The problem of the appearance of yellow foliage on tomatoes during greenhouse cultivation can affect not only beginner gardeners, but also experienced ones. Color changes occur for completely different reasons, and the main thing here is to figure out as soon as possible what led to this situation. This is necessary for the speedy solution of the problem, as well as the conservation of plants.
Causes of yellowing leaves in tomatoes in a greenhouse
Plants grown in greenhouse conditions have better protection from external influences compared to green inhabitants of street beds. The greenhouse is a reliable shelter from night frosts, heavy rainfall or heat on summer days.
The main task of the gardener is to create an ideal microclimate inside the greenhouse. But if any conditions are violated, then problems with plants immediately begin, incl. and yellowing of leaves in tomatoes. This is worth talking about in more detail.
Irrigation failure
A change in the color of the foliage may occur due to the fact that watering is not carried out correctly. For any crop, of course, for tomatoes, too, there are requirements that must be observed:
- soil moisture ratio. Tomatoes do not need daily watering, it is better to moisten them rarely, but plentifully. With too much moisture, various fungal diseases occur;
- watering technique. If yellowing of the foliage is observed, then the point may be that watering is carried out not under a shrub, but on a leaf. This approach to business leads to a change in color in the plant;
- humidity index. When deciding to grow tomatoes in closed greenhouses, a person must remember that he will have to monitor the air humidity indicator. The evaporation process in a greenhouse is somewhat slower than in an open garden, and therefore the humidity is higher.
An important point. When watering tomatoes, it is necessary to do it in such a way that the liquid gets into the ground, and not on the leaves of the plants.
Incorrect landing dates
Another reason for yellowing leaves on tomatoes is non-compliance with the rules for transplanting seedlings to a permanent place. The case may lie in an insufficient amount of soil or overgrown plants.
During transplantation, it is necessary to ensure that the roots of the shrubs do not form a lump, otherwise the tomato will wilt. This happens in cases where too small containers were chosen for seedlings. The root system has outgrown, and now it begins the stage of dying.
This process is invisible while the seedling is in the container, but in greenhouse conditions, the leaves die off along with the root system. To prevent this problem, it is important to prevent seedlings from overgrowing in individual containers.
If, however, the yellowing and drying of the leaves nevertheless began, you can try to change the situation by root spraying.
To prepare a solution for 1 liter of liquid, at least 10 grams of fertilizer is used. The affected parts may still die, but the new ones will begin to develop well. Here it is worth considering that there will be a delay in the growth of the culture for several weeks.
Note to the gardener. When growing seedlings in individual containers, for one plant the volume of the pot should be at least three liters.
Lack of mineral fertilizers
Another reason for the yellowing of the foliage of tomatoes is associated with a lack of trace elements, this factor is very important for tomatoes.
- inadequate nitrogen intake. With nitrogen starvation, the plant looks weakened, the stems become thinner, and the foliage becomes small. To solve the problem, manure or other fertilizing with nitrogen is used. Manure top dressing is prepared by diluting 1 part of the fertilizer in 10 liters of water.
- manganese deficiency. The foliage of plants changes its standard color to light yellow. First of all, this is noticeable on young foliage, a little later the problem spreads to older shoots. You can fight by adding a solution of mullein 1 part per 20 liters of water, or a manure mixture, with the addition of ash at the rate of 1 part fertilizer per 10 liters of liquid.
Root damage
Tomatoes have a well-developed root system, and the central root goes into the ground to a depth of 1,5 meters. Due to this feature, most varieties are immune to drought and irregular watering. But the lateral roots lie from the surface at a depth of only 15 – 20 cm, and they need a regular supply of moisture.
The health of the whole plant depends on how holistic the root system is. It is through the roots that the culture is supplied with liquid and nutrients. Yellowing foliage may indicate root problems.
Root damage occurs in the following cases:
- seedlings are grown in a very tight container. The roots begin to twist into a tight ball, unraveling the weave is a laborious task that does not always end in success, and therefore the roots are severely damaged during the transplantation of tomatoes to the main place. Plants adapt worse, begin to dry out and change the color of the foliage;
- overexposure of seedlings. The roots develop too much in a temporary capacity, and then the plant has difficulty adapting to a new place, which is expressed by yellowing of the leaves and their loss;
- damage to the root system by harmful insects. The greatest danger is represented by bears and wireworms. The only way out is to treat the soil with suitable means.
Defeat by diseases
The greatest danger to tomatoes is represented by various diseases, the symptom of which is the yellowness of the foliage. But this is not the worst thing that can be. The infection will not stop at the foliage, but will begin to spread further throughout the plant.
To date, there are a large number of infectious diseases affecting tomatoes. The most common is the defeat of late blight and fusarium, the first sign of these problems is the yellowing of the foliage.
The appearance of Fusarium can be seen by the loss of color and elasticity of the foliage of the culture. A fungal infection is spread by spores that can persist for several years in the soil layer, on seed material, inventory tools, or on greenhouse structures.
It is rather problematic to cure Fusarium wilt, and in just a few days you can lose the entire crop of tomatoes. In the presence of the first symptomatology, it is necessary to carry out the processing of the culture using such means as: “Trichodermin” and “Previkur”.
The disease spreads both to young shoots and to adult shrubs. Initially, the fungal infection spreads through the root system, because of this, the color of the foliage begins to change. At the next stage, the disease spreads to the stem, fruits and ovaries. The case ends with the death of the bush.
To prevent wilting caused by Fusarium, the following measures are taken:
- disinfection of greenhouse soil;
- processing of all greenhouse structures;
- disinfection of inventory tools;
- processing of seed material before it is sown to obtain seedlings.
Useful advice. Carrying out regular ventilation in the greenhouse allows you to significantly reduce the threat of infection of tomatoes with Fusarium.
Another dangerous and well-known disease is late blight. It manifests itself when the microclimatic conditions in the greenhouse are violated, for example: a high humidity index, too high a temperature, or, conversely, very low.
With most diseases, yellowing of the lower leaves of tomatoes is noted, but with late blight, the upper parts of the shoots, as well as the ovaries, suffer. The foliage turns brown and begins to dry.
To prevent the spread of phytophthora, it is recommended to use a drip irrigation system and treat tomatoes with antifungal agents. When a disease is detected, Bordeaux fluid is used. It is used regularly, up to the moment of picking tomatoes.
Note. If certain diseases are detected, it is worth refusing to collect seed material, because. there is a high risk of preserving an infection dangerous for the culture in it.
The appearance of harmful insects
There are a number of other reasons due to which yellowing of the foliage can be observed, for example, the appearance of harmful insects.
The change in the color of the foliage is due to the fact that there are some types of pests in the greenhouse: wireworm, bear, nematode. All of them choose the root part of the plants as food, damage it, which inevitably affects the color of the foliage. If such a problem is identified, it must be resolved as quickly as possible.
Specialized stores provide an opportunity to purchase various drugs to combat harmful insects. Medvedki, for example, are destroyed by “medvetoks” or “thunder”.
Violation of microclimatic conditions
When arranging a greenhouse on the site, you should follow simple rules:
- a place with shading at midday is suitable for building a greenhouse. You can build a greenhouse near trees or an outbuilding. With constant exposure to sunlight on the greenhouse, it will not be possible to maintain a temperature regime that is comfortable for plants;
- regular change of soil. Ideally, it is carried out before each season. Often, the soil protects the larvae of harmful insects, fungal spores, etc. all this can be in the ground for several years. If it is impossible to change the soil, disinfection measures are carried out (watering with boiling water, or a manganese solution);
- disinfection of the supporting structures of the greenhouse, and treatment of inventory tools used for gardening with antiseptic preparations;
- seed material for seedlings must be healthy. For prevention, the seeds are immersed in a weak manganese solution;
- the implementation of regular ventilation of the greenhouse to reduce the humidity index;
- with a lack of moisture (which can also cause yellowing of the foliage), they place containers with water in the room or use air humidifiers;
- the temperature indicator of the greenhouse room will depend on what is happening on the street. Full and quality control is carried out exclusively in heated greenhouses. In all other cases, the regulation of the microclimate is carried out by airing or humidifying the air.
Lack of lighting
The next reason lies in insufficient lighting. Such a problem occurs in bad weather conditions, a dense film coating, the presence of tall plants near the tomatoes, the tomatoes are planted too close to each other.
Soil problems also affect leaf color. The ideal acidity indicator for tomatoes is no more than 6,2 – 6,5 pH. The soil lacks nutrients; mineral complex preparations are used to solve the problem.
How to fix the situation
The main thing is, when yellowing foliage is found on tomatoes grown in greenhouse conditions, to identify what this is happening from. As soon as the cause is found, you should try to solve it as soon as possible. Almost all the problems described in the article have solutions and have been described earlier.
gardening tips
To avoid the appearance of yellowness on the leaves, experienced gardeners are advised to follow the following rules:
- adherence to landing dates. Too overgrown seedlings already have problems with the root system, which begins to die off. Such a process can rarely be reversed;
- proper watering. Root watering is suitable for tomatoes, water should not fall on the foliage and stem part;
- so that tomatoes do not suffer from a lack of useful trace elements, it is necessary to observe the term for fertilizing;
- excellent prevention of various diseases is the timely treatment with manganese and copper-containing preparations;
- carrying out any work with tomatoes should be careful, the plants should not be damaged by careless human actions. It is recommended to work with sharp and clean tools.
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Why do the leaves of tomatoes turn yellow in the greenhouse and in the open field – video
As a conclusion, we can say the following, tomatoes are a rather capricious crop, and they can have many problems, but almost all of them have the same manifestation in the form of a change in the color of the foliage. To solve the problem, it is necessary to establish what specifically does not suit the plant, why it withers, and only then are any measures taken.
