Wide fluctuations in soil moisture levels impair calcium uptake by the root system. Excessive nitrogen fertilization may also contribute to blossom-end rot. Avoid over-fertilizing with nitrogen. Sunscald Initial symptoms are shiny white or yellow areas on the sides of the fruit exposed to the sun. Later, the affected tissue dries out and collapses, forming slightly sunken, wrinkled areas.
Secondary organisms invade the affected areas causing the fruit to rot.
Sunscald occurs on fruit exposed to the sun during periods of extreme heat. Grow tomatoes in wire cages. Plants grown in wire cages provide good foliage protection. Also, control foliar diseases of tomatoes which defoliate the plants and expose the fruit to direct sunlight. Fruit Cracks Radial and concentric cracks develop at the stem end of the fruit.