Are you a tomato farmer?
Do you struggle with this kind of problems?
According to farmers, this is called BLOSSOM END ROT
Blossom end rot happens because your tomato isn’t utilizing calcium efficiently and that can either happen because you don’t have enough calcium in your container soil or in your ground or there is watering issues and your root system can’t use the calcium that is there. Either case, you want to treat it by making sure you begin watering regularly and also add calcium to your plant.
Most farmers solve this by introducing calcium to the soil by using a limestone slurry. That is, by dissolving and mixing powdered lime thoroughly in water and then applying it to the soil. This might result in an increase in the pH of the soil. This can serve as an emergency treatment for a plant that is already affected and also for preservative measures.
Nonetheless, due to our stand on organic farming, we suggest any organic means through which calcium can be added to the soil.