Causes of the appearance of black spots on tomatoes, methods of control and prevention

  • Sep 03, 2021
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The appearance of black spots on tomatoes is one of the common problems that gardeners face. Spots appear on fruits, stems and leaves. It is important to identify the cause in a timely manner and immediately begin to eliminate it in order to save the plants and the harvest.

Tomatoes. Illustration for this article is used under a standard license © ofazende.com
Tomatoes. Illustration for this article is used under a standard license © ofazende.com
Tomatoes. Illustration for this article is used under a standard license © ofazende.com

Reasons for the appearance of black spots on tomatoes

Black spots appear on tomatoes for the following reasons:

  • illness;
  • violation of agricultural technology;
  • wrong microclimate.

Signs of the disease

Spots may indicate damage to the plant by such diseases as:

  • brown spotting;
  • top rot;
  • watery rot;
  • anthracnose;
  • gray rot;
  • late blight;
  • stem necrosis.

Phytophthora

One of the most common and dangerous diseases that affects nightshade crops. The causative agent is a fungus that infects stems, leaves and fruits. If brown spots are found on the fruits, brown spots and white bloom on the leaves and stems, it is important to immediately begin to fight the disease, otherwise it will destroy the entire planting within a week.

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Phytophthora. Illustration for this article is used under a standard license © ofazende.com
Phytophthora. Illustration for this article is used under a standard license © ofazende.com

The reasons why late blight appears:

  • high humidity: violation of the irrigation scheme and stagnation of moisture at the roots, fog, abundant dew and precipitation;
  • sharp jumps in temperature;
  • dense planting;
  • poor ventilation of the bushes;
  • contaminated soil.

When the first signs of the disease are detected, the affected plants are removed and burned. The soil where they grew is disinfected.

Top rot

A disease resulting from plant overheating, excess nitrogen, high acidity, excess calcium.

Signs of the disease:

  1. Brown spots appear at the top, which spread throughout the plant.
  2. The fruits turn black and dry up.

Control methods:

  1. Destruction of plant parts and fruits with signs of disease.
  2. Fertilizing the bush with potassium sulfate.
  3. Disinfection of the plant and the soil under it with boric acid.

Tomatoes are processed once every 7 days until the signs of the disease disappear.

Brown spot

Fungal disease affecting nightshade crops. The first signs are found at the end of flowering. Light spots appear on the upper side of the leaf plate, and brown and gray bloom on the lower side. The leaves gradually curl and dry out. The bush does not receive enough nutrients and dies.

Brown spotting. Illustration for the article is used from the website selhozobzor.ru
Brown spotting. Illustration for the article is used from the website selhozobzor.ru

Preventive measures are taken to prevent the appearance of black spot:

  1. They prefer varieties with high disease resistance.
  2. Seed material is calcined before sowing.
  3. Cut the lower branches regularly to improve airing of the bush.
  4. Do not allow the soil to dry out.

Reasons for the appearance of black spots on tomatoes indoors

Tomatoes turn black in greenhouses and greenhouses for the following reasons:

  1. High humidity and temperature. These are optimal conditions for the appearance and active development of fungal diseases. They solve the problem by reducing the amount of moisture introduced and normalizing temperature indicators.
  2. Oversupply of fertilizers. In this case, the feeding scheme is revised.
  3. Exposure of the root system. The plant does not receive enough nutrients, as a result, the fruits turn black. In this case, cover the roots with earth.
  4. Lack of boron and magnesium. Tomatoes are fertilized with compounds with these elements.
  5. Poor ventilation. In this case, on one side of the greenhouse, a window is opened, and on the other, a door.

Plant processing

When black spots appear on the fruits, the bushes are treated:

  • Bordeaux liquid solution;
  • fungicides;
  • copper sulfate;
  • calcium nitrate;
  • potassium chloride.

Some gardeners prefer folk remedies:

  • infusion of garlic;
  • serum based solution;
  • iodine with milk;
  • infusion based on rotted straw;
  • salt and iodine.

Finding the cause of the appearance of black spots on tomatoes in a timely manner, you can save the crop. Planting varieties resistant to late blight, adherence to agricultural technology and the creation of a microclimate that is optimal for tomatoes will help to avoid the appearance of a problem in the future.

Read also: Flowers for sowing and planting at the end of summer

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