Crops
Nutritional disorders (deficiencies)
Like many cultivated plants, the tomato needs a variety of mineral elements to ensure its growth throughout its development cycle. When they are provided in excess or they are lacking, nutritional disorders occur (nutritional disorders). This perennial herb grows fairly well in an optimal temperature range of 16 to 32 ° C.
In addition to not always being easy to manage, its fertilization can be influenced by various parameters:
- the richness and balance of the soil in fertilizing elements (soil analyzes are therefore essential);
- the type of tomato cultivated and the variety chosen;
- the density of plantation;
- the production method (cultivation in soil or out of soil, nature of the substrate);
- the nature of the irrigation system and its conduct;
- and any other factor disrupting plant growth.
It is therefore not uncommon to be confronted in the field with plants suffering from deficiencies or an excess of nutrients. These conditions are part of the non-parasitic diseases and grouped together under the terminology “nutritional disorders”. The latter appear quite frequently on tomatoes by yellowing of variable nature and distribution on the plants (figures 1 to 3) . The following tables summarize the few deficiencies sometimes encountered on the tomato, describe the symptoms that can be encountered on this plant.
In addition to not always being easy to manage, its fertilization can be influenced by various parameters:
- the richness and balance of the soil in fertilizing elements (soil analyzes are therefore essential);
- the type of tomato cultivated and the variety chosen;
- the density of plantation;
- the production method (cultivation in soil or out of soil, nature of the substrate);
- the nature of the irrigation system and its conduct;
- and any other factor disrupting plant growth.
It is therefore not uncommon to be confronted in the field with plants suffering from deficiencies or an excess of nutrients. These conditions are part of the non-parasitic diseases and grouped together under the terminology “nutritional disorders”. The latter appear quite frequently on tomatoes by yellowing of variable nature and distribution on the plants (figures 1 to 3) . The following tables summarize the few deficiencies sometimes encountered on the tomato, describe the symptoms that can be encountered on this plant.
Symptoms of deficiencies appearing first on young leaflets and may later generalize to the entire foliage of the tomato
| Deficiencies | Symptoms |
| Calcium (Ca) | The periphery of the leaf blade of young leaflets is pale green and necrotic lesions gradually develop there. In the event of very marked deficiency, the terminal bud (s) turn brown, necrotize and die. The development of plants is thus more or less blocked. The fruits reveal moist changes becoming necrotic at their stylar end ( apical necrosis , blossom-end rot). |
| Bore (Bo) | The young leaflets near the apex are slightly chlorotic, necrotic and fragile and tend to deform, curl up. Plant growth is slowed down, the internodes of the upper parts of the stem are shorter. The terminal bud (s), also necrotic, eventually die. Internal browning, mottling are visible on and in the fruits. |
| Manganese (Mn) | The young leaflets undergo interveinal chlorosis, the discolored tissues are dotted with small necrotic changes but their veins remain green. In the case of severe deficiency, the old leaves will eventually turn yellow too. |
| Sulfur (S) | Young leaflets are pale green and slightly smaller. This slight chlorosis can be generalized to the whole plant. The stem and petioles may have more or less anthocyanin colouration. This deficiency is relatively rare in tomato. |
| Fer (Fe) | Interveinal chlorosis of young leaflets beginning at their base and gradually reaching their tip. The veins remain quite green and contrast with the interveinal tissues. Ultimately, the tissues may turn white and chlorosis may spread to the entire plant (Figures 1 and 2). |
| Zinc (Zn) | The leaflets are particularly small, chlorotic and necrotic between the veins, which are themselves thicker and tend to curve downwards. Heavily affected plants see their growth limited. |
Symptoms of deficiencies appearing first on the lower leaves and may later spread to the entire tomato foliage
| Deficiencies | Symptoms |
| Potassium (K) | Chlorotic spots, more or less marked, starting at the periphery of the limbus and progressively reaching the interveinal tissues. They eventually turn brown and necrose. Marginally, the blade turns brown and curves downwards. Plant growth is more or less reduced. Fruits may be softer, hollow, and irregular in size, poorly colored, and showing a symptom of graywall . |
| Magnesium (Mg) | Interveinal chlorosis beginning at the periphery of the leaf blade of young leaflets. At the end of the evolution, the yellowed tissues end up necrosis while the veins tend to retain their green color (Figures 3 and 4). Fruits may show a green collar . |
| Nitrogen (N) | The leaves are pale green, the older ones show more yellowing and can necrode and drop. Plant growth is limited. The stem and petiole are rather rigid. |
| Phosphorus (P) | Dark green leaflets eventually show a purplish color on the underside of the leaf blade, especially the veins. The petioles and the sometimes very thin stem show a comparable color. The plants are generally not very growing and show upright leaves with curved leaflets. The fruits are hollow and poorly colored. Old leaves may drop off. |
| Molybdenum (Mo) | Yellowish-brown necrotic changes developing on the periphery of the blade of old leaves with the edge rising. Vegetation and root system growth may be reduced. This deficiency seems quite rare in tomato. |
| Copper (Cu) | Interveinal chlorosis starting from the periphery of the limbus. Subsequently, the tissues may necrode and dry out, and the edge of the limbus may rise. Plants sometimes wilt, and their growth is reduced. This deficiency is uncommon in tomato. |
Remember that currently, when we talk about deficiency, we often tend to equate true deficiencies with induced deficiencies.
The true deficiencies (element in too small quantity in the soil) are more and more rare. Their diagnosis visual is very difficult because, with some exceptions, the symptoms they cause are materialized by discolorations, more or less intense leaf yellowing, very difficult to assess by a non-specialist.
In the majority of cases, we are dealing with induced deficiencies (elements present but not available), which does not facilitate their diagnosis. In addition to determining the deficiency, it is also necessary to look for the cause (s). These can be various, for example poorly conducted irrigation (too much or not enough water), too low or too high a temperature or soil pH, root systems in poor condition
When this type of symptom appears, one should not too hastily conclude that there is any deficiency without having spoken to a technician or consulted a specialist. Of course, in addition to these opinions, physical and chemical analyzes of the soil and vegetation may be required.
Deficiencies occur particularly in empirically fertilized crops, in the absence of soil analysis.
Figure 1
Figure 2
Figure 3
Figure 4