Main diseases of tomatoes, treatment and prevention


The tomato is one of the fruit vegetables that young and old particularly appreciate. Gardeners like to grow different varieties. But some very specific diseases can attack tomato plants despite all the good care given to them. Let’s take a look at the four main diseases of tomatoes, how to treat them (when possible) and also see how to avoid them.

Common tomato diseases, symptoms and treatments

Viral, bacterial or fungal diseases can devastate an entire tomato crop. Many factors are involved, namely:

  • Humidity,
  • Temperature,
  • Wind,
  • The vulnerability of certain varieties,
  • Soil infertility.

Four diseases are particularly recurrent in tomatoes and are noticeable by certain symptoms.

1 – Septoria leaf spot

It is a fungal disease which attacks specifically the tomato. Very devastating, it destroys the leaves. Identified at the beginning by rounded spots appearing first on the leaves close to the ground, it then spreads to the entire foliar system. The leaves turn brown, wither and fall. There isn’t much you can do to save your tomato bed when the disease is very advanced. It is therefore necessary to react very quickly from the first symptoms by treating with an organic copper-based fungicide.

2 – Fusarium wilt or fusarium wilt

This is a fungal disease more common in hot climates that can devastate an entire crop of tomato plants. The whole plant can wither and die. It is essential to resort to a biological fungal treatment, but if the infestation is very heavy, the only solution is to pull out all the plants.

3 – mildew

Downy mildew is caused by a pathogenic fungus. It is quickly identified by the appearance of brown spots on the foliage, yellowing and then leaf fall. It is the most common disease of tomatoes. It is treated with a fungicide based on sodium bicarbonate or else based on copper.

4 – Brown rot or bacterial wilt

This bacterial disease is caused by the bacteria Ralstonia solanacearum. The leaves wilt and drop after they have dried completely, and the stems are marked with large brown mottles. Note that it is always the youngest leaves that are attacked before the others. A viscous film can be seen to flow from the stems when they are cut. Unfortunately, this disease is spreading at lightning speed on many vegetable plants. All the tomato plants that are infested must be pulled out as quickly as possible. Currently, there is no product available to treat brown rot.

Prevent tomato diseases

To avoid trouble due to common tomato diseases, it is essential that the gardener follows the following recommendations.

  • Select resistant varieties.
  • Always respect the needs of plants, both in terms of exposure, soil and watering.
  • Never tighten your plants too much because you must allow the air to circulate within a bed but also in the heart of each plant in order to avoid as much as possible the excess of confinement which favors fungal diseases (or fungal diseases) .
  • Opt for the crop rotation which consists in not cultivating in the same place, several years in a row, the same vegetables.
  • At the slightest sign of disease, remove all affected parts or even entire plants and burn them to avoid contaminating other plants because some pathogenic organisms can live for several years in the soil.
  • Disinfect all the tools used to prune the tomato plants as well as the containers in which you want to transplant the seedlings if the project is to grow potted tomatoes.
  • Limit the risk of fungal diseases by taking care not to wet the leaves of the tomato plants during watering and protect the foliage from splashing rainwater by adequate mulching.
  • Practice companionship as soon as possible, that is to say plant near tomatoes friendly plants that repel pests and prevent certain diseases such as basil, tetragon, spinach, marigold, the lettuce, cucumber, cabbage, chives, marigold, carrot, garlic …

By adopting all these good habits, you can protect your crops against many diseases and benefit from a bountiful harvest of excellent quality tomatoes. But these tips remain valid for all vegetable plants. Note, however, that all tomato-friendly plants are not necessarily associated with all the plants in the kitchen garden. It is necessary to inquire well beforehand in order to choose the right associations.