Why do the leaves of tomatoes turn yellow and dry in a greenhouse

Tomato seeds were brought to Europe a long time ago, but at first these fruits were considered poisonous, then they could not find a way to grow subtropical tomatoes in a temperate climate. Today there are many varieties of tomatoes that perfectly tolerate changeable weather, low temperatures and other vagaries of nature. But, nevertheless, the highest yields can be obtained only as a result of greenhouse cultivation: here a person controls the microclimate, and tomatoes feel comfortable.

But even in such conditions, the gardener can face problems, and one of the most common is the yellowing of the leaves of greenhouse tomatoes.... Why tomato leaves turn yellow in a greenhouse, and what to do in such cases - let's try to figure it out.

Why do the leaves of tomatoes turn yellow in a greenhouse

Tomatoes in a greenhouse are undoubtedly more protected from external influences, here they are not afraid of night frosts, heavy showers or unbearable heat.... The gardener's task is to maintain an optimal microclimate inside his greenhouse.

Tomatoes love this "weather":

• air temperature within 23-30 degrees;
• constant humidity at the level of 60-70%;
• regular watering;
• enough sunlight, but not scorching midday heat.

To seedling tomato felt comfortable in greenhouse conditions, she needs to provide all of the above conditions. And besides, constantly monitor the condition of the plants and identify problems at an early stage.

Yellowness on the foliage of tomatoes can appear due to a number of reasons, such as:

1. Violation of the temperature and humidity conditions in the greenhouse.
2. Improper watering.
3. Damage to the root system.
4. Violation of the balance of trace elements in the soil.
5. Viral or fungal infections.

In each of these cases, the leaves of tomatoes turn yellow, but this manifests itself in different ways. The methods of "treatment" are also different.

Violation of the microclimate inside the greenhouse

When equipping a greenhouse on his site, the gardener must remember some rules:

• It is better to build a greenhouse not in a place open on all sides, but to choose a site that will be shaded by trees or outbuildings at lunchtime. If the sun constantly shines on the greenhouse with tomatoes, it will not be possible to keep the temperature inside it at around 30 degrees - the thermometer reading can exceed 45 degrees. In such conditions, tomatoes will turn yellow, dry out, drop ovaries and flowers.
• The soil in the greenhouse must be changed regularly, it is better to do this before the start of each season. It is in the soil that the larvae of insect pests lurk; pathogens or fungal spores can be found for several years. If you cannot change all the land from the greenhouse, you can disinfect it a couple of days before planting the seedlings by pouring boiling water or a solution of potassium permanganate.
• Every spring, the greenhouse must be disinfected, this also applies to walls and wooden pallets. You also need to treat garden tools with antiseptics.
• For planting, you should choose only tomato seeds collected from healthy plants. In any case, it is better to hold the seeds in a weak solution of potassium permanganate before planting.
• To reduce humidity, it is necessary to open the windows and doors of the greenhouse - thanks to the ventilation, excess moisture will quickly evaporate from the walls of the greenhouse and from the ground.
• If there is not enough moisture in the greenhouse and the air is too dry, tomato leaves may also turn yellow. In this case, you can place small open containers with water inside or use a humidifier.
• The temperature in the greenhouse is still highly dependent on the outside climate. Thermometer readings can only be fully monitored in a heated greenhouse. In other cases, it is necessary to regulate the microclimate by airing, opening doors, humidifying the air.

Damage to the roots of a tomato

The root system of tomatoes is well developed, the central root of tomatoes can go underground to a depth of 150 cm, so many varieties tolerate drought and irregular watering well. But most of the lateral roots, however, are only 15-20 cm above the ground, so tomatoes need regular watering.

The healthy appearance of tomatoes directly depends on the integrity and condition of the root system, because the roots are an organ that supplies plants with water and nutrients. If a tomato leaves turn yellow and dry up, this may indicate problems with the root system.

Tomato roots can be damaged in several cases:

• growing seedlings in too cramped cups or boxes. In this case, the roots of the tomato curl into a tight ball, it is very difficult to straighten and untangle them, so the roots are severely damaged when transplanted into a greenhouse. As a result, the adaptation of tomatoes in a new place worsens, their leaves begin to dry and turn yellow.
• The same effect can be obtained if you overexpose tomato seedlings in the house - the root system will become too developed, it will be difficult for plants to adapt to a new place, it will begin to turn yellow and lose foliage.
• Insect pests can also spoil the roots. The most dangerous for tomatoes are the bear and wireworm. If the gardener noticed yellowing of tomato seedlings after transplanting into a greenhouse, you need to treat the land with suitable insecticides.

Watering schedule

The appearance of yellowed leaves on tomatoes may indicate a lack of moisture in the soil, and its excess. How to figure out: a lot of water for tomatoes or not enough? It is very simple to do this - you need to carefully examine the ground and the plants themselves.

If tomatoes are deficient in moisture, the picture will be like this:

• the ground around the tomatoes is dry and cracked;
• tomato stems are sluggish with low turgor;
• the leaves are lifeless, hanging like rags;
• all leaves on the bushes can turn yellow at once.

Seeing such a situation on their site, gardeners often rush to help the tomatoes and fill them with plenty of water. This should not be done, especially if the tomatoes are in the stage of fruit ripening. Due to the large amount of moisture, tomatoes will crack - the crop will be spoiled.

Tomato leaves turn yellow when they do not have enough water. But in this case:

• the ground does not look dry, on the contrary, it can become silted or covered with moss;
• tomato stems are elastic, break easily;
• the plants show signs of fungal infections.

You can prevent problems with yellowed leaves if you water the tomato seedlings correctly:

1. Only in the morning or in the evening. Sunburn through water droplets also manifests itself as yellowing of the leaves.
2. Use settled warm water.
3. Avoid getting water on the leaves and stems of the tomato, so as not to provoke fungal infections.
4. Pour water only at the root or install a drip irrigation system in the greenhouse.
5. Watering tomatoes is rare, but abundant. Ideal watering schedule for tomatoes: twice a week.

Power problems

Both a deficiency and an excess of trace elements in the soil can cause yellowing of tomato leaves.... Therefore, it is very important to follow the fertilization schedule and constantly monitor the condition of the seedlings.

You can find out the balance of which substance is disturbed by the appearance of the tomato leaves:

1. In the greenhouse, the leaves turn yellow only in the lower part of the bush, the young leaves are green and look quite healthy, the plant itself is sluggish, undersized with small leaves, without flowers and ovaries - tomatoes lack nitrogen... Nitrophoska or other complexes containing nitrogen will help to correct the situation. You can also fertilize tomatoes with slurry (1:10 with water), mullein. A distinctive feature of the leaves during the period of nitrogen starvation is that green veins are preserved.
2. Discover about lack of potassium it is possible by small light dots that appear on all the leaves of a tomato bush. Over time, these spots grow until they merge into a large light spot. It is easy to help the plants: fertilize the soil with potassium-containing preparations.
3. That tomatoes lack manganese, tell the yellowing of the upper young leaves, gradually sinking down. Brown spots can appear against the background of excessive liming of the soil, as a result of which the amount of manganese is significantly reduced. A solution of slurry and wood ash or fresh mullein can help tomatoes.
   
4. If a there is not enough sulfur in the ground, tomato leaves not only turn yellow, but also become denser.
5. Lack of copper manifests itself in the yellowing of only the lower old leaves.
6. When tomatoes lack phosphorus, the tops of their leaves turn yellow and die off quickly. If the top of the leaf is dry, you need to feed the tomatoes with superphosphate.
   

Diseases and infections

Probably, the most dangerous for tomatoes is infections, which are also quite often manifested by yellowing of the leaves. However, this is not the worst - on the leaves disease does not stop, it destroys the entire plant: from the top to the roots.

Today, several dozen infections are known from which tomatoes can suffer. The most common and dangerous of them are fusarium and late blight, the first sign of which is the leaves that have turned yellow.

Fusarium, for example, it appears suddenly and is manifested by a violation of the color and elasticity of tomato leaves. Spores of this fungal infection can be stored for several years in the soil, on tomato seeds, in garden tools or in the structures of the greenhouse itself.

It is very difficult to fight fusarium wilting, often this disease destroys the entire tomato crop in a matter of days. If the first signs of fusarium are noticed, it is necessary to treat the bushes with "Trichodermin" or "Previkur".

Both young bushes and already adult plants with ripening fruits can get sick. At first, the fungus damages the roots, which is why yellowing of the foliage can be observed. Then the disease spreads along the stem, gets into the fruits and ovaries - the whole bush eventually dies.

Fusarium wilting can be prevented by disinfecting the soil in the greenhouse, all structures, tools, and treating the seeds before sowing for seedlings.

Late blight no less dangerous and very famous among gardeners.Its appearance is also facilitated by a violation of the microclimate, high humidity, heat, or, conversely, too low air temperature.

If in most cases the lower leaves of a tomato turn yellow, then when tomatoes are infected with late blight tops of the shoots and ovaries, they first of all acquire a brown tint and begin to dry out.

Drip irrigation and preventive treatment of plants with antifungal drugs will help prevent infection of tomatoes with late blight. When the bushes are already sick, you can treat them with a Bordeaux mixture, but the treatment will have to be repeated regularly until harvest.

Outcomes

There can be many problems with capricious tomatoes, but almost all of them manifest themselves in the same way - yellowing of the leaves or the appearance of strange spots. To solve the problem, you need to find out what the plant does not like, which leads to its wilting, and then take some measures.

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