Why do leaves grow sick and yellow in tomatoes in a greenhouse

Tomatoes came to our beds from South America, so this culture is very fond of heat, moisture and light. In our climatic zone, in order to provide the plant with suitable conditions, they are cultivated in greenhouses. But in this case, gardeners are faced with a lot of problems: poor germination and small crops, pathogenic bacteria and harmful insects. More vegetable growers are concerned about the question of why the leaves turn yellow in tomatoes in the greenhouse. The causes of this phenomenon are many, and the consequences can be very sad.

The leaves of tomatoes in the greenhouse are sick and turn yellow

Causes of Yellowing Leaves

Among the many probable causes of yellowing of greenery on tomato bushes in the first place is a violation of the roots, because the plant receives all the necessary substances through them. Damaged roots do not cope with their main function, and tomatoes do not receive the necessary amount of beneficial elements and water. This leads to the fact that the leaves of the tomatoes in the greenhouse turn yellow.

Damage to the roots are of a different nature:

  • mechanical intervention;
  • insect damage;
  • the development of disease.

Every violation of the root system of the plant must be fought.

Tomato leaves in the greenhouse may turn yellow under the influence of climatic conditions, soil composition, due to the characteristics of seeds and cultivars.

Mechanical damage

The root system of young tomato sprouts is very fragile, it is very easy to break it when planting. You can harm the roots by weeding the beds of tomatoes. Carrying out loosening of the soil, deeply driving the chopper, you can easily damage the lateral processes of the roots. In this case, one should not panic: if you properly look after the crop further, the roots will grow very quickly, and there will not be a trace of yellowed leaves.

Overgrowing Seedlings

Overexposure of seedlings also leads to a violation of the root system. To get an early harvest, gardeners early prepare seeds for seedlings. When the sprouted seeds are ready for planting, weather conditions or other reasons do not allow this. Seedlings continue to grow in small pots, the root system of these sprouts turns into a bundle of tangled thin strings. Many of them will be broken during a transplant. As a result, leaves on tomato beds turn yellow almost immediately after transplantation.


To help seedlings adapt and organize proper nutrition of tomato beds, you need to spray it with a weak fertilizer solution. It can be either phosphates, or nitrates, or chlorides. The solution is made unsaturated. The content of nutrients should not exceed 1% of the total volume of the solution. Foliar top dressing of seedlings is permissible to be carried out daily, until the appearance of new roots and leaves through which the plant will again be able to receive all the necessary nutrients.

To accelerate the adaptation process, the root system of the sprouts is treated with a root formation stimulator. They are used strictly in accordance with the instructions from the manufacturer.

Damage by pathogenic fungi

Pathogenic fungi can harm the root system of a plant

Pathogenic fungi can also damage the root system of tomatoes. The most common diseases that cause leaves to turn yellow in tomatoes in a greenhouse are fusarium and late blight.

Pathogenic fungi live in the soil, are found in tomato seeds, on a garden tool that treated contaminated soil.

Late blight develops on crops that are often watered on foliage in hot and sunny weather. Spots appear on the leaves, which soon begin to turn yellow.


In the fight against fungal diseases, it is necessary to use special drugs, available in large quantities in specialized stores. When using them, it is necessary to strictly adhere to the dosages recommended by the manufacturers.

To obtain the result, it is necessary to thoroughly disinfect the soil with a pink solution of manganese. It is useful to periodically prevent fungal diseases. For this, vegetable crops are treated with special compounds.

Insect damage

Damage to the root system can be the machinations of harmful insects that like to feast on the delicate and juicy roots of tomatoes. The greatest harm can be caused by:

  • a bear;
  • wireworm beetle.

Bear loves well-fertilized organic soil. She builds a nest, burying herself to a depth of no more than 15 cm, from there she gets to the roots of tomatoes and eats them. As a result, the leaves first turn yellow in the tomatoes, and then the entire vegetable crop disappears.

Fighting the Bear

To combat the bear, special medications “Medvedka” and “Thunder” have been developed. And among folk remedies, the infusion of bitter pepper has proven itself well. It is prepared at the rate of 150 g of pepper per bucket of water. The liquid is poured into the insect's mink.

Another proven method is acetic solution. In a bucket of water, 2 cups of ordinary vinegar are bred. This composition is filled with minks and passages laid by the bear.


The wireworm beetle harms tomatoes by laying off its larvae near or on the roots of the plant itself. They eat juicy roots and make their way into the stems of plants. Tomatoes not only acquire a yellow color, but also die soon.

To get rid of the larvae, use a mixture of sawdust, sand and the drug "Bazudin." The resulting composition is added dropwise into the soil around the plants.

If the appearance of beetles has already been observed at the place where the tomatoes will grow, it is necessary to cultivate the soil in advance, even before planting the seedlings in the greenhouse. To do this, a few days before transplanting, in several places throughout the garden to a depth of no more than 10 cm, small pieces of any vegetables strung on sticks 15-20 cm long are buried. The ends should look out. After 2-3 days, the beetles will gather on sticks. They need to be collected and burned.

Lack and excess of moisture

In the absence of ventilation, the plant may rot.

Tomatoes turn yellow in the greenhouse not only due to damage to the roots. Both yellowing and excessive moisture can lead to yellowing of the leaves. Plants evaporate a large amount of moisture, and although the main root of the tomatoes is very long, and the plant is quite drought-resistant, the side roots are very close to the surface, so tomatoes require heavy watering.

If the tomatoes lack moisture, the upper leaves of the plant turn yellow in the greenhouse and begin to curl. When growing tomatoes not in open ground, the opposite problem is more common: excess moisture. In this case, the leaves begin to turn yellow, the root system rots, and as a result the plant dies. To prevent this from happening, it is enough to ensure good ventilation of the greenhouse and adjust the irrigation mode.

Nutrient deficiency

The appearance of yellow leaves on tomatoes in a greenhouse may be a signal that the plant is not properly fed. Perhaps the wrong fertilizer is applied or in the wrong amount.

At all stages of development, garden crops require potassium, nitrogen, magnesium and other macro- and microelements. Their deficiency, as well as an oversupply, negatively affects not only the greens of tomatoes, but also on the plant as a whole.

If the sprouts of the culture are weak, with thin stems, small leaves, tomatoes do not receive nitrogen. In this case, the plant is watered with the use of nitrogen-containing fertilizers. The simplest solution is to water the tomatoes:

  • urea solution;
  • infusion of manure.

The lack of potassium is indicated by the appearance of small yellow dots, subsequently merging into a single yellow spot.

To replenish potassium reserves in tomato beds, you need to water them with a solution of potassium sulfate.

With a lack of manganese, young leaves first begin to turn yellow, and only then old ones. Missing reserves of phosphorus lead not only to the appearance of yellow leaves, but also to their subsequent death. By twisting yellowed leaves, the plant responds to a lack of magnesium.

How to fix the situation

The solution to the problem is the proper feeding of tomato beds. The best option would be to apply the complex fertilizer offered in specialized stores. They have in their composition all the nutrients necessary for vegetable crops.

If you give preference to folk methods, it is enough to use chicken droppings. First, a mother liquor is prepared, after which every 2 l is diluted with a bucket of clean water and watered tomato beds.

If healthy leaves began to turn yellow on the tomatoes in the greenhouse, an urgent need to be established. Yellow leaves can not be ignored, because the consequence of this can be a lack of harvest, complete destruction of plants, infected soil and proliferated insects.


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