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Greenhouses and covers

Biological methods of protecting greenhouse crops from pests and diseases

For gardeners

13 min read

GREENHOUSES AND COVERS G

The success of protecting vegetable crops from pests begins with prevention. On shaded and humid sites, the risk of disease infection is always higher, so choose open, well-ventilated locations for planting. To grow a harvest free of harmful substances, it is necessary to refrain from using chemicals. If pests appear on the plantings, the plants are sprayed not with herbicides, but with infusions and decoctions of insecticidal crops or harmless preparations. Their toxic effect on insects and pathogens is due to the presence of alkaloids, glycosides, esters, and essential oils.

Collection, drying, and storage of plant material

To achieve maximum toxicity of the material, it is important to strictly observe the timing of its collection. The aerial parts of insecticidal plants are harvested during their flowering period. Underground organs, such as tubers and rhizomes, are dug up in early spring or late autumn. Properly harvested material retains its properties for a long time if storage conditions are met.

  1. Collect the aerial parts of plants during the flowering period when they are most toxic.
  2. Harvest tubers and rhizomes in early spring or late autumn.
  3. Spread the collected plants in a thin layer on fabric or paper in the shade under a cover for drying.
  4. Periodically stir the material to prevent caking.
  5. Place the dry material in paper or fabric bags and store in a cool, well-ventilated room.
  • Shelf life of dried herbs — 1 year
  • Shelf life of fruits and seed — 2 years
  • Soap consumption for adhesion — 40 g per 10 l
  • Application frequency for onion — no more than 3 times

Recipes for working solutions and application methods

The effectiveness of plant-based preparations depends on correct dosage and adherence to the technology for preparing infusions and decoctions. To improve the adhesion of solutions to leaves, laundry soap is added to the strained mixture before application. Some insecticidal crops are used not in the form of spraying, but for physically repelling pests or for preventive planting in row spacings. When working with poisonous plant species, be sure to observe personal safety measures.

Black henbane, poison hemlock, and thorn apple are extremely poisonous. The infusion of poison hemlock should be kept exclusively in a tightly closed container, in a cool and dark place.

Insecticidal crop Effective against which pests and diseases Recipe and application specifics
Marigolds Aphids, damping-off (on aster and stock seed plants), diseases of gladiolus corms before planting. Cut completely during the flowering period and dry. Grind 1–2 kg of material, place in an enameled bucket, fill to the brim with warm water, and infuse for two days. Strain, add 40 g of laundry soap. For gladioli: immerse corms in the solution for 8–10 hours before planting.
Black henbane Aphids, psyllids, spider mites, plant-feeding bugs, caterpillars of hawthorn, brown-tail moth, cabbage white butterfly, and moth. Infusion: pour 10 l of water over 1 kg of crushed dry plants, infuse for 12 hours. When using powder, roots, or rosette leaves, reduce the material rate by half. Strain, add 40 g of soap for every 10 l of solution. Decoction: boil the material in the same proportions for 30 minutes, cool, and strain. Dry powder can be used to dust the plantings.
Poison hemlock Young caterpillars and larvae of sawflies. Crush leaves, inflorescences, unripe fruits, and small stems. Soak in water at a rate of 1 kg of material per 1 l of water. Grind to a pulp consistency, squeeze out the liquid. Pour 15 l of water over the pulp, stir, and squeeze again. Combine both liquids and stir before spraying.
Black and red elderberry Gooseberry fruitworm, leaf roller, codling moth, currant bud mite, rats, and mice. Against gooseberry fruitworm: stick a branch of elderberry into each bush. Against currant bud mite: before flowering, place fresh branches in water between currant bushes, changing them as they wilt. Against rodents: wrap tree trunks with black elderberry stems.
Thorn apple Aphids, spider mites, plant-feeding bugs. Prepare infusions and decoctions in the same way as from black henbane (1 kg of dry or 2 kg of fresh material per 10 l of water).
Pot marigold (calendula) Mites and root rots of strawberry. Sowing plants in the row spacings of strawberries.
Potato haulm Spider mite, aphids. Collect green haulm not affected by diseases. Grind 1–2 kg of fresh or 600–800 g of dry haulm, pour 10 l of water, and infuse for 3–4 hours. Use the freshly prepared infusion.
Onion Aphids, meadow bugs, owlet moth caterpillars, cereal leaf beetles, common earwig, spider mites, psyllids, codling moths. Recipe 1: pour 10 l of warm water over 200 g of onion skins, infuse for 4–5 days, strain. Spray every 5 days, but no more than 3 times. Recipe 2: fill a bucket halfway with skins, pour hot water over them, infuse for 1 day, strain, dilute with water 1:2.

Using botanical insecticides makes it possible to completely eliminate the accumulation of toxic residues in vegetables and berries, keeping the future produce pure and safe.

Insecticidal infusions and decoctions from wild herbs

The use of wild herbs allows for effective control of pest populations without the risk of pesticide accumulation in produce. Active ingredients of these plants—alkaloids, glycosides, and essential oils—start working immediately after application. To achieve the maximum effect, treatments should be carried out using freshly prepared mixtures, strictly observing dosages and intervals. This is especially important in greenhouse conditions, where high humidity and temperature can accelerate the breakdown of natural toxins.

For protection against codling moth, spraying is performed immediately after flowering at sunset. The ambient temperature during treatment must be at least 15 °С. The procedure is repeated every 7 days for a month.

  • Temperature for codling moth treatment — at least 15 °С
  • Dried chamomile consumption — 1 kg per 10 l of water
  • Dandelion infusion time — 2–3 hours
  • Sow thistle infusion time — 8–10 hours
Plant raw material Target objects (pests, diseases) Working solution preparation recipe Treatment schedule and frequency
Burdock (crushed leaves) Cabbage moth, white butterfly, and moth caterpillars Fill a bucket 1/3 full with crushed leaves, fill to the top with water, and let infuse for 3 days. Spray 3–4 times at intervals of 5–7 days.
Leafy spurge (leaves and stems, cut immediately after flowering) Leaf-eating caterpillars (cabbage and turnip white butterflies, moth, owlet moth) Boil 4 kg of crushed raw material for 2–3 hours in 3–5 l of water, strain, and top up with water to 10 l. Perform spraying 2 times at an interval of 4 days.
Common dandelion (rhizomes and green leaves) Aphids, mites, psyllids Pour 10 l of water over 200–300 g of crushed rhizomes and 400 g of green leaves, let infuse for 2–3 hours, then strain. Treat with a fresh solution. If pests are present, repeat several times at intervals of 10–15 days.
Perennial sow thistle (crushed stems and leaves) Powdery mildew Infuse 350 g of plant material in 1 l of water for 8–10 hours. Perform 3–4 abundant sprayings at intervals of 4–6 days using a freshly prepared infusion.
Common tansy (crushed raw material) Apple codling moth, psyllid, blossom weevil Crush 700–800 g of dried or 2–2.5 kg of fresh plants, fill a bucket with water to the brim, and let infuse for 2 days. Boil for 20–30 minutes, strain, and dilute with an equal amount of cold water. Perform 3–4 treatments at intervals of 5–6 days in the evening.
Wormwood (well-wilted plants) Leaf-eating caterpillars Boil 1 kg of raw material in a small amount of water for 10–15 minutes, cool, strain, and top up with water to 10 l. Spray at 7-day intervals until pests are completely eradicated.
German chamomile (leaves and flower heads) Sucking pests (mites, bugs), sawfly larvae, young caterpillars Grind dried raw material into powder, add water at a rate of 1 kg per 10 l, and let infuse for 12 hours. Before use, add 40 g of laundry soap. Spray when pests are detected.
Common yarrow (aerial part, harvested at the beginning of flowering) Aphids, psyllids, small caterpillars Steam 800 g of dried and crushed raw material with boiling water for 30–40 minutes, then bring the volume to 10 l with water and let infuse for another 40 minutes. Spray when pests appear.

Protective agents based on vegetable crops, pine needles, and tobacco

Garden crops, tobacco industry waste, and pine needles allow for the quick preparation of working solutions directly on the farm. The high concentration of phytoncides in needles and alkaloids in nightshades provides a pronounced insecticidal and repellent effect. Some preparations based on them can be stored for future use, which saves time during periods of mass pest flight. When planting companion plants, the protective effect is achieved through the constant release of volatile substances.

Plantings of garden or curly parsley act as a natural repellent. A border of parsley reliably protects strawberries from snails, and planting it under grapevines repels a dangerous pest — phylloxera.

To control sucking pests, small larvae, beetles, and caterpillars, a decoction of bittersweet nightshade works perfectly. This concentrate is convenient because it can be prepared in advance and stored in a tightly closed container.

  1. Pour 10 l of water over 5–6 kg of fresh nightshade raw material and let it infuse for 3–4 hours.
  2. Boil the mixture over low heat for 3 hours, cool, and strain thoroughly.
  3. Pour the finished decoction into glass jars with tight lids and leave to store in a dark, cool place.
  4. Before use, dilute the concentrate with water in a 1:2 ratio and add laundry soap at a rate of 40 g for every 10 l of the finished solution.
Plant-based raw materials Target objects (pests, diseases) Working solution preparation recipe Application schedule and specifics
Bulb onion Psyllids Grind 200–300 g of onion, dilute the mass in 10 l of water, and leave to infuse for 2 days. Apply only with a freshly prepared solution.
Hot chili pepper Leaf-eating caterpillars, aphids, slugs Boil 100 g of finely chopped pods for 1 hour in 1 l of water in a covered container, leave to infuse for 2 days. Mash the pepper, squeeze, and strain the decoction. Add half a glass of the decoction and 40 g of laundry soap to 10 l of water. Store the concentrate in a dark place, perform spraying as pests appear.
Scots pine (freshly cut annual shoots and needles) Aphids, psyllid, codling moth, leafroller, strawberry gray mold Method 1: Infuse 12 kg of needles or shoots for 5–7 days in 8 l of water in a dark place, stirring daily. Dilute with water 1:10 before spraying.
Method 2: Pour boiling water over the needles in a 1:1 ratio in a bucket under a lid. The next day, dilute with water 1:5.		 Spray every 7–10 days for one month.
Tobacco infusion (tobacco waste) Aphids, thrips, spider mites Pour 10 l of hot water (60–70 °C) over 1 kg of tobacco waste and infuse. Before spraying, dilute with water 1:3 and add 40 g of laundry soap per 10 l of solution. Treat upon the appearance of pests.
Tomato vines (suckers and vines) Sucking and leaf-eating pests of vegetable crops, cabbage moth, cabbage white butterflies, aphids Boil 1 kg of chopped vines in 10 l of water for 30 minutes, cool down and strain. For spraying, take 2–3 l of the prepared decoction, top up with water to 10 l and add 40 g of laundry soap. Treat as needed when pests are detected.

Before spraying, add 40 g of laundry soap.

\ Garlic infusion. Use it against mites and aphids. To prepare the solution, pour 10 l of water over 150-200 g of minced garlic, leave to infuse for 1 day, strain and perform spraying immediately.

Against such diseases of tomatoes and potatoes as late blight, macrosporiosis, and streak, use a garlic extract (30—50 g of crushed cloves per 10 l of water).

Treat potatoes at the beginning of flowering, and tomatoes — during the fruit set period. Perform the treatment 2-3 times every 10-15 days.

Greater celandine. Use in the fight against aphids, psyllids, thrips, scale insects, caterpillars, small white butterflies, cabbage butterflies, and other pests.

To prepare the infusion, take 3—4 kg of fresh or 1 kg of dry plants, leave to infuse in 10 l of water for 24-36 hours. Spray the plants with this infusion.

Powder made from dry celandine can be used for dusting against flea beetles and psyllid.

Horse sorrel. Used against aphids and cruciferous bugs on radishes and cabbage/radish seed crops.

To prepare the infusion, take 300—400 g of celandine roots harvested in autumn, leave to infuse for 2 hours in 10 l of warm water, strain, and spray the planting area.

Horseradish. Use against aphids and mites. Use cuttings, leaves, and roots.

For the infusion, grind the horseradish in a meat grinder, fill a bucket 1/3 full with it, pour water to the brim, stir, and leave to infuse for 1 hour. After this, you can proceed with spraying.

Besides this, a mixture of cow manure, rotted hay, or manure can be used to fight powdery mildew. Pour 3 l of water over 1/3 of a bucket of cow manure, leave to infuse for 3 days, top up with water to 10 l, strain, and spray the plants with this infusion. Repeat the treatment after 10—15 days by preparing a fresh infusion.

Decoctions and infusions can also be prepared from milkweed, dandelion, chamomile, horse sorrel, burdock, and other plants. Vegetable crops can be treated with such solutions up to five times during the growing season, preferably in the evening, as most of them lose their toxic properties in sunlight.

Plants used for pest control in vegetable crops can be harvested in advance and used the following year. Collected plants are tied into small bundles, dried in the shade, and stored in paper bags or cardboard boxes. For preparing infusions and decoctions, dry raw materials will require half the amount compared to fresh ones.

The mole cricket is a major pest of vegetable seedlings. With its powerful rake-like limbs, it cuts off young shoots, causing plants to die. It lives in the soil, and it can be very difficult to detect. Nevertheless, a method for controlling the mole cricket has been found. It cannot tolerate the smell of chrysanthemums. When planting tomatoes, a handful of dried flowers or leaves is placed in the holes, which ensures the survival of the growing transplants. And if chrysanthemums are planted between vegetable crops, the mole cricket will not breed its offspring in such garden beds.

To eliminate mole crickets, the following poisonous mixture is successfully used: a thick porridge is cooked from 1 kg of millet, to which 2 tablespoons of sugar and two teaspoons of one of the pesticides are added, and everything is mixed well. Shallow furrows are made between the rows of potatoes, tomatoes, or eggplants, the porridge is laid out, and covered with soil. The mole cricket soon crawls to the surface and dies. The value of this method also lies in the fact that it can be applied in spring — before the planting of vegetable crops, thus protecting the future harvest.

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