Tomato diseases

Tomato is one of the most common crops in any garden, especially urban ones. The tomato plant is a plant whose care is available to everyone, and its fruits can be enjoyed in so many recipes and in so many ways that it is difficult to resist planting a few to benefit from their harvest.

However, it is also a plant that tends to be attacked by some pests and diseases, since it is so widespread today. Therefore, it is important to know well what your enemies are in order to fight them properly. If you want to learn more about tomato diseases and see photos, keep reading this article.

Tomato pests

There are various pests of tomato plants that affect the entire plant, from the stem and leaves to the fruits themselves. Here we explain the most common:

  • One of the main pests that attack tomatoes is the spider mite . These small reddish or yellowish arachnids, as their name suggests, are very small and attack the plant by sucking its cellular juices to feed. The result is that the affected areas of the plant turn yellowish and end up necrotizing. When there are many, they form easily identifiable cobwebs, which they use to travel between plants.
  • The whitefly , for its part, lays its eggs on the underside of the young leaves of the plant, so that the larvae then feed on them.
  • Aphid attack is also common on tomato plants, which appears in spring and autumn and is very typical in a wide variety of plants.
  • We can also find thrips , which lay their eggs on fruits, leaves and flowers.
  • The leaf miners , which lay inside the young leaves, from where the larvae burrow and feed.

Tomato diseases

Among the most common tomato diseases we find the following:

  • Powdery mildew is a problem caused by fungi that cause yellow and brown spots to appear on the leaves, causing them to wrinkle and dry out.
  • Gray rot is caused by a fungus that causes brown or gray spots to appear on the leaves, stems and flowers, which also causes a moist and soft rot in the fruits.
  • Anthracnose appears during the ripening of the fruits, in the form of spots with the appearance of rottenness, which increase in size with time, making the tomatoes not useful for consumption. 
  • Tomato mildew is another fungus that affects the tomato plant in all its stages of development and causes wet-looking spots to appear on all its leaves and stems.
  • Alternariosis causes circular spots with concentric rings, which end up causing affected areas of dark and elongated color and darkened and sunken areas in the fruits.

How to prevent tomato diseases ecologically

Finally, we offer several tips to treat and prevent tomato pests and diseases :

Tomato mildew

To avoid the attack of this fungus, it is necessary for the tomato crop to have good ventilation, with the plants far enough apart. This is especially important in the case of greenhouses, where ventilation is less and the fungus can appear more often. We must ensure that there is never stagnant water on the leaves of the plant.


To prevent the appearance of alternariosis you must avoid that the environmental humidity in the harvest remains too high, in addition to keeping the crop clean. If symptoms of affected plants or fruits appear, remove them immediately.

Powdery mildew

As with pests, with powdery mildew the most important thing is good crop hygiene, without organic matter that decomposes or attracts pathogens. It is also important to remove all weeds. 


If your tomatoes are attacked by aphids, garlic infusions sprinkled on the plant are a very good way to fight the plague in an ecological way. If you want to prevent their occurrence, it is important to make sure to clean the garden of weeds and debris from other cultivated plants, and to keep humidity levels low.

Red spider

The measures to prevent the appearance of the spider mite are the same as with aphids. Keep in mind that these appear when the temperatures are very high, so be especially careful in the warmer months. Also, avoid fertilizers with too much nitrogen content.

White fly

Once again, the important thing is to maintain the strictest possible hygiene in our garden, removing any remaining organic matter from both the tomato and any other plant. In addition, it is advisable not to fertilize at the end of the cycle, to avoid that the adult specimens are attracted to the young shoots.

Tomato diseases

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