What is whitefly
The greenhouse whitefly (Trialeurodes vaporariorum) is a flying insect of the genus Aleyrodidae, family Homoptera. This butterfly looks like a microscopic moth with a yellowish body measuring 1-1.5 mm, and two pairs of white, powdery wings that fold into one plane.
The female lives about 30 days. During this time, she manages to lay from 85 to 130 eggs 0.24 mm long. They are located on the back side of the sheet plate in concentric circles of 20-30 pieces. At first the eggs are yellowish-green, gradually darken, and before the next phase of development they become almost black.
The larva is oval, flat, light green in color. It is characterized by 4 phases of development, during which the size changes from 0.3 to 0.9 mm. In the first stage, the whitefly larva is very mobile and easily moves from one plant to another. She needs excess nutrition, during which cell sap is actively sucked out of the leaves and a sticky secretion is released.
Starting from phase II of development, the larva becomes motionless, but continues to destroy plants. The first 3 stages after hatching from eggs last 10-14 days.
At the fourth instar, the whitefly larva becomes covered with a waxy coating and becomes invulnerable even to very strong insecticides of chemical origin. The phase lasts 13-15 days, then winged individuals appear - adults.
In a greenhouse heated in winter, the whitefly population reproduces continuously and produces 4 generations per calendar year. The most favorable temperature is 21-27° with humidity from 60 to 75%.
The pest cannot overwinter in the open ground of the Middle Zone, but is able to wait out unfavorable times in the substrate of greenhouses or on indoor flowers.
Pests on seedlings - how to recognize and fight
If measures are not taken in time, aphids, whiteflies, thrips and spider mites can destroy young seedlings. How to recognize pests and what to do if they attack plants? You can determine who exactly is harming your seedlings by the characteristic features that distinguish this or that pest.
Aphid
Insects are very voracious and reproduce quickly. You can tell that aphids have settled on plants by changes in the shape and color of the leaves: they curl and become discolored. Also, “honeydew” appears on the leaves of seedlings - sweet sticky secretions of aphids, which are a favorable environment for the proliferation of pathogenic fungi. Regular inspection of seedlings will help prevent the appearance of aphids, as well as creating optimal growing conditions:
maintaining the daytime temperature at 20-25°C, and the night temperature at 16-20°C; regular watering with settled water at room temperature; positioning the plants so that their leaves do not touch each other.
If aphids do appear on the seedlings, but there are not many of them, you can collect the insects by hand and spray the plants themselves with a solution of laundry soap (25-30 g per 1 liter of water). If there are a lot of aphids, the plants should be treated with insecticides - Inta-Vir, Decis, Kinmiks, Fitoverm, etc. (according to the instructions).
Thrips
Externally, these insects resemble miniature (about 1 mm) butterflies. They suck the juice from plants, leaving small silvery spots at the site of the “bite”.
Over time, these spots grow, merge and cover the entire leaf. You can deal with thrips using chemical insecticides - Fitoverma, Vermitek, Akarina, etc. Moreover, you will need to carry out at least 3 sprayings with an interval of 7-10 days. Tomato leaves damaged by thrips To prevent the appearance of the pest in the future, thoroughly disinfect the containers and substrate before sowing seeds for seedlings. Also strictly follow the plant requirements for growing conditions.
Whitefly
This voracious pest feeds on the sap of seedlings, not disdaining leaves, stems, or cuttings of plants. By sucking juice from leaves, whitefly larvae and adults secrete sticky enzymes, which provide a favorable environment for the development of pathogenic fungi.
Parts of plants damaged by “seedling moth” (also called whitefly) dry out and die. As a rule, whitefly appears in rooms with high temperatures and low air humidity. If this is not allowed - regularly ventilate the room, place wide containers of water near the plants to increase air humidity - the appearance of whiteflies can be avoided. Also, do not forget to periodically inspect the seedlings.
When a pest appears, you can spray it with garlic infusion or hang sticky yellow tapes throughout the room. To prepare the infusion, pass 2 tbsp through a meat grinder. peeled garlic cloves, transfer the resulting mass into a glass jar, add 1 liter of water and cover with a lid. After 5 days, the infusion will be ready. To spray seedlings, dilute 1 tsp. the resulting infusion in 1 liter of water.
Spider mite
Spider mites are practically invisible to the human eye. It is possible to understand that the pest has settled on the seedlings only when its leaves begin to wither and turn yellow, and small black dots appear on their reverse side.
If the plants are severely damaged, chlorotic spots with pinpoint necrosis appear on the leaves, on which the spider coating is clearly visible. As in previous cases, massive damage to seedlings by spider mites can be prevented by regularly inspecting the plants and creating optimal growing conditions for them. If you notice single black dots on the underside of the leaves, try regularly spraying the plants with water.
If the pest has managed to seriously “spoil” the seedlings, use insecticides - Fufanon, Chemix, Iskra M, Aktellik, Fitoverm, etc. Fitoverm is an insecticide of natural origin that is used to control piercing-sucking pests. The concentration of the drug solution is calculated based on the pest it is used against.
To protect seedlings from aphids, 8-12 ml of the drug are dissolved in 10 liters of water, 2 ml from spider mites, and 20 ml from thrips. The duration of the protective effect of Fitoverm is about 5 days, so repeated treatments (if necessary) are carried out no later than after 7-8 days. The appearance of most pests on seedlings can be avoided if optimal conditions are created for the plants.
Remember this so as not to resort to chemicals in the future.
Well, if you still have to use insecticides, do not forget about precautions
Why is whitefly dangerous for tomatoes?
The main nutritional base of whiteflies and larvae is plant cell sap. The insect produces it in quantities much greater than its own needs, and secretes honeydew, a sweet liquid that attracts other pests.
Following the whitefly, ants may appear on tomatoes. An indispensable companion of widespread butterflies is sooty fungus, which in itself is a serious problem.
The damage caused by whitefly to tomatoes is as follows:
- butterflies and their larvae suck out cell sap in quantities dangerous to plant life;
- leaves turn yellow, wither and fall off;
- after the whitefly, ants colonize tomatoes;
- honeydew is a nutrient medium for the development of a sooty fungus that covers the leaves with a black film, clogging the stomata and blocking access to light;
- vegetative organs affected by blackworm cannot participate in photosynthesis;
- tomatoes ripen slowly, whitish veins appear in the red pulp, which reduces their commercial and consumer value;
- the pest is often a carrier of viral diseases, from which it is impossible to save tomatoes, since there is no treatment;
- growth and development at best slows down, often stops; at worst, the butterfly and its larvae completely destroy the bush.
Whitefly on tomato seedlings is very dangerous. The sprouts are too weak and tender to resist the pest, so they die easily.
Tomatoes also have increased vulnerability during the adaptation period after moving to a greenhouse or soil.
Reasons for appearance
For whiteflies to appear on tomatoes, they must come from somewhere. In the southern regions of Russia, the insect overwinters in the ground, and then flies from site to site or is carried by the wind. Stray larvae can move to a neighboring plant, nothing more.
Already in the central zone, wintering for whiteflies in the ground becomes impossible. She can wait it out safely only in a room protected from frost, on a compost heap, indoor or greenhouse flowers.
The pest enters the greenhouse through transoms and doors that are open for ventilation and through unsealed cracks.
Whitefly can be introduced with purchased seedlings that have been treated to give them a decent appearance before sale. On already large bushes, which many gardeners prefer to plant, unscrupulous traders simply knock down insects with a stream of water. The butterflies will fall or fly away, but the larvae attached to the leaves will remain.
Whiteflies are also often brought into a greenhouse with contaminated soil. While the substrate for seedlings can be steamed, it is difficult to do this with large volumes. But not everyone carries out sanitary tillage of the soil. At least until they are faced with an invasion of some pest and massive crop loss.
When a whitefly-infested greenhouse is not sanitized at the end of the season, some larvae will survive. Even in an unheated room.
A few individuals are enough for the pest to spread quickly at high temperatures and humidity.
Greenhouse whitefly affects not only tomatoes, but also other nightshades: cucumbers, indoor flowers, and ornamental greenhouse crops. It moves onto nearby weeds and becomes a source of re-infection. Once in the compost with plant residues, it continues its life activity, and in a warm, gradually decomposing substrate it can overwinter even in regions with an unfavorable climate.
The whitefly causes the greatest harm to weakened tomatoes. In the greenhouse you can clearly see that one bush is completely populated, while only a few individuals are swarming on the other. The fact is that this butterfly is a gnawing pest. It is much easier for her to bite through a flaccid leaf that has lost turgor than a healthy and elastic one.
Improper agricultural practices alone cannot cause whiteflies to appear on tomatoes. But it makes the work of butterflies and their larvae easier and makes the bushes vulnerable. Since the fight against the pest will take a long time, weakened tomatoes may not survive until it is over.
Signs of defeat
The whitefly is clearly visible on tomatoes in the greenhouse. It is almost impossible to confuse it with some other problem; even in a photo, pest damage is usually immediately visible.
Signs of whitefly appearing on tomatoes:
- if detected late, any touch to the plant causes a cloud of butterflies to rise into the air;
- the reverse side of the leaf blades is covered with white, stick-like larvae, which are easy to erase or wash off (I-III stages of development), or greenish, covered with a waxy coating and tightly adjacent to the surface (IV phase);
- leaves affected by whitefly lose turgor, light spots first appear on the outer side, then they begin to shine with honeydew, turn yellow and fall off (sometimes, but not always - first they curl and dry);
- as an option (quite common) - the plant is colonized by a sooty fungus, which appears as a solid black sticky coating on the outside of the plate;
- the tomato slows down its development and begins to wither;
- On fruiting bushes, white veins may appear in the pulp of red tomatoes.
Ways to fight
When choosing a way to fight whiteflies on tomatoes in a greenhouse, you need to take into account that even chemicals that have a knockdown effect (acting powerfully and quickly) do not always give the desired result.
The larvae in the fourth phase of development are covered with a waxy coating; most conventional insecticides cannot penetrate their shell. It is impossible to spray tomatoes repeatedly with strong chemicals - they accumulate in the tissues, inhibit the plant, and make the fruits unsuitable for eating.
The fight against whitefly in a greenhouse on tomatoes will take a long time and requires a combination of various methods. You can choose one, but effective, at the very beginning, when the butterfly first appears. But only if it arrived from outside, and was not brought into the garden bed along with contaminated soil or seedlings.
Biological methods
Biological remedies for whiteflies on tomatoes are effective at different stages of infection, but it is better to use them as a preventive measure. If the butterflies fly up in a white cloud upon entering the greenhouse, you will have to repeatedly spray the bushes with chemicals.
The whitefly has natural enemies, for example, the macroflorus bug or the amblyseius mite. But the most effective is the tiny wasp Encarsia formosa, which parasitizes several species of pest. Each one eats from 60 to 100 larvae during its life.
The wasp, a parasite of the whitefly, can protect plants most effectively when the pest is detected early or in the middle stage of infection. For preventive purposes, once every 2 weeks, 5-6 encarsia individuals populate every square meter of the greenhouse. To combat whitefly that has already manifested itself, 10-15 pieces are used.
If fresh soil was brought into the greenhouse, or the butterfly was annoying in the previous season, in the fall or spring the substrate should be treated with the bioinsecticide Metarizin. It can be sold as Entocide. It can be applied in any convenient way - under digging, during watering, spraying, together with fertilizers.
Chemicals
It would seem that nothing could be easier than getting rid of whiteflies on tomatoes in a greenhouse using insecticides. But before the adult emerges, the larva becomes covered with a waxy coating, which makes it difficult for drugs to penetrate the shell.
Spraying the bushes 1-2 times will not work. Females lay eggs at different times rather than on a schedule.
Treatments with the following drugs help against whiteflies:
- peritroids - penetrate through the integument and instantly paralyze the pest, are especially effective against leaf-eating insects;
- Apploud (buprofezin) - blocks the formation of chitin, is safe for encarsia;
- Grinda (neonicotinoid) is a systemic pesticide with contact-intestinal action;
- Fufanon Expert (organophosphorus compound) – intestinal contact pesticide;
- Biotlin (neonicotinoid) - recommended for use in private farms, has an intestinal-contact effect, is not addictive;
- Teppeki (flonikamid) - stops the feeding of pests after 30 minutes, penetrates the plant cells, lasts for a month, allows you to destroy even individuals that were not treated;
- Aktara (neonicotinoid) - it is recommended to water the soil against whiteflies.
To more effectively get rid of pests, adhesives should be used when spraying the above-ground parts. It is not necessary to buy them; just add a solution of laundry soap to the bottle.
Folk recipes
Traditional methods make their contribution to the fight against whitefly. For spraying use:
- garlic infusion - 2-3 large cloves are crushed and infused in a liter of water for a day;
- concentrated solution 1:6 of tar soap (laundry soap does not have such a strong smell), repeat spraying after a week;
- yarrow - 100 g of herb is poured with a liter of liquid, treatment is carried out after 2-3 days.
An infusion of shag is often recommended for spraying, but it is effective only in the initial stages of the appearance of a butterfly. You can plant several tobacco bushes in a greenhouse - the whitefly loves it very much and will concentrate there first. The problem will become obvious before the tomatoes colonize; the bush can be destroyed along with the eggs laid there, and the fight against flying insects can immediately begin.
It is believed that representatives of the genus Aleyrodidae are partial to the color yellow. This is true, but they react the same way to white, it’s just that insects are not visible there. For prevention purposes, you can hang bright yellow sheets in the greenhouse, smeared with a sticky substance (for example, Vaseline).
This cannot completely solve the problem, but the owners will be notified in time about the appearance of the pest.
Whitefly on seedlings - how to get rid of it quickly at home
When a pest appears, it is important to take timely measures. Since the insect reproduces quickly, this can lead to the death of the entire area
What to do if whitefly appears on seedlings
When an insect appears, you can use special preparations. Chemical preparations are recommended for use in cases of large numbers of whiteflies. The most common ones include:
- Aktara - the drug does not affect plant growth. To eliminate whiteflies, it is necessary not only to spray the seedlings with the solution, but also to treat the soil. After treatment, the insect does not appear on the site for 4-5 weeks;
- Confidor - the drug has a contact effect on the pest. When contacted with an insect, it begins to act actively after 1 hour. Eliminates not only butterflies, but also larvae;
- Spark is a biological substance aimed at eliminating seedling pests. To use, the substance is dissolved in water according to the instructions and sprayed onto the seedlings. The active components penetrate the plant and remain effective for 20 days;
- Fitoverm - used to combat all types of pests. In order to remove insects and larvae, it is necessary to spray the seedlings several times.
It is necessary to use chemicals to treat seedlings with an interval of at least 10 days between treatments. Otherwise, burns may appear on the leaves of the plant.
How to get rid of whiteflies using traditional methods
In order to get rid of the pest on seedlings, you can use traditional methods. Among the most effective are:
- artificial decrease in temperature - the insect cannot tolerate temperatures less than 10 degrees. This method of controlling whiteflies can be used when growing seedlings in greenhouse conditions;
- soap solution - laundry soap has a negative effect on butterflies and larvae. To process it, you need to crush a bar of laundry soap and dissolve it in a bucket of warm water. Spray the seedlings thoroughly with a spray bottle;
- garlic infusion – suitable for eliminating adult insects. To prepare, you need to chop 200 grams of garlic and add a liter of water. Leave for 24 hours, dissolve the resulting solution in 5 liters of clean water and use it to treat plants;
- tobacco infusion – 100 grams of tobacco is poured into a liter of water and infused for several hours. The resulting tincture must be filtered and diluted with 3 liters of water. Use for spraying. The same result can be achieved if you use tobacco dust, which can be purchased at any store that sells fertilizers and pesticides;
- sticky tapes – can be used in greenhouses. Sticky tapes are hung in the greenhouse at a distance of 1 meter from each other.
Also, with a small concentration of insects, a mechanical method of pest control can be used. To do this, examine the leaves from the inside.
Prevention
Strictly speaking, the owners are to blame for the appearance of whiteflies in places where they cannot overwinter in the ground. If the rules of agricultural technology, well-known and already boring, are observed, the likelihood of a pest occurrence would be reduced to a minimum:
- Plants brought into the house or site are inspected for pests using a magnifying glass. It’s better to spend an hour or two on this right away than to heroically fight insects later, wasting time, money and nerves.
- Plants in open ground and greenhouses are inspected daily - the earlier the problem is identified, the easier it is to solve it.
- They destroy the weeds growing nearby - pests also live on them, but no one really cares about this.
- The substrate for seedlings must be steamed, and the greenhouse substrate must be disinfected.
- Every year they do a deep digging of the soil in closed ground.
- The integrity of the greenhouse is monitored; all openings are covered with a fine mesh, through which not a single insect can penetrate.
- What you can’t do is leave the door wide open for ventilation - first hang a protective curtain.
- In the fall, the greenhouse is disinfected.
As an auxiliary agent for the destruction of larvae, a deep pink solution of potassium permanganate is used, which is poured onto the soil at the end of the season. The whitefly does not like the smell of ammonia, so rags soaked in ammonia and hung in the greenhouse will help as a preventive measure.
Some gardeners believe that spraying will be more effective, but this should not be done. A solution of ammonia in a strong concentration will burn the leaves, a weak one is a nitrogen fertilizer. Not only do tomatoes need little nitrates, but an excess of the substance also loosens the tissues, simplifying the “work” of leaf-eating pests.
Whitefly on tomatoes is a serious problem that requires comprehensive measures, a combination of chemicals and biological protective agents. To prevent the appearance of the pest, you need to disinfect the soil, monitor cleanliness in and around the greenhouse, and carefully inspect the seedlings.
Traditional methods
Not every gardener wants to resort to chemicals, so traditional methods are also common that help effectively fight whiteflies. Among the most effective, which make it possible to destroy whiteflies both outdoors, indoors, and in greenhouses, we can highlight:
Glue-based traps - Sticky fly tape works well for this, but it's best to make your own. To do this you need plastic or a piece of fiberboard. The surface turns yellow (the whitefly is not indifferent to these shades). After drying, generously lubricate with Vaseline, castor oil or rosin with honey. The trap is then left near the whitefly-affected tomatoes. Having noticed an object of an attractive color, whiteflies land on the bait and stick. When there are a lot of whiteflies on the surface, the trap is wiped off and then smeared again. In a greenhouse, you need to hang such boards around the entire perimeter (approximately 30x30 cm from each other). This will help get rid of adult midges;
Garlic tincture – 150g of garlic is cut into small pieces and filled with 1 liter of water. This anti-whitefly substance is infused for 5 days. After this time, we obtain a concentrate, which is diluted at the rate of 6 g per 1 liter of water;
Herbal infusion against whiteflies - for preparation you need 40 g of leaves and the same amount of dandelion root. The ingredients are crushed and placed in a container of water (1 l). After a few days, the solution is filtered using gauze. After these simple steps, the product is completely ready for use. Spraying against whiteflies is done once every 2 weeks;
Spraying tomato leaves with water from a hose may help eliminate whiteflies for a while, but if there are a lot of insects, this will not help.
All methods work well if there are not too many whiteflies. When there is a whole colony of whiteflies on tomatoes, such methods will not give the maximum effect.
