What to do if the leaves of tomato seedlings turn yellow, reasons

Which leaves turn yellow on tomatoes?

Before you do anything, if the leaves of tomato seedlings turn yellow, you need to pay attention to what kind of leaves they are: upper, lower or cotyledons.

Lower

The lower leaves not only turn yellow, but also dry out. This happens immediately after landing. The reason is sudden climate change. When they begin to care for a drooping bush, the leaves return to normal in 3-5 days.

Tomato leaves turn yellow

In addition to changing color, the foliage has other signs of illness:

lethargy;
the fruits become smaller;
the edges and tips of the leaves curl.

If these signs are absent and the leaves are yellow, it means that the bush is actively growing. This is normal in late summer (then no intervention is required), but not early in the season. When intensive growth stops, the bush itself will turn green and stop curling its leaves.

Upper

The upper leaves are young, so if they change color and wither, this indicates problems. The yellow color is accompanied by the leaves curling inward. Causes:

lack of calcium, sulfur, iron, boron and manganese;
aphid;
root infection.

These problems do not affect the lower leaves.

Cotyledons

If the cotyledon leaves of tomato seedlings turn yellow, this is due to humidity. Either there is not enough water and the sprouts dry out, or the soil is too moist. Reasons for leaves turning yellow:

incorrectly selected soil;
excessive or insufficiently frequent watering;
lack or excess of nutrients;
lack of light;
small distance between bushes.

The cotyledon leaves of tomatoes turn yellow.
Also, in diseased plants, the leaves curl inward.

Mineral-organic fertilizers for tomato seedlings

How to water tomatoes to prevent leaves from turning yellow? Due to the fact that plants have to be content with little, growing on cramped window sills, they become weak and require additional nutrition to stimulate growth.

For these purposes, such preparations are used as: Organic Mix, Tomato, Krepysh, BioMaster and others. But, it is worth paying attention that soil fertilization must be combined with moderate watering, and waterlogging must be avoided. In addition, bushes will respond well to soil disinfection with a light manganese solution.

Causes

Depending on the situation, there are different reasons for yellow leaves.

In the greenhouse

When tomato seedlings turn yellow in a greenhouse, this indicates a violation of conditions. Under the film, plant leaves change color for two reasons:

Diseases or pests. They turn yellow on one bush, but the parasites can move to neighboring ones.
Improper care and living conditions. The problem applies to all plants.

The color does not change in the entire bush, but only in the upper or lower leaves.

The leaves of tomatoes in a greenhouse turn yellow for the following reasons:

The irrigation regime is not followed. Plants are watered too often or too infrequently.
The bushes are affected by disease or pests.
The feeding regime has been disrupted. Tomatoes lack essential nutrients.
The soil was chosen poorly. It is not rich in minerals and trace elements.
The roots are damaged by pests or were injured during loosening or replanting.
Humidity above 70%. Such an environment leads to the emergence of pests and dangerous bacteria.
Poor ventilation. If you do not ventilate the greenhouse, the tomatoes will suffer from a lack of nitrogen.
Lack of sunlight.

Reasons for yellowing of leaves in tomatoes
Protection from atmospheric agents does not guarantee comfort for vegetables.

In the open ground

Sometimes tomato seedlings turn yellow when transplanted into open ground. This is stress for the plant. Adaptation takes a week. Causes of yellowing foliage:

prolonged adaptation;
weakened immune system;
lack of water;
lack of nutrients;
soil is too wet;
pests;
diseases or damage to the root system.

The main reason is the change in temperature. The plant is cold and gets sick.

On the windowsill

Seedlings on a windowsill or balcony have the same problems as tomatoes in a greenhouse.

cramped pots;
a lot or little water;
hypothermia;
overheat;
rare ventilation, lack of nitrogen;
lack of light;
acidic soil.

The leaves of tomatoes on the windowsill turn yellow.
It makes sense to do something if the tomato seedlings on the windowsill turn yellow, in one case. First, they adjust the temperature regime (for example, remove the pots from the window into the interior of the house), and only then, if this does not help, provide the remaining conditions for the seedlings.

What to do if tomato seedlings turn yellow and dry: problem + solution

If you see a few yellow tomato leaves at the bottom of the plant, there is usually nothing to worry about.

Excess moisture

Tomato seedlings need an ideal level of soil moisture. The soil should not be over-moistened or over-dried - always stick to the golden mean. Determine how much water you need to water your seedlings, taking into account the climate conditions of the room where you are growing them and the type of soil you are using.

In low humidity and dry air, you will have to water the plants several times a day, and in other conditions - only a few times a week.

Root rot

When a plant's roots are flooded with water for an extended period of time, they can no longer breathe. Lack of oxygen leads to the death of plant tissue and, ultimately, its destruction. Destroyed areas of the root spread further, and the leaves on tomato seedlings turn yellow and dry. Over time, root rot leads to the death of the entire plant.

There are two possible causes of root rot:

Excessive moisture.
Fungus.

The fungus usually lies dormant in the soil and only becomes active under very wet conditions for a long time (such as when watered). Root rot causes leaves to wilt, turn yellow and decay.

To solve this problem:

Carefully lift the plants out of the soil and inspect the roots for rotted areas.
Rinse the roots of the seedlings under cool running water.
Using scissors, cut off the rotten black areas of the root system and rinse again.
Then treat them with a fungicide to kill the fungus.
Discard the old soil and wash the pot with bleach.
Add fresh soil.
Pull off a few leaves so the plant can focus on regenerating its roots.

Soil compaction

Tomato seedlings may turn yellow if the soil is not loosened and it has become too dense. Plants will recover once oxygen is supplied to the roots again. To do this, loosen the soil after each watering.

Viral, fungal or bacterial diseases

Prevention is the only guaranteed solution to these problems. If tomato leaves show signs of disease, it is best to uproot and discard the diseased plants, as pathogenic microorganisms can spread to neighboring plants. Here are the most common seedling diseases:

Septoria leaf spot is a fungus that causes gray or brown spots surrounded by yellowed areas. Usually starts from the lowest leaves. Remove affected leaves. Water the seedlings less often, without wetting the leaves, and loosen the soil to increase air circulation and evaporation. Be careful to avoid cross-contamination. Use fungicides for tomatoes:

Quadris;
Acrobat;
Ridomil;
Agate;
Maksim;
Fundazol;
Bordeaux mixture.

Alternaria blight is a fungus that appears first on the lowest and oldest leaves. It appears as small brown spots with concentric rings that form a bull's eye. Eventually, the leaves of the tomato seedlings turn yellow, wilt and die. Treat in the same way as septoria spot.

Bacterial wilt is a bacterium that is often found in wet, sandy soils. It rises quickly from the roots to the stem. The affected plant is removed to prevent the bacteria from spreading.

Verticillium is a soil-borne fungus that lives in many cool northeastern areas. It starts as yellow spots on the lower leaves of tomato seedlings and progresses to brown spots and curled dead leaves. The best way to be sure that verticillium is the cause of yellowing plants is to break off a branch that shows these symptoms and look for dark-colored rings on the cut. Unfortunately, in this case, it will not be possible to save the seedlings.

Read on Rblogs.ru: “What are the diseases of tomato seedlings: recognizing them from photos with descriptions and methods of treatment”

Nutrient deficiencies

A lack of macro- and microelements is a common factor in the appearance of yellow leaves in all plants, not just tomatoes. This does not always mean that there are few of them in the soil - it happens that the plant is simply unable to absorb nutrients. Read more about this in the next section on rblogs.ru.

Diseases

Tomatoes are often affected by a fungus. Possible diseases:

Fusarium. The leaves are yellow and curled, the veins of the stem are brown (visible when cut), the disease affects the bush from the bottom up. The stem stops functioning, the plant dries out, sheds its leaves, and the fruits rot. The fungus penetrates through damaged roots. The veins and petioles become discolored. At the initial stage, the plant is treated with drugs, but at the later stage it is thrown away.
Late blight. The front side of the leaf is yellow, and the back is covered with a white coating. The color of the branches changes. The fruits are rotten and do not grow. The causes of the disease are cold and dampness. Dry leaves are torn off, then the bush is treated with a solution.
Tomato mosaic. The leaves become covered with yellow spots and fall off, the stems become deformed, the fruits become smaller, and necrosis develops. The plant becomes infected through gardening tools, mechanical damage and infected seeds. At the onset of the disease, bushes are saved by removing the affected parts and treating the remaining ones. In advanced cases, treatment is useless.
Root rot. The foliage is yellow and withered, falling off, the stems become thin and black, as well as the stalk. The disease starts at the bottom of the plant and moves upward. If the stems are black or dark lilac, the plant cannot be treated. You can save a wilted plant. This requires treatment with chemicals and transplantation into prepared soil.
Cladosporiosis (brown spot). The lower leaves are yellow, but within 2 weeks the disease reaches the upper ones. Treated by spraying.

Root rot in tomatoes

Sometimes the problem is pests. These include mole crickets and wireworms. They eat the roots of plants, they do not receive nutrients and will wither if nothing is done. These diseases also affect cherry varieties, cucumbers and peppers.

How to fix

It's easier to prevent than to treat. Prevention measures:

disinfect seeds before planting;
take into account the characteristics of the variety;
use spacious pots;
control the plant (when it has turned yellow and is ready to shed its leaves);
Damaged parts of the bush are disposed of (leaves are torn off);
remove foliage with hands or scissors without damaging the stem.

If the plant is not in critical condition, comfortable conditions are created for it. If the leaves of tomato seedlings turn yellow, what to do first is to start treatment.

Provide normal amount of light

With a lack of light, the seedlings become thin and stretched, turn pale, and the leaves in the middle suffer. Plants should be placed in the sun or phytolamps placed nearby. The bushes are planted deeper and further away from each other so that they receive equal amounts of sun. If you leave them in the shade, the tops will remain yellow and the crop will be lost.

Excess sun is also harmful. To avoid burns, the bushes must be sprayed with water.

Checking soil moisture

To regulate moisture, you can use a drip system. This is not difficult to do. A bottle of water is buried next to the plant. Excess moisture is removed by digging small ditches to remove excess water. With abundant watering, the fruits become watery. When there is groundwater on the site, drainage or high beds are organized.

Soil moisture

Before watering, loosen the soil, moisten only the soil that has dried out from the previous time. Humidity levels up to 65% are optimal.

Cleaning from rot

Rotting occurs at high humidity. Rotten tomato bushes cannot be saved. Sick plants are removed so that they do not infect healthy ones. After removal, the soil is disinfected.

Top dressing

The following fertilizers are used when there is a deficiency of substances:

Nitrogen. Add a spoonful of urea to 10 liters of water and feed the tomatoes with the solution.
Phosphorus. Superphosphate is poured into 1 liter of hot water and left for 8 hours. Pour into 10 liters of water and pour half a liter under each bush.
Potassium. Add 1 spoon of saltpeter to 10 liters of water and water the bushes. Or 1 teaspoon of potassium chloride is dissolved in 1 liter of water.
Magnesium. 1 teaspoon of magnesium nitrate is diluted in 10 liters of water.
Molybdenum. Prepare a solution (2 g of ammonium molybdate per 10 liters of water).
Calcium. Calcium nitrate (20 g) is diluted in 10 liters of water.
Bor. The foliage is irrigated with a solution of boric acid.
Sulfur. 1 gram of magnesium sulfate is diluted in 1 liter of water.
Iron. Iron sulfate (1 g) is added to water (10 liters).
Copper. 1 gram of copper sulfate is mixed with water (10 liters).
Manganese. Make a solution for foliar fertilizer (add 5 g of manganese sulfate to 10 liters of water).
Chlorine. The deficiency can be eliminated by spraying with water containing potassium chloride (1 teaspoon per 1 liter of water).

Feeding tomato seedlings
To avoid deficiency, fertilizers with a complex of substances are used during the flowering period.

Ventilation of the room

Benefits of ventilation:

decrease in humidity;
increase in nitrogen content.

It is necessary to monitor the process. Hypothermia is unacceptable.

Temperature control

Temperature affects the absorption of trace elements and minerals. Indoors and in the greenhouse, monitor distance and ventilation. A shelter is arranged over the street beds and fabric is stretched. In hot weather, the soil is moistened, but the leaves are not sprayed during the day due to the likelihood of burns.

Irrigation control

Watering mode:

moderation;
each subsequent watering after the soil dries;
periodic loosening of the soil.

Water the plants at the base, not from above. Moisture should not get on the foliage.