THE EFFECTIVENESS OF 0.7-PERCENT OXYGEN TO ATTENUATE SCALD SYMPTOMS IN DELICIOUS-APPLES IS INFLUENCED BY HARVEST MATURITY AND CULTIVAR STRAIN

In a 3-year study, the effectiveness of 0.7 % and 1.5 % O-2 to attenua te scald was evaluated on three strains of 'Delicious' apples (Malus x domestica Borkh.)-'Harrold Red', 'Starking', and 'Starkrimson'-harvest ed five times at weekly intervals from a wide range of orchards, Scald susceptibility of fruit held in air, 1.5% O-2 + 1.0% CO2, and 0.7% O- 2 + 1.0% CO2 at 0 degrees C decreased sharply as the fruit matured on the tree (starch index 1.0 to 2.5 on a 0 to 9 scale), Later harvests ( starch index >2.8) further reduced scald but the fruit had more waterc ore-induced breakdown and were 3 N softer than fruit picked at a less advanced maturity, Early picked 'Starkrimson' (starch index <2.0) scal ded more than 'Starking' and 'Harrold Red' in air, 1.5% O-2, and 0.7% O-2 storage at 0 degrees C, and 0.7% Oz was less effective than 1.5% O z in scald control, While 0.7 % O-2 Storage effectively reduced scald (less than 10 %) for 8 months in 'Starking' and 'Harrold Red' picked o ver a wide range of maturity (starch index 0.7 to 4.3), it did not ade quately control scald (up to 45 %) in early picked 'Starkrimson' (star ch index <2.0), Storage in 0.7% also reduced watercore-induced breakdo wn in 'Starkrimson' (starch index >3.0) and did not result in skin pur pling or alcoholic taste in 'Harrold Red', 'Starking', and 'Starkrimso n'.