Abstract
Apple (Malus domestica, Borkh) and pear (Pyrus communis, L.) trees responded to nitrogen (N), phosphorus (P), and potassium (K) fertilizers. In low P soils, leaf, and fruit P concentrations were increased and yield was improved with moderate rates of mono‐ammonium phosphate (MAP) fertilizers. Improved fruit quality including fruit firmness, red fruit color of ‘Delicious’ apples, and a lower incidence of fruit disorders of apples (bitter pit) and pears (alfalfa greening and cork spot) was frequently associated with trees that were fertilized with calcium nitrate [Ca(NO3)2] (CN). Although yield was often improved in experiments containing N‐P‐K or MAP fertilizers, long‐term use of N‐P‐K or MAP could be associated with a higher incidence of fruit disorders and a lower soil pH than with CN fertilizer at equivalent rates of N.