The Effect of Succinic Acid 2,2-Dimethyl Hydrazide on the Uniform Maturity of Peaches and Nectarines12,3

Abstract ‘Dixon’ and ‘Fay Elberta’ peach and ‘Independence’ nectarine trees were sprayed with succinic acid 2,2-dimethyl hydrazide (Alar) at the onset of pit hardening in the fruits. Distribution of ‘Dixon’ fruits by color at harvest revealed that the fruits on the lower and upper halves of the treated trees were more uniformly colored than those from non-sprayed trees. Furthermore, maturity was advanced approximately 6 days. Fruits from trees in which just the lower half was treated were, likewise, more uniform than the controls but maturity was advanced only 2 to 3 days. The advancement in maturity was evidenced by increased carotene, lower acid, and higher soluble solids. At the same stage of ripeness, fruits treated with Alar were firmer than those harvested from the check trees. The maturity of ‘Independence’ and ‘Fay Elberta’ fruits was advanced 2 and 5 days, respectively, by Alar treatments. The physical and chemical changes which accompanied the ripening processes were similar to those found in the ‘Dixon’ fruits. Concomitant with the earlier ripening induced by Alar, the rates of CO 2 and ethylene evolution began to increase early in the treated fruits.