Effects of calcium nitrate (CN) and sodium sulfate (SS) blossom thinning agents applied after self-incompatibility control substance (SICS) treatment on the fruit set rate and quality of apple were investigated for 2 cropping seasons. CN and SS at 0.1% and 0.2% concentrations were applied once (3 or 4 days after SICS treatment) or twice (3 and 5 or 4 and 6 days after SICS treatment). Commercial Japanese flower thinning agent (FTA: Ekoruki) treated and untreated apple trees were used as treated and untreated controls. SICS was sprayed 7 days before full bloom. Both agents showed a fertilizing effect in 'Hongno', improving its fruit yield and quality. SS obtained 29.8% and 36.3% thinning rates in the central floret of 'Fuji'. Both CN and SS were effective in 'Gala', which induced a lower fruit set than SICS treated plants. Earlier and double applications of CN and SS at 0.2% concentration resulted in a higher thinning rate and improved fruit quality in 'Gala'. Results also showed similar thinning efficacies in Ekoruki, CN, and SS.

Effects of calcium nitrate (CN) and sodium sulfate (SS) blossom thinning agents applied after self-incompatibility control substance (SICS) treatment on the fruit set rate and quality of apple were investigated for 2 cropping seasons. CN and SS at 0.1% and 0.2% concentrations were applied once (3 or 4 days after SICS treatment) or twice (3 and 5 or 4 and 6 days after SICS treatment). Commercial Japanese flower thinning agent (FTA: Ekoruki) treated and untreated apple trees were used as treated and untreated controls. SICS was sprayed 7 days before full bloom. Both agents showed a fertilizing effect in 'Hongno', improving its fruit yield and quality. SS obtained 29.8% and 36.3% thinning rates in the central floret of 'Fuji'. Both CN and SS were effective in 'Gala', which induced a lower fruit set than SICS treated plants. Earlier and double applications of CN and SS at 0.2% concentration resulted in a higher thinning rate and improved fruit quality in 'Gala'. Results also showed similar thinning efficacies in Ekoruki, CN, and SS.