Many gardeners grow onions in their beds. Unfortunately, this healthy vegetable sometimes causes trouble for its owners. One of the signs of a dysfunctional condition of the onion is yellowing of the leaves. Before undertaking treatment, it is necessary to establish the cause of the disease correctly: it can be caused by pests and diseases, adverse weather conditions or poor care. We must remember that for any case there is an effective treatment!
Causes of yellowing onions
Onions ripen by autumn, so yellowing at the end of August is a normal physiological phenomenon. But if the green feathers begin to turn yellow in the spring or summer - this is a sign of improper development of the culture.
The reasons for this unpleasant phenomenon can be very different. The tips of the feathers quickly turn yellow in inclement weather, both too hot and excessively rainy. In addition, onions may turn yellow due to improper feeding; pest attacks and certain diseases.
Depending on these reasons, there are various ways to combat yellowing onions.
Why onions turn yellow - video
What to do if the reason for yellowing is weather conditions
Weather conditions are the most unpredictable cause of possible bow problems. Even the most experienced gardeners cannot predict in advance how the weather will change.
Only a greenhouse can guarantee protection against changes in humidity and temperature - in it the onion feathers will always remain green
Onions grown in the greenhouse usually do not turn yellow
If you grow onions in the open ground, you need to carefully monitor the watering regimen. In hot and dry weather, the tips of the onions may turn yellow due to lack of moisture. In this case, it is necessary to immediately water the plantings and then irrigate every 3-4 days during the dry period.
Onions require frequent watering with heated water
Onions generally like frequent watering. In order to avoid yellowing, young plants (the period of emergence of shoots and young leaves) should be watered 2 times a week, and then about 5 times a month (if the weather is not too dry).
For watering onions, it is not recommended to use cold well water: it must be collected in advance and left to bask in the sun.
The irrigation rate is 6-8 l / m2. After waiting for the soil to slightly dry after watering, be sure to loosen it.
In rainy weather and excessive watering, the onion rots from the rhizome. When the stems turn yellow, this means that the bulb is already completely spoiled and it is no longer possible to save it - it is better to dig out all the spoiled plants immediately.
What to do if onions lack nutrients
Lack of nutrition is one of the main causes of yellowing of onions. The lack of nitrogen affects the appearance especially (onions are especially demanding on its content in the soil). Leaf growth slows down, in shape they become short and thick, initially light green, and then yellow. If measures are not taken in a timely manner, the feathers will dry out, and the bulbs will die after them.
When such signs appear, it is necessary to immediately introduce nitrogen fertilizers into the soil. A good top dressing is a solution of organic and mineral fertilizers: 1 cup of mullein or chicken infusion and 1 tablespoon of urea are taken on a bucket of water.
Keep in mind that pathogens of fungal diseases can enter the soil along with organic fertilizers.
Despite the fact that nitrogen is the most important element of onion nutrition, its excess can lead to catastrophic consequences - the bulbs rot in the soil. Therefore, when applying nitrogenous fertilizers, it is necessary to adhere to the dose recommended for this variety.
Use of ammonia with a lack of nitrogen
Ammonia alcohol is ammonia, or rather, its solution of 10% concentration. Nitrogen is present in its composition, therefore ammonia is quite suitable for feeding onions, especially since the ammonia solution is well absorbed by plants. True, the use of ammonia is a rather expensive pleasure, but if there are no other suitable substances at hand, it will help to cope with the problem of yellowing onions.
To feed onions, ammonia is diluted in water (55-60 ml per 8-10 l) and the beds are watered (it is better to do this in the evening).
Feeding onions with ammonia - video
In addition to providing onion nutrition, ammonia improves the soil structure and helps to reduce its acidity. Another advantage of this tool is a pungent odor that scares off almost any pests.
According to the author (supported by his own experience), the key to the success of growing onions is planting in fertile soil. If you still work in the fall to prepare a garden (to put in it a rotten chicken droppings or mullein and dig it well), and to feed the plantings three times during the season, then you will not need to fight with the yellowing of the feather. By the way, top dressing should be carried out only during the period of growing leaves, and 2 months before harvesting, completely stop fertilizing.
How to deal with yellowing caused by pests
Despite its burning juice, onions very often become a “victim” of various pests, which can cause not only yellowing of the feathers, but also the death of the crop. The most active destroyers of onions are onion flies, onion moths, onion thrips, cryptocephalus (weevil), stem nematode.
Onion fly
This pest in appearance resembles a regular fly. It actively reproduces in April - May, just when onion greens develop. The fly lays eggs on the surface of the stem, in the soil near the plants and under the leaves. After 8-10 days, small white larvae emerge that penetrate the bulb and eat the scales. Affected plants slow down growth, turn yellow, wilt, and finally dry the leaves.
In order to know for sure whether the fly is the cause of yellowing, you need to dig the earth and see if there are white worms on the bulb.
Onion fly is one of the most common onion pests.
To prevent damage to the fly, planting material must be soaked in a solution of potassium permanganate. To control the pest, you can treat the beds with Mukhode, Aktapoy, Kreotsidom PRO or Kapate Zeon. True, the use of chemicals can reduce the quality of the crop.
There are folk remedies for pest control:
- carrots or parsley are planted next to onion beds: their smell repels the onion fly;
- applying a mixture of ash with tobacco, pepper and mustard to the soil to prevent damage;
- pollinate plantings with a mixture (in equal shares) of ash and tobacco dust. You can pour the beds with tobacco infusion (0.2 kg of tobacco you need to pour 2.5-3 liters of hot water and insist 3 days, then bring the volume to 10 liters), in which 1 tablespoon of laundry soap and red pepper are added before use;
- watering the soil with a solution of salt with ammonia (200 g of salt and a little ammonia are dissolved in a bucket of water). This solution does not work well on the soil, so it should not be used often. You can use just an ammonia solution, prepared in the same way as for feeding: they are watered between the rows during periods of maximum activity of the onion fly (twice in June and twice in July). After each watering, the earth needs to be slightly loosened.
To get rid of onion flies, the author successfully used a mixture of ash (1 cup), black or red pepper (1 tablespoon) and shag (1 tablespoon). This composition requires pollinating the beds. Before processing, all yellowed leaves are removed completely.
Nematode
If your onion leaves become wrinkled and covered with yellowish veins, then most likely you will find a nematode in the stems - whitish threadlike worms. They suck the juice from the stems, penetrate the bulb, causing cracking and rotting of its bottom. It is difficult to get rid of a nematode - it can live in the soil for many years.
The leaves affected by the nematode are deformed.
To prevent damage, carefully planting material (hot water at a temperature of 40-45 aboutC, and then with a strong salt solution for 15-20 minutes), and in the fall (after harvesting) treat the soil with Heterophos, Carbathion or Tiazon. It must be borne in mind that these drugs are toxic and the waiting time after their use is at least 2 months.
To folk remedies to combat the nematode include:
- planting marigolds or marigolds in the aisles (its volatile products repel pests);
- dressing beds with tincture of marigolds: the plants chopped with a knife are put in a bucket (filling it to half), poured with water heated to 50 degrees and left under the lid for two days;
- feeding with ammonium sulfate (first half of June) - 2 tablespoons of the drug are dissolved in 10 liters of water and watering beds at a rate of 4-5 l / m2;
- watering with a solution of salt (a glass of coarse salt in 10 liters of water).
Stem nematode - video
Onion moth
Onion moth looks similar to other varieties of moths. This pest is activated when the weather is warm and dry. Moth lays eggs in the ground near the bulbs. Emerging larvae invade the leaves and gnaw them from the inside. The feathers of the affected onion change color and dry first in the upper part, and then completely. The first wave of defeat is observed in May - June.
Onion moth larvae invade leaves
From chemical means of protection Metaphos and Spark are effective. Of folk remedies, processing with ash, tobacco dust, garlic or tobacco infusion is popular.
Onion or tobacco thrips
Onion (tobacco) thrips also often causes yellowing of the onion. These small (smaller aphids) insects, like aphids, suck the juices from the plant. They hibernate in soil and bulbs, so that they can appear even in well-cultivated areas.
Despite its small size, thrips can cause great damage.
For prevention, onion sets must be treated with hot water (10-12 minutes), and then immersed in cool water. If infection of plants in the beds is detected, treatments with Spark and Confidor will help.
To assess (and reduce) the degree of thrips infection, adhesive traps can be installed on the beds. It is desirable that their paper base be yellow or blue - these colors attract insects. If the infection is not too strong, you can use alternative methods of struggle:
- treat the plants with garlic or onion infusion (pour a tablespoon of crushed raw materials with a glass of hot water and insist for a day);
- use for processing tobacco infusion, aged 36 hours and diluted before use twice;
- spray plantings with a decoction of dried pomegranate, lemon and tangerine peels (0.2 kg), yarrow (70-80 g), ground red pepper (10-12 g) and crushed garlic (2 cloves).
Onion weevil (secretive worm)
Weevil larvae feed on green onion feathers. The first sign of damage is the yellowing of the feather, and then its withering and death of the plant. If you do not engage in the fight in a timely manner, the entire garden may die. It is necessary to carefully examine the plantings: if stripes appear on green feathers, cut the feather - most likely, the weevil larva hid there. The chemical control agent is Karbofos, which should be sprayed with plantings (then green onions should not be picked for 2-3 weeks).
Other methods of dealing with weevil are:
- manual collection of beetles;
- watering the beds with ammonia solution (50 ml of ammonia per bucket of water) every 7 days starting in mid-June;
- harvesting and burning all plant debris from the bed in the fall;
- sprinkling of beds in spring with ash, ground pepper or mustard.
Yellowing fungal diseases of the onion
Of the diseases of onions, yellowing is most often caused by fungal diseases: rot of the ground, fusarium, rust. The main method of prevention is the careful selection of a healthy set and soaking it in hot or salt water. The landing site should be sunny and ventilated. Excessive soil moisture must not be tolerated, and pests that often carry diseases are also necessary. Not the last place in disease prevention is crop rotation.
Before planting, it is advisable to treat the site with HOM - then the probability of the appearance of a yellow feather is reduced.
It is not advisable to treat diseased plants with pesticides, because after them you can’t eat a feather for a long time. You can use Trichodermin (in a suspension of 10 g / l of the drug soaked sevoc), as well as Fitosporin-M or Gamair (plantings are sprayed with these drugs). These fungicides are biological products and do not harm human health.
Effective against yellowing of the feather caused by disease, metronidazole. With a solution of 2 tablets per 5 liters of water, you need to water the beds (norm 4-6 l / m2).
Prevention of yellowing onions
Instead of determining the cause of the yellowing of the onion, choosing the right drugs and eradicating the problem, it is better not to allow such a situation. If you cultivate the soil in a timely manner, competently water and feed and regularly fight pests, then yellowing is unlikely to occur (unless due to adverse weather). For prevention, you must adhere to the following rules:
- annually in the fall, after harvesting completely, you should carefully dig the site. The depth of processing should not be less than the length of the bayonet of the shovel;
- observe crop rotation - onions can be planted in the same place only 1 time in 4 years, cereals are desirable as a precursor;
- for planting, use only high-quality planting material and properly prepare it (warm and dry before planting);
- to exclude diseases, disinfect the soil with copper sulfate just before sowing (1 tablespoon per bucket of water);
- fertilize strictly in accordance with the recommendations: excessive doses of fertilizers are just as harmful as too small quantities;
- ensure proper watering: it should be regular, but moderate;
- To eliminate the foci of disease, remove all diseased or diseased plants from harmful insects and burn them.
Yellowed feathers of onions - a joyless sight for the gardener. However, observing the simple rules of agricultural technology almost always helps to prevent this trouble, and if it happened, there is always a way to restore the health of onion beds.
