Effect of calcium spray materials, rate, time of spray application, and rootstocks on fruit quality of 'Red' and 'Golden delicious' apples

Calcium (Ca) spray materials improved fruit quality as measured by control of bitter pit, fruit finish (appearance), increased red skin color, reduced incidence of scald, increased juiciness, texture, and fruit firmness of 'Red' and 'Golden Delicious' apples (Malus domestica, Borkh.). Concentrations of Ca in leaf and fruit tissues were increased by Ca sprays, especially calcium chloride (CaCl2)-containing spray materials. Improved fruit firmness and control of bitter pit occurred for either standard recommended or high rates of Ca spray materials. At high rates of application, the only significant difference that occurred between early and late applications of Ca spray materials was that less leaf injury occurred with the early applications. Unsprayed 'Red Delicious' fruit from M.7 rootstocks had greater fruit peel Ca concentrations and a lower incidence of bitter pit but smaller fruit than fruit from trees on M.26 rootstocks. The above information is strong evidence that Ca sprays are important for the improvement of apple quality.