Comparisons of Calcium Chloride, Calcium Phosphate, and a Calcium Chelate as Foliar Sprays for ‘McIntosh’ Apple Trees

A 4-year study compared CaCl 2 , Ca(H 2 PO 4 ) 2 , and a polyphenolic acid chelate of Ca, applied as foliar sprays, for improving apple ( Malus domestica Borkh.) fruit quality. Technical grade 77% to 80% flake CaCl 2 consistently increased fruit Ca concentrations and reduced senescent breakdown after storage and occasionally reduced superficial scald after air storage. When materials other than Ca(H 2 P0 4 ) 2 were applied at concentrations providing soluble Ca concentrations equal to that of technical grade CaCl 2 , equal benefits were achieved. Treatments that increased Ca also usually reduced Mg concentrations in outer cortex tissue. Ca(H 2 PO 4 ) 2 increased fruit P but not fruit Ca concentration, and a reduction in superficial scald was the only accompanying benefit to the fruit.