How to control whiteflies on cucumbers in a greenhouse?

Cucumbers

The future harvest is threatened by the whitefly, a small insect that resembles a butterfly. Adults and larvae infest cucumbers planted in greenhouses and hotbeds. Their main food source is the plant's sap, which gradually weakens and wilts over the course of one to two weeks. Control methods are selected based on the number of affected bushes. Treatment takes 5-11 days, followed by recurrence prevention.

Characteristics of the pest

Control of whiteflies is complicated by the insect's ability to adapt to environmental conditions. Whiteflies, whose lifespan does not exceed three years, are not affected by temperatures down to -5°C. Harvest preservation is only possible through comprehensive treatment of the entire plot. Despite their short life cycle, the pest lays up to 100 eggs, depositing them on the underside of leaves. If a single section of the garden is treated, the whitefly will simply move to another area.

Causes and symptoms

The whitefly is an insect that prefers warm climates and high humidity. It doesn't survive long outdoors. Heifer owners who fail to follow basic preventative measures are at risk. Larvae can be introduced through contaminated seed. Preventative treatment of seedlings, tools, and the greenhouse itself with a saturated solution of potassium permanganate can help avoid problems. The pest penetrates the soil to a considerable depth. The severity of symptoms depends on the insect colony and its activity:

the leaf surface acquires a white coating;
leaves become sticky;
change in the color of the leaves, which curl up;
some leaves are affected by yellow or green spots;
the inner side of the leaf blade is covered with larvae;
black plaque covers the branches;
the rate of seedling development decreases.

As soon as one of these symptoms is detected, treatment should begin immediately. Otherwise, the damage will be significant. A gradual lack of nutrients will lead to fruit necrosis and rapid wilting.

Methods of pest control in greenhouses and open ground

A gardener has three possible sets of techniques, depending on the stage of the infestation. If the pest has settled on one to three bushes, mechanical methods are used. Whiteflies are collected by hand and placed in an airtight container. Each leaf where the parasite was found is wiped with a mild soap solution. If the greenhouse or plot is large, fly traps are set. These can be purchased at a store or made at home:

a container of bright yellow or orange waterproof paint;
plastic plate;
the plate is painted and allowed to dry;
cover it with a sticky substance;
the plate is equipped with a backlight;
The finished trap is hung above the cucumbers.

Folk remedies are effective for moderate infestations. These recommendations are suitable for both greenhouses and open ground.

Way	Dosage	Note	Application
Laundry soap	100 g of grated soap is dissolved in a 6-liter container with water	-	The resulting solution is sprayed on the seedlings once a week.
The smell of fresh garlic is detrimental to pests.	100 g of grated garlic is dissolved in ½ l of water	The mixture, which has been infused for 72 hours, is filtered and mixed with clean water in a proportion of 5 g for every 1 liter of liquid.	The root circle needs to be treated with the mixture.
Yarrow	100 g of crushed leaves of a fresh plant are poured with 1 liter of boiling water	The mixture is infused for 48 hours.	Spraying is carried out once every 3 days.
Dandelion	200 g of dandelion flower together with the root and inflorescences are washed with warm water and ground in a meat grinder	The gruel is poured with 1 liter of boiling water and infused for 48 hours.	The treatment is carried out once every 7 days.

The use of biologically active substances is recommended at any stage of infestation. The only caveat is that they should not be applied to areas where more than 50% of the seedlings are infected. Biologically active substances should be alternated, otherwise the pest develops immunity.

Note!

The whitefly's natural enemy is the ladybug, also known as the goldeneye. A small colony is enough to eliminate the pest.

You can use not only insect helpers but also beneficial plants. The scent of calendula or marigold flowers will act as a barrier to gnats.

Chemical control methods

Extensive infestations in a greenhouse or garden prevent the use of the techniques described above. Chemicals are the only effective pest control methods. The first rule is to follow the dosage indicated on the product packaging. Do not exceed the recommended concentration, otherwise the crop will be damaged. Here's a list of effective products:

Akarin is a broad-spectrum substance. It penetrates the plant's structure. As soon as the pest tries to feed on the seedling's sap, it absorbs the poison.
"Aktara" targets both larvae and adults. Seedlings are sprayed once every 5 days.
"Admiral" is a broad-spectrum product. It proved effective when a large colony of midges infested the garden. It penetrates deep into the soil and kills larvae, young insects, and adults.

Infection can be prevented

Action begins in the fall. After harvesting, disinfect the greenhouse walls and soil. A concentrated solution of potassium permanganate can be supplemented with a specialized product purchased at a gardening store. The next step is to cover the soil with a protective film. If there are any easily accessible areas where pests can enter, treat them with any disinfectant.

Note!

Its packaging should indicate that it dissolves even the protective shell of the insect's egg.

The product "Intar-Vir" and KRA aerosol have proven effective. If a gardener doesn't want to water their garden with chemicals, they can prepare a folk remedy. Pour a 1:1 mixture of industrial alcohol and water into a bucket. Water the area with the mixture. Adults and young insects have no chance.

Every corner of the greenhouse should be treated. If one dirty spot is left, the insect will reappear the following year. Another folk method is used for spraying seedlings: dissolve 3 tablespoons of alcohol (96%) in 1 liter of clean water. Other preventative recommendations:

Hormonal chemical treatments (Match, Admiral) are effective against larvae and young insects. They are useless if adults have previously been present in the area.
Alkali is lethal to pests. It's sufficient to dig up the soil immediately after harvesting and two weeks before planting a new crop. During this process, add slaked lime at a rate of 100 g per square meter.
Fumigation is only suitable for greenhouses. There are two options. The first is to purchase a ready-made smoke bomb from a gardening store. It doesn't matter whether you use a sulfur or tobacco smoke bomb. The smoke is safe for both humans and seedlings. The second option is to make your own fumigation solution. Use a metal pan and sulfur at a rate of 80 g per 1 m² of surface area. Close the greenhouse and heat the smoke bomb spread on the surface. The smoke even penetrates the soil, killing the pest.

A sulfur candle is a preventative method suitable for use in a large greenhouse. The treatment is carried out in the evening, when there is no wind or rain. Before beginning the treatment, wear a protective mask and suit.

Prevention in a repeatedly infected area

In greenhouses and open ground, where the pest has appeared more than 4-5 times, a more radical means of preventing repeat visits will be required. A radical way to get rid of midges is cold. Even a slight temperature change can kill both adults and juveniles. Gardeners close the greenhouse and cool it to -20°C (-4°F). There's a misconception that freezing can be replaced by snow. It's worth opening the greenhouse roof to expose the soil to a white blanket.

Whiteflies thrive under snow. For years, the insects lie dormant beneath the warm blanket. Only a sudden drop in temperature to -15°C to -20°C will kill the pest. This "thermal shock" lasts for 12 hours.

Note!

The described method is useless if the region experiences mild winters. An alternative to cold prevention is disinfection in the fall and spring. Three weeks before the expected planting, the garden is fumigated.

Whiteflies that appear on cucumbers in a greenhouse will destroy the entire crop within 1-2 weeks. This adaptable insect is virtually immune to chemicals during the pupal stage, making control difficult. Regular inspection will help prevent crop damage. As soon as white spots are detected on the bushes, they should be removed immediately. Treatment effectiveness is often poor. Regular preventative measures will help reduce the risk.