PERFORMANCE OF ‘ANJOU’ PEAR TREES SPRAYED WITH CALCIUM OR SUMMER PRUNED

Summer pruning and calcium sprays were compared to determine the effects on yield, fruit size, fruit and leaf mineral composition, fruit quality and control of fruit disorders of ‘Anjou’ pears (Pyrus communis L.) Treatments included two summer prunings during the third week of June, July or August in northcentral Washington. Several different calcium spray materials were used that included B, P, S and Zn. Summer pruning resulted in higher Ca and Mg concentrations in the fruit and leaves with a lower incidence of cork spot and alfalfa greening than in controls. Summer pruning had no apparent adverse effect on fruit production, and fruit finish and size were usually improved. Soluble solids in fruit were not reduced by summer pruning. Calcium chloride-sprayed trees resulted in the highest fruit Ca concentrations with the best control of fruit disorders, but some phytotoxicity occurred on fruit and leaves. However, fruit-spray injury was acceptable the latter 2 years, when Ca Cl₂ spray rates were reduced by one-half to 680 g/400 liters. While Nutraphos-24 sprays did not enhance Ca uptake, leaf color and tree vigor were improved, and Zn concentrations in fruit and leaves were increased when the rate and frequency of application of this material was increased. Calcium-boron sprays increased B concentrations in the fruit but did not increase Ca concentrations.