Reasons for the appearance of purple leaves on tomatoes
Among garden crops, tomatoes are probably the most whimsical plants. They are often attacked by all sorts of pests and get sick. Purple leaves on tomatoes are the most common problem gardeners encounter. The main reasons for the occurrence of many problems are improper care, one wrong step on the part of the gardener can result in loss of the crop.
Reasons for the appearance of purple leaves on tomatoes
Root reasons for changing the color palette
Why do tomato seedlings have purple leaves? - this question most often arises before many gardeners and not only beginners in this business. The main task of the gardener is to provide proper care for the sprouts. Healthy seedlings are the key to a good harvest. Some argue that the purple color of the stems and leaves of tomato plants should not be a cause for concern, as it indicates good adaptability to cold temperatures. But, all this is wrong, because changing the color scheme of greenery is a serious problem that can lead to a decrease in yield or even death of plants.
To cure a crop, you need to understand why tomato leaves turn purple. The main reason is poor grooming.
Factors affecting the change in the shade of foliage:
- poor illumination;
- low air temperature;
- high planting density;
- avitaminosis.
The foliage begins to change shade gradually, so it is not always possible to immediately identify the problem, especially when the lower part of the leaves begins to change color. The stem darkens, starting from the root part. The causes of the disease are interrelated. The color change, first of all, begins when the plant freezes, and this happens due to a lack of vitamins in the soil and a decrease in temperature to 14 ℃.
If the tomato leaves turn purple, you should immediately determine the cause of the pathological condition. Do not forget that some varieties of tomatoes, when germinating seedlings, acquire a purple-pink color immediately and this is a natural process. In order not to miss the symptoms of the disease, a constant inspection of the foliage and stem should be done, especially after the pick. Purple leaves and lethargy stems can be a sign of root damage.
Temperature regime
In tomatoes, the leaves turn purple from below when the rhizome freezes. If the soil is cold, the roots stop receiving nutrients because the plant directs all its energy to heat, the lower part becomes darker. Once the heating problem is resolved, the shade of the leaves will return to normal.
It is best to install fluorescent lamps near the sprouts. The purple hue in tomato seedlings appears due to the low production of chlorophylls, which are responsible for the green color of the foliage.Do not forget that fertilizer should be applied three times before transplanting. Organic fertilizers can help warm up the roots, but do not overdo it, an overabundance of organic matter can burn the rhizome. You can put a film on the soil itself in a glass with seedlings to warm up the rhizomes.
When planted in open ground, tomato sprouts freeze very often. The upper leaves begin to curl when there is a temperature difference between day and night, the difference is up to 10 ℃. In such situations, cover the seedlings overnight with plastic cups or bottle cuttings to protect them from the cold. Damaged leaves should be removed.
How is nutritional deficiency manifested?
From lack of sulfur, the leaves begin to curl
Often the reason for wilting and changing the color of the leaves is not a temperature drop, but a lack of nutrients. At the initial stage of growth, nutrients are very actively drawn from the soil. Ideally, the first time the soil should be fertilized with urea at the time of the pick. This helps to increase the viability of the tomato in the future, quick adaptation after picking, and also contributes to the full development of the root system.
If the plant lacks trace elements, the leaves turn purple on the back. Most often, the plant needs trace elements such as phosphorus, zinc, nitrogen, magnesium and potassium. In addition to changing the color scheme, the lower part of the leaves begins to curl. The stem becomes brittle, fibrous. Phosphorus is needed by a plant throughout its life. Its shortage sharply negatively affects the condition of the ground part and the root system. In the initial stages of growth, phosphorus is especially necessary for plants to form a full-fledged root. The lack of this substance leads to poor absorption of nitrogen, as a result of which the growth of sprouts is slowed down. Signs of a nutrient deficiency:
- with a lack of potassium salts, the leaves become brown at the edges, curl;
- the reason for the change in the color of the foliage to violet-red is a lack of phosphorus;
- when spots appear on the leaves, this may indicate a lack or excess of zinc, copper;
- the reason for the curling of the leaves is the lack of sulfur.
With a lack of sulfur, not only the top leaves become thin, but all the rest. The greenery itself begins to change color. Sulfur is the key to protein production. If this process is disturbed, the production of amino acids slows down. Symptoms of a lack of sulfur are similar to those of a lack of nitrogenous compounds in the soil, but the changes begin from the top. Veins of a violet-pink, sometimes bluish hue appear, the plant practically stops developing, the stem does not grow in thickness.
How to determine oversupply
An oversupply of nutrients is even worse than a lack of them. Too much organic fertilizer in the soil will cause the tops to curl, and pink-purple spots appear on them.
The thing is that the rhizome cannot assimilate such a huge amount of substances, and therefore begins to reduce the production of photosynthesis, as a result of which twisting occurs, a change in the color of greenery.
Chlorosis
When the leaves turn yellow on the outside, starting from the base, this is a symptom of iron deficiency - chlorosis. Initially, purple streaks appear on green leaves, and then they begin to turn yellow and fall off. Such symptoms are observed if the soil contains too much alkali.
Applying a lot of organic fertilizers, such as chicken manure, makes the soil alkaline. Most often, it manifests itself in the early stages of growth, when round-the-clock lighting is needed. If you do not start gradually transferring plants to daylight, chlorosis will begin sooner or later. It is quite simple to eliminate it with the help of iron sulfate. A solution should be made with an active substance content of no more than 1%.
Tomatoes require a high enough chloride content in the soil so that the lower part of the plant can fully develop. Its deficiency is also called chlorosis. Color changes are observed in the inter-vein areas of deciduous plates. The optimum chlorine content in greenhouse soil should not exceed 0.02%.
Lack of manganese
Manganese chlorosis is very rare
Manganese is involved in respiration and photosynthesis. The upper leaves begin to change color from the base. Most often, it manifests itself on young fragile leaves. Symptoms are similar to iron chlorosis, but streaks with a lack of manganese are darker in color.
Manganese chlorosis is quite rare, in places where the soil is not fertilized with trace elements or with an excess of lime. The reason for the lack of manganese can be watering with hard water. In this case, the veins remain green, and multi-colored spots appear on the leaf itself, resembling a viral mosaic.
Lack of boron and calcium
Boron is responsible for pollination, protein-carbohydrate synthesis. With its lack in plants, immunity is sharply reduced. The upper leaves go down, yellow spots appear at the base. The veins on the leaves take on a dark purple-brown hue on the outside.
The affected areas begin to disintegrate quickly. The upper leaves acquire an unhealthy color, curl downward. When touched, the sheets break quickly.
Calcium is needed to stimulate growth. He participates in the development of tissues, their strengthening, and also helps to speed up metabolic processes and activate enzymes. The deformation of young foliage begins from the outside. The surface dries up and takes on a light yellow color. On the contrary, old leaves become darker. To eliminate the lack of calcium, it is recommended to make an eggshell solution for plant nutrition.
How to help the sprouts
What to do when the leaves turn purple:
- first of all, the room temperature should be kept within 20 ℃ in the daytime, at night it can be reduced by 2 ℃;
- the soil should be fertilized with organic matter, this will help to slightly increase the temperature in the soil itself;
- use a drip irrigation system, make sure that moisture does not get on the tops and stem;
- install fluorescent lamps in the room where the seedlings grow.
If the lower part of the crown and foliage turns purple, it is recommended to make an additional pick. Too much overcrowding of sprouts in a small area is another reason for blue discoloration. The rhizomes of plants are close to each other, which slows down the process of absorption of nutrients, moreover, it prevents the roots from growing normally.
Another reason why color changes may appear is fungal diseases. They begin to reveal themselves at high air humidity. The most dangerous diseases are late blight and alternaria. In both cases, spots appear on the leaves, they begin to rot and wither. When infested at later stages of growth, tomatoes become purple, almost black.
How to avoid mistakes in growing
First of all, you need to understand how tomatoes develop. Almost all diseases, including color changes, begin with malfunctioning of the root system. Tomatoes are distinguished by a rod-type rhizome, which can grow to a distance of 1.5 to 2 m, so do not forget that you need to plant seedlings at a decent distance from each other.
Improper care is the main cause of problems. To be able to quickly remedy the situation, you need to do constant inspections of the plants for color changes. The affected leaves, which have curled up and turned yellow, should be removed, they only slow down the growth of the plant.
If the upper leaves are twisted in the morning, and straighten by lunchtime, there is no reason for concern.Grassing and thinning of foliage should be carried out a day before watering and foliar dressing. It is important to follow this rule, otherwise unhealed pores can cause the spread of infection if moisture gets into them.