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Although plants cannot speak, they are able to ask for help with their appearance - water me, shield me from the hot sun, feed me! Purple spots on the leaves of tomatoes tell the gardener that urgent feeding is needed.
For normal development, tomatoes need a variety of nutrients - some more, some just a little. An important element necessary for a crop during the growing season is phosphorus. It is his lack that leads to the fact that tomatoes have purple leaves.
For all shades of blue, including purple, anthocyanin is responsible - a natural pigment that all plants are supplied with. With a lack of phosphorus in the cell sap of tissues, its content increases, causing a change in the color of leaves and stems.
According to one hypothesis, on dark leaves with a purple tint, pests become more noticeable to birds - feathered friends peck on parasites, helping the weakened plant to cope with part of the problem.
The color change of the leaf plates does not come suddenly. Older leaves closer to the ground are the first to react. First, spots of a pink or lilac shade appear below, over time they acquire a more saturated color, appear on the outer surface, the leaf blades themselves fade.
Further, the leaves turn purple, curl, droop or, conversely, turn upward, pressing against the stem.
The next stage - the stems themselves became purple, tough, lost their elasticity, and easily break. The villi covering the stem elongate, making it feel like a toothbrush. The veins on the leaves coarse, acquire a violet-red, crimson color, rise above the leaf plate.
Plants do not grow, flowering begins later than the due date, fruits are tied extremely reluctantly. Tomatoes, formed under conditions of phosphorus deficiency, grow very slowly, ripen for a long time, and their taste deteriorates. The seeds do not ripen, their reproductive capacity becomes zero. The bushes react sharply to cold snaps, lose their resistance to diseases. In severe, neglected cases, the death of the root system begins.
Sometimes the stems of tomato seedlings turn blue at the base. This is not necessarily a sign of a lack of phosphorus or a reaction to low temperatures. Perhaps, during the disinfection of the substrate, an overdose of manganese was allowed. Another option is a varietal feature.
If the upper, young leaves change color and curl - the tomatoes lack magnesium, they are fed with magnesium sulfate (2 grams of powder is diluted in a liter of water).
Phosphorus is the main conductor of the orchestra. Without it, the normal course of metabolic processes inside the plant is disrupted. Due to the presence of this element in the substrate for germinating seeds, friendly strong shoots are obtained, a reliable branched root system develops, aerial parts grow, and fruiting begins faster.
However, not always signs of phosphorus deficiency appear when the fertilization schedule is violated. The low absorption of the element is also influenced by other reasons:
To determine if there is excess phosphorus in the soil, early varieties of radish are planted on the beds. A high percentage of shooted root crops (from 10%) indicates an excess content of the element.
Corrective measures are taken immediately after the first signs of phosphorus starvation appear. However, before deciding what to do with the plants, determine the cause that caused the lilac color.
Young plants are more likely to suffer from the cold, so it is enough to take measures to restore the required temperature. Seedlings grown at home are protected from cold air penetration, watered only with warm water. The windows and doors are closed in the greenhouse, the plants are watered with warm water, and heating devices are installed. On unprotected beds with tomatoes, light film shelters are mounted for the cooling period.
Seedlings often turn blue in the first days of hardening. In order not to stress the seedlings, they carefully monitor the temperature, exposing the pots to fresh air at a temperature of at least 18 ° C. Experienced gardeners do not see anything wrong with hardening at 16 ° C, even if the seedlings turn blue - such seedlings will be more resistant to bad weather.
If the temperature is maintained at the proper level, but the signs of starvation do not disappear, additional feeding is added:
The rules for crop rotation were not invented in vain: the introduction of fertilizing and the peculiarities of the work of the root system of plants by the end of the season clog the soil with salts of nutrient residues, including phosphorus, which formed a form that is not digestible by tomatoes.
If the area of the plot allocated for the garden does not allow regularly moving the plantings to a new place, a number of measures are taken to prepare the soil for the new season:
From how correctly the technology of applying phosphorus-containing fertilizers to the soil is followed, their chance of being assimilated by tomatoes depends.
Agronomists give the following recommendations:
Superphosphate is most effective when planting seedlings. 15-20 g of fertilizer is poured under each bush.
Ammophos is advisable to apply when planting, diammophos - during flowering.
Potassium monophosphate is fertilized twice a season under the root or on the leaves.
Nitrofoska is ideally balanced in composition for feeding planted seedlings.
Bone meal is added to the hole when planting 2 tbsp. l.
Wormwood compost enriches organic matter with easily digestible phosphorus compounds. Also, to enrich organic matter with this element, hawthorn berries and rowan fruit brushes are laid.
You need to feed with phosphorus strictly according to the instructions. Although phosphorus itself does not harm human health, its excess causes plant poisoning: the leaves turn yellow, fall off, brownish or yellowish necrotic spots appear on them, as well as on the stems.
There is another type of phosphorus fertilizer - phosphate rock, which is practically insoluble under normal conditions, but interacts well with acidic fertilizers, manure, or on acidified soils. The best application is for composting. Under the influence of microscopic inhabitants of the soil and chemical reactions occurring during the maturation of organic matter, phosphorites take a form that is available for assimilation by plants.
So, if the seedlings become purple or the leaves and stems of "adult" tomatoes have acquired a lilac hue - this is an alarming signal, but not the last point in the development of plants. The phosphorus deficiency is easily replenished; with foliar feeding, the result appears within a few hours. The main thing is to correctly determine the cause that led to the deficiency of the element, and quickly take action.
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