Diseases

1. Late Blight (Brown Rot): The “Plague” of Solanaceous Crops

Causal agent: Phytophthora infestans (Akhatov, 2010).

What it looks like: This is the most formidable enemy. On the leaves, blurred, watery brown spots appear, rapidly increasing in size. On the underside of the leaf, along the edge of the spot, in wet weather, a white, fluffy coating (fungal spores) is visible. Stems become covered with dark, elongated spots. Fruits develop hard, brown, oily spots that quickly rot and become unfit for consumption (Blancard, 2012).

Conditions for development: Cool (10‑20 °C), damp and rainy weather, heavy dews. Spreads very quickly.

How to distinguish: The spots have no clear border and quickly merge. The affected bush looks “scalded.” Unlike early blight, late blight spots are smooth, without concentric rings.

First aid: Remove all affected leaves and fruits. Immediately treat the bushes and the surrounding soil with fungicides based on mancozeb, metalaxyl, or copper (Kemble, 2022).

2. Early Blight (Dry Spot, Macrosporiosis)

Causal agent: Alternaria solani.

What it looks like: On the leaves, large, brown or dark‑brown spots appear with a characteristic concentric zoning, resembling a “target” or “bullseye.” The spots are often surrounded by a yellow halo. On fruits, dark, sunken spots form, most often near the stalk, covered with a black velvety coating of spores (Gavrish, 2005).

Conditions for development: Warm (25‑30 °C) and humid weather, frequent watering, poor soils. Especially dangerous during the fruiting period.

How to distinguish: By the clear concentric circles on the spots. This disease often starts on the lower, old leaves and gradually moves upward.

First aid: Regular collection and destruction of affected leaves. Treatment with fungicides containing difenoconazole, azoxystrobin, or mancozeb.

3. Grey Mould (Botrytis): Attack on Wounds

Causal agent: Botrytis cinerea.

What it looks like: Affects all above‑ground parts. On stems, at the places where leaves or suckers were removed, light‑brown, weeping spots appear, quickly girdling the stem. On fruits – soft, watery rots with a grey, fluffy coating resembling mould (Outko et al., 2012).

Conditions for development: High humidity (over 90%), cool weather, dense plantings, presence of wounds and dying tissues (flowers, leaves).

How to distinguish: By the abundant grey coating and the fact that the disease almost always starts from mechanical damage or ageing flowers.

First aid: Ventilation, removal of dead leaves and flowers. Treatment with preparations based on iprodione, fenhexamid. Smear wounds on stems with a paste of fungicide and chalk (Kemble, 2022).

4. Powdery Mildew: “White Dust”

Causal agents: Oidium neolycopersici, Leveillula taurica.

What it looks like: On the leaves (usually the upper side) a white, powdery coating appears, resembling flour or scattered ash. Unlike powdery mildew on cucumbers, in tomatoes the coating may appear on separate spots rather than covering the entire leaf. Leaves turn yellow and dry out (Blancard, 2012).

Conditions for development: Warm and dry weather, sharp temperature fluctuations, lack of light in greenhouses.

How to distinguish: By the white coating, which is easily rubbed off with a finger. Fruits are not affected by this disease.

First aid: Sulphur preparations (sulphur bombs, colloidal sulphur), as well as modern fungicides from the triazole and strobilurin groups.

5. Septoria Leaf Spot (White Leaf Spot)

Causal agent: Septoria lycopersici.

What it looks like: On the lower leaves, small (2‑3 mm), watery spots appear, which quickly turn white in the centre and have a dark‑brown border. Later, black dots (pycnidia of the fungus) appear on the white centre. The leaves turn yellow, curl, and dry up (Akhatov, 2010).

Conditions for development: Warm, humid weather, frequent rains, dense plantings. Transmitted through seeds and plant residues.

How to distinguish: By the light centre with a dark border and the small size of the spots. Unlike early blight, the spots have no concentric rings.

First aid: Removal of lower infected leaves. Treatment with fungicides containing mancozeb or chlorothalonil. Strictly observe crop rotation!

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What is the conclusion? Fungal diseases are easier to prevent than to cure. They all love moisture and crowding. Your main strategy is prevention: crop rotation, removal of diseased leaves, watering at the root, and regular treatments with biological products or copper‑containing fungicides at the beginning of the season (Jones, 2008).

1. Bacterial Canker: The Most Dangerous “Conqueror”

Causal agent: Clavibacter michiganensis subsp. michiganensis.

What it looks like: A true “chameleon” that can manifest in different ways, but is always insidious.

• On leaves: Interveinal areas become light‑green, then turn brown and dry out, forming irregular‑shaped patches. Leaves curl and wilt on one side (one‑sided wilting is an important symptom!).
• On stems: Brown streaks and cracks appear, from which yellowish slime oozes.
• On fruits: The most characteristic sign is “bird’s‑eye” spots: small (3‑4 mm) white, slightly raised spots with a dark centre and a crack in the middle (Akhatov, 2010).

Conditions for development: Warm (24‑27 °C) and humid weather. Transmitted through infected seeds and mechanically – during pruning and watering.

How to distinguish: By the combination of one‑sided wilting of leaves and the characteristic “bird’s‑eye” spots on fruits. No other disease works that way.

First aid: Immediately remove the diseased plant with its roots and burn it. Disinfect the secateur and hands (alcohol, potassium permanganate). Be sure to dress seeds before sowing (heat treatment in hot water).

2. Bacterial Wilt (Brown Rot): “Instant Death”

Causal agent: Ralstonia solanacearum.

What it looks like: The most terrible bacterial disease. The plant wilts instantly and completely, often overnight. The leaves do not turn yellow or curl – they simply lose turgor, become limp, and droop, remaining green. On a cut stem, darkening of the vessels is visible, and if you put the cut in water, within 1‑2 minutes a white cloudy stream of bacteria will start oozing out (Blancard, 2012).

Conditions for development: High temperature (30‑35 °C) and moist soil. Especially dangerous in tropical and subtropical regions, as well as in greenhouses with waterlogged soil. Transmitted through soil, water, and infected plant residues (Mattoo, 2017).

How to distinguish: By the sudden complete wilting without yellowing and the white “milky” stream from the stem cut.

First aid: There is no cure. The only strategy is immediate removal of diseased plants. Add fresh lime or drench the soil with a solution of copper sulphate. For the future – choose resistant varieties and follow strict crop rotation.

3. Bacterial Spot (Black Bacterial Spot): “Rain” Disease

Causal agent: Xanthomonas vesicatoria (and related species).

What it looks like: On the leaves, small (1‑2 mm), oily, dark spots appear, often with a yellow halo. The spots have an angular shape because they are limited by veins. The leaf turns yellow and dries up. On fruits, black, raised, wart‑like specks form, surrounded by a watery border (Gavrish, 2005).

Conditions for development: Rainy, humid, warm weather (25‑30 °C). Spread by water droplets – during overhead irrigation or rain. Very contagious.

How to distinguish: By the small, angular spots on leaves and the raised black dots on fruits. Unlike bacterial canker, this is a “superficial” disease.

First aid: Collect and remove affected leaves. Regular treatments with copper‑containing preparations (Bordeaux mixture, copper oxychloride) before the onset of rains. Use only high‑quality, dressed seeds.

4. Pith Necrosis (Hollow Stem)

Causal agent: Pseudomonas corrugata (and other Pseudomonas species).

What it looks like: Externally, the plant may appear quite healthy. But when you cut the stem, you can see that the pith has turned brown, softened, turned into mush, and collapsed, forming cavities. On the outside of the stem, brown, sunken streaks appear, often at the points where suckers were removed. A slimy exudate may be visible on the cut (Akhatov, 2010).

Conditions for development: Excess nitrogen fertilisation, high humidity, sharp fluctuations between day and night temperatures, especially in greenhouses. Often affects vigorous, “overfed” plants.

How to distinguish: By the internal cavities and destruction of the pith while the external appearance of the bush is preserved. External symptoms may resemble bacterial canker, but there is no “bird’s‑eye” on the fruits.

First aid: Balance nitrogen nutrition (reduce nitrogen dose). Improve ventilation in the greenhouse. Remove affected plants. It is possible to use copper‑containing preparations as a preventive measure.

To summarise: Bacterioses are infections through wounds and water. The main protection is clean seeds, disinfection of tools, watering at the root, crop rotation, and regular inspection. At the first signs of bacterial damage, do not hesitate – remove diseased plants to save the rest.

1. Tomato Mosaic Virus (ToMV): “Classic of the Genre”

Causal agent: Tomato mosaic virus (ToMV). A close relative of Tobacco mosaic virus (TMV).

What it looks like: On the leaves, a mosaic pattern appears – alternating dark‑green and light‑green or yellow areas. The leaves become wrinkled, curl, and sometimes take on a thread‑like shape (“fern‑leaf”). The plant is stunted. On fruits, internal necrosis may appear – brown spots inside the flesh, although the fruit looks normal from the outside (Gavrish, 2005).

Transmission routes: Mechanical – through the sap of a diseased plant during pruning, cutting, grafting, through hands and tools. The virus is also transmitted with seeds and through infected soil. Very persistent – can survive in plant residues for up to 2 years (Mattoo, 2017).

How to distinguish: By the mosaic colouring of the leaves. Unlike bacterioses, the spots do not have a clear border and do not “get wet.” Important: this virus is not transmitted by insects, only mechanically.

First aid: No cure. Remove diseased plants. Disinfect all tools and hands (milk, alcohol). For prevention – use resistant varieties (marked `Tm` or `ToMV` in the catalogue) and heat seeds before sowing (Blancard, 2012).

2. Cucumber Mosaic Virus (CMV): “Master of Disguise”

Causal agent: Cucumber mosaic virus (CMV). A universal virus that affects many crops (cucumbers, peppers, lettuce, etc.).

What it looks like: Symptoms are very variable and depend on the strain and weather. On the leaves, a fine mosaic appears, they become wrinkled and narrow, sometimes taking on a thread‑like (“string‑like”) form. The plant becomes dwarfed and bushy. On fruits, ring spots and necroses appear. Yellowing of veins is very characteristic (Akhatov, 2010).

Transmission routes: Transmitted by aphids (non‑persistent, i.e., within a short time). It can also be transmitted mechanically and with weed seeds (Mattoo, 2017). Persists in perennial weeds (sow thistle, chickweed, bindweed).

How to distinguish: By the thread‑like leaves and yellowing of veins. Importantly: CMV often causes stronger deformation than ToMV, and unlike it, is transmitted by aphids.

First aid: No cure. Controlling aphids is the main strategy. Remove weeds around the site. Growing resistant varieties (there are few, but breeding is ongoing).

3. Tomato Spotted Wilt Virus (TSWV): “Burn” and “Rings”

Causal agent: Tomato spotted wilt virus (TSWV). A very dangerous virus, especially in warm regions.

What it looks like: The most recognisable virus. On young leaves, bronze or brown rings and streaks appear – necrotic spots in the form of rings or lines. Leaves often curl and die. On stems and petioles, dark‑brown streaks (“striae”) are visible. Fruits become covered with concentric yellow, orange, or brown rings and become bumpy, losing marketable quality (Blancard, 2012).

Transmission routes: Transmitted by thrips (Frankliniella occidentalis – western flower thrips) in a persistent manner. That is, the virus multiplies in the thrips’ body and is transmitted to the next generation. A very fast route of spread (Mattoo, 2017).

How to distinguish: By the bronze tint of the leaves and the distinct concentric rings on the fruits. No other pathogen gives such a picture.

First aid: No cure. Remove diseased plants. Intense control of thrips – sticky traps, insecticides. Using resistant varieties (marked `TSWV`) is the only reliable method.

4. Tomato Yellow Leaf Curl Virus (TYLCV): “Whitefly Trouble”

Causal agent: Tomato yellow leaf curl virus (TYLCV). A virus that has become a real scourge in many regions of the world in recent decades.

What it looks like: Young leaves turn yellow, curl upwards (“boat‑shaped”), and become brittle. Internodes shorten, the plant becomes dwarfed and bushy (“witch’s broom”). Flowers drop, fruits either do not set or grow small and deformed (Blancard, 2012).

Transmission routes: Transmitted by whiteflies (Bemisia tabaci) in a persistent manner. The whitefly remains a carrier for life. The virus is not transmitted through seeds or mechanically.

How to distinguish: By the upward curling of leaves and strong yellowing. The plant looks as if it has been burned. Unlike other viruses, there is almost no mosaic – only chlorosis and deformation (Mattoo, 2017).

First aid: No cure. Destroying whiteflies is the only strategy (yellow sticky traps, insecticides, biologicals). Growing resistant varieties (marked `TYLCV`). In greenhouses – mandatory use of nets on ventilation.

How to Distinguish Viruses from Each Other (Cheat Sheet)

The main rule: Viral diseases cannot be cured! If you see characteristic symptoms – immediately remove the plant, without waiting for the virus to spread further. Your main protection is prevention: control of vectors (aphids, thrips, whiteflies), disinfection of tools, seed heat treatment, and use of resistant varieties.

Quick Diagnosis: Comparative Table

Algorithm of Actions When a Suspicious Plant is Found (Step‑by‑Step)

1. Assess the speed of spread. If within 1‑2 days the disease has covered half the bush or neighbouring plants – it is a fungal or bacterial infection. Viruses spread more slowly.

2. Examine the leaves. Is there a coating (fungus) or “wet” angular spots (bacteria)? If not, but there is mosaic, yellowing, curling – suspect a virus.

3. Examine the stem. Cut it lengthwise. If inside there are cavities or slime – it is bacteriosis. If vessels are brown, but dry – fungus. If everything is clean – virus (or non‑infectious problem).

4. Examine the fruits. Are there concentric rings (spotted wilt virus), bird’s‑eye (bacterial canker), or sunken spots with coating (fungus)?

5. Recall the weather. If there were rains, dew, cold – most likely fungus. If heat and humidity – bacteria. If many insects (aphids, thrips) – virus.

Practical Examples for Remembering

• “Wet” spot with white coating → Late blight (fungus).
• “Target” on the leaf (concentric rings) → Early blight (fungus).
• Angular oily spot → Bacterial spot (bacteria).
• White spot with a dark dot in the centre (“bird’s‑eye”) → Bacterial canker.
• Bronze rings on fruits → Spotted wilt virus (TSWV).
• Leaves curled upward, yellow, dwarf bush → Yellow leaf curl virus (TYLCV).

Golden rule: If you are not 100% sure of the diagnosis, do not rush with chemicals. Remove the suspicious plant (preferably with roots), burn it, disinfect tools and hands. Observe the neighbouring plants. Often one removed bush saves the entire plot (Blancard, 2012; Mattoo, 2017).

1. Correct Choice of Seeds and Their Preparation

It all starts with seeds. They are the source of the genetic health of your future harvest.

Buy varieties resistant to diseases. Modern breeding has created many hybrids and varieties resistant to major pathogens. When choosing, pay attention to the markings (Mattoo, 2017):

• `Tm` or `ToMV` – resistance to Tomato mosaic virus.
• `V` – resistance to Verticillium wilt.
• `F` (`F1`, `F2`) – resistance to Fusarium wilt (race 1, 2).
• `N` – resistance to root‑knot nematodes.
• `TSWV` – resistance to Tomato spotted wilt virus.
• `TYLCV` – resistance to Tomato yellow leaf curl virus.
• `ASC` – resistance to early blight (stem canker).

Disinfect the seeds. Even if you bought seeds from a trusted producer, additional treatment will not hurt. Use one of the following methods (Blancard, 2012):

• Heat treatment: Soak the seeds in hot water (50‑52 °C) for 20‑25 minutes, then immediately cool in cold water. This kills most fungal and bacterial infections on the seed surface.
• Chemical dressing: Soak the seeds in a 1% solution of potassium permanganate for 15‑20 minutes, then rinse. Or use special dressers (e.g., “Thiram”).
• To protect against viruses, seeds can be treated with a 10% solution of trisodium phosphate (30 minutes) or 2% hydrochloric acid (Akhatov, 2010).

2. Soil Preparation and Crop Rotation

Soil is the main reservoir of infection. Many pathogens can persist in it for years.

• Observe crop rotation. This is the most effective rule. Do not plant tomatoes in the same place more often than once every 3‑4 years. The best predecessors are cabbage, cucumbers, legumes, onions, carrots. Do not plant tomatoes after potatoes, peppers, or eggplants – they share common diseases (Outko et al., 2012).
• Remove plant residues. After harvest, carefully remove all leaves, stems, and roots. Do not bury them in the soil – burn or take them away from the site. They may harbour disease agents.
• Disinfect the soil. In greenhouses and hotbeds, replace the top layer of soil (5‑10 cm) annually or carry out disinfection: steaming, drenching with boiling water, application of biological products (“Fitosporin”, “Trichodermin”) (Jones, 2008).

3. Proper Watering – the Key to Health

Most diseases are activated at high humidity. Watering must be competent.

• Water at the root. This is the main rule. Water should not get on leaves, stems, or fruits. Drip irrigation is the ideal option.
• Water in the morning. So that the leaves have time to dry by evening. Night humidity is the main enemy.
• Use warm water. Cold water causes stress in plants and weakens their protective mechanisms. The water temperature should be at least 20‑22 °C (Gavrish, 2005).
• Do not over‑moisten the soil. Excess moisture leads to root rot and the development of fungal diseases.

4. Space and Air: Do Not Allow Crowding

The denser the plantings, the higher the humidity inside the bush and the faster diseases spread.

• Observe planting schemes. Indeterminate (tall) varieties should be planted at a distance of at least 50‑60 cm from each other, determinate (short) – 30‑40 cm (Kemble, 2022).
• Regularly remove suckers and lower leaves. This improves ventilation and lighting. Removing lower leaves up to the first cluster prevents contact of the plant with the soil, where pathogens live.
• Ventilate greenhouses. Leave vents and doors open, especially in hot and humid weather. Air circulation is the best protection against fungi.

5. Proper Nutrition: Strengthening Immunity

A healthy, well‑fed plant has a stronger immunity.

• Balance fertilisation. Excess nitrogen makes tissues loose and attracts pests. At the same time, sufficient potassium and phosphorus strengthens cell walls and increases resistance to diseases (Outko et al., 2012).
• Use microelements. Especially important are boron, manganese, zinc, and iron. They participate in enzymatic defence processes. Carry out foliar feeding with complex fertilisers containing microelements.
• Do not forget about calcium. Calcium deficiency leads to blossom‑end rot of fruits. Regularly add calcium nitrate to fertilisation (especially during fruiting) (Gavrish, 2005).

6. Control of Disease Vectors

Insects are the main carriers of viruses and bacteria. Without them, many diseases could not spread.

• Use yellow and blue sticky traps. They help to notice the appearance of whiteflies, aphids, and thrips in time.
• Apply biological insecticides. “Bitoxibacillin”, “Lepidocide” against caterpillars, “Fitoverm” against mites, “Verticillin” against whiteflies. They are safe for humans and beneficial insects (Jones, 2008).
• Do not allow weeds to grow. Many weeds (especially nightshades and goosefoots) are reservoirs of viruses and thrips. Regularly weed the plot.

7. Biological Protection: Working Proactively

Modern agronomy offers effective biological products that work like vaccines.

• Immunity inducers. Preparations based on arachidonic acid (“Immunocytophyte”, “El‑1”, “Obereg”) increase plant resistance to diseases and stress (Akhatov, 2010). They do not cure, but strengthen immunity, forcing the plant to produce its own protective substances.
• Biofungicides. Regular preventive treatments with preparations based on hay bacillus (Bacillus subtilis) – “Fitosporin‑M”, “Gamair”, “Alirin‑B” – suppress the development of fungal and bacterial diseases at the initial stages (Kemble, 2022). They can be used in tank mixtures with immunity inducers.

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What to do if prevention did not help?

If, despite all efforts, the first signs of disease appear – do not panic, but act quickly:

1. Isolate the diseased plant. If possible, remove it with its roots to save the neighbouring ones.

2. Identify the pathogen (Chapter 6). The choice of remedy depends on this.

3. Use a targeted preparation. If it is a fungus – apply a fungicide, bacteria – copper‑containing preparations or antibiotics (as a last resort), virus – only removal (Blancard, 2012).

Remember: prevention is not a one‑time action, but a system. Only an integrated approach, including all seven rules, will provide reliable protection for your harvest.

When Removal Is Mandatory (Red Zone)

These are cases when the disease is incurable, and the plant itself becomes a “factory” for producing infection.

1. All viral diseases. Viruses cannot be cured. No chemical preparations act on them inside the plant cell (Blancard, 2012). You can only suppress the symptoms, but the virus will remain and be transmitted by insects and through hands to neighbouring plants.

• SOS signal: Mosaic on leaves, thread‑like appearance, yellow rings on fruits, curling, bronzing, dwarfing. See this – remove immediately!

2. Bacterial wilt (Ralstonia solanacearum). This is a “heart attack” for the plant. It wilts completely and quickly, often within a day. Bacteria multiply in the vessels, blocking water flow, and release toxins (Akhatov, 2010).

• SOS signal: The plant has drooped and wilted completely, the leaves do not turn yellow but simply wilt, remaining green. On a cut stem in water – a white cloudy stream. Remove with a clod of soil to avoid leaving bacteria in the soil.

3. Bacterial canker (Clavibacter michiganensis). A dangerous “conqueror” that slowly but surely kills the plant and infects neighbours through tools and insects. Unlike fungi, bacterial canker cannot be treated with systemic preparations (Blancard, 2012).

• SOS signal: One‑sided wilting of leaves, brown streaks on stems with cracks and slime, fruits with “bird’s‑eye” spots. See at least two of these signs – remove.

5. A disease that has affected more than 30‑40% of the bush. If the disease has covered most of the leaves, stem, or fruits, it is pointless to treat the plant. It will no longer be able to recover and produce a full harvest, and will only be a source of spores or bacteria.

• SOS signal: More than a third of the leaves are covered with spots or have turned yellow, the stem has turned brown, fruits are rotting. Remove to save the remaining bushes.

When You Can Try to Save (Yellow Zone)

If the disease has just started and affected a small part of the plant, you can try to help, but be prepared to remove the plant at any moment.

1. Initial stage of fungal diseases. If you notice late blight, early blight, or grey mould at the very beginning (1‑2 spots on the lower leaves), you can try to cure it.

• What to do: Immediately remove all affected leaves, burn them. Treat the whole bush and the surrounding soil with a systemic fungicide (e.g., “Ridomil Gold”, “Quadris”, “Skor”) (Kemble, 2022).
• Critical condition: If after 3‑4 days after treatment no new spots appear – there is a chance. If the disease progresses – remove without regret.

2. Bacterial spot or speck. If single oily spots appear on the leaves and the weather has become dry, try to save the plant.

• What to do: Remove affected leaves. Treat with a copper‑containing preparation (Bordeaux mixture, “HOM”, “Oxyhom”). Stop overhead watering (Gavrish, 2005).
• Critical condition: If spots appear on new leaves or on fruits – remove.

SOS Signals: When You Cannot Delay

1. The disease is spreading to neighbouring plants. If you see that from one bush, neighbouring ones are starting to yellow or wilt – this is the main signal for immediate removal.

2. The disease has appeared in the greenhouse. In protected cultivation, infection spreads many times faster. One diseased plant in a greenhouse is a potential epidemic for all the others.

3. The diseased plant is a weed or a non‑crop plant. If you notice viral symptoms on a weed next to the bed – remove it immediately. Weeds are the main reservoirs of viruses (Mattoo, 2017).

How to Properly Remove a Diseased Plant (Step‑by‑Step Instructions)

To avoid spreading the infection, follow this algorithm:

1. Put on gloves. If you do not have gloves, after working with the diseased plant, thoroughly wash your hands with soap.

2. Prepare a bag or bucket. Immediately place the removed parts into it so that the infection does not get onto the soil.

3. Remove the whole plant with its roots. Carefully dig or pull it out, trying not to shake off soil. If the plant is severely affected, it is better to dig it out with a clod of soil.

4. Burn the plant. Never put diseased plants in compost! A compost heap is not a place for pathogens. Only burning guarantees their destruction (Akhatov, 2010).

5. Disinfect the hole. After removing the plant, drench the soil where it grew with boiling water, a solution of potassium permanganate, or copper sulphate.

6. Disinfect the tools. Secateurs, knife, gloves – everything that came into contact with the diseased plant – treat with alcohol, bleach, or a strong solution of potassium permanganate.

7. Do not plant in that spot this season. Leave the ground empty or sow green manure (mustard, phacelia).

What to Do with Neighbouring Plants?

• Observe. Over the next 7‑10 days, carefully inspect all neighbouring bushes. At the first signs of disease – repeat the algorithm.
• Treat preventively. If you removed a plant with a virus, treat the neighbours with an insecticide against vectors (aphids, thrips, whiteflies). If with a fungus – carry out a preventive treatment with a fungicide.
• Do not take seeds from diseased plants. Even if the fruits look healthy, the virus may be inside the seed (Blancard, 2012).

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Final rule: It is better to remove one plant and save ten than to try to cure one and lose them all. In growing tomatoes, sometimes the main victory is to retreat in time. Removing a diseased plant is not an admission of defeat, but a strategic step to preserve the entire garden (Jones, 2008).