Onion diseases: how to help the plant

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Despite the existing opinion that it is easy to grow onions, reality shows that this is far from the case. Not only is it picky about the composition of the soil and moisture regime, onions are inherent in a large number of diseases, which are not always easy to cope with. Onion plants are especially often affected by waterlogged clay soils overfed with nitrogen fertilizers.

Onion diseases

Onions are among the crops that not every gardener is engaged in growing, and one must understand the risk associated with the possibility of planting diseases with both viral and fungal diseases. This applies both to onions grown for a turnip and to those varieties for which the green feather is of nutritional value.

Despite the fact that the essence of the diseases, of which there are several dozen, is different, it can be considered that the approaches to their treatment are relatively uniform. So, fungal diseases, which are especially pronounced in conditions of high humidity, can be cured with a limited number of drugs if you start to do it on time. Viral diseases, as a rule, are not cured; diseased plants have to be destroyed. However, viral diseases can be prevented by combating their distributors - a variety of harmful insects.

Powdery mildew

Powdery mildew is a disease that is characteristic not only of onions, and its symptoms are similar in all cases. They can appear already at the very beginning of spring: for perennial onions soon after foliage regrowth, for those planted in early spring - a little later. Yellowish spots appear on the leaves, and soon their color turns into grayish-purple, this phenomenon is accompanied by the formation of an abundant powdery coating of white color, reminiscent of flour.

This plaque, which is especially noticeable in the morning, gradually darkens, becoming brownish-pink, the leaves become fragile, dry out, and the bulbs stop growing. Especially often the disease manifests itself in thickened plantings, in rainy weather, with a lack of sunlight.

Seed material is usually the source of infection, so disinfection is mandatory before planting. Both seeds and seedlings can be simply held in hot water (40–42 ºС) for 6–7 hours, or even better - in a pink solution of potassium permanganate. To increase the guarantee of neutralization, after that, some gardeners use treatment with biofungicides (such as Baktofit or Poliram).

In addition to processing the planting material, thorough cleaning of plant residues after digging the onions and immediate digging of the beds helps in preventing onion infestation for the next year. Crop rotation is also of great importance: it is better to change the location of the onion bed annually, but if it has remained in one place for 2-3 years, then take a break for the same period. A good prevention is the periodic scattering of wood ash on onion beds, and from chemical agents - autumn soil treatment with Horus or Oxyhom preparations.

If the disease manifests itself, the amount of watering should be sharply reduced and nitrogen fertilization should be stopped, and the onion and the soil around it should be treated with fungicide solutions (for example, Bordeaux liquid or Polycarbacin). Of course, eating onions after such treatments will not be possible very soon, and feathers may not be worth it at all. However, the bulbs can be saved if the processing is carried out in a timely manner.

Peronosporosis (downy mildew)

The symptoms of downy mildew are similar to those of powdery mildew: first, a gray-purple powdery coating forms on the feathers. Subsequently, the leaves are deformed, darken and dry out. In this regard, the entire plant weakens, which can lead to death: the bulbs begin to rot. The disease spreads very quickly throughout the garden. It can appear about a month after the start of feather regrowth, it is promoted by the same factors as powdery mildew.

With peronosporosis, everything looks like powdery mildew, and the control measures are similar.

Both prevention and treatment of the disease are almost the same as in the case of powdery mildew. Peronosporosis in the non-started stage is well treated with infusions of various weeds (dandelion, nettle, etc.), which are also fertilizers. An effective remedy is the drug Ridomil Gold.

Video: the fight against onion peronosporosis

Gray or cervical rot

Cervical rot rarely manifests itself directly in the garden: this can only happen in the case of prolonged rains that come after the lodging of the feather. Usually, signs of the disease become visible about a month after harvest. The bulb at the very neck becomes wet, begins to rot, and decay quickly captures its entire volume. The husk becomes covered with gray mold, due to which the adjacent bulbs become infected.

Since the causative agent of the disease penetrates the bulbs through mechanical damage, periodic disinfection of the knife with which the feather is cut by rinsing with a dark solution of potassium permanganate is a good prevention.

The most common bulbs are those that were stored undried, as well as those with a particularly thick neck. Therefore, proper drying of the crop is of great importance: it should last at least one and a half weeks at a temperature of about 30 aboutC and good air ventilation.

Cervical rot starts at the top, but then the whole bulb decays

Of the chemicals, Quadris is sometimes used, which is used to cultivate the soil on an onion bed a week before harvesting. Pre-sowing treatment of seedlings with fungicides is also essential, as well as thorough cleaning of all weeds and plant residues.

Gray mold

Gray mold is a fungal disease; the fungus is capable of infecting the bulbs at any time: this can occur both during growth and in winter, during storage of the crop. Unlike gray rot, this disease does not affect the neck of the bulb, but develops on all other parts of it. Sources of infection are the same as in the case of cervical rot. The tissues affected by the fungus become flabby, become cloudy, acquire a disgusting odor and yellowish color, and become covered with a gray coating. Prevention measures for infection are the same as for cervical rot.

Fusarium (fusarium rot of the bottom)

Fusarium rot starts from the bottom, and then goes higher and higher

Since pests contribute to fusarium infection by weakening plants, one of the methods of disease prevention is the destruction of the pests. In addition, it is important to know that early ripening onion varieties are least susceptible to fusarium, especially in the case of early planting of healthy sets. Thermal neutralization of it before landing is mandatory. It is important to observe the correct crop rotation, the absence of waterlogging, as well as the timely digging of the bulbs and their careful preparation for storage, including sorting.

Bacterial onion rot

Bacterial rot, like fusarium, can manifest itself already in the garden, by the very end of onion growth, or maybe only during storage. Even in the garden, onion leaves can be covered with small weeping wounds, but they are difficult to see, so the gardener sends the crop for storage without expecting trouble. The disease can manifest itself only closer to winter, gradually destroying the bulb. Bacterial rot is noticeable only when the bulb is cut: normal scales alternate with softened, translucent ones. Soon, the whole onion rots, emitting an unpleasant odor.

With bacteriosis, the bulb rots from the inside

As a rule, bacterial rot develops in unripe and poorly dried onions, the source of infection is uncleaned plant debris, on which bacteria can live for several years. Therefore, thorough cleaning of the beds after harvest, as well as the observance of crop rotation, is absolutely necessary. In addition, damage must be avoided when digging the onion and transporting it.

Onion rust

Rust is a common fungal disease of all onion plants, as well as garlic. This is the real scourge of perennial green onions. When infected, the leaves develop convex spots of various shapes of light yellow color, which can change color up to bright orange. These spots (pads) represent colonies of the fungus. As a result of its influence, the development of leaves, and subsequently bulbs, stops.

Rust only looks beautiful, but it can ruin the harvest.

Rust is extremely infectious, and its pathogen is resistant, and if plant residues are not carefully removed after the end of the garden season, onion infection can continue for several years in the garden. Infection is facilitated by saving space: you can not thicken the plantings, no matter how much you want. In general, the measures for the prevention and treatment of the disease are the same as in the case of other fungal diseases.

Onion mosaic

Mosaic is a dangerous viral disease that cannot be cured. Upon infection, onion leaves flatten, various spots, stripes and streaks are formed on them, mainly yellow, sometimes whitish in color. The bulbs are elongated, their ripening stops. In the future, the leaves lie ahead of time, many plants die. The probability of complete destruction of the crop is low, but its quantity and quality is significantly reduced.

Since the carriers of the virus are small insects (ticks, aphids, nematodes), the prevention of infection is to combat them. In addition, timely extermination of weeds, moderation in irrigation and dressing, correct crop rotation and avoidance of excessive thickening are extremely important.

Onion jaundice

Jaundice is also a viral disease and cannot be cured. When attacked by a virus, onion feathers and arrows turn yellow, starting at the tips and gradually completely changing color. The leaves become flat, often intertwined. The bulbs stop growing. The carrier of the virus is the cicada, on which, as well as on various weeds, it hibernates. Affected specimens of onions must be destroyed. Preventive measures are the same as for mosaics.


When they talk about the curliness of the onion, they make an inaccuracy: there is no disease under this name, but the curliness (or curliness) of the feathers accompanies various, mainly viral, diseases. Most often, feathers become curly when infected with mosaic or jaundice. In addition, the onion stem nematode also carries a disease such as ditylenchiasis. Nematodes are almost invisible to the naked eye, live in the ground, harm both bulbs and onion foliage. As a result, the bulbs crack, and the feathers, intertwining and curling, eventually droop and die.

Prevention of onion diseases

Although viral diseases are incurable, they can be prevented by proper agricultural practices. Fungal diseases that can be cured should also be avoided in the garden. And if nothing can be done with the rainy and cold weather, everything else is in the hands of the gardener. In the prevention of diseases of onion plants, each item from the following list is important:

  • observance of the correct crop rotation (periodically the onion bed moves to another place, new plantings are organized where onions, garlic, lily plants, beets did not grow);
  • compulsory disinfection of planting material;
  • planting or sowing onions as early as possible, without thickening;
  • the choice of a sunny location for the onion beds;
  • prevention of waterlogging of the soil;
  • applying only the necessary doses of nitrogen fertilizers, without excess;
  • constant destruction of weeds, accompanied by loosening of the soil;
  • thorough cleaning of plant residues after harvesting and immediate digging of the soil;
  • harvesting onions only in dry weather;
  • thorough drying of the crop before sending it to storage;
  • careful transportation of the crop to a storage location that has been well cleaned and disinfected in advance.

With full compliance with these measures, the likelihood of onion disease is minimized. If this did happen, it is necessary to find out the cause as soon as possible and, if the disease is curable, to start processing the plantings, otherwise, to the immediate removal of diseased plants.

Processing of onion plantings in case of diseases

When signs of fungal diseases appear, they stop excessive watering and nitrogen fertilization, sprinkle the beds with wood ash, loosen the soil well and destroy weed residues, and choose means for treating plants. Chemical means of control can be used only in the first half of summer, and if onions are grown for feathers, it is advisable to refrain from them. In any case, before spraying with any preparations, it is worth pulling out the infected plants, if there are few of them.

In the initial stages of the disease, folk remedies can help. These are infusions and decoctions of various plants (dandelion, celandine, marigolds) or tobacco dust. Planting plants such as marigolds, dill, hyssop and other odorous herbs greatly reduces the risk of disease and wards off pests. If only a few plants are sick, they should be pulled out, and the pits in their place should be watered with a solution of potassium permanganate or copper sulfate (1%).

Marigolds are not only beautiful flowers, but also reliable protectors of the harvest

If a fungal disease has affected a large number of plants, the whole garden is sprayed with copper preparations, for example, copper chloride (40 g per bucket of water) twice a week. However, the leaves after such processing should not be eaten for 3-4 weeks. Among other drugs, Aktara, Karate, Fitoverm, etc. are popular. They allow you to fight insect pests that carry dangerous viruses.

Video: spraying onions from fungal diseases

Problems with growing onions

In addition to dangerous diseases, gardeners often face other problems when growing onions that are not directly related to diseases, but require a solution. Some of them are shown in the table.

Table: problems in growing onions and their solutions

As you can see, each problem that arises has a lot of reasons, they are often intertwined, and it is not always possible to resolve the problem. However, the correct agricultural technique almost always allows you to grow a good harvest of healthy onions.

Growing onions rarely goes without problems, since it requires careful adherence to agricultural technology. The slightest violation of it can cause difficulties, including diseases that are not always curable. However, disease prevention dramatically reduces the risk of disease occurrence, and constant monitoring of plant health can save most of the crop even in the event of a sudden attack by fungi or viruses.

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A popular type of onion grown for feathers is batun (Ural family, Seryozha, Semiletka, Maisky). It has a well-developed ground part, the feather is thin and can reach 1 meter in length. Greens contain much more nutrients than onion feathers.

You can plant bulbs or sow seeds. Planting begins in early May. The bulbs are planted to a depth of 3 cm. In July, you can cut the greens, and after a while they will grow back. Since the batun has been growing in one place for several years, the next year the first harvest can be harvested after a month.

For the sake of greens, Schnitt onions are also grown.Long narrow leaves with a strong odor can grow up to 50 cm. A small bulb can also form, which is also used for food. Such varieties are known as Bohemia, Lilac ringing, Chemal, Medonos.

Leeks form delicate and fragrant feathers, flat like garlic leaves that fan out. The bulb is absent, but there is a thick, white stem. Popular varieties include: Vesta, Columbus, Elephant, Casimir, Alligator.

Shallots allow the greens to be cut multiple times throughout the season. Recommended varieties are Afonya, Aristocratic, Starorussky, Leader, Green, Dwarf.

You can also get greens from onions. For this, medium-sized turnips are selected. For these purposes, the following varieties are better suited: Union, Strigunovsky, Rostovsky, Bessonovsky.

They begin to plant turnips or onion seeds on greens at the end of April, but on condition that the soil has warmed up to +12 degrees. Already in the middle of summer, the first harvest can be harvested. If you plan to collect fresh herbs in the spring, then the seeds can be sown in the middle of summer.

Black leg, what is the danger of the disease, and how to deal with it

This is the most common disease of black-haired weeds, especially of young shoots.

If, after carefully examining the lower part of the stem, you notice a small light bloom, which darkened and turned into specks in a few days, then the decay process begins. Whatever you try to do, the flowers cannot be saved; they will die.

Sick plants need to be dug up by the root and taken out of the site and burned. The main thing is that no harmful bacteria remain in the soil. But, as you know, it is easier to prevent a disease than to cure it, therefore, one must not forget about preventive measures:

  • the seed is treated with any fungicide
  • the soil at the site of the future planting also needs to be treated with a fungicide
  • young shoots are recommended to be watered with a light manganese solution.

If a black leg appears on the seedlings, the seedlings are removed.

  • When starting to work with any pesticide, including a fungicide, you need to carefully study the instructions. A large dose of the drug can cause stunted growth and little or no flowering.
  • If you notice bloom on young plants, take ash or calcined sand and sprinkle them on the soil under the flowers. It so happens that these control methods are not effective, and the disease progresses, do not be discouraged, be careful not to damage the root, dig up healthy flowers and transplant them to another place, do not forget to treat the ground with fungicides in the same way.


They are the real enemies of vegetable gardens. They affect almost all crops, including onion beds. Their danger is not only that they completely suck out all the juice from plants, but first of all that they are carriers of viruses and infections. Insects can be compared to locusts, but how to deal with it? Only by cardinal methods.

If rusty spots appear on the leaves (as if they were dotted with aphids), it is quite possible these are thrips. Processing of onions from pests can be carried out using chemicals, but it does not hurt to find out that marigolds, carrots, parsley and mustard planted nearby, no less reliably protect the beds.

There are many other pests for onions. This is whitefly, and sooty fungus, and aphids and many others. But there is a very important point. Almost any disease and bad insects can be damaged with the help of this spicy vegetable itself. Why onions have a disinfecting effect is not worth explaining. Most often, a decoction of onion husks is prepared, infused before fermentation and spraying. This tool helps protect the entire garden from pests and infections, but only if the treatment is carried out on a sunny dry day, and it does not last long. The procedure must be carried out at least once every 10-14 days.

Afraid of such a decoction and whitefly, and aphids, as well as onion disease. It can be used both for garden plantings and for indoor plants.

Diseases and pests pose a danger to all plants and onions are no exception. Now you know how the problem manifests itself, how to protect the plantings from infections and what measures to take to save the crop.

Watch the video: pyaj ke rog ka karan or bachavपयज क रग क करण और बचव

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