Blossom-end rot is caused by a localized calcium deficiency and is induced by uneven water supply, especially dry conditions. Hot, dry periods followed by large applications of water results in the plant not be able to absorb calcium quickly. Rapid plant growth, low potassium and calcium, excess magnesium and nitrogen, high salinity, root damage, and high relative humidity all predispose plants to Blossom-end Rot. The best way to avoid Blossom-end Rot is by careful irrigation, balanced fertilization, and steady plant growth. Applications of lime to the soil or foliar sprays of calcium chloride or calcium nitrate may be helpful. Cultivars differ in their susceptibility to blossom-end rot.
Updated MB Dicklow, 11/2010