Early fruits on the plant may have blossom end rot, while those that develop later are normal. Blossom end rot is a symptom of calcium deficiency in the fruit. It can occur even when there is abundant calcium in the soil and tissue tests show high levels of calcium in the plant. Poor calcium distribution in the plant results in low calcium levels where the lesion occurs. Calcium, dissolved in water, moves through the plant in the vascular system from the roots to the leaves.
Leaves are the primary sink for movement of water because of water loss through transpiration.
Under high moisture stress, the water containing calcium and other minerals moves rapidly to the leaves. Fruit does not transpire as much as leaves and thus tends to be bypassed. This results in a localized calcium deficiency. This calcium deficiency in an area of rapid growth, the end of the fruit, causes cells to collapse and the sunken-lesion symptom of blossom end rot. Blossom end rot may appear on some of the first fruit clusters on a plant.