Thinning Efficiency of Ammonium Thiosulfate and Hydrogen Cyanamid on “Golden Reinders” Apple

Abstract

Efficacy of ammonium thiosulfate and hydrogen cyanamid on the fruit quality and return bloom in ‘Golden Reinders’ apple grafted on the M9 rootstock was evaluated in this experiment. Studies were conducted at the Eğirdir Fruit Research Institute for two years on same trees. Three different doses of ammonium thiosulfate (ATS) (1%, 2%, and 3%) and hydrogen cyanamid (0.25%, 0.5%, and 0.75%) (Dormex) were used as
the flower thinners at the full bloom period. To compare chemical applications, hand fruit thinning (HFT) at the producer level was performed after June drop. The effect of thinning practices on the fruit quality and yield was found the different year to year. Percentage of large fruit (75- 85 mm diameter) increased by hand thinning and ATS 2% in the first year of the study. In the second year, the majority of fruits were into 75-85 mm size category and fruit yield with high commercial value was higher in 3% ATS and 0.75% Dormex. 2%, 3% ATS and 0.75% Dormex were effective applications to partially or even reduce alternate bearing compared to other applications. However, fruit thinning was not effective in reducing biennial bearing severity.