Spider mites on tomatoes in a greenhouse: signs of damage, photos, control measures

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Published: 06/10/2019

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Every vegetable grower has to deal with a variety of pests that strive to destroy the crop. One of the biggest problems that calls into question not only the availability of crops, but also the very existence of plants is the invasion of spider mites on tomatoes and other vegetable crops.

This arthropod insect was first described in the mid-19th century; since then, scientists have proposed more than 50 classification options for the spider mite or Tetranychus urticae. But such a detailed description did not in any way contribute to the search for a 100% effective remedy to combat it.

You should not think that the appearance of Tetranychus urticae on your land is an absolute death sentence for your plantings and harvest. If you recognize the presence of the enemy in time and take action, you can still get rid of spider mites on tomatoes.

• 1 How does infection occur?
• 2 How to detect it?
• 3 Control methods

Why are spider mites dangerous on tomatoes?

Every gardener knows that tomatoes are a very capricious crop. The main danger for tomatoes is that the insect feeds on the sap of the plant, gradually sucking all the vitality out of it. Plant death occurs suddenly.

Parasites live in colonies and remain in the soil, contaminating it with their presence. Further seedlings that are planted on the ground with mites are already doomed in advance.

Typically, ticks immediately attack greenhouses, because there are favorable conditions for their existence. The result of such attacks is the complete destruction of the crop.

Causes and signs of infection

The appearance of a spider mite is indicated by the web on the leaves of a tomato, and it is very difficult to detect the pest itself. This is due to its small size, which is no more than 0.6 mm. This mite can only be seen clearly under a microscope. Its body has an oval shape and soft covers. The color of adults can be bright red or reddish-brown, while the larvae can be light green or brownish-green with clearly visible dark spots on the sides.

The spider mite is omnivorous and can infect more than two hundred species of plants. Prefers low humidity - no more than 50% and high air temperature - about +28...30°C. These parasites overwinter under fallen leaves or simply go into the soil. With the onset of spring, they crawl to the surface and develop throughout the warm season.

Spider mites can penetrate tomato beds in several ways:

• if last year, after harvesting, you did not bother to destroy weeds and the remains of cultivated plants, then the pest could survive the winter under them, and in the spring attack young shoots with renewed vigor;
• if wildflowers grow in close proximity to tomatoes, then the spider mite could migrate from them;
• the substrate in a new area or in a nearby bed may also be infected with the pest.

There are actually quite a few ways of infection, and the situation is complicated by the fact that the parasite, due to its small size, is not immediately detected.

Spider mites usually attach themselves to that part of the bush that is very close to the ground, or on the lower surface of the leaves!

By feeding on the juices of plants, the mite draws out all the nutrients from them, which immediately affects the condition of the crop. The foliage is the first to be damaged - white and yellow dots appear on it, which are puncture sites. Afterwards, a cobweb appears on the leaves of the tomato, and if the infection is severe, it can spread further throughout the plant: to the stem, flowers, and fruits. And if steps are not taken to eliminate the problem, the foliage will soon completely fall off and the crop will die.

Causes of the pest

Basically, spider mites appear in places where comfortable living conditions are created for them. Greenhouses and greenhouses are an ideal place both for living and breeding, and for overwintering a colony. For complete comfort they need a temperature of +22 to +25 degrees Celsius and low humidity up to 60%.

The pest can enter the soil along with the transplantation of infected seedlings, in which case the soil is affected for several seasons. Most often this happens if ready-made seedlings were purchased. It may also be that seeds or seedlings are planted in already contaminated soil. After all, spider mites hide all winter at a depth of 3 meters.

Another common reason for the appearance of this pest in your garden may be the presence of nearby wildflowers that are infected with the parasite.

How does infection occur?

Spider mites on tomato seedlings can appear due to a number of reasons:

• adult parasites and their eggs are carried by the wind;
• ticks can travel by accidentally catching on the fur of animals, bird feathers, human clothing, and even the legs of large insects;
• parasites may be present in the soil and attack the seedlings as they begin to develop;
• Ticks can crawl from an infected bush to a healthy one.

These arthropods are most often brought into greenhouses by the wind or arrive with contaminated soil.

Signs of tick infestation

Spider mites on tomatoes do not have wings or antennae. He has 4 pairs of legs. Females are slightly larger than males and reach a size of 0.5 mm. Males have an elongated body and are yellow-green in color, their size reaches 0.4 mm. The eggs of these insects are yellowish and translucent, so it is almost impossible to see them.

Ticks are practically omnivorous and, in addition to tomatoes, readily destroy melons, eggplants, cucumbers and other plant crops. They live mainly in greenhouses and greenhouses. This is due to the ideal conditions that form inside. Arachnids overwinter three meters deep in the ground, under greenhouse boards or under plant waste in open ground.

In the advanced phase, a sign of damage will be the presence of thin and dense cobwebs on the leaves.

You definitely have spider mites in your garden if you have the following symptoms:

1. Whitish dots appear on the main veins of the leaves, which subsequently turn yellow.
2. The same dots may appear on plant stems.
3. The lower leaves curl at the edges and then dry out.
4. Small grayish lumps, similar to specks of dust, accumulate on the reverse side of the leaf.
5. The appearance of a thin, dense cobweb throughout the plant.
6. Lack of flowers.
7. The plant dries out despite regular watering or spraying.

Note! After you see the web, you must immediately take measures to combat spider mites in the greenhouse, dig up the plant and burn it in a remote place. And also cultivate the soil nearby.

Differences from other pests

Signs:

• white small dots on the back of the leaves;
• the leaves of the plant dry out;
• the presence of a delicate white cobweb on seedlings;
• very few flowers on the plant;
• frequent watering does not produce results;
• the reproduction process begins earlier than in other pests.

Pest control methods

Before starting to treat plants, it is worth choosing the optimal and effective way to combat spider mites. To do this, it is necessary to assess and take into account the degree of contamination of the site.

When taking measures to combat spider mites on tomatoes, it is worth paying attention to their maturity and the possible source of infection.

Below we will introduce you to the most effective means of combating this pest. It is a representative of arachnids, so standard remedies for garden parasites will not work.

Chemicals

Acaricides or insectoacaricides should be used against an almost invisible enemy. During the period when the plant begins to bear fruit, you should not treat it with chemicals. Disinfection with strong poisons should be carried out at least 2-3 weeks before collection.

For chemical treatment, you can choose one of the following drugs:

• Neoron;
• Anti-mite;
• Aktellik;
• Fufanon;
• Sunmite;
• Aktofit;
• Spark – BIO;
• Flumite;
• Borneo.

The method of application is identical for everyone. First, a solution is prepared, which is then used to spray the tomatoes themselves. It is imperative to disinfect the soil near the planting. The walls of greenhouses and greenhouses should be treated at the same time; experienced gardeners prepare for the season and spray them in advance.

It is better to apply a loading dose of drugs immediately in order to prevent further proliferation of pests.

Worth remembering! Spider mites develop immunity to certain chemicals.

Biological methods

Unlike toxic chemicals, biological control of spider mites on tomatoes in a greenhouse is safe and non-toxic. They should be used when the situation is not critical, as they act more slowly and less aggressively. But the safety of the future product and the effectiveness of its impact are excellent.

There is a good Russian proverb “they knock out a wedge with a wedge”; it applies to one of the methods of getting rid of parasites. It is necessary to release predatory mites into the area. Such insects will destroy their relatives and free the garden from harmful parasites. Another advantage is that predators feed not only on adults, but also on eggs, which means that next season the problem can be forgotten.

In addition to the army of carnivorous mites, you can declare a full-fledged biological war on pests. To do this, you need to purchase special products that contain special bacteria that infect spider mites. The following drugs are particularly effective:

• Akarin;
• Phytofarm;
• Krafi;
• Mites.

Biological agents can be used at any stage, during flowering and fruiting too.

How to detect it?

Most often, this pest is found in greenhouses, but it also feels very good in open ground. It prefers tomatoes, but can also parasitize other vegetable crops. It literally sucks the juices from plants, which leads to weakening of the crop, cessation of its growth and death.

The presence of this unpleasant parasite on plants can be detected by the following signs:

• discolored areas of leaves appear on the foliage of plants; over time, the coloring becomes not monochromatic;
• the leaves become covered with transparent dots and over time completely dry out and fall off;
• barely noticeable cobwebs appear on the bushes.

You can only see the tick itself through a magnifying glass, since its size does not even reach 1 mm in length. The insect itself is located on the back (bottom) side of the leaves.

Folk remedies

Folk remedies will be an excellent alternative to various poisons in the fight against mites on tomatoes. Such remedies for mites on tomatoes have been tested for centuries and many generations, so there is no doubt about their effectiveness.

Laundry soap

Ordinary laundry soap should be dissolved in hot water. To make the process easier, you can grate it. Observe the proportions: for 100 g of soap, 1 liter of water. After this, pour water into a spray bottle and gently spray the leaves of the infected plants.

After some time, it is worth spraying the same plants with clean water so that they do not suffocate. Repeat the treatment after a few days to consolidate the effect.

Do not water the soil around the tomatoes, only the leaves and stems as needed.

Garlic

This method of controlling spider mites is effective in the early stages of damage.

There are several recipes for the infusion:

1. 30 g of chopped garlic is poured into 10 liters of hot water and left for 24 hours. After straining, it is necessary to spray the leaves of infected plants.
2. Chop 500 g of garlic and add 3 liters of water at room temperature. Infuse for 5 days in a dark place, after which be sure to strain the infusion. Use 50 ml of infusion per 10 liters of water and spray the plants.
3. For emergency disinfection, mix 200 g of chopped garlic in 10 liters of water. Plants can be treated with this solution immediately.

For prevention purposes, you can plant garlic next to tomatoes; spider mites do not get along next to them.

Onion peel

Onions are extremely unpleasant for the parasite. In order to make an effective decoction, you will need 200 g of onion peel per 10 liters of warm water. The mixture is infused for 12 hours in a warm place, then filtered, and everything is ready for spraying.

Makhorka

Shag can be used in 2 ways: to fumigate plants or to irrigate. To prepare the infusion you will need 200 g of shag, 20 liters of water and 50 g of soap. You need to infuse 10 liters of water in shag for 24 hours, then filter, boil the broth and add soap to it. After this, dilute the infusion with another 10 liters of warm water.

Next, after thorough mixing, you can carry out the spraying procedure. Fumigation is carried out in a standard way.

Henbane

Black henbane is widely known for its poisonous properties. The high level of toxicity of this plant will help in the fight against parasites. It will not be possible to dry henbane, because it quickly loses its properties while in a jar or bag.

To prepare the decoction, you should collect 3 kg of fresh plant, preferably during flowering. Then you need to boil the herb in 7 liters of water in an enamel pan for about 2 hours. Strain the broth and it is ready for spraying.

If you still use dried henbane, then 10 liters of water will require 1 kg of plants. The solution should be infused for 12 hours, and then add a little laundry soap for better effectiveness.

Alcohol

There are many opinions about how to properly treat plants with alcohol. Some gardeners say that it is necessary to dilute this product before spraying so as not to injure the plant. However, this is a serious misconception.

Tomatoes should be treated with 96% alcohol in low humidity conditions. Only in this case will it quickly evaporate from the surface of the leaves and not cause harm. If you dilute the concentrate, the substance will slowly evaporate and penetrate into the pores of plants along with moisture, thereby corroding their tissue.

Treatment should be carried out for 4 weeks in a row, once every 7 days.

Agrotechnical measures

If the pest does reach your garden, you need to take a number of measures to repel the parasite from your tomatoes:

1. Supplementary irrigation. As you know, mites do not like excess moisture, so additional watering will immediately rid you of pests. But it is important not to overdo it with this method, otherwise the crop will simply drown.
2. If you notice an infected bush, it should be dug up and burned immediately. You need to do the same with fallen dry leaves. This method is good if the affected area is single.
3. In autumn or spring, the soil should be dug up and fumigated with sulfur. After these activities, it is worth leaving the greenhouse closed for 5 days, and after a specified time, ventilate for 2 days.
4. Chemical treatment of all parts of the greenhouse and soil after harvest will save you. The soil must be treated with chemicals before the onset of winter. The walls of the greenhouse also need to be sprayed with compounds, dried and reinstalled.

Note! Try to chemically treat the area before planting tomatoes or after harvesting.

How to treat a greenhouse

You can say goodbye to the pest once and for all only with a comprehensive confrontation with it. Therefore, I do not forget about processing not only during the season, but before it begins and after it ends.

How to get rid of spider mites in a greenhouse in the spring

In the spring, any greenhouse needs general cleaning and disinfection. I conduct simple traditional events:

1. Deep digging of the substrate.
2. Disinfection by pouring boiling water. To prolong the effect that is destructive for eggs and larvae of pests, I cover the soil after watering with a thick film. The hot steam will continue to have a derogatory effect.
3. Disinfection with manganese solution. I water the greenhouse substrate with a 1% suspension of potassium permanganate.

If ticks settled in the greenhouse last summer, preventative fumigation with a sulfur bomb would not be amiss.

autumn digging in the greenhouse

How to get rid of spider mites in a greenhouse in the fall

At the end of the season, I turn to a simple treatment:

1. I remove and destroy all plant remains - tops, roots, fruits.
2. I disinfect auxiliary structures - trellises, pegs, garters - with a solution of potassium permanganate.
3. I wash the interior surfaces of the greenhouse with a chlorine solution.
4. I carry out a deep digging of the earth, having previously scattered lime or phosphate preparations over the ridge. These fertilizers have a negative effect on spider mites.

If arachnids have settled in the greenhouse in the summer, I turn to additional treatment:

1. I wash the internal surfaces and glass with a 20% alcohol solution.
2. I treat the soil with a solution of colloidal sulfur (100 g per 10 liters of water).

To reach hard-to-reach places, I spray all secluded places and recesses in the greenhouse with disinfectant solutions from a sprayer. All kinds of pests often stay there for the winter.

Preventing the appearance of spider mites on tomatoes

The best way to combat spider mites is to prevent their occurrence. After all, if you do not allow the parasite into your garden, then there will be no problems with its removal and loss of harvest. Here are a few rules that can prevent the appearance of this insect:

1. Plant seedlings at a distance of at least 25 cm from each other. Too frequent planting promotes the development of mites and increases the likelihood of complete destruction of the crop.
2. Avoid weeds and weed the area frequently.
3. After harvesting, be sure to remove the remaining tops and dig up the soil, otherwise you will create an ideal place for overwintering ticks with your own hands.
4. Plant crops next to tomatoes where spider mites cannot survive: garlic, dill, celery, calendula, basil.
5. Try not to use nitrogen supplements, since it is this element that creates favorable conditions in the soil for the proliferation of spider mites.
6. The insect does not tolerate phosphorus, so the soil in which root nutrition is organized with this element will not allow the appearance of parasites.

The best preventive measure would be good, comprehensive garden care. A weakened plant that lacks something will certainly be attacked by mites.

Prevention

To prevent the appearance of such a difficult pest as spider mites, you need to regularly carry out preventive measures.

All debris and dead parts of plants must be promptly collected and thrown away from the soil surface.

Prevention

Twice a year, treat the soil with chemicals or water it with hot water.

In the fall, after harvesting the greenhouse, it is necessary to carry out general cleaning with thorough treatment of all surfaces and all garden tools.

The seedlings are carefully examined before planting, and if spider mites are found on the tomatoes, they are discarded (the photo shows the most characteristic signs).

When planting in the ground, they try to make a sufficiently large distance between the bushes.

Fertilize the soil, following the measure and recommendations for applying fertilizers (the appearance of mites is facilitated by an overdose of nitrogen-containing agents and a lack of phosphorus-containing agents).

Mistakes of novice gardeners

Inexperienced gardeners make mistakes that will later become critical for the entire harvest. Here are examples of the most serious violations:

1. Reuse of prepared chemical solutions.
2. The desire to cure a plant at a critical stage. After you notice a cobweb, the bush must be immediately removed and the soil under it disinfected.
3. The use of cheap chemicals from previous generations that harm humans, the soil and the plants themselves.
4. Excessive moisture when signs of damage to tomatoes are detected.

Before using chemical agents, carefully read the composition and conditions of use so as not to harvest a poisonous crop later.

Effective folk and chemical remedies for spider mites

Spider mites are a very unpleasant parasite that is difficult to remove and difficult to detect. If you grow tomatoes, be sure to check the backs of the plants' leaves. Maintain conditions of acceptable humidity, which will be fatal to the insect. Try to heat-treat the soil for seedlings, this will prevent the appearance of uninvited guests. Remember, it’s easier to keep any parasite out of the garden than to remove it!