“Last season, onions were very sick, because of this, part of the crop was not suitable for human consumption or storage. This year the situation repeated. Unfortunately, it is very difficult to determine “by eye” exactly how the disease affected the plants. Therefore, we appeal to experts with a request to tell about the most common diseases of onions and their signs in order to choose the right methods of protection and avoid similar problems in subsequent seasons. ”
STRUGGLE AGING ON DISEASES - ON HOT TRACKS
Bulb onion refers to the biennial cold-resistant herbaceous vegetable crops. Propagated by generative and vegetative ways. Crop is obtained directly by sowing seeds into the soil, through sevka and growing by seedling. Despite the fact that onions are rich in phytoncides, which have a detrimental effect on various microorganisms, it is affected by many phytopathogens - fungi, bacteria and viruses. The most common diseases that cause significant harm during the growing season are peronospora, fusarium and bacterial wilt, as well as black-gray spotting, or stimfilioz. Onion yield losses due to disease are 30-35%, and in the years of epiphytotics. that is, mass distribution, more than 50%.
Downy mildew, or perinospora, - the most harmful disease during the growing season of onions. The disease is widespread where onions are grown. The greatest damage is observed in years with cool, wet weather.
The disease causes the fungus Peronospora destructor (Berk) Casp. Mycelium of the fungus has a wintering (resting) and summer (vegetative) form. Peronosporosis is characterized by multiple recovery during the growing season, powerful reproductive ability and a high rate of increase of infection, with the result that the disease spreads rapidly.
The source of infection in the initial period of the growing season are plants grown from the affected bulbs. Planting affected bulbs poses the greatest danger, since after 2-3 weeks a conidial plaque forms on the leaves of the plants, which indicates the presence of infection.
The main signs of downy mildew are the appearance of pale yellow solid spots on the leaves or flower arrows, which later become covered with a grayish-purple patina. Over time, the spots increase in size, become brown in color, necrotic. The affected organs turn yellow and dry up. Flowering arrows break, so that the seeds do not ripen.
Conidia of the fungus are spread by air currents and raindrops. Favorable for the epiphytotics of onion peronosporoza are conditions when cool nights alternate with relatively warm days, and abundant dew falls out. Such conditions are characteristic of diseases caused by peronosporic fungi, - peronosporoza cucumber, late blight of tomatoes.
In the future, the affected leaves and arrows are populated by other mushrooms - Alternaria, Stemphilium, etc.
Often there are signs of onion plantings fusarium wilt. The colonization of bulbs by various species of fungi of the genus Fusarium causes fusarium wilting during the growing season and fusarium rot during storage.
This disease develops as a result of the disembarkation of infected bulbs. Characteristic features: premature yellowing, twisting and dying off of the leaves, which starts from the top. Then the disease spreads to the entire leaf blade. Affected leaves wither and rot. Infected parts of the bulb become brown in color. On a vertical section of the affected bulb clearly shows a soft brown spot. A white or pinkish-carmine felt patina forms on the bottom. The roots can completely rot, so the affected plants are easily pulled out of the soil. During harvest, the bulbs can be overlooked, and then they will rot during storage.
The temperature of the air contributes to the development of the air 21-26 ° C and the increased soil moisture that is created during irrigation. Once on the roots of the plant, the conidia of the fungus germinate and infect it. The pathogen prevents the germination of bulbs, inhibits the growth of seedlings and causes the leaves to die. It is characteristic of fusarians that they produce toxins that are detrimental to the plant.
Such symptoms are also caused by bacteria that penetrate into the bulbs from the soil. Under the influence of bacteria, plants become “boiled”. On the bulb will not be visible mycelial plaque, that is, sporulation, which is characteristic of fungi. Affected bulbs have an unpleasant putrid odor. The development of onion bacteriosis contributes to warm, wet weather.
Quite often, black-and-gray spotting of onions is becoming widespread, or stems.
Stemfiliosis is usually a secondary disease, as it develops on tissue already affected by other diseases. Often it is necessary to observe lesions with stemfiliozom and alternariosis on weakened plants, oppressed by herbicides or suffering from drought. The development of stemfilioza contributes to dry warm weather. Pathogens - an imperfect mushroom Stemphylium allii oud.
Infection of plants occurs, as a rule, in the second half of the growing season of onions on old leaves. Often, due to prolonged air drought, there is a drying up of the tips of the leaves, on which the causative agents are colonized. alternariosis and stems. Infection begins with small light yellow or brown spots, which then develop into elongated protuberances. These bulges are light brown in the middle, gradually becoming darker at the edges. They can merge and hit the leaf completely. An abundant dark brown or black patina appears on the affected surface of the leaves, as well as on the stems of the testes. The stems turn yellow and break down, the seeds do not have time to form or are puny.
Re-infection with stemfiliosis during the growing season of onions is carried out by conidia. The main source of the disease are diseased plant debris, as well as bulbs of infected plants, on which the fungus can persist for a long time.
Harm from diseases is quite high. Due to the defeat of the plants, the early dying off of the leaves occurs, the period of increase in mass and ripening is reduced, which affects the quality, size of the bulbs, as well as their keeping quality.
To prevent the development of stemfilia and other diseases, plants should be watered with warm water, and also thoroughly disinfect greenhouses and garden tools. Before planting, planting material must be decontaminated by heating the bulbs in hot water at 50 ° C.
STRUGGLE AGAINST COLORED BOW DISEASES
To prevent the development of diseases, one should adhere to the main agrotechnical measures. Onions should be sown or planted in well-ventilated areas so that drip-liquid moisture does not accumulate on the leaves. Spatial isolation between onion crops of the first year of cultivation and planting of testes is obligatory. Considering the fact that phytopathogen spores are stored in plant residues, it is recommended to burn them after harvesting. To return the onion to its former place is necessary not earlier than in 3-5 years. During the growing season in time to carry out weeding plots. It is very important to control pests (ticks, aphids, thrips), which significantly weaken the plants, as a result of which they become vulnerable to infection by pathogens.
A number of registered modern fungicides that well control peronosporosis and other diseases (Acrobat MC, Alette, Quadris, Consento, Infinito, Ridomid Gold MC) are offered on the market against vegetation diseases against onion diseases. Recently, a new drug of systemic action Fandango with two active ingredients - fluoxastrobin, 100 g / l and prothioconazole, 100 g / l was introduced. He perfectly controls peronospora, stemfilioz, alternarioz and other diseases. According to experts, this preparation can be used for late processing at the end of the growing season, when about 10% of the green mass dies, which allows the bulb to form good and even covering scales. After all, the lack of scales threatens the loss of presentation, poor keeping quality, reducing the shelf life.
Our studies have shown that fungicides provide high efficiency of protection against onion diseases: downy mildew (peronosporosis) - at the level of 70-86%, black and gray spot and fusarium wilt - at the level of 58-63%.
It should be noted that the effectiveness of fungicides largely depends on the consumption rate, the timing of the appearance of the disease, the rate of increase of infection. As a rule, the highest efficacy of the drug provides for prophylactic use, that is, until the onset of signs of the disease. According to our observations, the first processing of onions with fungicides should be carried out in the third decade of May - First decade of June, depending on the meteorological indications. Timely preventive treatments reduce the level of damage to onion plants by 2-3 times. The second treatment with a fungicide is carried out at the first signs of a lesion. The interval between treatments should not exceed 12-14 days. Usually, two treatments are enough during the growing season. But if the phytopathological situation requires more treatments, it is desirable to alternate the drugs. It is not necessary to carry out more than two treatments in succession with the same preparation in order to prevent the occurrence of resistant (resistant) forms of pathogens.
It should be noted that modern fungicides - low-toxic drugs. For their safe use, it is necessary to adhere to the regulations of use and to comply with sanitary and hygienic rules.
After harvesting the onions must be well dried. Recommended drying mode: temperature 40-45 ° C for 9-12 h, and then at 30-35 ° C - 8-12 days. In dry weather, the dug onions are left to dry for several days right on the garden bed.
© Author: Valentina SERGIENKO, Candidate of Agricultural Sciences
Common Onion Diseases
When growing onions, most gardeners face the same problems. Knowing how frequent diseases manifest themselves, it will be possible, when the first symptoms appear, to start processing plants and preserve the harvest. Diseases of seedlings differ in various signs and consequences, but the fight against them is carried out according to similar methods.
Onion or powdery mildew
The disease is triggered by the development of the fungus and affects the ground part of the plants. The main symptoms are: poor growth of leaves, yellowing, wilting and drying, rupture of peduncles. Peronosporosis shows these signs in the case of the penetration of the fungus from the remains of plants remaining on the garden after harvesting. Most often, powdery mildew develops at the beginning of the growing season in a rainy climate.
To prevent the development of infection on the bulbs, you must adhere to certain rules. Including:
- Disinfect planting stock before sowing.
- Remove the remains of plants from the beds, not leaving them for the winter period.
- Do not plant onions in the same place for several years in a row.
- After weeding, treat the soil with a solution of Bordeaux liquids with a concentration of 1%.
- When fertilizing, do not use a large amount of nitrogen supplements. Minerals are an alternative.
- During prolonged rains cover beds with polyethylene.
- Immediately remove affected bulbs from the beds and destroy them.
With the development of rust onion yellow feathers of seedlings, resulting in growth stops. The fungus that causes the disease appears due to rotting weeds left on the beds. For the prevention of the disease, it is necessary to timely remove the tops and other plant residues from the ground after harvesting.
The culture is also susceptible to rust in case of excessive planting density. Between rows of bows should leave space for free growth of the root system. Throughout the entire growth of seedlings requires regular and thorough care in compliance with basic agrotechnical techniques. You need to water the plants under the root so as not to damage the leaves and not create conditions for the development of fungus.
Fusarium rot of Donets
Fusarium rot seedlings are affected due to an infection that develops in the soil. Owing to the disease of the bulb ends, during growth they begin to rot, after which leaves fall and the root system collapses.
The causes of the disease include:
- excessive soil moisture during ripening,
- late harvest
- dry weather and overheating of the soil.
Damaged bulbs should be removed from the beds so that the infection does not spread to other plants. To preserve the crop, it is also necessary to treat the ground part of the seedlings with a disinfectant solution. When signs of the disease appear, it is necessary to take a set of measures, including feeding onions, controlling the frequency of watering, eliminating weeds.
Neck onion rot
On seedlings appears neck rot when the leaves lie on the ground surface, and there are prolonged rains. Detecting onion disease in the garden is almost impossible, as the signs appear already during storage. After 1-1.5 months after harvest, the onion neck infects the fungus, and the fruits become watery. If you do not destroy the spoiled bulbs, their shell will completely cover the mold.
After harvesting, it is recommended to warm the heads during the day at a temperature of 30-40 degrees. Chalk processing will provide additional protection. These measures affect the infection and help fight negative consequences.
Wet Bacterial Rot and Black Rot
At the end of the growing season, the risk of bacterial decay increases. On the feathers of the bulbs there are small cracks through which the disease penetrates into the fruit. If you cut the affected fruit longitudinally, you can find translucent scales with a mucous surface. The affected crop viruses eventually completely rot and begins to smell unpleasant, so these bulbs need to be removed from the garden.
The cause of bacterial rot is damage to seedlings when loosening the earth or hilling. Also, the disease can be provoked by such factors as constant direct exposure to ultraviolet rays, abrupt changes in weather conditions, the presence of ticks and thrips in the soil.
In order to prevent the development of the disease, it is necessary to use disinfected seeds when planting, to take care when taking care of and to eliminate pests in a timely manner.
A sign of the development of onion mosaic is the appearance of yellow stripes on the surface of the leaves. Due to the impact of the infection, the feathers of the seedlings acquire a wavy or corrugated surface, and the greens eventually turn yellow and dry. As a result, the plants gradually wither, lie down on the ground and die.
The disease can occur if poor quality sevok has been used, or infection with ticks and aphids has been transferred from other plants. The main distinguishing feature of the disease is the impossibility of treatment, so the affected vegetables must be removed from the beds and destroyed. To prevent infection, it is recommended to use mineral supplements and apply parasite-removing agents for processing.
Green mold rot
When green moldy mold occurs, the ground part and the root system of seedlings are damaged. Detect the disease is possible by visual inspection - the leaves of the plant are covered with dark spots, which over time increase in volume. Periodically inspecting the garden, you can track the development of the disease and treat the green part of the onion with a disinfectant solution.
For the treatment of onion diseases, you can use common folk remedies or proven methods using specialized drugs. The main folk method is to artificially accelerate the ripening process by increasing potash-phosphate fertilizers. Top dressing will lead to the rapid development and closure of the bulb neck before infection.
Black rot (aspergillosis)
Black Rot Affects Culture with improper storage (fever and poor ventilation). At the onset of the disease, the bulbs become soft, then the scales dry. Then the whole plant is mummified and a black and dusty mass appears between the scales.
The causative agent of the disease is mold aspergillosis, which is carried by air and by direct contact. Subject to ailment mostly nevzrevshaya, with a thick neck and insufficiently dried culture.
Downy mildew (perinospora)
The causative agent is a fungus that overwinter in the bulbs themselves, on the seeds, roots and in the soil. it the disease is very insidious, since it does not appear outwardly. Первые незначительные признаки можно заметить через 3–4 недели после высадки в открытый грунт. Растение теряет свой «бодрый вид».
Со временем на листьях образуются бледно-зелёные пятнышки, которые во влажных условиях покрываются налётом серовато-фиолетового цвета. Когда отмирают листья, грибок поражает молодые луковицы. У больных растений мясистая и неровная поверхность.
The greatest harm from this disease is the dying off of the leaves ahead of time, which entails a decrease in yield. But the quality also deteriorates and the number of seeds decreases.
Green mold rot
This disease affects the plant during storage. The main symptom is the appearance of brown watery spots on the scales and on the bottom. Over time, the bulbs to the touch become like empty, there is a moldy smell.
External signs of the disease are visible on the 2-3rd month of storage. The main causes of the disease:
- damaged or frozen bulbs,
- increased air humidity at the storage location.
Onions pests also cause a lot of trouble, as well as diseases. Often, pests infect the whole plant and are able to destroy the entire crop:
- Onion fly. This insect actively manifests itself in May. Oblong-brown flies parasitize between the leaves, laying their eggs there. The hatched larvae crawl into the plant, feed on it and kill it. So, the bulbs gradually rotting right in the ground, and then the leaves turn yellow and dry.
- Onion (tobacco) thrips. Pests overwinter in plant residues in the ground, and in spring they get over to the plant. Thrips is a small brown insect that lays eggs at the feather base. The main symptom of the appearance of the pest is silver spots and black dots on the leaves. The affected culture turns yellow and dies. Chemicals are used to combat thrips, but it is also recommended to use smells of ash, tobacco, naphthalene and carrots to scare away.
- Onion mite. Mite infects the bulbs both during growth and at the time of storage. In general, the spread of the insect occurs through infected planting material. The mite feeds on the roots and the bulb itself, which later becomes covered with dust and becomes friable. The fight against onion mites is preventive measures.
Disease and pest prevention
The best way to combat diseases and pests of onions is prevention. The main preventive measures:
- Most of the diseases and pests are carried by contaminated planting material. Therefore, before sowing, sevka should be disinfected with elevated temperature.
- Almost all diseases and pests overwinter in the soil on plant residues. In the autumn should be disinfected and dig the beds. Categorically you can not use the remains of plants for the manufacture of compost. It is not recommended to re-plant onions in the same place (it is possible only after 5 years).
- The use of all the rules of crop rotation will protect the plant from many diseases. The best precursor crops are cabbage, cucumbers, tomatoes.
- Subsequent storage of the crop at the correct temperature, will protect the plant from most diseases and pests.
If the landing area is small, then you can do without the use of chemicals. To scare away unwanted pests use plants or substances with a pungent odor:
- Onion fly does not tolerate the aroma of phytoncids, which produces carrots. Therefore, onions should be planted next to the carrots.
- Scare away the pests also tobacco dust and wood ash or their solution with hydrated lime (1: 1).
- Planting can be sprayed with wormwood infusion.
Thus, with the observance of all the rules of crop rotation, prophylaxis and agricultural technology, it is possible to fully protect the site from diseases and pests that carry them. Buy planting material is necessary only from responsible and trusted sellers.
Pests on the beds of onions and their photos
Onion Root Mite everywhere injures onions in open and protected ground storage. Ticks predominantly colonize damaged or diseased plants. In the affected bulbs, the outer surface of the succulent scales is covered with brownish dust, the bottom is thinned along the edges, then falls off, the roots are not formed.
These pests are hardly visible in the onion beds, as the mites are very small (0.5-1 mm). In the bulbs penetrate through the bottom. Spread with the remnants of damaged plants, soil, inventory.
Onion Western Concealed - pest larvae gnaw longitudinal whitish passages in the pulp of leaves, translucent through the skin. Larvae up to 7 mm long, yellowish, legless, with brown head. In adulthood, they leave the leaves and go to the soil. At the end of July, black beetles appear, which, before harvesting, feed on the leaves of the onion, wintering under the remains of plants, clumps of soil, and stones.
In spring at an air temperature of +8. + 10 ° С beetles begin to additionally feed on young onion leaves.
Onion moth causes significant damage to onions, leeks and garlic in warm, dry weather. Damaged leaves, starting from the tops, turn yellow and dry. On them are visible light longitudinal spots - mines. Caterpillars penetrate into the unopened inflorescences of onions and eat the rudiments of flowers there. During flowering, the pedicels are gnawed.
As can be seen in the photo, the caterpillars of this pest of onions in length reach 1 cm, and the butterflies in the wingspan up to 1.5 cm:
Butterflies winter in various secluded places, plant residues, and in the spring at the end of April - May they begin to fly.
Onion fly Dangerous for onions, leeks, garlic and other onion crops. Damaged plants are stunted, their leaves wither, become yellowish-gray, and then dry. Damaged bulbs become soft, rot, emit an unpleasant smell.
White larvae up to 1 cm long, which develop about three weeks, are harmful. Then they pupate in the soil near the damaged plants.
In the conditions of the southern region, the onion fly has two generations. Flies of the first generation fly in the lilac flowering period, the second - in July. They hibernate as a pupa in the soil at a depth of 5-8 cm.
Onion hover especially harmful to weakened plants of various types of onions. The affected plants are stunted, the tops of the leaves turn yellow and fade. The bulbs become soft, rot and give off an unpleasant odor.
The larvae of the pest are rather large, up to 1 cm. They turn into pupae in the soil near the damaged plants.
Hoverlings fly at the end of May - June during the flowering of wild rose. Lay eggs on the bulbs or near them in the soil. Hatching larvae penetrate the bulbs and feed there for about a month. The pest overwinters in the bulb itself.
Onion Stem Nematode affects onions and garlic during the growing season and storage. Infected shoots grow slowly, the first leaf is swollen and curved. With a strong lesion plants die. Grayish spots appear on the surface of infected bulbs, the internal scales become friable, soft, unevenly thickened. Cavities form between the scales, and the bulb feels soft to the touch. Outer scales, and sometimes the bottom cracks, in the fall such bulbs are without roots. Near the cracks are visible gray spots - clusters of nematodes.
Nematodes overwinter in bulbs, remnants of leaves and scales, seeds. Retain viability in dry scales up to five years.
The following is a photo and description of diseases of the onion, affecting crops on household plots.
Diseases when growing onions: photo and description of fungal diseases
Downy mildew (perinospora) - one of the most common fungal diseases when growing onions. Especially dangerous in rainy years and with frequent irrigation. It affects different types of onions and garlic. The disease is very dangerous for the testes. Pale green blurred oval spots appear on the leaves, flower arrows. Gradually, they increase, and a grayish-purple patina appears on them. Almost always on the affected leaves other semi-parasitic fungi settle, forming black mold. With the defeat of this fungus disease, onion leaves slightly corrugate, turn yellow and dry. Flower arrows testes nadlamyvayutsya. Seed yield drops sharply. Bulbs are underdeveloped. The causative agent of the disease is stored on plant debris, as well as in the bulb itself.
Neck rot - the most harmful disease of onions during storage. Its development begins on the garden bed. In the second half of the summer, when the leaves of the onion roll up and fall down, the fungus penetrates the neck of the bulb. Its tissues soften, a dent is formed. After 1-2 months after harvesting, the rot covers the entire bulb, it becomes watery, gets a yellow-pink tint, emits an unpleasant smell.
Look at the photo - with this disease of onion, the affected scales are covered with a smoky gray bloom of the fungus:
The bulb dries out, only dry scales remain. During storage, the rot spreads from diseased bulbs to healthy ones. In this case, the lesion begins on the side or bottom of the bulb.
Varieties with dark-colored scales have a shorter growing season, faster ripening, and are more resistant to this disease.
Rust affects onion, leek, garlic. In the spring on the leaves of the onion are formed orange, later reddish-yellow powdered small "warts", which blacken in summer. With a strong development of the disease, the leaves dry up early, the bulbs become shallow. The pathogen overwinters on plant debris, as well as on perennial onion species.
Green mold rot often found onion when stored. Initially, brown watery spots appear on the bottom or outer scales of the bulbs. On spots and under dry scales, a whitish form is formed first, then a green or bluish-green patina. The causative agent of this fungal disease of onions is stored in the soil on plant debris, as well as in places where the harvest is stored. The development of rot during storage contributes to high humidity and freezing of the bulbs.
These photos show diseases and pests of onions that threaten planting:
Below you will learn how to protect onions from pests and diseases.
Protection of onions planting against diseases and pests
To grow and keep the crop healthy, you need to take measures to protect the onions from pests and diseases. For this you need:
- use healthy planting material
- plant zoned varieties showing the highest resistance to pest and disease damage,
- strictly observe the rotation of cultures. Return the bow to the former bed no earlier than in 3-4 years.
- For the prevention of onion diseases, it must be remembered that the best precursors for these crops are potatoes, zucchini, cucumbers, cabbage, parsnip, celery, turnip, radish.
- Before sowing, heat treatment of the seeds (scalding them with boiling water through a sieve) is carried out; sevage should be heated for 2-3 days at a temperature of +30. + 35 ° С or within 20-25 days at + 25 ° С.
- For the treatment of onions from diseases and protection from pests, it is necessary to apply to the soil when planting or with the dressing “Basudin”, “Zemlin” or “Pochin”.
- When growing onions on a turnip with the appearance of the first signs of peronosporosis, sprinkle “Profit Gold”. Repeat treatment after 12-15 days,
- Onion seed crops from pests (moths of the stealth) sprinkle one of the insecticides recommended for cabbage protection,
- during the growing season to carry out all agrotechnical activities (watering, feeding, weeding, loosening, etc.).
- To protect against diseases and pests of onions, timely harvesting of ripe onions is necessary. Overexposed beds are poorly stored
- Before storing, recycle bulbs with mechanical damage and signs of damage by pests and diseases, dry well. Observe the optimal storage mode,
- on the garden bed, carefully remove all plant debris, destroy the heavily affected bulbs. Rejected to let the flow in the first place.
Below is a selection of photos dedicated to the treatment of onions from diseases and protection from pests:
What is sick onion
This plant, which in the garden spreads revitalizing phytoncides around, and on our table serves as a source of healthy food, is affected by many pests and diseases.
Timely warning and getting rid of them will help to grow a great onion without problems.
If you do not treat diseases affecting the plant in a timely manner, it will affect the quality of the bulbs - they will grow small, start to rot, will be poorly stored.
Most often, onions are infected with fungal infections, viruses and pests that can attack both the above-ground part — the green feathers and the underground — the roots of the emerging bulb.
To notice the problem, especially if it is hidden underground, is difficult at the initial stage. But the onion is a “smart” plant. It will signal an unhealthy state by yellowing or lodging the feather and other signs that will enable an experienced gardener to determine the cause of the disease.
At the initial stage of the disease is much easier to treat. And you need to get rid of pests when they have not spoiled most of the landings. Each disease or variety of pest has its own signs by which they can be detected.
Sick onions due to the fact that the rules of agricultural technology are not respected. Not according to the rules, the cultivated plant is weakened and cannot protect itself against the effects of the fungi attacking it. Fungal and viral infections in garden crops are different - there are about 50 varieties. They can attack the onion plants, both in the greenhouse soil, and when grown in the garden.
Frequent onion diseases:
- Powdery mildew,
- Gray (neck) rot,
- Yellow dwarfism,
If onion diseases are ranked by weediness, the first of them can be powdery mildew. Perinosporosis onion re considered the most serious lesion. The following types of onions are especially susceptible to peronospora:
If the summer is rainy, and the humidity is kept at around 80% for a long time, infection of onion plantings with powdery mildew is almost guaranteed.
At defeat by mealy dew the bulb stops in development and changes the habitual form. The causative agent of the disease is a parasitic fungus that can live in seed - onion seedlings. If you sow infected sevok, a month later, the disease will spread not only to nearby, but also to neighboring plantings. The virus "walks" on the soil, remaining in the ground for a long time and not losing vitality.
The first symptom of the disease with powdery mildew is a dirty yellow bloom on the feathers of the onion. To prevent infection, it is necessary to disinfect all bacteria that live in the soil and seeds.
- Before planting, the soil in the garden is treated with a special agent that prevents the spread of the fungal infection. Do not use aggressive chemicals, it is better to use drugs from the series Baikal EM
- The soil is fertilized with supplements containing potassium and phosphorus. It is not necessary to give a nitrogen-containing top-dressing directly for planting, it is better to do this when preparing the soil for autumn by adding humus.
- The bulbs, as a preplant preparation, are disinfected in a solution of potassium permanganate (soak for an hour, the solution is of medium intensity, saturated pink).
- When disembarking, the distance between the bulbs is 10 cm, the distance between rows is 20 cm. In thickened plantings, the risk of fungal infections is higher.
If you looked at the onset of the disease, and it entered the main phase, after hitting more than half of the onion plantations, nothing remains but to use the fungicides.
The following drugs are used for treatment, according to the instructions:
If you find signs at the initial stage, you can try to do with folk remedies and opposing measures.
- Stop watering and temporarily do not feed.
- Formed onions removed from the soil and sent to dry.
- Unformed, affected fungus, remove.
- Treat all planting garlic decoction.
To make a decoction, untreated heads weighing 600 g are crushed and immersed in a ten-liter container filled with hot water. Next you need to boil everything on a small fire for about three hours. The resulting concentrated broth is diluted in half with water and watered weekly in an onion planting soil.
This fungal disease affects the neck of the onion head and okolosheynye scales. The penetration of the disease to the plant occurs through the soil. Gray rot spreads quite quickly, especially when rainy weather and mechanical damage to the bulbs, as well as with a parallel defeat of their pests.
The main period of mass destruction of bulbs by gray mold fungus is pre-harvest. As a result, the bulbs lose their keeping quality and rot in storage.
In order to prevent rot to the onion crop, in the second half of the growing season, it is necessary to start spraying the soil with triazole class fungicides, which destroy the fungus spores.
A common viral disease that is treated with great difficulty, so the most effective are preventive measures.
When infected, the plants lag far behind in growth, then growth and development cease completely, the feather turns yellow, and the bulbs do not form.
The aphid virus, which is the main carrier of the disease, is spreading. Поэтому желтая карликовость напрямую связана с наличием на луке вредителей, от которых необходимо вовремя избавляться.
To prevent yellow dwarfism from destroying the crop, it is necessary to sow healthy planting material, carefully sorting out all the deformed and seemingly not healthy onion seedlings, and deal with aphids on the bow with insecticides.
Mosaic virus often infects onions in parallel with the yellow dwarfism virus, since it is also carried by aphids. Also spread can be earth mites and nematodes.
With the defeat of mosaic leaves and stalks are the first to suffer. They are deformed, acquire a mosaic color. Then the disease goes into the bulb, which becomes unfit for human consumption.
Treating plants from viral diseases is useless. It is possible to prevent diseases only by sowing healthy seeds and destroying all onion pests in a timely manner.
One of the worst pests that, along with the onion moth, destroys the crop, penetrating into the bulbs at the larval stage.
The plant stops growing, turns yellow and withers. The larvae gnaw the onions from the inside. If there are many pests, there is every chance that the onions will not remain at all.
Insecticides can be used against pests, but not desirable. Especially you should not use chemicals at the stage of ripening bulbs, and in fact at this stage onion plants are most affected by pests. Therefore, for food safety, it is better to use folk remedies.
You will need products that have a strong smell to scare away the fly and its "colleague" mole.
For more information about fighting the onion fly, read our other article: Onion fly - how to fight it? Overview of drugs and folk remedies
Ammonia - a very effective tool that will scare pests for a long time. Dissolve 3 spoons in 10 liters of water. Carefully water the plants with this solution. Do not pour on the leaves and do not even fall on them. Repeat in a week.
Another strongly smelling drug, from which it is necessary to prepare a solution in the same proportion as when using liquid ammonia. After watering with ammonia solution, it is recommended to shed the bulbs with clean warm water.
If the sharp aromas of ammonia and ammonia cause you to reject, treat the onions with saline. 300 g of sodium salt dissolve well in 10 liters of water. This composition can be watered at the same time feather, onion and soil. Do not spend more than three treatments with an interval of 10 days, otherwise salinization of the soil will occur.
So that no diseases threaten your onions, it is necessary to follow the techniques of agricultural engineering and carefully prepare for sowing. Prepare and disinfect the soil, use healthy planting material and additionally process it before sowing. In the care to avoid extremes, do not flood the planting and do not overdry. Timely fertilize in the recommended doses. And most importantly - to treat plants with attention. To notice the slightest signs of pathological changes that first appear on the leaves. As soon as the plant signals a problem that has begun, it is necessary to protect it. And then the harvest will be generous.
It should be carried out not only the fight against disease, but also prevention. This will significantly reduce the likelihood of diseases in grown vegetables on the site.
To reduce the risk of occurrence and development of diseases in onions, carry out the following preventive measures:
- prematurely process the seed material so that there are no pathogens on it,
- Before planting, they disinfect and treat the area where vegetables will grow,
- observe crop rotation to protect planting,
- do not use plant residues as compost.