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.
Folk tricks against moths
Whiteflies can be exterminated without chemicals
Many gardeners who do not want to treat their future harvest with chemicals prefer to use folk remedies and methods to destroy whiteflies on tomatoes.
Garlic
You can fight the pest with garlic tinctures, which are made from 100 grams per liter of water. The garlic solution is infused for treatment for 5 days in a closed container, and then the tomato bushes are sprayed with it.
Yarrow
Plants infected with whitefly can be treated with infused yarrow. It is brewed at a ratio of 80 grams per liter of boiling water. It is recommended to wipe large leaves with cotton pads, and spray small leaves with infusion.
Soap
Along with garlic, another folk remedy against whiteflies is effective - simple laundry soap, which is grated and diluted in water at room temperature in a ratio of 1 to 6.
Low temperatures
Among the folk measures that have a detrimental effect on the life of the pest and its larvae is a decrease in temperature. For cold-tolerant tomato varieties, moving tomato plants out of the greenhouse can be an effective way to get rid of insects.
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.
Sooty fungus successfully develops on the sugary secretions of pests, which manifests 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.
The most effective means to combat whitefly
Damage from insects: loss of crops, death of plants, development of diseases (butterflies are carriers of bacteria and viruses) and the appearance of fungi. Vegetable or garden crops are harmed by imagoes and whitefly larvae.
On a note! The larva is an active pest. The caterpillar attaches to the inside of the leaf and feeds on plant juices.
To reduce the negative consequences or avoid them altogether, you will need an effective whitefly remedy. There are 4 groups of methods: folk recipes, agrochemistry, mechanical, biological methods.
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.
Symptoms of plant damage
The main signs of damage to tomatoes by insect pests:
- The growth and development of the plant is noticeably reduced, in the absence of obvious signs of damage.
- The presence of white midges when touching the plant and its leaves.
- The presence of larvae similar to scale insects under the leaf.
- Sticky substance on leaves.
- Curling, yellowing and falling leaves.
- The appearance of black and gray spots on leaves, stems and fruits.
Having discovered these signs, you need to urgently take measures to get rid of the pest.
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” is a 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.
- " Actellik " based on pirimiphos-methyl - is 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.
Possible damage
The whitefly is a carrier of dangerous and incurable viral diseases.
In the future, the plant may suffer from chlorosis, curling, and jaundice, which will cause deformation of tomato seedlings and fruits.
Large infestations of this insect pest lead to the death of seedlings and crops.
The appearance of whiteflies on tomato seedlings is a great disappointment for the gardener, a signal to find ways and begin to combat the pest. The insect will not disappear on its own and, having finished with the tomatoes, will settle on other plants.
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.
Whitefly prevention
Preventative work to protect plantings must be carried out regularly. First of all, this is a regular inspection of plants. By paying attention to every 5-7 bushes, you can determine whether there is a lesion or not. This should be done at least once a week, and when the windows and doors of the greenhouse will be opened often, every other day.
Butterfly larvae can land in beds with infected seedlings or untreated tools and work clothes. To avoid this, before planting, it is advisable to treat young sprouts in a rich pink solution of potassium permanganate; you can also water the holes with it. It is recommended to use a separate tool for the greenhouse and also process it regularly.
One way to prevent infection is to comply with planting standards. The denser the plants are, the more favorable the environment for whiteflies will be created. Adequate ventilation is also of great importance. It is necessary that the air does not stagnate.
Take note! If mosquito nets are installed on the windows and doors of the greenhouse, the butterfly will not be able to fly inside.
Preventive measures to protect the garden from whiteflies
Whiteflies can live and reproduce indoors and outdoors. After winter, the insect can enter the greenhouse along with the seedlings.
When purchasing planting material, it is recommended to carefully check all the leaves and stems of the plant. The pest can climb into the cracks of the greenhouse for the winter, so such places should be carefully treated.
Planting density and excessive watering are the main reasons for the appearance of whiteflies in the garden.
The insect can switch to planting material from indoor plants. It is recommended to regularly inspect all home flowers, and periodically disinfect tools and containers for planting. To minimize the influence of insects, you need to plant plants correctly, respect the proximity, and avoid crowding.
