Effect of Growth Regulators on the Development of ‘Delicious’ Apples1

Abstract The color and shape of ‘Delicious’ apples were improved with a combination treatment of (2-chlorethyl)phosphonic acid + α-(2,4,5-trichlorophenoxy)propionic acid (ethephon/fenoprop) and gibberellin A 4 A 7 plus N-(phenylmethyl) 1H-purin-6-amine (GA 4,7 /BA). All ethephon/fenoprop treatments improved red color development. The length/diameter (L/D) ratio of fruit treated with GA 4,7 /BA, GA 4,7 /BA plus ethephon/2,4,5-TP, and GA 4,7 /BA plus ethephon/2,4,5-TP plus daminozide was greater than untreated fruit. The L/D ratio of fruit treated with GA 4,7 /BA plus daminozide did not differ from those not treated. The length, diameter, and weight of fruit treated with daminozide alone was less than for untreated fruit. Diameter of fruit treated with GA 4,7 /BA + daminozide or daminozide + GA 4,7 /BA + ethephon/fenoprop was less than for untreated fruit.