If your tomatoes have brown and rotten spots on the ends, it is usually blossom end rot caused by a nutrient deficiency.
If your tomatoes (Solanum lycopersicum) develop brown, enlarging spots on the ends of the fruit, you have tomato blossom end rot. In our expert interview with Floragard you have already learned a lot about this nutrient deficiency. Here is some additional information on tomato blossom end rot.
Detect blossom end rot
Typical symptoms of blossom end rot are the brown or black spots on the tomato fruit base. This means that rotten spots form just opposite the fruit stalk. These dots get bigger and look watery. Tomato varieties that produce very large fruits are particularly badly affected. These include a wide variety of beefsteak tomatoes or ox hearts. The leaves sometimes show yellowish discolorations.
The affected areas on the tomatoes also collapse, dry out later and become hard. Starting from the tips, the whole tomatoes eventually turn black. Especially in the months of June, July and August you have to be careful and keep an eye on the tomatoes. Because if nothing is done about blossom end rot, the fruit will fall off. In rare cases, blossom end rot can also occur in peppers (Capsicum) and courgettes (Curcurbita pepo subsp. Pepo convar. giromntiina) and shows the same symptoms as tomatoes.
Blossom end rot and its cause
The cause of this physiological disorder in the tomatoes can be a lack of calcium or often too much humidity. Due to this calcium deficiency, the cell walls contain too little calcium and the cell walls are therefore not stable. The cell walls then collapse, the affected tissue dies and eventually turns brown.
On the one hand, calcium deficiency can occur when there is too little calcium in your soil, but an imbalance in other nutrients can also cause itcause calcium deficiency. For example, high levels of potassium or magnesium can impede calcium absorption. If there is little calcium in the soil, this also goes hand in hand with a lower pH value. Soil that is too acidic can be brought back into the neutral pH range with liming.
Prevention and control of blossom end rot
One way to prevent blossom end rot on your tomatoes is to keep humidity levels low to encourage transpiration. This is especially important if you are growing your tomatoes in a greenhouse. Since calcium is transported with the water flow in the plants, transpiration ensures that the calcium is transported upwards quickly. You should also pay attention to an even water supply.
Humidity can also be reduced by increased air circulation. The circulation can be improved if the stand is not too dense. In this way you promote the transpiration of the individual parts of the plant and reduce the humidity and can thus prevent blossom end rot.
You can also use a fertilizer containing calcium as a preventive measure. Here you will find more information on the correct fertilization of tomatoes. In solid form, you can use algae lime or rock powder to prevent and combat algae. Just sprinkle it around the tomatoes and pour gently. However, liming can often result in a lack of other nutrients, such as iron, because the pH value changes as a result of liming. You can also add calcium in liquid form with calcareous irrigation water or use liquid tomato fertilizers that contain calcium.
Can you still eat tomatoes with blossom end rot?
Because blossom end rot is not caused by bacteria or fungi, you can eat these tomatoes with a clear conscience. All you have to do is cut out the discolored areas if they aren't too big and use the tomatoes as normal. However, be careful when using these tomatoes. Because the affected areas are entry points for fungi and bacteria and can make the tomatoes inedible.
You can simply compost the cut off parts or badly affected tomatoes - so they still serve a purpose. Here you can find out why each of us should have a compost bin. In general, it is better to remove the affected tomatoes from the plant, fertilize them sufficiently and you with itreally give it some more power to form many more flawless tomatoes.
Tip: A suitable supply of nutrients is important for he althy tomatoes. It is therefore best to use high-quality vegetable soil such as our peat-free Plantura organic tomato and vegetable soil when planting.