Pests

1. Chemical “Invitations”: Scent and Taste

The tomato plant releases a complex bouquet of volatile organic compounds into the air. To us, it may be just the aroma of fresh greenery, but to insects, it is a detailed map indicating the plant’s location and condition.

• Attractants: Many pests, especially aphids, whiteflies, and cutworms, use the plant’s scent to find food. The complex “cocktail” of terpenes and other substances serves as a “food here” signal (Blancard, 2012).
• Color and Light: Most flying pests, such as whiteflies, aphids, and thrips, are guided by color. Yellow and green are particularly attractive to them. That is why gardeners successfully use yellow sticky traps for monitoring (Blancard, 2012).
• Heat and Carbon Dioxide: Night-flying moths, for example cutworms, can detect infrared radiation and the carbon dioxide emitted by the plant, helping them locate their target in the dark.

2. Weakened Defenses: Vulnerability of “Overfed” Plants

A healthy, strong plant is better able to withstand attacks, but paradoxically, it may be the most attractive to some pests.

• Excess Nitrogen: Over-fertilization with nitrogen makes plant tissues more succulent, soft, and rich in nutrients. This is a paradise for aphids and spider mites, which prefer plants with high nitrogen content (Akhatov, 2010). An “overfed” plant is easy prey.
• Stress: Plants weakened by drought, waterlogging, or diseases become more vulnerable. For example, root-knot nematodes more actively infect roots already damaged by other pathogens or under stress (Blancard, 2012).

3. External Factors: Wind, Transport, and “Hitchhikers”

Pests rarely limit themselves to crawling from plant to plant. They have many ways to spread over long distances.

• Wind and Air Currents: Many small insects, such as whiteflies, aphids, thrips, as well as fungal spores, can be carried by wind for many kilometers. This is the main dispersal method for many species (Mattoo et al., 2017).
• With Planting Material: This is one of the most dangerous routes. Eggs, larvae, or adults of pests can be brought onto the site with purchased seedlings, seeds, or even soil in pots.
• Via Humans and Tools: When removing suckers, harvesting fruits, or weeding, the gardener themselves can carry pests from an infected plant to a healthy one. For example, the tomato leafminer and some bacterial diseases spread precisely by this mechanical route (Blancard, 2012). In addition, aphids and whiteflies excrete “honeydew,” which attracts ants. The ants, in turn, protect aphid colonies from predators, helping them survive and reproduce (Akhatov, 2010).

4. The Human Factor: Creating Ideal Conditions for Pests

Sometimes, unwittingly, we create conditions on our plots that are ideal for the mass reproduction of pests.

• Monoculture: Planting tomatoes year after year in the same place is a “goldmine” for specialized pests and diseases. For example, root-knot nematodes and Fusarium pathogens accumulate in the soil, and their numbers increase with each season (Blancard, 2012).
• Dense Plantings: Crowded planting creates high humidity and shade, weakening plants and making it easier for pests to move from one bush to another. It also reduces the effectiveness of spraying.
• Lack of Crop Rotation: Alternating crops from different families is one of the most effective ways to break the reproduction cycle of many soil-borne pests and diseases.

Conclusion:

Knowing how pests find tomatoes is the first step toward effective protection. By understanding these mechanisms, you can purposefully create conditions unfavorable for pests and apply the right preventative measures. In the next chapter, we will analyze which parts of the plant are most often affected and how that can help with diagnosis.

1. Root System and Root Collar (Underground Part)

Damage here often goes unnoticed until the plant begins to wilt. This is the most insidious group of pests.

• Larvae of Scarab Beetles (May beetles) and Wireworms (larvae of click beetles): They gnaw roots, leading to stunted growth, yellowing, and wilting. Particularly dangerous for young seedlings (Blancard, 2012).
• Root-knot Nematodes (Meloidogyne spp.): Microscopic worms that penetrate roots and form characteristic swellings—galls. These growths disrupt the vascular system, preventing the plant from getting enough water and nutrients. Signs: dwarfism, wilting on hot days, leaf chlorosis (Mattoo et al., 2017; Blancard, 2012).
• Mole Cricket: A polyphagous soil pest that gnaws through roots and stems of young plants at soil level. Plants quickly wilt and die.

Tip: If you suspect root pests, carefully dig up an affected plant and examine the root system. The presence of swellings (galls) is a clear sign of nematodes.

2. Stem

Stem damage can be both external and internal.

Internal (hidden) pests:

• Larvae of stem borers and tomato leaf miner (Tuta absoluta): They bore tunnels inside the stem, causing wilting of the top or entire branch. Holes on the stem are often accompanied by dark frass (Mattoo et al., 2017).

External (open) pests:

• Whiteflies and aphids: Although they usually settle on leaves, when numerous they can cover stems with sticky honeydew, on which sooty mold then develops (Blancard, 2012; Akhatov, 2010).

Tip: Regularly inspect stems for holes, frass, and sticky residue. Pay special attention to the lower part of the stem and the base of suckers.

3. Leaves

This is the most visible part of the damage. This is where the main signs of the “work” of sucking and leaf-chewing pests manifest.

Sucking pests (aphids, whitefly, thrips, mites): They pierce leaf tissues and suck out sap. External signs:

• Deformation: leaves curl, wrinkle (especially from aphids) (Blancard, 2012; Gavrish, 2005).
• Discoloration: fine light spots (thrips and mite stippling), mosaic patterns (with viral infections transmitted by aphids and whitefly), chlorotic spots (Blancard, 2012).
• Sticky coating (honeydew): characteristic of aphids and whitefly. Later, black sooty mold appears on it, impairing photosynthesis (Akhatov, 2010).

Leaf-chewing pests (cutworm caterpillars, beetle larvae, leafmining flies): They eat leaf tissues. Signs:

• Leaf edges eaten or holes in the center: left by caterpillars and beetles.
• Mines: winding or spotted tunnels inside the leaf, chewed by leafminer larvae. This is a very characteristic sign (Blancard, 2012; Mattoo et al., 2017).

Tip: Examine the underside of leaves—that’s where aphids, whiteflies, thrips, and mite eggs often hide.

4. Fruits

Fruit damage is the most painful loss for the gardener, as the harvest suffers.

Fruit pests:

• Cutworm caterpillars (cotton, vegetable, etc.): They gnaw holes in fruits and eat the internal contents, leaving behind frass and wet spots, leading to fruit rot (Mattoo et al., 2017; Gavrish, 2005).
• Tomato leaf miner (Tuta absoluta): This is the most dangerous fruit pest. Caterpillars penetrate inside, making tunnels and completely destroying the fruit from within. Outside, only black dots (frass) near the stalk or small holes may be visible (Mattoo et al., 2017).
• Thrips: Their feeding causes silvery, corky spots (“silvering”) on fruits, deforming them (Blancard, 2012).
• Bugs (plant bugs, stink bugs): They puncture fruits, leaving white or dark spots. Inside the fruit, at the puncture site, dense whitish areas form, making it inedible (Blancard, 2012).

Tip: Inspect not only ripening fruits but also young set. Damage to young fruits can often be noticed at early stages.

5. Overall Conclusion: How Does This Help in Diagnosis?

Remember a simple rule: the nature of damage = a clue.

• Deformed, curled leaves and sticky coating → look for aphids.
• Silvery streaks and spots on leaves and fruits → most likely thrips.
• Slow growth, wilting, swellings on roots → suspect nematodes.
• Eaten leaves and large holes in fruits → look for cutworm caterpillars.
• Numerous small light spots on leaves → check for mites.
• Winding “mines” in leaves → sign of leafmining flies.
• Top wilting and small holes in stem with frass → tomato leaf miner is at work.

In the next chapter, we will detail pest groups and learn to distinguish them.

1. Aphids (Aphididae)

These are among the most common and noticeable pests.

How to identify: Small insects (1–4 mm) pear‑shaped, usually green, yellow, black, or pinkish. Whole colonies are often visible on the underside of leaves and young shoots. A characteristic sign is the presence of honeydew (sticky droplets on leaves and fruits), on which black sooty mold later grows (Akhatov, 2010; Blancard, 2012).

Damage symptoms:

• Leaves curl and deform.
• Shoots become distorted and stunted.
• Sticky shiny coating on leaves.
• At heavy infestation, black sooty mold impairs photosynthesis (Mattoo et al., 2017).

Most dangerous species on tomato: Peach (greenhouse) aphid (Myzus persicae), potato aphid (Aulacorthum solani), cotton aphid (Aphis gossypii) (Akhatov, 2010).

2. Whiteflies (Aleyrodidae)

Small white “moths” that fly up from plants at the slightest touch.

How to identify: Small (1–2 mm) white or yellowish insects with white wings. Larvae are translucent, flat scales attached to the underside of leaves (Blancard, 2012). Like aphids, they secrete honeydew.

Damage symptoms:

• Leaves become covered with sticky coating and sooty mold.
• Plants weaken, leaves yellow and dry.
• Most dangerous are greenhouse whitefly and tobacco whitefly (Trialeurodes vaporariorum and Bemisia tabaci). Tobacco whitefly is a dangerous vector of viruses, e.g., Tomato Yellow Leaf Curl Virus (TYLCV) (Blancard, 2012; Mattoo et al., 2017).

Peculiarity: Whiteflies prefer warm and humid conditions, so in open ground they are most active in hot weather.

3. Thrips (Thysanoptera)

Very small, mobile insects with narrow elongated bodies.

How to identify: Size 0.5–2 mm, color from light yellow to dark brown. They are difficult to see with the naked eye, but the damage pattern reveals their presence (Blancard, 2012).

Damage symptoms:

• Numerous small silvery streaks and spots—puncture marks—appear on leaves.
• Leaves become deformed, take on a “marbled” hue.
• On fruits—silvery or corky spots (“silvering”) and deformations (Blancard, 2012; Akhatov, 2010).
• Particularly dangerous is the western flower thrips (Frankliniella occidentalis), which transmits Tomato Spotted Wilt Virus (TSWV) (Mattoo et al., 2017).

4. Spider and Russet Mites (Acari)

These are not insects but arachnids, yet by the nature of damage they are grouped with sucking pests.

Two‑spotted spider mite (Tetranychus urticae):

• How to identify: Very small (0.3–0.5 mm), usually reddish, orange, or greenish. Live on the underside of leaves, covering them with fine webbing (Blancard, 2012; Akhatov, 2010).
• Symptoms: Fine light spots (stippling) on leaves, then leaves yellow, dry, and fall off. Webbing is a characteristic sign of high numbers.

Tomato russet mite (Aculops lycopersici):

• How to identify: Microscopic (0.14–0.24 mm), colonies appear as a rusty or brownish coating on stems and leaves (Akhatov, 2010).
• Symptoms: Stems and leaves acquire a rusty‑brown or bronze tint, as if rusted. Leaves become brittle, dry, and fall. Fruits become covered with corky tissue and crack (Akhatov, 2010; Blancard, 2012).

How to Quickly Tell Which Pest Is Causing Damage?

Important note: All sucking pests are potential virus vectors (e.g., aphids and whitefly transmit mosaic and yellow leaf curl viruses, thrips transmit spotted wilt virus) (Blancard, 2012; Mattoo et al., 2017). Therefore, controlling them is also a prevention of viral diseases.

In the next chapter, we will talk about leaf‑chewing pests—those that leave holes and eat leaves and fruits.

1. Cutworm Caterpillars (Noctuidae)

These are among the most dangerous leaf‑chewing pests of tomato. The moths are inconspicuous, but their caterpillars can destroy a significant part of the crop.

How to identify: Cutworm caterpillars are thick, smooth caterpillars up to 3–5 cm long, coloration varies from green to brown and black, often with longitudinal stripes. They are active at dusk and night, hiding in the soil or under plant debris during the day (Blancard, 2012).

Damage symptoms:

• Leaves: Coarse chewing, often from the edges, or large irregular holes. Caterpillars may eat the entire leaf, leaving only veins.
• Fruits: The most dangerous damage. Caterpillars (especially cotton bollworm Helicoverpa armigera) chew deep holes in fruits, often near the stalk, and eat the internal contents. Dark frass is visible around the holes. Damaged fruits quickly rot (Mattoo et al., 2017; Akhatov, 2010).

Most dangerous species on tomato:

• Cotton bollworm (Helicoverpa armigera): Prefers fruits, most harmful in southern regions. One caterpillar can damage several fruits.
• Tomato moth (Lacanobia oleracea): Damages leaves and fruits.
• Potato stem borer (Hydraecia micacea): More often damages stems at the base and roots, but may also eat leaves (Akhatov, 2010).

2. Tomato Leaf Miner (Tuta absoluta)

This invasive pest, native to South America, has spread worldwide in recent years and poses a serious threat to tomatoes in open and protected cultivation (Mattoo et al., 2017).

How to identify: Moth is small (wingspan about 1 cm), greyish‑brown. Caterpillar is small, up to 0.7–0.9 cm, initially cream, then greenish or pinkish. It is hard to see—it hides inside leaves or fruits.

Damage symptoms:

• Leaves: Caterpillars mine leaves, forming irregularly shaped, wide mines (unlike the narrow, winding mines of leafminer flies). Damaged areas turn brown and dry.
• Stems and suckers: Caterpillars may bore into stems and suckers, causing wilting.
• Fruits: The most dangerous sign. Caterpillars enter the fruit, making tunnels near the stalk, and eat the flesh. The entry hole may be inconspicuous, but the fruit rots internally. This leads to total crop loss (Mattoo et al., 2017; Gavrish, 2005).

3. Leafmining Flies (Agromyzidae)

Larvae of these flies are true “underground” pests that live and feed inside the leaf blade.

How to identify: Flies themselves are small, 2–3 mm, grey or black with yellow markings. But they are identified not by adults but by characteristic damage— “mines.”

Damage symptoms:

• Leaves: Winding, narrow, light “tunnels” (mines) appear on leaves, widening each day. Inside the mine you can see the larva and a dark strip of frass. Heavily damaged leaves dry and fall off (Blancard, 2012; Mattoo et al., 2017).

Most dangerous species: Tomato leaf miner (Liriomyza bryoniae), South American leaf miner (Liriomyza huidobrensis). They are dangerous not only by direct damage but also by opening the way for bacterial and fungal infections (Mattoo et al., 2017).

4. Leaf Beetles (Chrysomelidae)

Beetles that eat leaves, often from the edges.

Colorado potato beetle (Leptinotarsa decemlineata):

• How to identify: Striped orange‑yellow beetle with black stripes. Larvae are reddish or orange with black spots on the sides (Akhatov, 2010).
• Symptoms: Beetles and larvae completely eat leaves, leaving only veins. They may damage young stems. Although the Colorado potato beetle prefers potato, in its absence it readily moves to tomatoes (Akhatov, 2010).

Other leaf beetles: In some regions, other species may occur, e.g., tortoise beetles, but they are less dangerous.

How to Quickly Determine Which Pest Is Causing Damage?

Important note: Leaf‑chewing pests, especially cutworm caterpillars and tomato leaf miner, often damage fruits, making them unfit for consumption and storage (Mattoo et al., 2017). Early detection and control are key to preserving the harvest. Monitoring with pheromone traps (for cutworms and tomato leaf miner) will help detect the start of moth flight and take action.

In the next chapter, we will talk about soil pests—those that hide in the ground and attack roots.

1. Root‑knot Nematodes (Meloidogyne spp.)

These are microscopic roundworms that are among the most dangerous soil pests of tomato worldwide (Mattoo et al., 2017).

How to identify: Nematodes cannot be seen without a microscope, but their presence is revealed by characteristic swellings (galls) on roots. Galls can range from pinhead size to large growths, especially on young roots (Blancard, 2012; Akhatov, 2010).

Damage symptoms:

• Round swellings (galls) form on roots, disrupting the root’s conducting system.
• Plants are stunted, appear depressed.
• Leaves yellow and wilt, especially on hot sunny days (damaged roots cannot supply water).
• In severe infestation, roots become a tangled mass of galls, and the plant dies (Akhatov, 2010).

Biological peculiarities: Female nematodes live inside galls and lay up to 2000 eggs. In greenhouses, up to 7 generations can develop per year, making them particularly dangerous in protected cultivation (Akhatov, 2010).

2. Wireworms (larvae of click beetles, Agriotes spp.)

These are hard, shiny, yellow‑brown larvae 1–3 cm long, resembling pieces of wire (Blancard, 2012).

Damage symptoms:

• Wireworms gnaw roots and the underground part of stems of young plants.
• Damaged plants wilt and may die.
• Especially dangerous for seedlings and young plants in the first weeks after transplanting.

3. Larvae of Scarab Beetles (white grubs, Phyllophaga spp.)

Thick, white or cream, C‑shaped larvae with a well‑visible brown head and three pairs of legs (Blancard, 2012).

Damage symptoms:

• Gnaw the roots of young plants.
• Plants wilt and die.
• Particularly dangerous in areas where there was previously sod or lawn.

4. Mole Cricket (Gryllotalpa gryllotalpa)

Large (3–5 cm) brown insect with powerful digging forelegs, resembling a hybrid of a cricket and a crayfish.

Damage symptoms:

• The mole cricket makes tunnels in the soil and gnaws roots, root collars, and stems of young plants at the surface.
• Plants quickly wilt and lodge.
• A characteristic sign is the presence of winding ridges of loose soil on the surface.

5. Cutworms (Agrotis spp.) – subterranean species

Caterpillars of some cutworm species (e.g., the black cutworm) lead a subterranean lifestyle.

Damage symptoms:

• Caterpillars cut stems of young plants at the soil surface.
• Plants fall and die (Blancard, 2012).
• During the day, caterpillars hide in the soil, and at night they come out to feed.

How to Detect Soil Pests?

Prevention: Your Main Tool in Fighting Soil Pests

Unlike above‑ground pests, controlling underground ones is much more difficult. Chemical soil treatment is a last resort, often unsafe and not always effective. The main emphasis should be on prevention:

1. Crop rotation: The golden rule! Do not plant tomatoes in the same place for several years in a row. Nematodes and other soil pathogens accumulate in the soil. Best predecessors: cabbage, cucumbers, onions, legumes. It is recommended to return tomatoes to the same spot no earlier than after 3–4 years (Blancard, 2012; Gavrish, 2005).

2. Deep digging: Autumn and spring digging helps destroy part of the overwintering larvae and pupae.

3. Green manure (trap crops): Planting marigolds, calendula, or some legumes as green manure can reduce nematode numbers. Root exudates of these plants are detrimental to them (Mattoo et al., 2017). Invasive nematode larvae penetrate the roots of green manure but cannot complete development and die (Akhatov, 2010).

4. Use healthy planting material: Carefully inspect seedling roots before purchase. If there are swellings, reject that seedling.

5. Maintain proper watering: Over‑watering, especially with cold water, weakens plants and makes them more vulnerable to root rots and nematodes (Blancard, 2012).

Remember that timely prevention of soil pests is much more effective and safer than attempts to destroy them when they are already actively harming the crops. In the next chapter, we will summarize and give a practical algorithm for quickly identifying the pest by characteristic signs.

Step 1. Start by Examining the Affected Area

Ask yourself: which part of the plant is primarily damaged?

1. Root problems:

• Plants wilt in the heat but recover by evening?
• Stunted growth, yellowing?
• Dig up the plant and inspect the roots. If you see:
• Swellings (galls) on roots → root‑knot nematodes (Blancard, 2012; Akhatov, 2010).
• Eaten roots and stem at ground level → wireworm, mole cricket or white grub (Blancard, 2012).

2. Leaf problems:

• Leaves deformed, curled, sticky coating? → look for colonies of aphids (Mattoo et al., 2017; Akhatov, 2010).
• Leaves covered with fine light spots or silvery streaks? → suspect thrips (Blancard, 2012).
• Fine webbing and yellowing spots on leaves? → spider mite (Blancard, 2012).
• Stems and leaves acquired a rusty‑brown tint? → russet mite (Akhatov, 2010).
• Large holes, chewed edges on leaves? → cutworm caterpillars (Mattoo et al., 2017).
• Inside the leaf – winding light “tunnels” (mines)? → leafminer fly larvae (Blancard, 2012; Mattoo et al., 2017).
• Wide, irregular mines on leaves that dry out? → tomato leaf miner (Tuta absoluta) (Mattoo et al., 2017).

3. Fruit problems:

• Deep holes in fruits, dark frass nearby? → cutworm caterpillars (Mattoo et al., 2017; Akhatov, 2010).
• Fruits wilt, rot from inside, and only small holes near the stalk are visible outside? → tomato leaf miner (Tuta absoluta) (Mattoo et al., 2017).
• Silvery or corky spots on fruits? → thrips (Blancard, 2012).
• Sticky coating on fruits? → aphids or whitefly (Akhatov, 2010).

Step 2. Look for “Living” Clues

Sometimes the pest hides, but leaves clear traces:

• Sticky honeydew — a sure sign of aphids or whitefly (Mattoo et al., 2017).
• Black coating (sooty mold) — develops on honeydew (Akhatov, 2010).
• Swarms of white “moths” flying up when the plant is shaken — whitefly (Blancard, 2012).
• Webbing on leaves — spider mite (Blancard, 2012).
• Dark frass near damage — caterpillars or tomato leaf miner (Mattoo et al., 2017).
• Swellings on roots — root‑knot nematodes (Blancard, 2012).

Step 3. Determine the Timing of Appearance

• Early spring, right after planting: most often suffer from soil pests (wireworm, mole cricket) or aphids.
• Mid‑summer, hot weather: peak activity of spider mite, whitefly, and thrips. Also, cutworms actively reproduce.
• Late summer – autumn: most dangerous are tomato leaf miner and late‑generation cutworms damaging fruits (Akhatov, 2010).

Step 4. Use Traps for Monitoring

Don’t wait for the pest to show itself!

• Yellow sticky traps: effective for early detection of whitefly, aphids, and thrips (Blancard, 2012). Place them at plant top level. Blue traps attract thrips better (Akhatov, 2010).
• Pheromone traps: indispensable for tracking the flight of cutworms and tomato leaf miner. You will be able to notice the appearance of moths in time and start treatments before caterpillars cause damage (Mattoo et al., 2017).

“Cheat Sheet” for Quick Diagnosis

Remember this table, and you will be able to make a “diagnosis” in seconds:

In the next chapter, we will discuss biological control in detail—how to enlist natural enemies of pests and reduce the number of treatments.

Why Does Biological Control Work?

Nature has already created mechanisms for population regulation. Pests rarely multiply unchecked because they have natural enemies: predatory insects, parasitic wasps, entomopathogenic fungi and bacteria. The gardener’s task is to create conditions in which these helpers work actively. It is important to understand: biological control is not a one‑off action but a long‑term strategy that pays off with stable yields and clean produce (Blancard, 2012).

1. Who Are Your Allies? Main Groups of Entomophages

2. Biopesticides: Microorganisms in the Service of Protection

These are preparations based on living microorganisms (bacteria, fungi) that cause diseases in pests. They are safe for humans and beneficial insects.

• Bacillus thuringiensis (Bt): This bacterium produces a toxin that affects the gut of caterpillars. Preparations based on it (Lepidocide, Bitoxibacillin, Bicol) are effective against cutworm caterpillars, tomato leaf miner, Colorado potato beetle, and other leaf‑chewing pests. It is important to apply them against younger instars (1‑2 instars) when they are most susceptible (Mattoo et al., 2017; Akhatov, 2010).
• Entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae, Verticillium lecanii): These fungi infect insects by penetrating their cuticle. Preparations based on them (Boverin, Verticillin) are effective against whitefly, aphids, thrips, and mites. For effective action, high air humidity (about 80‑90%) is required during the first 24 hours after treatment (Blancard, 2012; Akhatov, 2010).
• Entomopathogenic nematodes (Heterorhabditis, Steinernema): Microscopic worms that penetrate the body of pest insects (cutworm larvae, wireworms) and infect them with symbiotic bacteria, causing death. Effective against soil‑dwelling and hidden pests.

3. Practical Tips: How to Implement Biocontrol on Your Plot

1. Attract natural enemies by creating conditions for them:

• Plant nectar‑producing plants next to tomatoes (dill, fennel, buckwheat, marigolds, phacelia) to attract adult lacewings, ladybirds, and parasitic wasps. They need pollen and nectar for reproduction (Akhatov, 2010).
• Leave small areas with wild vegetation—reservations for beneficial insects.

2. Use biopreparations correctly:

• Apply them at the first signs of pest appearance, when the population is still small.
• Strictly follow the instructions: temperature and humidity greatly affect the effectiveness of bacterial and fungal preparations (Blancard, 2012).
• Rotate biopreparations with different modes of action to prevent pest resistance.

3. Be careful with chemicals:

• Chemical insecticides kill not only pests but also their natural enemies. Use them only as a last resort when other methods fail, and choose narrow‑spectrum products that are safer for entomophages (Mattoo et al., 2017).

4. Use biological control in the greenhouse:

• In protected cultivation, conditions are ideal for mass pest reproduction, but biocontrol is also especially effective. Regularly release Encarsia against whitefly, Amblyseius against thrips, Phytoseiulus against mites (Akhatov, 2010).
• Conduct preventive releases of entomophages without waiting for a pest outbreak.

Important to Remember

Biological control is not an instant result. It requires time, patience, and a systemic approach. But it provides long‑term, sustainable protection that does not harm your health or the environment. By integrating biological methods with agronomic practices (crop rotation, proper watering, choosing resistant varieties), you create a reliable tomato protection system (Blancard, 2012).

In the next, final chapter, we will consider when and how to apply all this knowledge in practice to make the right decisions for crop protection.

1. The Concept of Economic Threshold: Your Main Guide

In professional agriculture, there is the concept of “economic injury level” (EIL) or “economic threshold.” This is the pest population level at which the cost of potential damage exceeds the cost of control. For the home gardener, it means: “When the pest becomes numerous enough to pose a real threat to the crop, and when intervention is truly justified.”

If you see a few individual aphids or a couple of thrips—that is not a reason for a chemical attack. In a healthy ecosystem, they will quickly be “eaten” by ladybirds, lacewings, or parasitic wasps. By applying insecticide, you risk killing these beneficial allies and causing a real population explosion of pests (Akhatov, 2010; Blancard, 2012).

2. Three Decision‑Making Scenarios

So, there are three main scenarios in which you may find yourself.

3. How to Monitor for Decision‑Making

To make the right decisions, you need to regularly monitor the situation. Here’s how to do it effectively:

• Regular plant inspection: Walk through the plot at least once a week. Examine the underside of leaves—that’s where aphids, whitefly, and mites often settle (Blancard, 2012).
• Yellow and blue sticky traps: Place them in the greenhouse or in the beds. Yellow traps attract whitefly and aphids, blue traps attract thrips. Change them every 1‑2 weeks. The number of captured insects gives an indication of population dynamics (Akhatov, 2010; Blancard, 2012).
• Pheromone traps: Especially useful for tracking the flight of cutworms and tomato leaf miner. As soon as moths appear in the traps, it is a signal that egg‑laying will soon begin, and you need to prepare for treatments (Mattoo et al., 2017).

4. Important Caveats

• Don’t sacrifice biocontrol for “cleanliness”: If you notice many beneficial insects on your plot and few pests, do not carry out “preventive” chemical treatments. You will upset the balance, and next season pests will increase.
• Folk remedies are not a panacea: Infusions of garlic, tobacco, wormwood can help at early stages, but they are ineffective in mass infestations. Don’t waste time if you see the situation getting out of control.
• Crop rotation is the best medicine: The most reliable prevention is proper crop rotation and agronomy. Do not allow pests and diseases to accumulate in the soil and on plants (Blancard, 2012).

Summary: Your Strategy

1. Prevent: Use resistant varieties, crop rotation, preventive treatments with biopreparations, attract beneficial insects.

2. Observe: Regularly inspect plants and use traps to know what is happening on the plot.

3. Make decisions: Act on the principle: “Better less, but better.” Start with biological methods and resort to chemicals only as a last resort.

4. Analyse: After each season, draw conclusions. What worked? What didn’t? This will help you become an experienced defender of your tomatoes.

Remember that your goal is not perfect, sterile plants, but a healthy, tasty harvest grown with respect for nature. And this knowledge‑based approach will certainly bear fruit!