Hi-Yield Calcium Nitrate is used primarily in vegetable gardens, particularly for tomatoes and peppers, in the prevention of blossom end rot. Blossom end rot is a physiological disorder (not a disease) caused by a lack of calcium. When fruits are enlarging rapidly, sufficient amounts of calcium fail to reach the end of the fruit resulting in a deficiency of calcium in the developing fruit. Use as a soil application or as a foliar spray.