How to destroy whiteflies on tomatoes: proven methods and methods of prevention
Tomatoes can die from whitefly infestation within 12-14 days. Knowledge of biological features and weak points will help save plantings from a small insect that is dangerous for many crops. pest.
For a detailed description of the pest, how and how to destroy whiteflies in a greenhouse on tomatoes, read the article.
What is whitefly
Whiteflies, or aleurodids, belong to the family of small homoptera insects. There are about 1,550 species of whitefly.
Greenhouse or hothouse whitefly poses a danger to tomato plantings.
The pest is widespread. Infection occurs from imported plants, less often - as a result of independent flights.
For the development of the insect, a warm, humid climate is necessary, so the whitefly appears mainly in greenhouses and greenhouses. Under favorable weather conditions, moths in temperate latitudes begin to appear in mid-June. The whitefly remains constantly active only in the southern regions.
Biological features
From egg laying to the appearance of mature whiteflies, it takes from 22 (at +24 ºС) to 60 (at +12 ºС) days. The most favorable temperature for the pest is +18 - +24 ºС. At +30 ºС, the life expectancy of moths is sharply reduced, sometimes up to four days. The lower limit for the development of embryos, larvae and nymphs is +7 ºС.
The lifespan and fertility of moths also depends on the food plant.When settling on tomatoes, the oviposition period is 15-17 days and the female manages to lay 35-40 eggs. On average, the size of the insect population increases 10 times per generation.
The life of a whitefly is divided into 4 stages: egg, larva, nymph, and mature individual (imago).
A description of each of them is given in the table.
| Stage | Where to look | Description | Duration |
| Egg | Underside of young leaves | Masonry can be crowded and scattered. The egg size is 0.2-0.25 mm, attached to the surface of the leaf with a thin stalk. At the initial stage it is pale green in color. After 1-2 days it turns brown until the end of embryo development. | 7 – 13 days |
| Larva | Bottom side of the sheet | Immediately after hatching from the egg, the size of the larva is about 0.25 mm, the body is transparent, similar to scales. She is mobile for several hours. Then it attaches to the leaf with its mouthparts and begins feeding. During its life, it releases a wax-like substance that creates a dense barrier. As it grows, the body length increases to 0.8-0.9 mm. At the end of development, it stops feeding, the body thickens, and the larva turns into a nymph. | 7 – 15 days |
| Nymph | Back of leaves | About 0.8-0.9 mm in length, whitish in color. Along the edges there are wavy bristles. At the end of the development period, a fully formed moth flies out through the formed stomata. | 10 – 16 days |
| Imago | After metamorphosing from nymphs, they remain on the same leaves, then spread up the plant | The body is white or yellowish, 1.3-1.8 mm long. The wings are white and covered with a dusty coating. Females begin to mate and lay eggs 12-20 hours after leaving the nymph. | Up to 20 days for females, 8 - 12 days for males. |
Generations of whiteflies overlap each other, so that on one plant there are insects of all stages of development: from embryos to adults.
Why is whitefly on tomatoes dangerous?
Both adult and whitefly larvae damage tomato plants.
By feeding on plant juices, the insect damages green cells. Waste products completely or partially cover the stomata of leaf blades. The processes of photosynthesis and respiration are disrupted. Growth, flowering and ovary formation slow down.
On sugary secretions pests Sooty fungus develops successfully, manifesting itself in the form of a dark coating on the tops and fruits. The mycelium clogs the microscopic breathing holes on tomato foliage and interferes with photosynthesis.
The whitefly is a carrier of viral diseases. The appearance of the insect is often accompanied by outbreaks of tomato mosaic, aspermia (no seeds in the fruit), etc.
Reasons for appearance
The whitefly most often enters the site together with infected seedlings or seedlings.
The prosperity of the pest is promoted by:
- elevated temperature (above + 20 ºС);
- high humidity;
- lack of ventilation;
- thickened plantings.
Signs of a pest infestation
The presence of whiteflies on tomato bushes is indicated by the following signs:
- White moths flutter over the beds. If you shake the plants, a swarm of insects will appear.
- On the back of the leaves, small transparent scales are visible - the larvae of the pest.
- White spots, sticky to the touch, appear on the tops - whitefly secretions.
- Leaves curl, turn yellow and fall off. The growth and formation of fruits slows down sharply.
- Dark brown spots on foliage and fruits indicate the development of sooty fungus.
Fighting methods
Methods for controlling whiteflies on tomatoes in greenhouses and open ground are similar. Only in a greenhouse it is easier to regulate the microclimate: regular ventilation will help reduce temperature and humidity.
To remove whiteflies, gardeners use insecticides and biological agents. Traditional recipes are also popular.
Biological methods
Biological methods consist of colonizing tomato plantings with natural enemies of whiteflies. The most famous entomophages are Encarsia and Macrolophus.
The use of such “biological weapons” does not harm humans, plants, or beneficial insects.
Encarzia
A representative of a large family of wasps. The adult lays eggs in the body of the whitefly larvae. The newly hatched microscopic encarsia feed on the tissues of the host’s body, and then pupate in it. The whitefly larvae turn black and mummify.
Adult encarsia feeds on the hemolymph of whitefly larvae and nymphs, destroying up to 15 pests during its life (20-40 days).
To control the number of pests, five individuals per 1 m2 are enough.
Cages with encarsia pupae are hung around the greenhouse. After about a day, the mature entomophages emerge and begin to destroy the whitefly.
Macrolophus
This predatory bug feeds on pest larvae and eggs.
The lifespan of an adult insect is 25-30 days. During this time, the bug eats up to 2500 whitefly larvae and 3500 whitefly eggs. Also, the presence of macrolophus helps remove aphids. To destroy and curb the growth of pests, 4-6 individuals per 1 m2 are needed.
Live predators are sold in special bottles with a nutrient substrate. They are released evenly over the entire planting area.
Important! Entomophages are released in the evening and in calm weather. It is necessary to populate living organisms into the beds no later than 18 hours after purchase.
For the development of encarsia and macrolophus, temperatures of 25-27 ºС and humidity of about 70% are favorable, so they are used mainly in greenhouses.
The effect of the activity of beneficial predators appears gradually. Biological methods are best used as prophylaxis or in the initial stages of whitefly infection.
Chemicals
Pesticides are effective in the fight against whiteflies, subject to two simple rules:
With a single treatment, as a rule, only larvae and adults die - the eggs remain viable. Therefore, after 7-10 days, repeat spraying is carried out.
Insects quickly adapt and develop resistance to “chemistry”. To avoid this, drugs are used only in the doses indicated in the instructions and do not use the same drug during the season.
On a note. In case of significant damage, in order to destroy newly hatched whitefly larvae, it is useful to release the entomophages a week to a week and a half after treatment with chemicals.
Examples of popular powerful drugs against whiteflies:
- "Fitoverm" — 5% aqueous emulsion of aversectin C. It has a nerve-paralytic effect, the death of pests occurs 1-3 days after treatment. Does not cause resistance, safe for humans. Spraying is carried out 2-3 times during the growing season with an interval of 14-20 days. The harvest can be harvested 3 days after treatment.
- «Aktellik"based on pirimiphos-methyl - available in the form of an emulsion concentrate, packaged in ampoules of 2 and 5 ml. Causes paralysis and almost immediate death of pests.Dangerous for humans and bees. Apply no more than twice per season. The waiting period before harvesting fruits is at least 30 days after the last treatment.
- «Aktara»—contains thiamethoxam. 15 minutes after treatment, the insects stop feeding and die within 24 hours. It goes on sale in the form of water-dispersible granules and concentrated suspension. Low danger to humans. Dangerous for bees. Used for root watering and spraying of plants. Can be used once. It is recommended to harvest the crop no earlier than three days after using the drug.
Important! When working with chemicals, strictly follow the instructions and observe safety precautions.
Folk recipes
For preventive purposes and with a small number of pests, experienced vegetable growers recommend treating tomatoes with folk remedies.
Popular tinctures for whitefly:
- Garlic. 15 g of crushed garlic cloves are poured into 100 ml of water and left for 5 days. For spraying, 5-6 ml of the resulting concentrate is diluted in 1 liter of water.
- From yarrow. 200 g of chopped herbs are poured into 3 liters of boiling water and left for 2 hours. Strain and spray the tomato bushes.
- Tobacco. 100 g of tobacco or shag are infused in 1 liter of water for two days, filtered and the beds are treated.
When spraying, the leaves are well moistened on both sides. Infusions should be used every 3-4 days throughout the growing season.
To combat moths, special traps are effective. They are easy to make yourself. Grease a sheet of bright cardboard (for example, red or yellow) with honey or Vaseline and place it on the garden bed. The butterflies will flock to the bright bait, stick to the paper and die.
Preventive actions
To protect against the appearance of whiteflies, the following measures are effective:
- Cleaning the beds of all plant debris.
- Autumn and pre-planting preparation of greenhouses: cleaning of all garters and equipment, washing of structures and disinfection of the premises with insecticides.
- Freezing greenhouses before snow falls.
- Inspection of seedlings. Instances with signs of infection are immediately disposed of.
- Regular ventilation of greenhouses.
- Plant no more than two tomato bushes per 1 m2 for tall varieties and no more than four for medium-sized ones.
- Compliance with the regime of watering and fertilizing plants.
Read also:
How to get rid of whiteflies in a greenhouse on cucumbers.
Conclusion
The whitefly is a small butterfly that causes great damage to tomato plantings in open beds and in protected ground. By feeding on plant juices and poisoning the foliage with waste products, moths and larvae slow down the growth and formation of fruits; in advanced cases, tomatoes die. Pests cause viral and fungal diseases.
To combat whiteflies, insecticides are used and entomophages are released into the beds. Infusions according to folk recipes are effective as prophylaxis and in the initial stages of damage. Cleanliness in the beds, autumn treatment of greenhouses with insecticides, and maintaining healthy plants will prevent the appearance of whiteflies.