Content
Tomatoes turn black on the bottom for many reasons. Most often, darkening is caused by fungal diseases, but sometimes spots appear due to improper care.
Why do tomato fruits turn black on the bottom and what to do?
Tomato bushes turn black both in greenhouses and in open ground. To understand what is causing the problem, you need to carefully study the symptoms and location of the spots. For various reasons, tomatoes turn black at the base of the stem and at the tips of the leaves, at the tops of the fruits and on the shoots.
Late blight (late blight)
Late blight is a fungal disease that primarily affects tomato leaves. First, brown spots appear on the plates, and then a dense white coating forms. If left untreated, brown marks will eventually appear on the fruit, grow rapidly and lead to rotting.
Phytophthora of tomatoes often develops when the crop is adjacent to peppers, potatoes and eggplants
Late blight on tomatoes usually appears in mid-summer.The disease is provoked by factors such as high air humidity and a significant difference between day and night temperatures. Late blight can spread to tomatoes from contaminated soil and from contaminated tools, and spores also land on bushes with wind or water.
Late blight is difficult to treat. But in the first stages of the development of the disease, certain measures can be taken - eliminate the infected bushes and spray healthy plantings with Fitosporin or Bordeaux mixture.
Apical rot
If the tip of a tomato turns black, the most likely cause is blossom end rot. The disease develops against the background of violations of agricultural technology - it is provoked by too much watering and overheating of the bushes in dry weather. Flat, wide brown spots form on the tops of the tomatoes, which gradually darken and enlarge. The fruits rot or dry out and become mummified, and the bushes die over time.
Blossom rot often develops in tomatoes in acidic soil.
Blossom rot affects tomatoes when there is an excess of nitrogen and a lack of potassium and calcium in the soil. To get rid of the disease, you must first destroy the affected fruits, and then treat the bushes with a solution of boric acid 15 g per 10 liters. It is also recommended to fertilize tomatoes with potassium sulfate to strengthen the roots and vascular system.
Gray rot
Gray rot is a disease that causes tomatoes to turn black mainly in a greenhouse, but can also suffer in open ground if planted too densely. The disease develops due to waterlogging and lack of fresh air.Grayish-brown spots first appear on tomato leaves, which then increase in size and spread to the stems. Tomato bushes develop vascular necrosis and nutritional processes are disrupted, as a result of which the crop turns black and dies.
Gray rot affects tomatoes in rainy weather at a temperature of 20-25 ° C
When symptoms of gray rot appear, it is necessary to trim the tomatoes and remove all affected parts. After this, the bushes are sprayed with 1% Bordeaux mixture and a light pink solution of potassium permanganate. You can also sprinkle chalk on the soil near the roots to reduce acidity levels.
Watery rot
The nose of tomatoes turns black due to watery rot, a dangerous disease of bacterial origin. The causative agent of the disease penetrates the tissue through cracks in the skin, the flesh of the fruit darkens and rots, over time turning into a liquid pulp with an unpleasant odor.
Watery rot often develops in tomatoes damaged by caterpillars and beetles.
It is impossible to save tomatoes already affected by watery rot - all that remains is to eliminate them. The remaining plants on the site or in the greenhouse are treated with copper preparations to strengthen immune resistance. To ensure the prevention of watery rot, it is necessary to promptly spray the bushes against pests and fungi, monitor the cleanliness of the soil and remove plant debris from the beds.
Spotting
Tomato fruits turn black under the influence of spots - brown and black. The diseases have a common symptom - they leave light or brownish marks on the leaves of the bushes and a coating on the lower surface of the plates. Tomatoes begin to wither and dry out and stop forming ovaries.Ripening fruits turn black and deformed, and then fall off the shoots.
Tomato spots develop in damp and cold weather with a lack of light and ventilation.
To get rid of spots, it is necessary to thin out the plantings and eliminate severely damaged plants from the area. The remaining ones are treated with copper sulfate or similar preparations. Spraying must be repeated every two weeks until the symptoms of the disease disappear.
Anthracnose
Anthracnose is a fungal disease that mainly affects adult tomatoes during the formation of the ovary and at the stage of fruit ripening. Under its influence, green tomatoes often turn black and fall off the shoots without being fully formed.
You can recognize the disease by indented spots on the surface of tomatoes and by wilting of the upper leaf plates. Tomato bushes that are severely damaged by anthracnose are very easy to pull out of the ground because their roots weaken.
Anthracnose develops at a temperature of 25-30 ° C with a lack of phosphorus and potassium in the soil
The causative agent of the disease spreads to tomatoes from the soil, from plant debris and from dirty garden tools; the infection is carried by some insects. Anthracnose is resistant to low temperatures and overwinters in the ground without problems. Symptoms of the disease appear especially often on tomato bushes at the end of summer, when humidity rises in open soil.
It is recommended to treat tomato anthracnose with copper preparations - such as Oksikhom, Kuproskat, Skor and Ridomil Gold.You can also use products based on Bacillus subtilis, for example, Polyram or Cumulus. Treatments are carried out 2-3 times per season at weekly intervals.
Alternaria blight
The disease is also known as macrosporiosis, brown spot or dry spot. It appears as dark marks on tomato leaves - at first they are small, then they increase to 2 cm in diameter. Gradually, the spots spread to the fruit, and a velvety brownish coating also forms on the skin. Blackened tomatoes fall from the bushes even before ripening; the few surviving tomatoes remain very small and are not very juicy.
Alternaria blight affects tomatoes mainly after transplanting seedlings into the ground.
The development of Alternaria blight is promoted by high humidity; the fungus exhibits maximum activity at a temperature of 25-30 °C. Treatment boils down to removing the affected bushes from the site and treating the remaining plants with 1% copper sulfate. It is recommended not only to spray the tomatoes, but also to disinfect the soil.
To prevent Alternaria blight, you must first control humidity levels and provide the bushes with a sufficient amount of air. It is recommended to tie tall varieties to trellises so that the leaves and ripening fruits do not fall to the ground.
Improper care
The tops of tomatoes turn black not only due to fungi, but also due to violations of agricultural practices. Rot and darkening of fruits is caused by:
- uneven watering - it is especially dangerous to over-moisten the soil under the bushes after a long period of drought;
- improper feeding - tomatoes turn black mainly due to excess nitrogen, accompanied by a deficiency of potassium and phosphorus;
- unsuitable soil - you need to plant tomatoes on neutral or slightly acidic loose soil; if the soil is dense and poorly ventilated, the crop will suffer;
- thickening - tomatoes in the open ground and in the greenhouse require formation, in addition, by 1 m2 You should place no more than 3-4 bushes so that the plants do not suffer from lack of air.
Sometimes tomato stems turn black when grown in a brightly lit area. Hot rays of the sun leave burns on the leaves, the tomato's nutritional processes are disrupted, and as a result, the volume and quality of the harvest decreases.
Why do tomatoes turn black in a greenhouse?
The bottom of tomatoes turns black both in open ground and in greenhouses. In closed soil, gardeners encounter the problem even more often. Spots on tomato fruits and leaves appear:
- due to too high humidity in the greenhouse and insufficient ventilation;
- due to an excess of nitrogen fertilizers in the soil with a lack of manganese and boron;
- If the temperature regime is violated, you need to grow tomatoes in a greenhouse at 26-28 °C.
Sometimes tomatoes turn black in the greenhouse due to exposed roots. If the feeding shoots partially protrude from the ground, the bushes do not receive adequate nutrition. The problem is easy to fix - you just need to hill up the tomatoes.
Why did the collected tomatoes begin to turn black?
Sometimes tomatoes ripen safely on the bushes, but turn black after storage. Typically the problem is caused by the following factors:
- too high humidity in the room;
- insufficient ventilation;
- The storage temperature is too high or low.
Tomatoes may turn black after harvest due to anthracnose infection. The disease does not always appear at the beginning of the season; sometimes the first symptoms become noticeable only on the harvested fruits.Rotting begins if there is damage on the tomatoes - dents and cracks. Infections quickly penetrate the tomatoes through the skin, and as a result, the crop quickly dies.
To prevent black spots from appearing on the fruits, you must carefully follow the storage rules. Tomatoes are kept in a room with moderate humidity and good ventilation at a temperature of 12-15 ° C.
How to treat tomatoes to prevent them from turning black
It is best to plant tomatoes correctly so that they do not turn black, since it can be quite difficult to deal with the existing problem. When growing crops, you need to follow several rules:
- place the bushes in a moderately lit area with fertile but loose soil;
- water the tomatoes only as needed with lukewarm water;
- regularly apply balanced fertilizers with a minimum nitrogen content;
- provide bushes in the open ground and in the greenhouse with good ventilation;
- control the temperature.
Before planting, it is recommended to pickle tomato seeds in a light solution of potassium permanganate. This will strengthen the immunity of the plant material. Developing bushes can be sprayed with Bordeaux mixture from time to time for preventative purposes, even in the absence of black spots on the fruit.
Store tomatoes away from direct sunlight to prevent them from turning black.
Conclusion
Tomatoes turn black on the bottom due to fungal infection, improper feeding or excessive watering. If the fruits are already damaged, all that remains is to throw them away. However, healthy plantings can be saved by spraying and adjusting conditions.
