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The appearance of yellow leaves on tomatoes indicates a violation of the rules for growing plants. There are several explanations for why tomato leaves turn yellow. These include violation of the microclimate in the cultivation of tomatoes, lack of fertilizers, the spread of diseases and pests.
Causes of yellowing leaves
Violation of the microclimate
For normal growth, tomatoes require the maintenance of certain climatic conditions. Usually, the drying of the leaves is associated with incorrect temperature conditions and non-compliance with the rules of watering. If the tomatoes turn yellow and the leaves dry, what to do depends on the cause of the microclimate disturbance.
Temperature
For normal growth, tomatoes require a temperature of 20 to 25 degrees during the day. At the same time, at night, its value should remain at the level of 18-20 degrees. Sharp temperature fluctuations adversely affect the condition of plants.
When the temperature rises above normal, the plants wilt. The first sign of this process is the yellowing of the leaves of tomatoes. If measures are not taken in a timely manner, then the inflorescences will begin to crumble at the tomatoes.
Glasses in a greenhouse can be coated with lime to reduce exposure to sunlight. To reduce the temperature, containers with water are placed between the bushes.
If tomatoes grow in open ground, then a canopy can be built over them. Its functions will be performed by a white fabric.
Watering tomatoes
Violation of the moisture regime also leads to drying of plant leaves. Tomatoes require abundant, but infrequent watering. Due to the developed root system, tomatoes can receive moisture and nutrients from a depth of up to one meter.
With sufficient rainfall in open ground, plants will need less watering. Moisture should be applied under the root. It is not allowed to get on the stems and tops of tomatoes. Otherwise, it will cause leaf burn.
Watering tomatoes requires warm water. It is best to use rainwater that has warmed up in the sun. Plants should be watered in the morning or evening in the absence of direct sunlight. The intensity of watering increases during the flowering period of tomatoes.
Mulching will help maintain the required level of soil moisture. For this, straw and compost are laid on the surface of the soil. Mulch avoids loosening and reduces the number of weeds.
If the leaves of tomatoes turn yellow, then this is the first sign of a lack of moisture. Therefore, it is imperative to revise the irrigation scheme and, if necessary, make adjustments.
Fertilizer shortage
The appearance of yellowness on the leaves of plants is often associated with a lack of nutrients in the soil. This is usually seen on tomatoes in the open field or large greenhouses, where it is difficult to control the quality of the land.
Nitrogen
With a lack of nitrogen, tomato leaves turn yellow, after which the dried tops fall off. If you do not take timely measures, then the bush will begin to stretch, and the young shoots will become pale and small.
Due to nitrogen, plant growth improves and green mass builds up. Tomatoes can be fed with urea. A bucket of water requires 40 g of this substance. The resulting solution is used for spraying plantings.
When using nitrogenous fertilizers, the dosage of substances must be observed. Frequent fertilizing with nitrogen will lead to increased growth of tomato tops. If after top dressing the condition of the plants has improved, then in the future the introduction of nitrogen should be stopped.
potassium
With a potassium deficiency in tomatoes, the old leaves turn yellow and dry, and the young tops curl in a boat. Small spots appear along the edges of the leaf plate, after which they merge into a single line. As a result, the leaves of tomatoes dry up.
Plants can be fertilized with potassium at any stage of the growing season. This trace element is especially important for adult tomatoes when the fruit ripens.
One of the options for feeding is the use of potassium sulfate. After its use in fertilized vegetables, the content of vitamins and sugars increases, and plants become resistant to diseases.
To feed tomatoes, 40 g of potassium sulfate per bucket of water is required. Plants are watered under the root or sprayed on the leaf.
Magnesium
With a lack of magnesium, yellowness first occurs between the veins, then the leaf plate is twisted.
Magnesium sulfate will help to fill the deficiency of this element. 40 g of the substance are diluted in 10 liters of water, after which they are applied under the root of the plants. For spraying tomatoes, the indicated rate is halved.
Magnesium allows plants to better absorb nitrogen, calcium and phosphorus. As a result, the development of tomatoes is activated, the yield increases and the taste characteristics of the fruit improve.
Sulfur
Sulfur deficiency is determined by the light green tint of the leaves, which gradually turn yellow. In this case, the veins become red. With a prolonged lack of sulfur, the stem weakens and becomes brittle.
Ammonized superphosphate will help to fill the lack of this element. This substance dissolves well in the form and provides tomatoes with sulfur and potassium.
Hardware
Iron deficiency causes chlorosis. This disease is characterized by the appearance of yellow leaves, and the veins remain green. Over time, the top of the tomatoes loses color, and the plant stops developing.
Ferrous vitriol will help to fill the deficit, on the basis of which a spray solution is prepared. 5 g of the substance is added to a bucket of water, after which the treatment is carried out. A week later, the procedure is repeated.
Development of diseases
Diseases often become the cause of yellowing of tomato tops. Most of them develop with the appearance of excessive moisture, thickening of plantings and other violations in the care of plants. To combat diseases, special drugs are used.
Fuzarioz
Fusarium is spread by fungal spores. The defeat covers the roots, stems, tops and fruits of tomatoes. Signs of the disease can occur at any stage of plant development, however, most often they can be detected during fruit formation.
With fusarium, the leaves of the tomato turn yellow, which then curl and wither. Brown vessels are visible on the section of the stem. The disease occurs from below, after which it moves to the top.
When Fusarium appears, the plant is recommended to be removed and burned to avoid the spread of infection. To prevent the disease, it is necessary to treat seeds and soil with fungicides before planting, plant plants at a distance of 30 cm from each other, eliminate weeds, loosen the soil.
Phytophthora
If the leaves turn yellow on tomatoes, this may be a sign of phytophthora. This is a fungal disease, which is characterized by the presence of brown spots on yellowing leaves.
When phytophthora appears, all yellowed leaves must be eliminated. In the greenhouse, the humidity level should be reduced by airing it.
Healthy bushes are treated with biological preparations (“Fitosporin”, “Trichofit”, etc.). After their use, the fruits must be thoroughly washed and only then used for food.
If more than a month remains before the start of the harvest, then it is allowed to use chemicals (Ridomil, Quadris, Hom). They are also used after harvest to disinfect the greenhouse and soil.
Additionally, tomatoes are treated with a solution based on iodine and milk (15 drops of iodine per 1 liter of milk and 9 liters of water). The procedure is carried out by spraying plants. As a result, a film forms on the surface of the tops, which prevents the penetration of harmful bacteria.
Pest spread
The main pests of tomatoes are whiteflies, aphids, spider mites. If these insects are found, it is necessary to spray the plantings. Pests feed on the sap of plants and draw vitality from them. As a result, the upper leaves turn yellow, and the plants gradually fade.
If more than a month remains before harvesting, then Inta-vir or Iskra preparations are used. These drugs have a paralytic effect on the nervous system of insects. Preparations do not harm tomatoes and the environment.
When the harvest time is less than a month, then the Biotlin preparation is used. This tool has a fast effect.
Other reasons
Seedlings may turn yellow with a lack of lighting. Installing a white fluorescent lamp will help solve the problem. For tomatoes, daylight hours should be 8-10 hours.
If the lower leaves of a tomato turn yellow, then this indicates damage to the root system. This usually occurs during deep loosening or during transplantation of plants to a permanent place. In this case, the color of the leaves will be restored when the adventitious roots appear in the tomatoes.
Conclusion
Why the leaves of a tomato dry depends on the state of the environment and the application of fertilizers. If the temperature rises above normal, you can completely lose the crop. The scheme of watering tomatoes is necessarily adjusted, if necessary, plants are fed.
If signs of diseases or the presence of pests are found, the tomatoes are processed. For this, special preparations are used, on the basis of which a solution for spraying is prepared. You can process plantings with folk methods that are as safe as possible for plants.
