Methods for combating diseases and pests of onions
It is believed that onions are unpretentious in their care and gardeners have no problems growing them. Onion infusion helps prevent fungal diseases, and it is also often used to repel pests. At the same time, the plant itself is often susceptible to various diseases and insect attacks.
Characteristic diseases
Diseases can affect onions both during cultivation and during storage.
- powdery mildew - This is a fungal disease, especially often affecting many horticultural crops. It is transmitted most often through seeds. With untimely measures taken, the crop can suffer greatly. Moreover, the factors contributing to infection may not depend on the person - this is the shading of the planted area, heavy rainfall, improper watering of plants. Symptoms of powdery mildew can be seen already in late April - early May, these include yellow-green spots on the plant, gradually becoming gray-purple with a white bloom that looks like flour. Over time, the plaque darkens and becomes denser, the greenery droops, and the bulbs stop growing. Specialists have developed varieties that are less affected by the fungus. These are, for example, "Antey", "Centurion", "Stimulus" and "Kasatik".
- Peronosporosis - a disease that is also called downy mildew.The yellow spots that appear on the onion acquire a lilac tint over time, the greens wither and dry out. Coolness, shade and rain are especially conducive to the development of this disease. The bulbs begin to rot in the process. During dry summers and high air temperatures, the fungus does not have the opportunity to develop, but its spores can remain in the soil until next year.
Varieties that do not suffer from this scourge do not exist, but varieties such as Ellan, Christina, Stuttgarter Rizn are less likely to become infected.
- Rust. Symptoms of this disease are only visible on onion feathers. First, spots of a reddish color and bright yellow with small villi appear. Then they become denser and change color to terracotta and rust, after which they turn black. Most often, the fungus is transmitted through the soil.
- Aspargillosis (black rot) - This disease manifests itself during the storage of onions. The reason is its poor drying and immaturity. In order for the disease to develop rapidly, it is enough to violate the storage rules and place the onion in a hot, unventilated room. The bulbs themselves become soft after infection, their neck loses color, the top dries. Between the scales appears a plaque resembling a black powder. These are fungal spores.
- Gray rot of the neck also appears during storage. The first symptoms are visible in just a couple of weeks. First, the neck dries up, and the area under it is covered with a gray coating with small black dots, which gradually captures an increasing area. If you cut the onion, it will have a pinkish tint. The fungus is introduced when the surface is mechanically damaged, for example, when the greens are cut.
- Fusarium manifested by yellowing of feathers, stunting of the bulbs, the neck of which is covered with a light bloom like mold, the smell of rot spreads. It develops well in hot and dry weather and can even affect a harvested crop. Black dots appear inside the bulbs, they completely dry out.
- Mosaic - This is a virus that is characterized by a slowdown in the growth of onions, deformation of flowers and a mosaic light pattern on the leaves. The bulbs become elongated, while they are quite possible to eat.
- Jaundice - a virus that is also not treated. The bulbs do not grow, the feathers turn yellow from the ends.
parasites
There are pests that are very fond of this crop and bring a lot of problems to gardeners. We give a description of the most common.
- onion fly - This is a harmful insect that especially loves onions grown from seeds, as it grows thicker, which means it is easier for the larvae to move. If the plant has been affected by rot or a nematode, it becomes especially easy prey. Greens gradually begin to fade, starting from the base. After that, the larvae penetrate the bulb through the neck, starting the process of its decay.
The end of April - the beginning of May is the most dangerous period. As soon as bird cherry and lilac have blossomed, insects begin to multiply, leaving larvae in the soil or in the onion itself.
- shallot aphid attacks the onion en masse and sucks out its juice. The greenery is deformed and twisted into a tube, on which light spots appear, turning yellow over time. The aphid has a dark color, after its attack, the onion is covered with a black coating, which is nothing more than a fungus and the skins of larvae.
- Tobacco thrips prefers tobacco, but it can also do a lot of harm to onions.After his attack, the leaves lighten and dry out, the bulbs stop growing and their scales dry out. Most of these insects are at the base of the green, where the dying feathers are.
- Onion Stalker has a small size, a greenish-bronze tint and a long proboscis, for which it is nicknamed the weevil. It is with his nose that he sucks the juice from the onion, and the larvae eat the greens from the inside. Light dots appear on the green, which, when dried, lead to the death of the whole plant. The pest attacks only onions that grow from seeds, and does not like the process of loosening the soil.
- onion moth is a brown butterfly. Caterpillar larvae are yellowish-green, have small bristles, and they are the ones that harm plants. The larvae penetrate the leaves and devour them; from the outside, the passages look like tunnels. Also, the insect does not disdain the bulb itself.
- onion mite - an arachnid insect, almost invisible during visual inspection due to the fact that it has an almost transparent body. Also, the pest enjoys eating potatoes, beets, carrots and some types of flowers, for example, tulips and gladioli. The tick is very fond of high temperatures and dry weather, and eats the juice of plant leaves for food. After his attack on the greenery, yellow spots and a light coating appear, eventually leading to the drying of the plant.
This bug is also unsafe for the bow, which has already been removed. It penetrates into it through the bottom and devours from the inside, which leads to the processes of decay and drying.
- stem nematode - a parasite that can attack both onions and garlic. It is microscopic in size and shaped like a worm. The pest penetrates the onion through the roots and gradually moves up, poisoning it with its waste.Since there can be several thousand worms per bulb, the plant dies quickly enough. First, the leaves change their shape, then sag, the bulb becomes softer and cracks appear on it. When precipitation falls, the smell of rot becomes noticeable. A cut onion has swollen and grainy scales.
- Onion hoverfly, or root beetle, as gardeners call it, visually very much resembles an onion fly, but it is larger. Attacks the crop from late June to early July, eating away the bulb from the inside. The plant rots and dies.
What can be processed?
Every gardener hopes for a good and healthy harvest. To get one, you need to take certain protective measures. In the situation with onions, you can use both store-bought preparations and folk methods.
Effective drugs
Drugs that can help with various diseases and in pest control may be different in each case. However, there are those who are able to cope with several problems at the same time.
With powdery mildew, peronosporosis and a number of other diseases, it is necessary to process both onions and the beds themselves. For treatment, solutions of Topaz, Skora, Polycarbacin are used. Copper sulfate and Bordeaux liquid are also suitable, but with one limitation - if green onions are not grown. After using these drugs, a blue tint on the green is possible, this is absolutely normal. Spray the plants once every 1-2 weeks, repeat the procedure 2-3 times. For a longer and more effective effect, soap can be added to the solutions. It can be both liquid and household, grated, which will also improve the adhesion of the compositions.
With peronosporosis, drugs such as Thanos, Ridomil-Gold and Abiga-Peak help well. If rust appeared on the greenery, it is worth using "Kaptan" or "Tsineb".
If pests have appeared on the garden, getting rid of them can be quite problematic. Even if you water the entire garden with pesticides, there is no guarantee of a successful outcome.
Bazudin and Fufanon help well against onion flies and hoverflies, in addition, they also destroy larvae, subject to double treatment. The scoop and the moth are afraid of the Iskra M preparation, the secretive proboscis is afraid of Carbofox. Also effective among gardeners are such means as "Aktara", "Karate" and "Inta-Vir".
It should be borne in mind that small insects, such as aphids and mites, can endure exposure to chemicals. A solution of colloidal sulfur has an excellent effect on them. Shallot aphid is afraid of universal insecticides. In the fight against it, you can use Intra-Vir, Tanrek, Mospilan. To combat the onion moth, Entobacterin and Lepidocide are suitable.
Onion mites are not insects, so you should not use universal insecticides to get rid of them. Moreover, the treatment must be carried out up to 4 times and the preparations must be changed in its process, otherwise the pest will have immunity and the fight against it will be ineffective. Acaricides such as Neoron, Apollo, Binom and Vertimek help well.
Folk remedies
Due to the fact that onions are often attacked by pests, gardeners have adapted to use folk remedies to preserve the crop.
In the fight against flies, an infusion to which black ground pepper or tobacco is added helps. Their larvae are able to destroy the saline solution. It should be applied directly under the root.It would also be useful to dust the area where the onion grows with tobacco dust, ash and ground red pepper, while the ingredients must be mixed in equal amounts.
So that the onion fly does not choose the beds with onions, you need to plant carrots nearby. This is an excellent neighborhood also in view of the fact that onions repel carrot flour. A solution of ammonia also repels pests well, it is enough to dilute 3 tablespoons of the agent in 10 liters of water, and water the plantings with this composition.
However, you need to act carefully so that the liquid does not get on the greens, and after 7 days the procedure should be repeated. Ammonia can be used in the same way. The effect is similar, but after treatment, the plants need to be watered with clean water.
Salt solution is convenient in that it does not have a sharp unpleasant odor. For its preparation, it is required to dissolve 300 grams of table salt in 10 liters of liquid. In addition, the composition does not harm when it hits the ground and greenery. In this case, a maximum of 3 treatments can be carried out, and the pause between them should be 9-10 days, since a larger number of irrigations can cause salinization of the soil.
Preventive measures
So that diseases and pests do not spoil the crop, you should think about prevention, which will protect future plantings. First of all, it is recommended to process the seeds and heads of onions before planting. To do this, they should be placed for 6-8 hours in hot water, the temperature of which is approximately 40 degrees. Potassium permanganate solution is also suitable. After the procedure, the heads and seeds must be lowered into one of such compositions as Bactofit, Fitolavin or Polyram and kept there for about 20 minutes.
After the crop is harvested, all plant debris must be removed and the bed dug up. Crop rotation plays a very important role, as planting onions in the same place for more than 4 years in a row will adversely affect its yield. An onion bed should not be made in places where parsley, garlic, irises or beets grew.
When loosening the beds, you can add crushed chalk or wood ash. Onion strength will also be given by potassium permanganate, with a weak solution of which it is recommended to water the plantings once every 2 weeks. Gardeners also recommend using diluted whey or sour kefir, to which a few drops of iodine should be added. In autumn, the beds are treated with an Oxychoma or Horus solution.
When the first signs of diseases are detected, it is necessary to reduce watering as much as possible, stop adding fertilizing containing nitrogen and organic matter.
To prevent black rot, it is useful to treat the onion and the garden bed with a one percent solution of Bordeaux liquid, but this should be done approximately 3 weeks before the crop is planned to be harvested. Hydrated lime should be used when disinfecting storage areas. Dusting the bulbs with ash or chalk will also not hurt.
To prevent gray rot, the harvested onion must be dried for 10 days in a warm and well-ventilated area. It should be stored at a humidity of about 70 percent and a temperature just above 0 degrees. A week before harvesting, the plants are treated with a solution of Switch or Quadris. To exclude the appearance of fusarium, the bulbs are kept in Fundazol or Quadris before planting. Once every 10-12 days, you need to water the beds with solutions of biofungicides.
Viral diseases can be transmitted from diseased plants to healthy ones, and insects help spread them, so pest control can save you other problems as well. To prevent insects from attacking plantings, the land should be cultivated with a mixture of tobacco dust, ground pepper and ash. The procedure is carried out 10-15 days after the onion is planted in the garden. Also, when loosening the soil in the spring, it will be possible to add granules of such preparations as Zemlin, Mukhoed and Medvetoks to it. Spraying with ammonia and vinegar will be useful.
Aphids are afraid of the smells of marigolds, mint, calendula and coriander, so these plants can be planted next to onions. Spraying with a compound with hot pepper, ash or colloidal sulfur will also help. These infusions help not only to scare away insects, but also to fight those who have already chosen a bed for living, however, for this, spraying must be done every day.
Batun has juicy green leaves, so it can be used as bait. When insects stick around greenery, it is cut off and destroyed along with pests.
Excellent preventive measures for the healthy growth of onions are proper watering, weeding, crop rotation.
The soil must be prepared for planting, disinfection measures should be taken, and only healthy seeds and heads should be used for sowing.
For onion diseases and methods of struggle, see the following video.