We talked about all the main ways to combat the onion fly, tried to talk about the most effective folk methods of combating this pest, like gnat insecticides and traps, without using chemicals, as our readers love. Of course, sometimes it is much easier to prevent the appearance of a pest in a plot than to cure plants of it, therefore, it is also necessary to tell about the prevention of a pest in a plot.
So, in order to prevent the accumulation of pests in the soil and prevent mass infection of plants, the garden on which you plan to plant onions should be returned to their original place no earlier than four years later, during which time the onion fly larvae will simply die without food. Everything else, changing the place of growing onions, you thereby save the soil and from severe depletion of one or another element, for example, from nitrogen, to which onions show high demands. In the autumn season, always dig a plot, as we described above, to the full bayonet of a shovel, but try not to break the lumps so that the soil is frozen harder. Remember that onion fly larvae can “dig” into the soil to a depth of two tens of centimeters and winter there. Digging a plot, we minimize the number of overwintered larvae.
Next, try to alternate the beds with onions the beds with carrots, the onion fly does not tolerate the smell of carrots, and the carrot fly does not smell the onions, so you can “kill two birds with one stone”, on top of that, onions and carrots planted nearby get along quite well.
Before planting and digging onions, try to inspect the bulbs for larvae. To exterminate them, just dip the bulb in salted water (a tablespoon of five liters), heated to 45 degrees Celsius for 8-10 minutes. It also helps to place the bulbs for two minutes in a 1% solution of potassium permanganate. Such treatment of the bulbs is necessary because if they are infected, neither high agricultural technology nor a clean plot will save the onion plantings from infection because you will place the larvae yourself in your soil.
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 onions and onion sets, try to comply with the possible recommended dates in your area. This is necessary so that by the time the onion fly begins to summer and the appearance of larvae, the plants are already strong enough and the damage from the larvae is minimal.
Throughout the season, carry out work around the site, be sure to loosen the soil, not allowing the formation of soil crust, remove weeds located closer than ten meters to the site. If there is an active year of onion flies, and you do not want to use chemistry, then you must try to minimize watering the soil in the area so that its top layer is dried, then the larvae from the ovipositor may not spawn. 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 larvae. If loosening the soil constantly is difficult for you, then you can mulch it with hummus or wood ash, a layer of about a centimeter. By the way, after the end of the summer of onion flies, hummus or ash can be collected and thrown away – 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 infection of the site with an onion fly, it is necessary to clear this area of snow in winter so that the soil freezes harder and the larvae of the onion fly die. If you combine digging the soil with the turnover of the reservoir and without loosening, also with the removal of snow, then this will be most effective.