A water-soaked, sunken, or brown spot appears on the blossom end of the fruit. The spot then enlarges and turns into a leathery brown or black patch. If the problem is severe, the fruit will have a flattened or somewhat concave bottom end.
MEANS OF CONTROL
Blossom end rot is caused by a calcium deficiency in the plant. While plenty of calicium may be present in the soil, not enough is reaching the plant tissue usually due to uneven water being available to the plant.
Avoid excessive nitrogen fertilization.
Avoid extreme variations in water that is available to the plant due to overwatering, heavy rain, or drought. Maintain even watering by applying a thick layer of mulch.
The problem can be very pronounced during hot, dry weather espcially if the plants are growing rapidly, again applying mulch is very helpful.
At the first sign of blossom end rot, pay attention to watering and mulching. Even out water supply to the plant so that it is never super dry and then super wet, instead make sure it has a steady, even supply of water.
Most plants usually grow out of the problem later in the season when growing conditions have been corrected.
Spray with seaweed extract to help supply some calcium to affected plants.
Spray developing fruit with products like Enz-Rot which corrects calicum deficiency to prevent blossom end rot