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Why do tomatoes turn yellow in a greenhouse or greenhouse and what to do

Why do tomatoes turn yellow in a greenhouse or greenhouse and what to do


Often, even experienced farmers are faced with the problem of yellowing of tomato leaves in greenhouses. Why tomatoes can turn yellow in a greenhouse and what to do about it, we will tell you in this article.

The reason for the yellowing of the leaves can be:

  1. Untimely transplantation of seedlings;
  2. Damage to the root system during transplantation;
  3. Improper organization of watering;
  4. Failure to comply with the temperature regime;
  5. Heavy soil;
  6. Lack of nutrients in the soil;
  7. Diseases and pests.

Let's consider each of the reasons separately.

Untimely planting of tomato seedlings in a greenhouse

When growing seedlings at home, you must remember the timing of the transplant. It is necessary to start planting seedlings in greenhouses or a polycarbonate greenhouse at the age of 55-60 days... In overgrown seedlings, the root system gathers into a lump due to lack of space in the containers and begins to die off.

At the time of transplanting the seedlings into the greenhouse, new roots and young foliage grow. The required amount of nutrients no longer reaches the old leaves. Therefore, they turn yellow and die off.

In this case, you need to do root irrigation... Preparing the solution:

  • water - 10 liters;
  • fertilizers - 100 gr.

We irrigate the root system with this solution. The seedlings will develop well in the future, but there will be a delay in the development of the bush for several weeks.

Damage to the root system when transplanting a tomato

Mechanical damage to the roots can occur as a result of careless planting of seedlings, or careless loosening of the soil. In this case, the lower part of the seedling and the leaves may turn yellow.

When a new root grows back, the plant will soon return to normal. You can help the plant recover by watering with the drug "Kornevin"And spraying the leaves complex feeding.

Improper watering of tomatoes

Tomatoes are a drought-tolerant crop. Despite the fact that the root system of plants is quite powerful and goes deep, the bulk of the roots that absorb moisture are close to the soil surface. Therefore, irregular watering adversely affects the plant.

Also tomatoes do not like excess moisture... Watering should be done rarely, but abundantly. In greenhouses, moisture evaporates much more slowly than in open beds, so an excess of moisture can lead to fungal diseases.

Watering must be done under the root... Water that gets on the leaves causes them to turn yellow.

Non-compliance with the temperature regime

If there are sudden temperature changes in the greenhouse during the day and night, this negatively affects the seedlings. If the leaves turn yellow and dry out, this is speaks of overheating of seedlings... With hypothermia, the leaves turn yellow, lose their elasticity and wither. This indicates poor performance of the root system.

The highest permissible temperature in the greenhouse is + 30-32 degrees. The lowest is + 16-18 degrees.

You can prevent temperature drops in the greenhouse using barrels of water... In the daytime, water heats up, absorbing heat, at night it gives it off.

Heavy acidic soil

Tomatoes do not tolerate heavy soil and high acidity... It is better to prepare the soil for tomatoes yourself before planting.

It is necessary to mix in equal parts garden soil, peat and sifted river sand and add ash to normalize the acidity level. The soil is necessary loosen after each wateringto prevent stagnation of moisture in the soil, leading to soil acidification.

When loosening, additional oxygen is supplied to the roots, which ensures normal plant growth. Lack of these measures leads to yellowing.

Lack of trace elements in the soil

It is very important for tomatoes to have enough minerals in the soil. Their lack leads to yellowing of the leaves.

Signs of micronutrient deficiencies:

  • Nitrogen deficiency... With a lack of nitrogen in the soil, the plant will be weak, with a thinned stem, small foliage. The lower leaves begin to turn yellow and the veins become bluish in color. This drawback can be eliminated by watering with a mullein solution: for 10 liters of water, 1 liter of fermented mullein and 200 grams of ash.
  • Lack of magnesium... The leaves are covered with brown-brown spots and fall off. You can eliminate it by applying fertilizers with magnesium nitrate.
  • Potassium deficiency... The leaf becomes covered with yellow spots and curls. Until the fruit sets, it is necessary to make a top dressing based on potassium chloride, then potassium phosphate can be used.
  • Lack of sulfur... In the process of fruiting, add fertilizing twice with a high sulfur content.
  • Boron deficiency... The leaf at the top of the bush turns yellow. Apply boric acid-based fertilizing.
  • Manganese starvation... The leaves are light yellow in color. Young leaves are affected first, and then old ones.

In the latter case, it is necessary to add to the soil fermented mullein solution, diluted in the ratio:

  • mullein -1 liter
  • water - 20 liters

It is also recommended to spray tomato bushes. potassium permanganate solution in relation to:

  • warm water - 10 liters
  • manganese - 1 tablespoon

Diseases and pests

Yellowish foliage can occur as a result of the appearance of pests in the soil such as:

  • bear;
  • wireworm;
  • nematodes;
  • tobacco aphid.

The wireworm, nematode and bear feed on the root system of plants, damaging it. Each of these pests is fought with different means.

It is recommended to use the drug against the bear "Medvetox". To combat the wireworm, use "Bazudin". If nematodes are found in the greenhouse, it is recommended that replace soil... It is extremely difficult to deal with this type of pest.

If the root system of plants is not damaged and there are no pests in the greenhouse, and the leaves continue to turn yellow, this indicates the presence of fungal diseases.

These diseases include:

  • late blight;
  • fusarium.

Late blight

With this disease, brown spots appear on the leaves, which subsequently affect the fruits. The cause of this disease is improper watering.

It must be remembered that watering must be carried out at the root, without falling on the leaves. In case of late blight disease, the bushes must be processed Bordeaux liquid.

At home, you can make it yourself. When preparing this solution, it is necessary to strictly observe the proportions. To obtain a 1% solution, the components are diluted in the following ratio:

  • water - 10 liters;
  • copper sulfate - 100 grams;
  • quicklime — 150 grams.

For spraying tomatoes per 1 sq. meter will need 2 liters of solution.

Fusarium

With this disease, tomato leaves lose their elasticity and change color... The cause of this disease is:

  • infected tool;
  • infected seeds.

Penetrating into the soil, the fungus can be present in it for a long time, since the high humidity and high temperature in the greenhouse are ideal conditions for its life.

This disease can manifest itself both in an adult plant and in seedlings. You can get rid of this problem with the help of drugs "Previkur Energy"And"Trichodermin».

Reasons why leaves turn yellow, prevention and elimination

  • Lack of micronutrients... With this problem, regular feeding is necessary.
  • Pest infestation... Regular destruction of weeds, pest control of the soil, strengthening of plant immunity, normalization of the microclimate in the greenhouse will help to avoid this problem.
  • Diseases... To prevent diseases, it is necessary to disinfect the greenhouse, seeds, soil in a timely manner. Avoid thickening of plants, as well as regularly ventilate the greenhouse.
  • Root damage... This problem can be avoided by growing seedlings in separate containers. Transplant with a lump of earth from the previous place of growth. Loosening carefully.
  • Temperature drops... Ventilate regularly. Place barrels of water in the greenhouse.

By taking preventive measures to eliminate the causes of yellowing of the leaves, you can harvest a good harvest of tomatoes with excellent taste in the greenhouse.


Tomatoes: diseases and their treatment in the greenhouse and in the garden

Author: Natalia Category: Garden plants Published: February 15, 2019 Last revised: January 06, 2021

  • Tomato leaf diseases - symptoms
    • Why do tomatoes turn yellow
    • Why do tomatoes dry
    • Why do tomatoes rot
    • Spots on tomato leaves
    • Why do tomatoes fall
    • Why tomato leaves turn black
    • The leaves of tomatoes wither
    • Tomato leaves turn white
  • Diseases of tomatoes in the greenhouse and their treatment
    • Tomato phytophthora
    • Tomato septoria (white spot)
    • Gray rot of tomatoes
    • Rotting tomatoes
    • Tomato spots
    • Verticillosis of tomatoes
    • Powdery mildew of tomatoes
    • Tomato leaf mold
    • Bronze, or spotted wilting of tomatoes
    • Cracking tomato fruit
    • Tomato viral diseases
    • Tomato bacterial diseases
  • Diseases of tomatoes in the open field and the fight against them
    • Tomato anthracnose, or copperhead
    • Bacteriosis, or bacterial wilting of tomatoes
    • Pith necrosis
    • Chloratic curl of tomato leaves
    • Tomato bacterial cancer
    • The threadiness of tomato leaves
  • Prevention of tomato diseases
  • Disease Resistant Tomato Varieties
  • Literature
  • Comments (1)

Tomatoes often get sick, and, unfortunately, they have plenty of diseases, so those who are engaged in the cultivation of this crop need to know as much as possible not only about diseases, but also about how to deal with them.
We invite you to get acquainted with the most basic problems in growing this crop, as well as with those tools that will help you cope with diseases and prevent tomatoes from getting infected in the garden or in the greenhouse.


Causes of yellowing tomato leaves

On the fly, you can name almost a dozen different reasons why your plants have yellow leaves. All of them are associated with improper crop care.

Thus, tomatoes signal that the created growing conditions are not suitable for them.

Tomatoes lack nutrition

In general, tomatoes are not considered a "gluttonous" crop. Usually they have enough nutrients that are already contained in the soil, as well as rare spot feeding.

Nevertheless, it also happens that there is a deficiency of a trace element in the diet. In this case, the plant signals a change in the color of the leaf plate.

What to do

It is necessary to feed the plant with fertilizer containing the necessary substances.

Yellowing due to soil

Tomatoes love loose, fertile soil. Heavy soil causes micronutrient deficiencies and depletes plants. As a result, the leaves turn yellow.

What to do

Fertilize with complex fertilizer. For example, Azofoskoy or Nitrofoskoy. In spring and autumn, add organic matter, and during the growing season, feed with a yeast solution.

Tomatoes are planted too close

For tomatoes to grow well, they need at least 40 cm of space between adjacent bushes. Of course, there are low-growing varieties that can do with a smaller area, but on average, this is just such a value.

If planted too often, neighboring plants lack sufficient nutrients in the soil. In addition, they shield each other from sunlight. As a result, all the bushes planted nearby begin to hurt.

What to do

In this case, it is too late to do something. You can advise, only pinch the tomatoes, tie them up and periodically spray them with growth stimulants. But these are all half measures that will not solve the problem.

Plants lack light

This reason is related to the previous one. Due to thickened plantings, the lower leaves do not have enough light, and they begin to turn yellow.

What to do

In this particular case, only pinching can help. This procedure will thin out the tomato "crown" a little. But in general, try not to allow thickening of tomato plantings, as this is fraught not only with yellow foliage, but also with the spread of fungal diseases.

Incorrect watering

Incorrect hydration is one of the most common causes of yellow foliage. Moreover, this is true both with a shortage of water and with its excess.

With excessive watering, the leaves begin to turn yellow and become watery, as it were. This begins the process of decay.

What to do

First of all, to normalize the watering regime. Tomatoes should be watered every day only in case of extreme heat and drought.

In normal weather, humidification should occur every 3-4 days. Watering should be abundant and carried out strictly at the root.

If you have already poured tomatoes, then be sure to loosen the soil to provide air access to the roots, and so that the earth dries out faster.

Incorrect temperature conditions

For tomatoes, moderately warm weather during the day and at night (25 and 18 degrees), respectively, is optimal.

Increasing and decreasing temperatures can equally cause discoloration of the sheet plates. Temperature changes are especially destructive when the day is very hot and the night is cold.

What to do

Of course, there is little you can do about the wrong temperature. Especially if the tomatoes grow in a regular garden without shelter.

But there are also some tricks here to help the plants. Use portable greenhouses, cover the bushes with old buckets. All this will help to equalize the temperature regime.

Incorrect feeding

Improper feeding is closely related to nutritional deficiencies in the tomato diet. You need to apply fertilizers wisely, understanding which element is responsible for what. Thoughtless addition of organic matter or "mineral water" leads to plant diseases.

What to do

Normalize the diet of plants.

Diseases and pests

Attack of parasitic insects and infection with fungal infections can also provoke a discoloration of the leaf plates.

What to do

Spraying with fungicides and insecticides will help deal with the problem.

Plants have a weak root system

Yellow foliage can be a sign of a weakened root system. If the roots of tomatoes do not absorb nutrients well from the soil, then this will inevitably affect the aboveground part of the plant.

The roots can be damaged during transplantation, they can be gnawed by pests.

What to do

Plants need to be treated with a solution of a rooting stimulant.

ON A NOTE. But remember that it will not help if the damage is severe.


Natural yellowing of foliage

In the event that a large seedling with a sufficiently developed root system is transplanted into the greenhouse, then it should be understood that some of the roots will still die off. And along with this, the leaves will turn yellow. This is completely normal.

Often inexperienced gardeners are surprised why the leaves of tomatoes in the greenhouse in the lower part of the bush turn yellow. This phenomenon is also considered normal. Especially when it comes to adult large bushes of tomatoes. The lower leaves should be periodically cut off, then they will not turn yellow. Sometimes the yellowing of the lower leaves is associated with minor mechanical damage to the roots, but one should not worry about this either.


Why do tomato leaves turn yellow after planting

Transplanting a tomato to a permanent place is perhaps the most crucial moment in growing tomatoes.Even if the seedlings were initially strong and seemingly healthy, then in the new soil they can seriously deteriorate. The following reasons lead to yellowing of foliage after planting:

  1. Poor soil quality. The quality of the soil plays a decisive role in the survival of plants in a new place. If the land, or rather its composition, is not suitable, then the seedlings will not only not take root, but will die altogether. For greenhouse tomatoes, it is especially important to prepare a balanced potting mix that will also be sterile. Tomatoes prefer loose and semi-moist soil, enriched with organic matter and a portion of minerals. The pH should be neutral. If the soil is not provided with everything necessary, the rapidly developing root system will have nowhere to take food, which will immediately affect the appearance of the plants: the foliage will turn yellow and become colorless. In addition, pathogenic microflora often accumulates in the greenhouse soil, which winter comfortably in warm conditions, and in the spring begins to rapidly multiply and capture plantings. To prevent the appearance of dangerous insects, the land must be disinfected.
  2. Improper watering. For the first 7-10 days, watering tomatoes is extremely undesirable, since the plant is taking root. If they are constantly poured, the leaves will wither and become yellow, lifeless.
  3. Root damage. The most common mistake leading to plant oppression is improper transplantation, during which the roots break off. In order for the damaged part to start functioning again, the plant needs up to two weeks.
  4. Hypothermia. If the seedlings were planted early, then it is possible that return frosts will cause hypothermia. Frozen seedlings will wither and turn yellow. It is possible to exclude such a course of events by first covering the garden bed with warm material or by supplying the greenhouse with a heating device.


What to do if the top leaves of a tomato turn yellow

If only the upper leaves of tomatoes turn yellow, and the lower ones remain green, the reason is the lack of nutrients.

Yellowing of the upper leaves is a sign of a deficiency of elements

1. Calcium. With a calcium deficiency, the upper leaves turn yellow, the tips of the leaves are deformed, the flowers fall off, and dark growing spots form at the top of the fruits. If you've limed the soil before planting, chances are you've overdone it with nitrogen fertilizers, which interfere with the free absorption of calcium. You can correct the situation by spraying the bushes with calcium nitrate (20 g per bucket of water).

2. Sulfur. Sulfur "starvation" can lead to lignification and thinning of stems, reddening of veins and gradual yellowing of leaves. In this case, the tomatoes are sprayed with a solution of magnesium sulfate (10 g per 10 l of water).

3. Iron. A symptom of insufficient iron content in the soil is yellow spots in the center of the tomato leaf and along the midrib. To return the plants to a healthy color, they are sprayed with a 1% solution of ferrous sulfate or iron chelate. You can also root top dressing with the same substances. The yellowness should go away in a day.

4. Manganese. Signs of manganese deficiency are similar to signs of iron deficiency. The only difference is that the color of the veins is not uniform, yellow-green. To restore the required amount of manganese, foliar treatment is carried out with a 1% solution of potassium permanganate.

5. Boron. Initially, with a lack of boron, the upper leaves retain their green color, but are deformed at the base. If the problem is not addressed, the leaves turn yellow, the veins turn dark brown. To prevent this, tomatoes are sprayed with a solution of boric acid (10 g per 10 L of water).


Recommendations

To understand the reason for the appearance of yellowness on tomato leaves, you need to carefully examine the appearance of the plant. By evaluating all the metrics, you can determine what the problem is. Do not forget about the basic recommendations for caring for seedlings:

  • follow the content rules
  • water the plant regularly and correctly
  • carry out timely feeding.

Only if the care is right, tomatoes will be able to cope with most diseases on their own, resist pests and bring you a good and tasty harvest.

For information on how to identify and distinguish tomato diseases, see the next video.


Watch the video: How to Prune Tomatoes for Maximum Yield and Plant Health