Blossom-end Rot
Blossom-end rot is most common in watermelons, although it may also occasionally occur in cantaloupe and other cucurbits. The bottom end of affected fruit fails to develop properly. The area around the blossom scar turns dark, leathery brown. As the fruit expands the affected area becomes sunken and dry. Under humid conditions, secondary rots may cause the fruit to break down.
Blossom-end rot is caused by a localized calcium deficiency. It occurs when dry soil conditions reduce the amount of water movement into the plant, thus reducing the movement of calcium to the fruit. Calcium is an important component of cell development. Blossom-end rot is caused primarily by drought-stress and not a deficiency of calcium in the soil.
Foliar calcium sprays will not prevent blossom-end rot. Foliar-applied calcium is taken up and fixed in the leaves; it is not readily transported to the fruit. Follow a regular irrigation schedule to maintain even soil moisture conditions during fruit expansion and development.
