What plants are affected by black rot. Gray rot: treatment and prevention, control measures. Gray grill disease - prevention

Black rot, niello, soot fungus, black mold are the names of the same disease. Scientists call it Aspergillosis. It is a widespread fungal infection affecting cucumbers, peas, beets, carrots, onions. Suffer from it and vegetables, and fruits, and even houseplants. But most often it is found on onions and garlic. Therefore, the fight against black mold in the garden is usually an activity aimed at preserving this particular product.

The disease is caused by the fungus Aspergillus niger. Spores enter the bulbs through damage and affect the upper succulent scales. The heads soften, and dust-like black powder appears between the scales.

Outwardly, on diseased bulbs, only dark spots with characteristic spores. Then the upper scales dry up. Small heads of onions and garlic can even dry out completely. Most often, poorly dried and unripe specimens are affected.

The disease usually manifests itself during storage. But this does not mean that it began at that time. Although re-infestation of bulbs in storage is a very common phenomenon, and with direct contact of healthy heads with diseased ones, the transmission of infection occurs very quickly. You can not discount the possibility of obtaining disputes by air - still in the garden.

The fungus of this species is able to live on vegetables, fruits, damaged or dead plants. The range of his "interests" is quite wide, especially in dry and warm areas. In the southern regions, it is often found on many products at once, both of plant and animal origin.

The pathogen persists on post-harvest residues and affected bulbs. With an increase in air temperature above 28 ° C, its activity increases sharply. For infection with conidia, it is enough that the leaves of gourds were moist for just over six hours. For onions, this time is even less. Moreover, it is almost impossible to notice the first symptoms. Is that the discoloration of the neck, where the fungus has penetrated the inside of the bulb or the yellowing of the leaves of the garlic. After a while, the affected scales become watery. And when the mycelium grows, black spores appear, with a diameter of not more than 5 microns.

To protect against the spread of soot fungus, it is necessary, first of all, to use a healthy planting material. And this assumes:

Correct crop rotation;
- growing sevka separately from turnip;
- timely cleaning;
- good drying first on open space, then indoors at an air temperature of at least 26 ° C;
- sufficient pruning - the neck of the bulb should be from 3 to 6 cm;
- optimal temperature seed storage;
- careful sorting when laying for storage - all suspicious or dark bulbs must be additionally checked for spores under the scales.

It will not be superfluous to dress the sevka and nigella with a fungicide, for example, Fitosporin. You can use ordinary potassium permanganate for this. But preparations such as "Maxim" in case of black rot disease may not give the expected results.

During the cultivation of onions and garlic, leaves and heads should be protected from damage. Any wound is the entrance gate for infection.

During storage, it is necessary to monitor the air temperature and humidity. It is better if the first is maintained no higher than 15 ° C, and the second - as low as possible. If the bulbs are already infected, they will have to pay special attention to:

Separate from healthy as soon as possible;
- additionally dry;
- dust with chalk.

In a warm room, room temperature black rot spreads very quickly. Sick and obviously not subject to further storage specimens must be immediately destroyed - this is the only way to protect still healthy heads from re-infection.

black mold eggplant

On eggplants, black mold disease is considered harmless. It occurs more often in open field, but can affect fruits in greenhouses.

The pathogen gets on the fruit when they come into contact with the ground. Small wounds on the skin and other mechanical damage contribute to infection. The affected tissue becomes watery, covered with a gray coating with characteristic black sporangia.

Black mold gourd

Black mold on the leaves of cucumbers and other cucurbits commonly infects protected ground plants. All aboveground organs are susceptible to disease. Outwardly, it is expressed in small spots of light Brown color various shapes. Gradually they merge, forming areas of necrosis. Then the stems and leaves dry up, becoming covered with a black coating. Diseased fruits stop their development and wrinkle. This disease develops especially quickly with a large difference between day and night air temperatures.

To combat black rot of cucurbits, it is necessary to follow the rules of crop rotation, remove plant residues in time, disinfect greenhouses and disinfect the soil.

Sheet vine, affected by black rot (in a reduced form).

Berry affected by black rot (increased several times).

The course of the disease is extremely fast, so that only 2-3 days pass from the time an almost imperceptible spot appears to the entire surface of the berry is affected. In this brush, only individual berries are always affected; but the disease quickly passes from one berry to another, so that in a short time, under favorable conditions, the whole brush is destroyed. Depending on the climatic conditions, as well as from grape varieties, deviations from the normal course of the lesion are often noticed: for example, it sometimes happens that part of the berry is occupied by a dark blue depressed spot, while the rest continues to develop, remaining green and smooth; in such cases, the defeat is suspended by drought; if wet weather sets in, the development of the disease resumes, the whole berry takes on a brown color and is covered entirely with dark blue pustules. Another deviation from the normal course is that the berry does not dry out and does not wrinkle, but, on the contrary, remains juicy and rots, taking on a brown color, then turning into a blackish-blue. Affected berries usually remain hanging on clusters even when completely dry and fall off in late autumn or even winter. In some cases, in the described pycnidia on berries, instead of ordinary stylospores, small, cylindrical, rod-shaped microstylospores are formed, having 5-5.5 μ length and 0.5-0.7 μ width. Germination of microstylospores has not yet been observed; as for ordinary or so-called macrostylospores, they are able to germinate immediately after their formation and infect new berries. Thus, the infection of berries and the appearance of new pustules with the help of microstylospores continues all summer and until late autumn; at this time, in the pustules covering the berries lying on the ground or still attached to the brushes, instead of stylospores, there is a white dense core; such pustules, called sclerotia, or rather resting pycnidia, are specially designed for overwintering; in spring, from the core of such pustules, club-shaped bags 70–90 μ long and 10–12 μ wide are formed, containing 8 unicellular, colorless, elongated spores, measuring 12–16 μ long and 4.5–6 μ wide. Thus, the pustules have now turned into perithecia (see Mushrooms).

Various stages of grape berry damage by black rot (in a reduced form).

Pycnidia on berries were known as Phoma uvicola Berk. et Curtis, and the perithecia under the name Guignardia Bidwellii Viala et Ravaz. This last name must be preserved exclusively, since the forms Phyllosticta viticola and Phoma uvicola represent only the stages of development of the aforementioned marsupial fungus, which, according to its signs, belongs to the division pyrenomycetes. When in 1896 attention was paid to the disease of berries in the Caucasus, it turned out that here Ch. rot is caused not only by Guignardia Bidwellii, but also by a number of other fungi that are very close to each other in appearance. Of these fungi, the most common in the Caucasus is Guignardia baccae Jacz., the pycnidia of which, known as Phoma reniformis Viala et Ravaz, contain spindle-shaped or cylindrical, more or less arcuately bent stylospores of 12-22 and 6-8 μ and are found exclusively on shoots. and on berries, but have not yet been found on leaves. The perithecia of this fungus contain cylindrical or club-shaped bags 80-110 µ long and 9-12 µ wide, which contain 8 colorless, oblong, unicellular spores 12-16 µ long and 5-7 µ wide. I found Guignardia baccae in France and Italy, but in small quantities, and it can be said that in France, as in America, black rot is caused almost exclusively by G. Bidwellii, while in the Caucasus, on the contrary, G. baccae predominates. , which is occasionally joined by other fungi, in addition to G. Bidwellii. So, for example, in some areas of the Caucasus, among other things in the Gori district and in Kakheti, on berries affected by dark blue spots, very small pustules of the pycnidial fungus Phoma lenticularis Sacc. 4μ. Exactly the same pycnidia with similar stylospores are found on leaves, on rounded brown spots. The perithecial stage of this fungus is not yet known. In 1897, in the Zakatala district, in Kakheti and near Batum, A. Yachevsky discovered another pycnidial form on berries, which also does not have perithecia and causes Ch. rot of berries. The stylospores here are ellipsoidal, 8-12 µ long and 4-5 µ wide, olive color and are equipped with one transverse partition. This fungus was subsequently described by H. H. Speshnev under the name Diplodia uvico la.

D. Yachevsky.

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Gray rot disease - description

The gray rot disease manifests itself in spots on the leaves and shoots. The spots grow rapidly, and under conditions high humidity air, these brown necroses are covered with a gray fluffy coating, consisting of mycelium and spores. When botrytis reaches the fetus, it first affects the stalk, and then the disease covers the fetus itself. Spores are carried by the wind, and since gray rot is omnivorous, it easily spreads from one plant to another. Most often, garden strawberries, grapes, cabbage, buckwheat, gladioli and peonies suffer from botrytis. Gray rot that affects root crops is called clamp rot.

Especially dangerous disease becomes during vaccinations, since it affects both the place of vaccination and the harvested cuttings.

Gray rot - control measures

Fight against gray mold

At the first stage of the development of the disease in plants, the chances of recovering are quite high. How to get rid of gray mold? Previously, soap treatments were used against this disease, but it turned out that even a high concentration of alkali in the solution could not destroy the causative agent of gray rot. The drugs of the benzimidazole group successfully coped with the disease, however, mutated strains of gray rot not only found resistance to them, but also found useful substances in them. The treatment of plants with Bordeaux liquid is effective, but it negatively affects the quality of the fruits, therefore, spraying plants with this preparation can only be carried out in early spring and late autumn. And in general, fungicides are resorted to only when all other control measures have been exhausted.

However, it should be said that a remedy has not yet been found that can completely cure affected plants from this dangerous disease, and all control measures are preventive in nature - they do not allow unaffected fruits to get sick. Sick plants or their affected parts must be disposed of.

Gray grill disease - prevention

In order to prevent the appearance of gray rot on plants, it is necessary to treat seeds and bulbs with sulfur-based fungicides before sowing or planting, and when shoots appear, you need to spray them twice with an interval of 7-10 days with one percent Bordeaux liquid. The third treatment is carried out after harvest.

Particular attention should be paid to the fulfillment of the conditions of agricultural technology and, first of all, the observance of crop rotation. It is also necessary to collect and destroy fruits affected by botrytis, remove diseased branches, leaves and shoots. It is necessary to fight codling moths, caterpillars and other insects that damage the tissues of fruits and plants and make them vulnerable to the pathogen. And before laying the crop in the storage, sanitization of the premises should be carried out. In addition, it is very important that plants are not deficient in magnesium and potassium during the growing season, as these minerals increase their resistance to disease.

An effective way to prevent disease of plants with gray rot is to pre-plant in the area where botrytis may appear, plants that produce phytoncides - marigolds, calendula, mustard or nasturtium. In autumn, the site should be dug up, planting these plants in the soil, and next spring the planned crops can be planted on it.

How to treat gray mold on vegetables

Gray rot of tomatoes

Gray rot on tomatoes in a greenhouse is a fairly common occurrence. All surface organs of the plant are affected - fruits, leaves, stems and inflorescences. Weeping brown spots form on the tissues, which are covered with a fluffy gray bloom, and dry gray or brown elongated spots are visible on the lower leaves and parts of the stems, which, with the development of the disease, become covered with mucus and close on the stems with a ring. Under optimal conditions for the development of infection, the causative agent of gray rot is able to infect even those fruits that do not have mechanical damage.

In order to combat gray rot on tomatoes, it is recommended to grow disease-resistant hybrids (for example, Vasilievna, Pilgrim), treat seeds with sulfur-based fungicides before sowing seedlings, maintain low level humidity in the greenhouse, protect plants and fruits from mechanical damage - cut leaves, stems and side shoots only in dry weather and with a sharp sterile knife. How to treat gray rot on tomatoes? If spots characteristic of the disease are found, it is necessary to immediately treat them with a paste based on fungicides - HOM preparations, Bordeaux liquid, blue vitriol and others. Remove pruning residues from the garden, as they are sources of infection.

In open ground, treat tomatoes during the growing season with sodium humate - this reduces the spread and development of gray rot on tomato stems by one and a half to two times. Nice results with a prolonged effect, prophylactic treatment of tomato stems with a suspension of Trichodermin after removal of the affected leaves and treatment of weeping spots with this remedy gives. Processing is carried out during the day, so that the plants have time to dry by evening.

Gray rot of cabbage

Quite often, botrytis affects cabbages, as well as other cruciferous crops, and infection usually occurs during heavy dew or rainy weather in late summer. Favorable conditions for the development of the fungus can aggravate the freezing of plants. Defeat starts with lower leaves, at the point of attachment of the petiole to the stalk, then, already during storage, the heads are covered with a gray bloom, and the leaves are affected wet rot. How to deal with gray mold on cabbage? Unfortunately, the process of development of the disease proceeds very quickly.

To prevent the defeat of cabbage with gray rot, the following preventive measures should be taken:

• observe crop rotation - four-field or five-field;
• grow disease-resistant varieties of cabbage;
• water the plants with settled warm water;
• observe moderation when applying nitrogen fertilizers;
• harvest heads of cabbage on time;
• after harvesting, do not leave plant stems on the site - all plant residues must be destroyed;
• lay the heads for storage in a completely dry form, without a single drop on the surface;
• store cabbage at a temperature of 0 to 2 ºC and air humidity at 90%;
• disinfect the room before placing the cabbage in the storage.

Treatment of gray rot on cabbage involves the removal of affected areas and specimens immediately after signs of the disease are detected. If you have identified them already during storage, place boxes with quicklime to lower the humidity in the room, and separate the affected heads from healthy heads.

Gray mold on cucumbers

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Rainy and damp cool weather, which persists for a long period of time, poses a great danger to orchids, as it contributes to the appearance of such a formidable disease as black rot. This disease occurs as a result of the colonization of a plant by fungi (for example, Pythium ultimate or Phytophthora cactorum) and affects a wide variety of orchids, but cattleya (lat. Cattleya). Black rot, if left untreated, quickly spreads throughout the plant and is also quickly transmitted from one plant to another, therefore, in short time can destroy the entire collection of orchids.

The fungi that cause orchid black rot can only live in a humid environment. These fungi consist of so-called zoospores, capable of independent movement in water - they swim in it. If such contaminated water ends up on an orchid leaf, then zoospores can penetrate the plant tissues and there they will begin the next stage of their life cycle. At this stage, the fungus develops a vegetative part or mycelium, consisting of hyphae, thin, filamentous tubes that quickly spread throughout all plant tissues. And as soon as this happens, the first visible signs of infection are small, watery, clear spots that grow and turn into large brown or black patches.

If the fungus infects seedlings - and this usually occurs on the surface of the soil - then young plants die due to the black leg. In adult plants, the disease can strike any part of it - leaves, roots or pseudobulbs, but most often it originates on new growing leaves and progresses down the plant, reaching the roots. Affected leaves may turn yellow around the infected area, and the lesions will be soft and ooze when pressed. However, the most dangerous is the rot of the roots and bases of the pseudobulb, as it leads to the most rapid death of the orchid.

Unsterilized pots, contaminated water for irrigation, and water from infected plants are all sources of fungus spread. To avoid contamination of outdoor plants, they should be raised 90-120 cm above the ground. Do not leave orchid leaves wet for an extended period. key point in the prevention of the disease is good air circulation in the place where the orchids grow, which will ensure that the plants dry quickly after watering or rain. To improve air circulation and thereby prevent rotting orchids at home, for example, fans will help. At the first sign of infection, all affected plants should be isolated to avoid further infection of the entire collection. Finally, in order to prevent black rot from appearing on new shoots, some growers recommend using fertilizers with high content calcium.

To stop the spread of black rot on an orchid, it is necessary, first of all, to cut off (cut out) the affected part of the plant so as to remove a small amount of healthy tissue bordering the infected area. You can only use a sterile instrument (knife, scalpel, etc.). Next, you need to carefully study the cut off part. Sometimes you can see brown lesions inside tissue that looks healthy on the outside. In the case of sympodial plants such as cattleya, to stop the further spread of the disease, it is necessary to cut out all diseased pseudobulbs. If the plant is heavily infested, it is necessary to cut out part of the rhizome, piece by piece, until healthy tissue appears. In a monopodial orchid such as vanda or phalaenopsis, the infected part of the leaf or, if necessary, the entire leaf must be removed. It is necessary to stop the spread of the fungus as soon as possible before it reaches the crown, and when the death of the orchid is already inevitable. Then you need to put the plant in a well-ventilated area and make sure that the cut is well dried and healed.

After the infected parts of the plant have been removed, a fungicide must be applied to protect the remaining healthy tissue. Cinnamon is an excellent fungicide. You can sprinkle ground cinnamon directly on the affected areas where the infected parts of the plant have been cut. It is also recommended to mix cinnamon with casein-based glue or with vegetable oil> for a thick paste. This paste is quite waterproof and can be used to cover a wound. Regardless of the method chosen, all open (cut) places should be protected with a fungicide. It acts as a sealant, sealing all wounds so that new infections cannot enter. Another treatment option is to impregnate the affected plants with a fungicide. For example, to protect seedlings from blackleg, you can water them with fungicide water immediately after planting. Two weeks after this, it is necessary to repeat the treatment with a fungicide for preventive purposes.

black rot on carrots - this is a fungus that causes not wet, but dry rot, which outwardly is very similar to phomosis. Dark or grayish, slightly depressed dry spots form on the surface of the root crop in different places.

In conditions of high humidity, a gray coating first forms on the spots, which later becomes dark, greenish or almost black. In the section, the diseased tissue of the root crop is coal-black (whereas with phomosis it is brown). The affected tissue is separated from healthy tissue by a sharp border.

What vegetables are affected by black rot?

In addition to carrots, this fungus infects parsley, celery, and parsnips. Sources of black rot infection are seed roots and seeds, as well as plant debris.

The occurrence of black rot on carrots or planting already infected root crops

• When planting root crops affected by black rot, seed bushes may not form at all (if the growth point is affected). If other parts of the root crop are affected, the plants dry up in the first half of summer, before flowering. The plaque of conidial sporulation formed on them re-spreads the infection. Seed material, re-infected, usually does not die, but gives a low yield.
• Plants of the first year are slightly affected by black rot. Usually these are single leaves that turn yellow and die. But from them, the infection spreads along the petiole to the root crop, affects its top and subsequently causes it to rot.

Black rot on carrots, disease development

The development of the disease in the soil is favored by warm, humid weather. The development of rot in storage largely depends on storage conditions. If the storage temperature is not low enough, the disease develops and spreads faster. Carrot farming is important for the prevention of this disease. Root crops grown at increased rates nitrogen, on soils fertilized with household waste, are affected by black rot more than when using the complex mineral fertilizers with a predominance of phosphorus and potassium.