Table of contents:
- What does an onion fly look like?
- How to treat plants against onion flies?
- Fighting onion fly folk remedies
- How to deal with onion fly larvae?
- What to do to prevent the onion fly from appearing?
This fly is called an onion fly because it most often attacks onion plants, but sometimes it can attack garlic and even bulbous flowers. Usually, signs of onion damage by an onion or leek fly are visible to the naked eye. If the onion in your area suddenly began to grow slowly, if its leaves-feathers began to turn yellow, wither and dry, and the smell from the onion does not come from an onion at all, then it is definitely affected by an onion fly. If a bulb is dug up from the affected plants, then it will be possible to see a plaque resembling putrefactive on it, subsequently the bulbs will become soft and it will be impossible to either store or eat them.
What does an onion fly look like?
This insect really looks like a small fly with a light gray color. The length of the fly is about a centimeter, you can distinguish a female that is capable of laying an ovipositor from a male that is not capable of this by a dark strip on the abdomen: this strip is only found in males.
Onion fly females are very fertile, during their life they are able to lay on the leaf blades of the onion or on the bulbs themselves, if they protrude from the ground, up to six dozen eggs, which are white in color with a noticeable longitudinal stripe. Each egg is about a millimeter long. From the moment of the ovipositor to the appearance of the larvae, it usually takes from six to eight days, that is, a rather short time. After the larva is full enough, it pupates and young individuals of the fly - males or females - emerge from the cocoon. The onion fly begins its age very early, usually already in April, which is why it is considered a very dangerous pest.
How to treat plants against onion flies?
To protect against onion flies on large plantations, where there is simply nothing to do with folk remedies, modern and approved insecticides are used. For example, neonicotinoids - Thiamethoxam and Imidacloprid, as well as organophosphorus compounds - Diazinon and Dimethoate, have gained popularity. Pyrethroids - Stomazin, Ripkord, Cypermethrin, Stomoxin and Baytikol - have proven themselves quite well in the fight against onion fly.
These drugs are used in liquid form, dissolved in water, with their help they fight the onion fly by spraying. When processing with these drugs, you must strictly follow the instructions on the packages. The active substances of these drugs affect exactly adult insects, causing their death.
For those who do not accept the use of chemistry in their areas, we can recommend one of the alternative methods of fighting the onion fly, which we will now talk about.
Fighting onion fly folk remedies
Tobacco dust is popular among gardeners, and therefore it is freely available and there is no need to grind tobacco into dust, as many think. You can use tobacco dust to protect against onion flies by simply scattering it over the soil surface of the area where onions grow, spending about a tablespoon per square meter of soil, without peas, dust. If the pest has already appeared, that is, the years of the fly have begun, then you can mix tobacco dust with ordinary river sand or, more effectively, with equal proportions of naphthalene (this is more effective, because naphthalene smells strongly, driving away the fly).
They say that the onion fly will not harm if the soil of the garden is generously sprinkled with a mixture of wood ash and ground hot pepper or a mixture of ground hot pepper and tobacco dust (a tablespoon of this mixture per square meter of soil).
Infected areas on which the onion fly flies and may have already laid eggs or there was an infection last season can be sprayed with tobacco infusion. To do this, dissolve 250 g of tobacco in a bucket of water, let it brew for a couple of days, strain, fill the spray bottle and you can process the plants, spending about a liter of solution per square meter.
Ammonia against onion fly
If the onion fly flies actively and there is a high probability that larvae are about to appear, then ammonia can be used to combat them at the earliest stages, when they are especially sensitive. To do this, dissolve three tablespoons of ammonia in a bucket of water and in the second half of the day, towards evening, process the onion plants with this composition.
Onion plants can be treated with ammonia two or three times per season, given the rapid development and fertility of onion flies. The frequency of treatments is usually once every 30 days.
Wood ash is not only a pretty good source of potassium (it contains up to five percent), but also protection against onion flies. Wood ash is now sold in garden shops and flower shops, but you can get it yourself, it is not at all difficult. To obtain wood ash, you need to collect dry branches, logs, bark and other parts of wood and burn them to the state of ash. To protect against onion flies, the soil can be completely covered with wood ash, with a layer of a couple of millimeters, or it is possible to carry out processing with wood ash dissolved in water. To do this, about 500 g of wood ash must be diluted in a bucket of water, let it brew for a day in a warm room, strain, fill the spray bottle and you can process onion plants, trying to completely process both the leaves and the soil around. Consumption rate: one and a half liters per square meter of the garden.
Onion Fly Salt Solution
This method is considered effective, but it is quite harmful to the soil, because the use of salt can lead to salinization of the soil. It is advisable to carry out treatments for onion fly with salt-based formulations no more than once a season, and only if crop rotation is taken into account, that is, if onions are planted on the same site every four years. Usually, onions are treated with saline solution two weeks after germination. To do this, dilute 200 grams of salt (no more!) In a bucket of water and treat the soil with a solution, trying not to get on the onion leaves. It is advisable to carry out such treatments in the evening, and early in the morning it is good to moisten the area with soft water.
How to deal with onion fly larvae?
So, we told how to deal with an onion fly, now let's talk about how to deal with its larvae. If the infection has already begun, and you see not only a fly, but also notice the yellowing of the onion leaves, then as soon as possible you need to sprinkle the areas of the garden where the infection has occurred with a mixture of river sand and naphthalene. In this case, ten parts of naphthalene are needed for part of the sand. You need to scatter without creating a layer, just so that the soil is slightly covered.
They can effectively cope with onion fly larvae by processing with infusions of needles, valerian, mint and wormwood. Needles per liter need 50-100 g, this is a dose per square meter; valerian herbs - about 500 g per bucket of water, this is the norm for 3-4 square meters; mint can be more, for a sharp aroma, about a third of a bucket and consumption is also 3-4 square meters, and wormwood - pour a quarter of a bucket with water, let it brew for a day and can be used, spending 2-3 square meters of beds.
Gardeners also respond well to treatments against onion flies with laundry soap or liquid antibacterial soap. Laundry soap needs about half a piece for a bucket of water, antibacterial liquid soap - 50 grams per bucket of water. Do not forget that soap dissolves best (without flakes) in soft water; rain water is ideal. Soap can be used to treat both the soil and the leaf blades, wetting the surface well, especially in those plants whose feathers have begun to turn yellow. In the case of soap, you can carry out up to three treatments with a break of one week.
Another interesting option: the oldest insecticide is kerosene. Kerosene can also be used to control onion fly larvae. Kerosene is good because it is practically safe for humans and the soil, but destructive for onion fly larvae. Naturally, pure kerosene cannot be used; it must be greatly diluted. So, to fight the larvae, you need only 50 g of kerosene per bucket of water, this composition can be filled into a spray bottle and thoroughly treat the soil with it on each bulb, especially carefully for those whose leaves have begun to turn yellow.
Do not forget that to consolidate the result immediately after harvesting, the soil must be dug up onto a full bayonet of a shovel with a seam turn, but without loosening the clods, then the larvae that accumulated in the soil for the winter will die from frost.
What to do to prevent the onion fly from appearing?
We talked about all the main methods of fighting the onion fly, tried to talk about the most effective folk methods of fighting this pest, without the use of chemistry, as our readers love. Of course, sometimes it is much easier to prevent the appearance of a pest on the site than to cure plants from it, therefore, it is also necessary to tell about the prevention of the appearance of a pest on the site.
So, in order to exclude the accumulation of the pest in the soil and prevent mass infection of plants, the garden on which you plan to plant onions must be returned to its original place no earlier than four years later, during which time the onion fly larvae will simply die without food. In addition, by changing the place where the onion is grown, you thereby save the soil from a strong depletion of one or another element, for example, from nitrogen, to which onions have high demands.
In the autumn, always dig up the area, as we talked about above, with a full bayonet of a shovel, but try not to break the lumps so that the soil will freeze harder. Remember that onion fly larvae can "burrow" into the soil to a depth of two tens of centimeters and winter there. Digging up the site, we minimize the number of overwintered larvae.
Next, try to alternate the beds with onions and beds with carrots, the onion fly does not tolerate the smell of carrots, and the carrot fly does not tolerate the smell of onions, so you can “kill two birds with one stone,” in addition, onions and carrots planted next to each other get along quite well.
Try to examine the bulbs for larvae before planting and digging onions. To exterminate them, it is enough to dip the onion into salted water (a tablespoon for five liters), heated to 45 degrees Celsius for 8-10 minutes. It also helps to put the bulbs in a 1% solution of potassium permanganate for two minutes. Such treatments of the bulbs are necessary, because if they are infected, then neither high agricultural technology nor a clean area will save the onion plantations from infection, because you will place the larvae in your soil with your own hands.
With a strong infection of plants with an onion fly, when the bulb begins to rot, they can no longer be helped, it is better to remove them from the site and burn them.
When planting onion and onion sets, try to comply with the possible recommended dates in your area. This is necessary so that by the time the summer of the onion fly begins and the larvae appear, the plants are already strong enough and the harm from the larvae is minimal.
Throughout the season, carry out work around the site, be sure to loosen the soil, not allowing a soil crust to form, remove weeds located closer than ten meters to the site.
If there is an active onion fly, and you do not want to use chemistry, then you must try to minimize watering the soil on the site so that its top layer is dried, then the larvae from the ovipositor may not hatch. You need to endure only a week, given the timing of the appearance of the larvae, which we described above.
The question may arise - why loosen the soil? Biologically, onion flies have developed a kind of protective reflex; they do not lay eggs in loose soil, considering it unsuitable for hatching. If it is constantly difficult for you to loosen the soil, then you can mulch it with humus or wood ash, with a layer of about a centimeter. By the way, after the summer of onion flies is over, humus or ash can be collected and discarded - there may be eggs or larvae.
In case of severe infection or when preparing the soil for planting onions, when there is a risk of contamination of the site with an onion fly, it is necessary to clear the area from snow in winter so that the soil freezes more and the larvae of the onion fly die. If you combine soil digging with seam turnover and without loosening, and also with snow removal, then this will be as effective as possible.
So, we now know a lot about the onion fly, we know that it can give up to six dozen eggs per life, that it starts flying in April and that the larvae hatch in a week or so. We know how to deal with a fly and how to minimize the risk of its appearance or larvae wintering, all this remains to be applied in practice, and then it will be possible to forget about chemical preparations forever, how to forget about the lean years.