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Black Spots on Tomatoes

Black Spots on Tomatoes

It can be very difficult for an inexperienced gardener to find out the reason behind dark and black spots on tomatoes. This article lists out the probable causes and symptoms that will help you identify the problem correctly and take appropriate measures for the same.
Rutuja Jathar
Growing tomatoes is a hobby most gardeners like to develop and maintain. While people are so interested in growing these plants, they must also be aware of several basic things that are very important in their proper growth and maintenance. Even people who take proper care while planting the best healthy plants complaint that there are several problems with them and the health of the tomatoes. The most common problem is the black spots on the tomatoes in the garden.

Understandably, finding dark spots on the tomatoes and leaves in the middle of the growing season can frustrate any gardener. Well, when the damage is already done there is just one most important thing that remains in your hands and that is the perfect planning for the next growing season.


Black spots on green or ripend tomatoes and the leaves is definitely not a good sign. Such signs indicate that the plant has fallen for any of the tomato plant diseases. There are several culprits involved that can be responsible for these symptoms. Here are the predominant reasons.

Tomato Blight
This is the main disease that can single-handedly destroy your plant if proper care is not taken. There are three type of blights that can be very harmful for a healthy plant and is the reason for the spots on the leaves as well. These three types include - septoria leaf spot on tomato leaves, early blight, and late blight. While the first one attacks only the leaves, the rest can harm the fruit as well. While late blight spreads the fungus Phytophthora infestans, the early blight is caused by the fungus Alternaria solani. Infestation by both of these fungi can cause dark brown and black spots on the leaves and stem of the plant. It can gradually get worse and cause dark spots on the tomatoes.

Blossom End Rot
Blossom end rot is the reason behind most spots on the bottom of tomatoes, especially green ones. This condition is caused by calcium deficiency in the plant that is due to the huge fluctuations in the atmospheric moisture. These spots are sunken and brownish at the beginning and get really widespread and destroy the fruit completely. Blossom end rot is dangerous not only because it causes the potential local injury to the fruit, but also makes that plant more susceptible to fall for several other harmful conditions.

Bacterial Spots
The bacterial spots are caused by the bacterium called Xanthomonas campestris pv. vesicatoria,. It is the same bacteria that also troubles peppers. It generally causes dark and black spots on the leaves and stems of the plant. It causes spots on green tomatoes that look slightly bumpy and are usually surrounded by water soaked areas. Moreover, this bacteria hibernates in the plant debris and soil and hence provides a potential threat to the crop of the next season as well. Hence, it is important to remove the threat completely, before the plantation in the next season.

Preventive Measures

As said earlier, once formed, black spots on the leaves cannot be treated. Hence, it is for the benefit of a healthy crop to prevent them before they appear. It is important to prevent the blights from attacking the tomato plant. Extreme wet or extreme hot conditions suit blights the best and hence it is best for the gardeners in that region to take proper prevention and spray the best fertilizers before the plant gets infected. Using flood irrigation can also be useful rather than spraying fungicides on the leaves. One can also use a bicarbonate of soda instead of the chemical fertilizers.

If the crop is wasted this season due to the black spots and blights, there is no reason to put your head down. One can always begin from the start and get the best crop the next time. One thing that can be done is rotating the crop. Rotate the location of the plants and you will see that there are no spots on the leaves and tomatoes as well. Dilute 20gms of bicarbonate of soda in 10 liters of water and spray the solution biweekly on the plant to keep it safe.