Performance of Benzyladenine as a Chemical Thinner on Eight Apple Cultivars

Abstract

Benzyladenine (BA) was applied at various rates and in combination with other thinning chemicals to eight apple cultivars in 26 different studies from 1987-94. BA at 100 or 150 ppm caused reductions in fruit set similar to that caused by NAA at recommended rates. NAA, however, resulted in increased fruit size in only 13% of the trials, while BA in concentrations fro m50-150 ppm increased fruit size in 38% of the trials. BA at 50 ppm reduced fruit set, increased size, and had no influence on yield of 'Jonathan.' Generally, higher rates (100-150 ppm) of BA were required for positive thinning results with 'Gallia Beauty.' Results with 'Melrose' were inconsistent. BA at 100 and 150 ppm reduced fruit set and increased fruit size of standard-habit 'Delicious' and 'Golden Delicious' in half of the trails. Spur-habit 'Delicious' was not thinned successfully with BA. Fruit size of 'Empire' was increased with little effect on yield. Thus, BA in this series of trials was a more consistent chemical thinner than NAA w...