Fruits of tomatoes grown in gardens are commonly affected by blossom-end rot. At first, a water-soaked area develops on the fruit near the blossom end (opposite from the stem end). The area enlarges and turns black and leathery, and secondary organisms often invade the affected tissue.
Blossom-end rot is caused by a localized calcium deficiency in the blossom end of the fruit. Because calcium does not migrate well within the plant, a deficiency in the developing fruit can occur with fluctuations in soil water supply for the roots, even for a short period of time.
Apply mulch around tomato plants to reduce evaporation and minimize soil moisture fluctuations. Ensure a steady supply of water during fruit production. Do a soil test to ensure that the pH is between 6 and 6.5.
