Growth, Yield, and Fruit Weight of Spur-bound `Delicious' Apple Trees following Spur-pruning and BA Plus GA4+7 Application

Abstract

Twenty-eight-year-old `Starkrimson Delicious' and 10-year-old `Fullred Delicious' apple (Malus domestics Borkh.) trees were spur-pruned in 1986 and 1987 and/or treated with 500 mg BA + GA 4+7 /liter in 1986 in an attempt to improve spur growth and increase fruit weight. All treatment combinations generally failed to improve yield or fruit size. BA + GA 4+7 reduced yield and fruit weight and increased the number of pygmy fruit in 1986, but had little effect on fruiting or vegetative growth for 3 years after treatment. Spur-pruning reduced spur density in 1986 and 1987 and increased yield, but not fruit weight, in 1987. Although spur-pruning improved spur length, spur bud diameter, leaf area per spur, and leaf dry weight per spur, fruit weight was not improved. Chemical names used: N -(phenylmethyl)-1H -purine-6-amine [benzyladenine (BA)]; gibberellin (GA 4+7 ).