Complete guide to diseases, viruses, and pests affecting tomato crops
Tomato cultivation (Solanum lycopersicum) is exposed to numerous phytosanitary threats that can compromise the productivity and quality of the crop. diseases and pests that affect tomatoes are multiple and, for their adequate control, it is essential to know their causal agents, symptoms and management strategies.
The main causes of problems in tomatoes are agents fungal, bacterial, viral and pests of various kindsThese pathogens and parasites are favored by environmental conditions such as humidity, temperature, planting density, and agricultural management. Therefore, their timely identification, prevention, and control are essential to avoid significant economic losses.
This comprehensive guide details the main tomato diseases and pests, their diagnosis, control methods, and practical recommendations for technicians and farmers.
Viral diseases that damage tomatoes
Viruses represent one of the most serious threats for tomatoes, which can cause total crop losses. They spread mainly through insect vectors (such as whiteflies, thrips and aphids), contaminated tools and plant-to-plant contact.
- Tobacco mosaic virus (TMV): Transmitted by contact, it causes mosaic symptoms, necrosis, mottling and leaf deformations.
- Tomato yellow leaf curl virus (TYLCV): The most characteristic symptom is the spooning of leaves, chlorosis, reduction in plant size and flower abortion. Its main vector is the whitefly (Bemisia tabaci).
- Tanning plague virus (TSWV): It causes browning, necrotic spots, and deformations on leaves and fruit. Transmitted by various species of thrips.
- Tobacco ringspot virus (TRSV), cucumber mosaic virus (CMV), potato virus Y (PVY) and others: These viruses can cause similar symptoms, such as mosaicism, chlorosis, deformations, and reduced yield.
The sure identification of a viral disease requires, in addition to observing symptoms, laboratory analysisPreventive measures include the use of certified seeds, vector control, removal of infected plants, and disinfection of tools.
Fungal diseases in tomatoes
The mushrooms They are the main cause of diseases in tomato plants and are usually spread by spores carried by wind, water or contaminated tools.
- Powdery mildew (tauric leveillula, Oidium spp.): White powder on the upper and lower sides of leaves, reducing their photosynthetic activity and weakening the plant.
- Early blight (Alternaria Solani): Concentric brown spots on leaves, stems, and fruit. Very common in conditions of high humidity and mild temperatures.
- Late blight (Phytophthora infestans): Large, dark, oily patches with progressive defoliation and fruit rot. They thrive in high humidity and mild temperatures.
- Botrytis or gray mold (Botrytis cinerea): Soft rots covered by greyish mould on fruits and tender tissues.
- Cladosporiosis (passalora fulva o fulvia fulva): Irregular spots on the upper side of the leaf and brown dust on the underside.
- Fusarium wilt (Fusarium oxysporum – f. sp. lycopersici/root-lycopersici): Vascular fungus causing wilting and necrosis.
- Verticillium wilt (Verticillium dahliae): Progressive decline, yellowing and death of leaves due to damage to the vascular system.
- Septoria (Septoria lycopersici): Small spots with gray centers and dark edges on leaves.
- Anthracnose (Colletotrichum spp.): Sunken, blackish spots on ripe fruit.
El integrated management Management of fungal diseases includes crop rotation, use of resistant varieties, removal of plant debris, irrigation management, and application of fungicides when necessary. Alternating products and combining cultural measures is key to preventing the development of resistance.
Bacterial diseases in tomatoes
The bacteria Tomato disease-causing organisms spread rapidly through water, wind, insects, agricultural tools, and contaminated seeds. The most significant problems include:
- Bacterial wilt (Ralstonia solanacearum): It causes rapid decline of the plant, vascular darkening and total collapse.
- Bacterial cancer (Clavibacter michiganensis): Lesions on stems, leaves and fruits, and bacterial exudations.
- Bacterial spot (Xanthomonas spp.): Angular watery spots on leaves, stems and fruits.
- Bacterial freckle (Pseudomonas syringae p.v. tomato): Small dark spots on leaves and fruits, depreciating quality.
La prevention It is based on the use of healthy seeds, disinfection of tools, crop rotation and the application of copper-based products if necessary.
Main pests affecting tomato crops
Pests can cause direct damage through feeding and serious indirect damage through their role as vectors of diseases, especially viruses. The most common threats to tomatoes include:
- Vasates (Aculops lycopersici): Microscopic mites that cause necrosis, browning, leaf drop, and plant collapse and death. They spread rapidly in warm, dry conditions.
- Red spider (Tetranychus urticae): It causes yellow spots, leaf drop, weakening and defoliation.
- White fly (Bemisia tabaci y Trialeurodes vaporariorum): They cause yellowing, weakening, and transmission of viruses such as TYLCV.
- tomato moth (Tuta absoluta): Their larvae mine leaves, stems and fruits, causing galleries and losses in quality and quantity.
- aphids (Aulacorthum solani, Macrosiphum euphorbiae, Myzus persicae, Aphis gossypii): They suck sap and transmit numerous viruses. They cause deformities, cockling, and general weakness.
- Thrips (Frankliniella occidentalis): They damage leaves and flowers and are vectors of viruses such as TSWV.
- Leaf miners (Liriomyza spp.): They form galleries in the leaf mesophyll, weakening the plant.
- Mealybugs (Pseudococcus viburni): They cause growth retardation and yellowing.
- Caterpillars (Helicoverpa armigera, Spodoptera exigua, Tuta absoluta): They attack leaves, flowers and fruits at different stages.
- Bed bugs (Nezara viridula, Nesidiocoris tenuis, Engytatus modestus): They can deform fruit and, depending on the species, act as predators of pests.
- Other mites: The tomato sliver mite can quickly dry out the plant if it reaches high densities.
Integrated pest management: It is based on periodic monitoring, the use of color traps, weed management, the use of phytosanitary products at the appropriate time and dose, the introduction of natural enemies, and the use of resistant varieties.
General symptoms for identifying tomato diseases and pests
- Leaf spots: They may be necrotic, chlorotic, concentric, oily, or have halos. Their color, size, and location aid in diagnosis.
- Deformations: Curling, curling, spooning, mosaics, and leaf reduction are often associated with viral or pest attacks.
- Rots and molds: Fruits and stems may have soft, moist areas covered by visible fungal mycelium (grey, white or black).
- Collapse and wilting: Vascular alterations caused by fungi or bacteria can cause progressive or sudden wilting, which is often irreversible.
- Galleries and mining: Damage from insects such as leaf miners, tuta or caterpillar larvae, visible to the naked eye.
- Other symptoms: Stipple, apical necrosis, ring spots, surface powder, exudates, deformations in fruits and fall of flowers and leaves.
Preventive and integrated management measures
- Use of certified and healthy seeds.
- Crop rotation, avoiding repeated planting of solanaceous crops in the same plot.
- Removal of infected plant debris and weeds.
- Proper irrigation and ventilation management to reduce humidity and the spread of pathogens.
- Rational use of specific phytosanitary products and alternating modes of action to avoid resistance.
- Introduction and conservation of auxiliary fauna (predators and parasitoids).
- Periodic control and professional phytosanitary monitoring.
Additional resources and specialized guides
- Phytosanitary Products Registry
- FAO Complete Guide on Tomato Disease and Pest Management.
- PDF on virus identification in tomato crops
