Correctly interpret the damage
The blossom end rot on tomatoes is neither a fungal infection nor a pest infestation. Rather, the scientists assume a metabolic disease. The picture of damage is devastating. It manifests itself just as often in the field as in the greenhouse. How to recognize the symptoms:
- black necroses spread on older leaves
- Watery, brownish discolouration appears at the flower base of unripe tomatoes
- the spots dry up and harden
- in the final stage, the tomatoes turn black from the tip
- emergency ripening takes place and the fruits fall off
- Tomatoes are turning black - now we need to act quickly
- Do tomatoes also thrive in partial shade?
- Nature provides the best fertilizer for tomatoes
The current status of research into the causes provides information
Blossom end rot goes hand in hand with an undersupply of the plant with the vital nutrient calcium. A healthy tomato plant also receives a sufficient amount of calcium along with the water, which is transported into the leaves and from there into the tomatoes.
Fluctuations in irrigation, strong growth, too low a pH value in the soil and excessive salt content disrupt this flow of perspiration. Since the fruits are naturally supplied with less calcium than the leaves, the deficiency is particularly devastating here.
So flower end rot does not get any points of attack
You can immunize your tomato plants against the metabolic disease with the following measures:
- pour the tomatoes evenly
- Pay attention to a balanced fertilization, preferably organic
- If the pH value of the soil is too low, treat with rock flour, algae lime or Azet vital lime
If the emergency has already occurred, the specialist trade offers special calcium fertilizers. These work particularly quickly when applied over the leaves. Alternatively, you can dissolve 30 grams of calcium nitrate in 1 liter of water and water the diseased plant with it.
Tips & Tricks
You can easily determine the pH of the soil yourself. In DIY stores and garden centers, inexpensive test sets are available that can be used without chemical knowledge. A simple coloring reaction shows how things are going with the lime content of the soil.