Why do tomatoes sometimes turn black

Atnug Aniduarg July 7, 2023 in HOME & GARDENING - 7 Minutes

Tomatoes are one of the vegetable crops that have long been loved by summer residents. They are grown in almost every garden, in the open field, and in greenhouses. Every experienced gardener has his own tricks to help get a generous harvest.

But sometimes it’s impossible to grow juicy and healthy fruits without problems. At that moment, when, it would seem, all that remains is to harvest, you suddenly find that the bushes have begun to dry, and the unripe tomatoes have turned black.

Why is this happening? Experts say that the reason is usually associated with improper care of plants or diseases. To prevent the problem, you need to understand the causes that cause the blackening of the fruit.

Why do tomatoes turn black?

Inspection of damaged fruits will allow you to accurately determine the cause of the appearance of black spots. It is necessary to pick a tomato with spots and cut it in half at the place of darkening. If there is no juice at the place of spoilage, and the pulp is noticeably compacted, then we are talking about dry-type vertex rot.

This disease develops due to excessive salinity of the soil. The reason may be too frequent use of fertilizers or excessive concentration. In this case, it is recommended to refuse any top dressing and fertilizers for some time in order to allow the earth to recover, or plant tomatoes in a new place by changing the dosage of fertilizers.

Incorrect watering can also be the cause of blossom end rot. With a lack of moisture during the period of active development and the beginning of fruiting, the plant experiences water stress. As a result, the leaves begin to pull moisture onto themselves, including taking moisture from the fruit. This is what causes rot.

Any varieties of tomatoes require careful observance of all the rules of care. Even pits when planting seedlings need to be dug to a certain depth, which can vary depending on the variety. For example, if the holes are shallow, then the roots of the plant may come to the surface, which can also lead to blackening of the fruit before ripening.

Diseases leading to the blackening of the fruit

Tomatoes get sick too, just like people. They can become infected by surrounding plants. Pathogens can get on fruits with wind, compost, or they can simply be in the ground.

Late blight
Phytophthora infestans is a simple fungus with a phenomenal ability to reproduce. This “crop eater” is able to reduce the yield from 10 to 50%, and in some cases completely destroy it.

Late blight develops especially quickly in rainy, damp weather. Initially, the disease appears on the leaves of tomatoes: their upper part is covered with brown spots, and the lower part with a gray coating. Gradually, the leaves turn black, and then spots begin to appear on the fruits.

Late blight is most dangerous in July-August. Indeed, at this time there are large temperature differences and abundant dews fall. The appearance of phytophthora can also cause too much watering. In this case, it is worth abandoning waterlogging and treating the plants with a Bordeaux mixture.

Phomosis
This disease affects only the fruit. Tomatoes turn black near the stem. From it, the disease spreads deep into the vegetable. As a result, the tomatoes fall off, never fully ripening.

Macrosporiosis
Another common fungal disease of tomatoes. At the initial stage, signs of damage are noticeable on the lower leaves: rounded dry brown spots appear with clear outlines and a characteristic concentric pattern.

Gradually, the fungus spreads to the stems and upper leaves. Infected stems have elongated brown spots. Then rounded depressed spots appear on the fruits.

Soon the disease covers the entire bush, and the leaves curl and die. Developing, the fungus begins sporulation. Spores of the pathogen overwinter in the soil and on plant debris and remain viable for more than 3 years.

Prevention methods

As a preventive measure, experienced gardeners warn against planting tomatoes in the same place for several years. The plot for tomatoes needs to be updated regularly. This will prevent soil depletion.

Tomatoes are highly discouraged from planting in places where potatoes grew before them, these plants consume the same substances from the ground and also suffer from the same diseases, late blight is especially dangerous in this regard.

It is necessary to correctly divide the space into beds, providing sufficient distance between them. The ideal spacing is 30 centimeters. Between rows it is worth alternating a distance of 30 and 70 centimeters, then the plants will have enough nutrients.

Top dressing must be done in exact dosages because a glut of some minerals leads to the blackening of the fruits, leaves, and stems of tomatoes. It is necessary to provide sufficient illumination, it is also desirable that the bed is blown by the wind. Watering should be carried out not with cold, but with warm water, under the root, and not on the leaves. Shoots need to be tied up, and damaged and old leaves should be removed in time.

What to do if the tomatoes are already blackened?

If, despite all the preventive measures, the tomatoes still begin to turn black, an urgent need to save the crop. Choose one of the cloudy days and spray the tomato bushes. For this, different compositions are used – garlic, kefir-water, and chloride. All of them protect healthy plants from fungal spores.

Plant watering should be stopped. Not badly affected fruits must be removed, treated with hot water at a temperature of up to 70 degrees, and laid out for ripening. Bushes and leaves damaged by the disease must be burned at the stake.

Thus, the blackening of tomatoes can occur due to improper care, as well as due to diseases. If you apply fertilizers correctly and properly care for the plants, you can minimize the risks and get an excellent harvest of juicy and ripe tomatoes. If the tomatoes are sick, you must respond immediately.