Damage is largely unraveled
The home-grown tomatoes can get into trouble even without being attacked by pests, fungi or bacteria. When these three causes were ruled out, researchers discovered a lack of calcium in blackened tomatoes. This symptom revealed a metabolic disease.
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For a previously unknown reason, the tomato plant is no longer able to transport the calcium, which is actually abundant in the soil, to the fruit. Here this mineral is urgently needed as a building material for the ripening of the tomatoes. Ultimately, the lack of calcium causes the buds to turn black first and then the tomatoes. The flower end rot has struck.
Correctly correct calcium deficiency
Various approaches are available for a tomato plant to optimize its absorption of calcium. The first step is to check the pH of the soil. In the acidic soil there is mostly a lack of lime, which causes an undersupply of calcium. You can use a simple test set from the garden center to check the value. If it is below 5.5, the floor is limed with:
- Algae lime
- Rock flour
- Azet vital lime
- Cottage lime
- Basalt flour
It is essential to avoid overdosing. Add the lime gradually and check the pH again. A value of 6 to 7 must not be exceeded, because from 8 the soil tips over into the equally harmful alkaline range. In this case, the tomatoes no longer turn black, but they nevertheless lapse into an equally undesirable growth depression.
Effectively prevent flower end rot
To prevent your tomatoes from turning black in the first place, we recommend the following prophylactic measures:
- an even water supply with no upward or downward deflections
- balanced organic fertilization with compost, horn shavings (6,39 € at Amazon *) or nettle manure
- Regularly check the pH value and re-scale if necessary
- Refrain from irrigation only with low-calcium rainwater
Tips & Tricks
As a first aid measure in the event of an infestation by flower end rot, dissolve 30 grams of calcium nitrate in 10 liters of water. With this solution, repeatedly water the diseased tomato plant. Alternatively, you can apply an immediately effective calcium-containing foliar fertilizer.
