carbide with the addition of water, cutting out the affected tissue and parts of the healthy one, watering with warm water in the evening, using foliar fertilizers (urea, copper sulfate, zinc sulfate), thoroughly removing plant residues from the top layer of soil (up to 4 cm), air ventilation in greenhouses or greenhouses.

The concentration of copper sulfate is selected depending on the type of plant. So, to spray apple and pear trees, as well as quince, you need to make a solution at the rate of 100 g of copper sulfate per 10 liters of water. But for spraying plums, cherries, cherries, as well as peach and apricot trees, a different concentration is used - 50-75 g per 10 liters of water. The same concentration is also used to prepare a solution of copper sulfate for spraying currants and gooseberries. Now let’s talk about the quantities needed to spray a particular tree. Fruit trees need to be sprayed at the rate of 2-3 liters per tree, and shrubs (gooseberries, currants) - at the rate of 1.5 liters per bush.

Zinc sulfate is used for feeding in this way: dissolve the required amount (fruit crops, berries, flowers - 3g, cabbage, cucumbers - 5g, root vegetables, tomatoes - 10g) of the drug in 10 liters of water. Spray the plants with a freshly prepared working solution of the drug in dry, windless weather in the morning or evening, evenly wetting the leaves. Spray the upper and lower surfaces of the leaves for better absorption of microelements by the plant.

A mixture of potassium permanganate and carbide should be applied in microdoses in the form of foliar feeding (3 g of potassium permanganate and 2 g of carbide per 10 liters of water). When spraying trees with Bordeaux mixture, you can add 20 g of manganese sulfate per 10 liters of solution. On loamy soils, it is recommended to add manganese sulfate in the amount of 5 g per 1 sq. m. m. Manganese is found in manure and wood ash. When disinfecting the soil under vegetable crops and feeding them, you need to follow the dosage.

In case of infection of cabbage, the same measures should be taken as in the fight against gray rot - thorough cleaning and disinfection of storage facilities, maintaining good storage conditions, pruning affected areas, selecting only suitable seeds.

The rotation of crops in crop rotation is also important. The predecessors of cabbage should not be those plants that are not immune to this disease (cucumbers, lupines, carrots, beans).

If root crops (potatoes, turnips, beets, radishes, celery and others) are affected, correct crop rotation must be observed, only healthy queen cells must be selected, and seeds must be thermally disinfected at 45 degrees Celsius. Store fruits only at a temperature of no more than 3 degrees and air humidity of no more than 85%. If onions or garlic are sick, use the same measures as in the fight against neck rot - selecting healthy planting material, harvesting the bulbs only when they are fully ripe. Next, you need to dry them completely in an open area, trimming the onions, leaving the neck up to 7 centimeters long, and storing them in optimal conditions: 1-5 degrees Celsius and a relative humidity of no more than 80%.

For prevention of damage For tomatoes and cucumbers, the soil should be thermally disinfected before planting and ensure optimal air humidity and temperature.

To disinfect a small amount of soil (in small greenhouses or for growing seedlings), boiling water is poured onto the soil. After spilling boiling water, the soil takes a long time to dry.

Also, the thermal method involves heating the soil on an iron sheet or on various baking sheets over a fire. First, the soil is moistened abundantly. During thermal heating, the soil is constantly mixed so that there is no overheating (more than 100 degrees).

At high air temperatures from mid-July to mid-August, on hot sunny days, the soil may be heated by sunlight. To do this, in small greenhouses or containers the soil is loosened and air access is closed. You can cover it with glass frames with clean glass, all cracks should be sealed. This warming up should last about a week. Such disinfection by sunlight is recommended in southern regions.

One of the soil treatment technologies is described.

But, if the plants are still sick, then it is necessary to use a comprehensive method of soil disinfection and plant treatment.

Unfortunately, errors are periodically found in articles; they are corrected, articles are supplemented, developed, and new ones are prepared.

When using film to protect the soil, the disease appears more often. Absolutely all parts of plants are affected - fruits, tendrils, petioles, stems. The most dangerous manifestation of white rot on the stem is when the root part is affected. In the affected area, the stem looks damp, rotten and covered with mycelium, which is very reminiscent of cotton wool. The leaves gradually droop and turn yellow, after which the stem breaks and the plant dies.

On fruits, white rot appears as a white coating, the fruits soften and become flabby. As the disease continues, black spots, approximately the size of a pea, form in the damaged areas.

The mushroom has 2 stages of growth, which are determined by external signs. The first stage is the formation of sclerotia; they are spherical in shape and black in color. The second stage is the formation of fruiting bodies, their shape in the form of a saucer or glass. Cylindrical bags develop inside the fruiting bodies in which ascospores mature. This fungus does not produce conidia. Sclerotia overwinter, remaining in the soil for up to 10 years, while the ability to germinate is maintained throughout this time.

Why is it dangerous?

As the disease develops, the plants die. Fruits and roots rot and become unfit for consumption

What caused

The causative agent of the disease is the omnivorous phytophagous fungus, the marsupial Sclerotinia sclerotiorum.

When appears

At a temperature of 10-15 degrees Celsius above zero.

What contributes

The spread of sclerotinia is facilitated by prolonged rains and sudden temperature changes. The risk of the disease also increases with dense crops and the presence of a large number of weeds.

How it spreads

The spread of the disease occurs through contaminated soil and planting material. Sclerotia can be carried by wind over long distances.

Prevention

• If a disease is detected, the affected plants must be isolated and burned;
• timely destruction of weeds;
• inspection of crops every 10 days;
• competent compliance with crop rotation: the basic rule is that growing a crop in one place is repeated no earlier than after 3 years;
• acidic soils need to be limed and it is advisable to avoid applying phosphorus fertilizers.

Fighting methods

• Applying potassium fertilizers will reduce the risk of carrot contamination. Before storing, treat mother root crops with TMTD in proportions of 6-8 liters of working solution per 10 liters of water. The resulting quantity is calculated for a ton of queen cells;
• The biological control method is to use a culture of the fungus Trichoderma lignorum (Trichodermin-3), it must first be propagated on heated peat, it is added to mixtures for seedlings and during planting, per 1 square meter. meter of soil consumption 150-400 g;
• complete elimination of infected plants, after which treat the area with powders, you can use fluff lime or crushed charcoal;
• Copper-containing fungicides are effective: 1% Bordeaux mixture, "Profit Gold", "Ridomil GOLD MC", "Ordan", "Oksikhom", "Hom", "Acrobat MC", "Abiga-pik", "Previkur". Use according to instructions.

Simple measures will help prevent the loss of your crop due to white rot. Vegetables will not get sick during the growing season and storage.

How does white rot appear on different plants?

White rot is especially severe in cold, rainy weather. Having settled on one plant, under suitable conditions, the fungus quickly affects neighboring heads of cabbage. The disease can appear not only during the growing season, but also during storage, especially if the basement or cellar has poor ventilation and high humidity.

The photos demonstrate eloquently how white rot manifests itself on pumpkin plants. In this case, the tissues of the stems, leaves, and fruits become covered with a white coating and rot. Then the disease moves to the next stage, then the white new growths turn black, they overwinter on unharvested plant debris and the next year can cause damage to new crops planted in this place. Since the fungus loves high humidity, for the most part it progresses in greenhouses, where there is poor ventilation.

High humidity in the greenhouse is the main cause of the spread of white rot on tomatoes. Low air temperatures also contribute to this. To recognize the disease, just look at the tops of the plants; if they have wilted, this should alert the gardener. Other signs of white rot are rotting of the lower part of the stems and their softening. Sometimes a white coating appears here too.

This disease can also affect garlic and onions. If this happens during the growing season, then the leaves of the plant turn yellow prematurely, starting from the top, and then die. The fungus penetrates the roots and covers them with fluffy white mycelium. Due to the harmful effects of the disease, garlic cloves and bulbs become watery and rot. If you do not disinfect the storage, after placing a new crop there, it may be affected by fungus left over from last year.

Among root vegetables, white rot likes to settle on carrots, celery, and parsley. In this case, a white mycelium forms on the surface of the root crops, and subsequently black sclerotia of the fungus appear on it. This leads to softening of the tissue, and as a result, the vegetables completely rot.

Mycelia on beans and peas like to settle on the surface of the pods, penetrate inside them and infect, gradually turning into black fungal sclerotia.

Prevention of white rot

• 5 grams of urea;
• 1 gram of copper sulfate;
• 0.5 grams of zinc sulfate.

Treatment of white rot on cucumbers

After this, it is necessary to ventilate the greenhouse. It is better to carry out this treatment early in the morning so that during the day the air temperature does not drop below +20°C, and at night - +18°C. If at night the temperature drops below this mark, then the lashes need additional cover with non-woven material or film. After a week, treatment with Topaz is repeated.

If you prefer folk remedies, then spray the plants with whey or prepare a solution consisting of:

• 3.5 liters of water;
• 1.5 liters of whey;
• 0.5 tsp. copper sulfate.

Resistant cucumber hybrids can resist this disease. Where you plan to grow pumpkins, do not plant celery and parsley 3 years before, which often have white rot.

Treatment of diseases on root crops

Root vegetables should be stored in a cool place at +3°C and the air humidity should be monitored, it should not be higher than 85%.

Learn more about how to cure cucumbers from white rot in this video:

Secondly, white rot is an infectious disease that is dangerous for many useful plants. In other words: this is a source of unpleasant worries for all gardeners and field growers. It affects Watermelon (Citrullus lanatus), Rutabaga (Brassica napobrassica), Grapes (Vitis), Hibiscus cannabinus (aka Kenaf), Peas (Pisum), Melon (Cucumis melo), White cabbage (Brassica oleracea), Hemp (Cannabis), Sweet Corn (Zea mays, also known as Maize), Leeks (Allium porrum) and Onions (Allium cepa), Carrots (Daucus), Cucumber (Cucumis), Pepper (from the genera Piper and Capsicum), Parsley (Petroselinum), Sunflower (Helianthus), Radish (Raphanus sativus convar. radicula), Radish (Raphanus), Turnip (Brassica rapa), Rose (Rosa), Lettuce (Lactuca sativa, also known as Lettuce), Beetroot (Beta vulgaris ), Celery (Apium graveolens), Soybean (Glycine), Tobacco (Nicotiana), Tomato (Solanum lycopersicum), Turnip (Brassica rapa subsp. rapifera, also known as turnip), Beans (Phaseolus), Cotton (Gossypium), Horseradish rustic (Armoracia rusticana), Garlic (Allium sativum), etc.

The most universal (polyphagous) causative agent of the described disease is the marsupial fungus Sclerotinia sclerotiorum. He is almost “indifferent” to heat: if the temperature rises at least half a dozen degrees above zero, this is already enough for the “agent” to become active. It is found everywhere in the CIS countries.
Coniothyrium diplodiella specializes in Grapes.
Sclerotium cepivorum is “occupied” with different types of onions (and among them Garlic).
Tomato - not only Sclerotinia sclerotiorum, but also Sclerotinia libertiana.

The conidial formation stage is absent in the life cycle of these fungi. Nature “trained” them to survive unfavorable conditions (winter) with the help of sclerotia. Imagine: in an absolutely dry environment, sclerotia can survive for several years (up to 10) without losing their ability to germinate!
With good soil and air humidity, spores develop quickly (the optimal temperature range for this is 14-20°C). They easily travel on the wind, and more often spread through planting and seeding materials, weeds, the remains of dead plants and the soil on which or in which they grew. Often, some poorly maintained vegetable storage facility plays the role of a “patrimony” of pathogenic microorganisms. Their vigorous activity is favored by the richness of nitrogen N in the soil (especially if its acidity is higher than neutral: pH = 5.5--6.0), as well as excessive planting density.

Symptoms of white rot

White rot of cabbage. At the end of its growing season (that is, on the eve of harvesting), the outer leaves of the heads of cabbage begin to mucus. Then the same “white cotton wool” with droplets develops on them and between them. You will see black sclerotia in it (size: 0.1-3 centimeters). If this head of cabbage is placed in storage, it will rot very soon, but before that it will generously share the “infection” with its neighbors, forming a large center of it. They will accept infection especially readily if they are overripe, frostbitten or injured.

White rot Luke. If a young specimen of Onion is affected, the leaves turn yellow and die from top to bottom. A similar chlorosis on young Leeks or Garlic comes from the lower leaves upward. Seedlings may die immediately.
Dig up the plant to examine the scales of the already emerging bulb and the root system. Will be revealed:
1) fluffy white coating -
2) soft rotten areas -
3) on their surfaces there are sclerotia, similar to poppy seeds.
If the disease “clings on” later, then it does not affect the leaves. Diagnose it by the bottom of the bulb - it shows a scattering of black small sclerotia on the “white cotton wool” - mycelium (mycelium). Often, it can be revealed that the outer scales have rotted and the inner scales are already rotting with might and main.

White rot of peas. It is attacked by white rot mainly at the end of summer with wet weather. If a pod is attacked, do not expect seeds from it: they either are not formed at all, or the fungus “eats” them and turns them into sclerotia. If the stem is attacked, the part of the plant located above the “point of impact” dries out.

Measures to combat and prevent white rot

1a. Control weeds.

1b. In the fall, do not neglect plowing the soil.

1st century Lime acidic soil.

1 year Properly balance the composition of the mineral fertilizers applied to it (the proportion of potassium and/or phosphorus should probably be increased if there is an excess of nitrogen in the soil).

2. Maintain a temperature of 1—-3°C in the storage.

2a. Ventilate it heavily.

2b. Before planting a new crop, thoroughly clean and disinfect all storage compartments.

2c. Select only healthy vegetables to send to it.

2g. Before shipping, dust carrot root vegetables with ground chalk or soak them in thick lime milk.

3. Disinfect the structural elements of greenhouses and greenhouses.

4. Follow the rules of crop rotation - for example, do not plan to plant Cucumber in the bed where Parsley was.

4a. One of the general rules: it is permissible to return the culture to its original place no earlier than after 3 years.

5. Sort, clean, and treat the seeds before planting.

6. Make it a habit to inspect your crops regularly (weekly or every 10 days).

7. Having noticed the first signs of the disease, immediately use fungicides containing copper Cu. 1% Bordeaux mixture will do, even if you prepare it yourself from copper sulfate CuSO 4 and slaked lime Ca (OH) 2, as indicated in the article “-Ascochitosis”-. Purchased options: “-Abiga-pik”-, “-Bordeaux mixture”-, “-Oksikhom”-, “-Hom”-.

7a. Contact action preparations “Ditan M-45”, “Profit”, “Rovral” are not always effective against white rot.

7b. Try combined systemic contact fungicides - “Acrobat MC”, “Ordan”, “Previkur”, “Profit Gold”, “Ridomil Gold MC”, etc.

8. Pumpkin crops respond well (strengthening physically and increasing their immunity) to foliar feeding with a mixture, the recipe for which is as follows: for 10 liters of water - 2 grams of copper sulfate, 10 grams of urea (NH 2) 2 CO and 1 gram of zinc sulfate ZnSO 4.

A fungal disease that can affect many plant species.

When pumpkin crops are damaged on the stems, leaf petioles and fruits, the tissue softens and rots, becoming covered with a dense white coating (mycelium). Subsequently, the mycelium becomes denser, first white and then black formations (sclerotia) the size of a pea develop, overwintering on plant debris. The disease progresses at high humidity in greenhouses.

White rot is a common disease of cabbage, especially in heavy loamy soils. During the growing season of cabbage, mainly the root collar and lower leaves become infected. The affected tissues become discolored, become watery, and become covered with cotton-like white mycelium. By autumn, the mycelium thickens, turning into black sclerotia of various shapes.

White rot is especially harmful during cabbage storage. The defeat usually begins with the outer leaves in the field, especially in rainy weather. The leaves rot and become slimy. An abundant mycelium develops between the leaves, from which numerous sclerotia subsequently form. The mushroom does not develop sporulation on heads of cabbage. The disease is easily transmitted to neighboring heads of cabbage. The development of white rot in storage facilities is favored by poor storage conditions and high humidity.

White rot is also the cause of significant losses of carrots during storage and death of testes during the growing season. Other root vegetables that are affected are parsley and celery. A white mycelium forms on the surface of the root crops, on which black sclerotia of the fungus subsequently form. The tissue softens, turns brown, and the roots completely rot.

Onions and garlic also suffer from white rot. Plants are affected both during the growing season and during storage. When infected in the field, young plants' leaves turn yellow, starting from the top, and die. Plants quickly wither and die. A white fluffy mycelium forms on the roots and scales of the bulbs, the garlic cloves become watery and rot. Small dotted sclerotia appear on the affected tissue. The mushroom develops well at a temperature of 10-20°. Overwinters as sclerotia in the soil and in storage on infected bulbs.

White rot is dangerous for tomatoes. The disease manifests itself sharply if there is low air temperature (12-15°) and high humidity (95%) in greenhouses during planting tomato seedlings in the ground. Characteristic signs of white rot of a tomato are wilting of the top of the plant and rotting of the lower part of the stem. The root part of the stem softens, sometimes becoming covered with a white flake-like coating. Large black sclerotia are visible on the cut of the stem. Sometimes they form on the surface of the stem. As a rule, white rot appears in patches and causes loss of a small number of plants.

When a cucumber is infected, the disease can develop on all parts of the plant - roots, stems, petioles, leaves and fruits. When terrestrial organs are affected, the tissues become soft, slightly slimy, and covered with dense white mycelium, in which black sclerotia subsequently form. Plants wither, leaves lose turgor and dry out.

The disease is especially harmful where it is the result of a permanent crop. cucumbers, infection accumulates in the soil, as well as in greenhouses where there is no heating and poor ventilation. The first foci of the disease usually appear with a sharp drop in air temperature to 14-16°C and high relative humidity (95-98%). The causative agent of white rot is transmitted through the air using broken pieces of mycelium, and is also transmitted mechanically (on hands and tools).

White rot is dangerous for peas and beans. The stems and especially the beans of these crops are affected. Characteristic signs of the disease are softening and whitening of the affected tissues, the formation of abundant white mycelium on the surface and inside the stem and beans. Later, rather large black sclerotia of the fungus form on it. The infection can accumulate from year to year in the soil in the form of sclerotia, especially when crops affected by white rot are frequently cultivated in the same area: cucumber, carrots, lettuce, parsley, etc. The causative agent of white rot is transmitted with the seeds of peas and beans.

Control measures

When pumpkin crops are affected by white rot, it is necessary to maintain an optimal hydrothermal regime in the greenhouse; sprinkle the affected tissue with crushed coal or chalk; coat the affected areas with pink paste (chalk mixed with potassium permanganate with added water); cut out the diseased part while capturing the healthy part; In the evening, water the plants with warm water.

It is also recommended to use foliar fertilizers: zinc sulfate - 1 g, copper sulfate - 2 g, urea - 10 g per 10 liters of water; carefully remove all plant residues from the top 2-3 centimeter layer of soil; reduce air humidity in a greenhouse or greenhouse by periodic ventilation.

When cabbage is infected, the measures to combat the disease are the same as for gray mold. Reducing the susceptibility of plants is facilitated by later sowing of seeds and planting of seedlings intended for seed purposes, cleaning of queen cells before frost, thorough cleaning and disinfection of storage facilities, compliance with optimal storage conditions (temperature from 0 to -1°), cleaning of affected heads of cabbage with mandatory waste removal , careful selection of only healthy testes.

Particular attention should be paid to alternating crops in crop rotation. The predecessors of cabbage should not be carrots, cucumbers, lupins, beans, which are also affected by the causative agent of this disease.

If root crops - carrots, parsley, celery - are affected, a set of measures is recommended. It includes the following: compliance with correct crop rotation with the return of root crops to the previous field no earlier than after 3-4 years and the exclusion from predecessors of crops affected by white and gray rot (tomatoes, cucumbers, cabbage); selection of healthy queen cells before storage and planting in the field, spatial isolation between the first and second year crops; thermal disinfection of seeds at a temperature of 45-50° for 30 minutes; spraying the second year plants with 1% Bordeaux mixture, starting from the moment the first signs of disease appear. Root vegetables should be stored at a temperature of 1-2° and air humidity of 80-85%.

Measures to combat white rot of onions and garlic include the same techniques as with neck rot. First of all, you need to get healthy planting material. Harvesting the bulbs should be carried out during the period of their full ripening, followed by drying the bulbs in sunny weather in an open place in one layer, in wet weather - first under a canopy, and then for 7-10 days indoors with the air heated to 26-35 °. When trimming onions, you should leave a neck 3-6 cm long. It is recommended to store onions under optimal conditions: food - at a temperature of 1-3° and a relative humidity of 75-80%, mother bulbs - at 2-5° and 70-80%, sets – at 18-20° and 60-70%.

If a tomato is damaged, thermal disinfection of the soil is carried out, diseased plants and fruits are destroyed. The temperature and humidity in greenhouses must be optimal.

If a cucumber is damaged, the greenhouse soil is disinfected and the affected parts of the plants are removed. The optimal air temperature in the greenhouse should be no lower than 18°. You cannot grow cucumber in soil where parsley and celery used to grow.

The main measures to reduce the harmfulness of white rot for peas and beans are compliance with crop rotation, removal of diseased plants from the field, especially in seed plots, optimal sowing times and pre-sowing seed treatment.