SUPPRESSION OF APPLE BLOOM WITH GIBBERELLIN SPRAYS

Gibberellin A4+7 at concentrations of 250 mg l-1 active ingredient (a.i.) or less, applied as one, two or three sprays 4-16 weeks after petal fall gave inconsistent flower thinning on five year old redchief 'Delicious' apple trees. Four sprays, each a month apart, beginning one month after petal fall on similar six year old trees, with concentrations of 250 or 500 mg l-1 a.i., eliminated 95% or 99% of return bloom, respectively.