Use of Chemical Blossom Thinners in ‘Jerseymac’ and ‘Jonagold’ Apples

1 Fruit Research Station 32500 Egirdir, Isparta, Turkey
2 Suleyman Demirel University, Faculty of Agriculture, Department of Horticulture 32260 Isparta, Turkey


KACAL, E. and F. KOYUNCU, 2012. Use of chemical blossom thinners in ‘Jerseymac’ and ‘Jonagold’ apples. Bulg. J. Agric. Sci., 18: 898-904

The effects of flower thinning agents as ATS (1.0%, 2.0%, 3.0%) and Dormex (0.25%, 0.5%, 0.75%) on some fruit characteristics and return bloom were evaluated to create alternatives for hand fruit thinning. Chemical thinning treatments were applied at full bloom, and also hand fruit thinning was done after June drop in six years old apple trees of ‘Jerseymac’ and ‘Jonagold’ grafted on M9 apple rootstock. Trials were conducted to determine the efficiency and repeatability of thinners during three experimental years. 0.5% Dormex was the most effective application, which increased quality components such as fruit diameter, and fruit weight in ‘Jerseymac’. Furthermore, hand thinning gave similar results. ‘Jonagold’ variety is unstable thinning respond to applications. The results showed that ‘Jerseymac’ has regular bearing but ‘Jonagold’ has tended to biennial bearing. Thinning applications for ‘Jonagold’ was not effective in reducing biennial bearing severity.

Key words: Malus x domestica, ammonium thiosulfate, hydrogen cyanamide, biennial bearing
Abbreviations: ATS (Ammonium thiosulfate), BA (6-benzyladenine), NAA (Naphtalene acetic acid), NAD (Naphtalene acetamid)

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