THINNING APPLES AND PEARS IN A NORDIC CLIMATE. III. THE EFFECT OF NAA, ETHEPHON AND LIME SULFUR ON FRUIT SET, YIELD AND RETURN BLOOM OF THREE APPLE CULTIVARS

M. Meland
A field experiment examined the effect of using naphthalene acetic acid (NAA), lime sulfur and ethephon to thin the three apple cultivars ‘Summerred’, ‘Red Gravenstein’ and ‘Aroma’. NAA at three concentrations; 10, 20 and 30 mg/l and 5 % lime sulfur with or without the addition of 150 mg/l ethephon were applied at petal fall and full bloom, respectively. The experiment started in 1990 and was conducted for a period of three years for ‘Red Gravenstein’ and ‘Aroma’ and two years for ‘Summerred’. The effects of NAA were largely additive; fruit set, yield and fruit number decreased with increasing concentration for all the three cultivars. Neither thinning nor return bloom were promoted of a low dosage of ethephon. Increasing NAA-concentrations promoted return bloom only for the ‘Aroma’ cultivar. Lime sulfur thinned ‘Aroma’ slightly. Minor phytotoxic symptoms on the leaves of the highest concentrations of NAA were observed.
Meland, M. (1998). THINNING APPLES AND PEARS IN A NORDIC CLIMATE. III. THE EFFECT OF NAA, ETHEPHON AND LIME SULFUR ON FRUIT SET, YIELD AND RETURN BLOOM OF THREE APPLE CULTIVARS. Acta Hortic. 463, 517-525
DOI: 10.17660/ActaHortic.1998.463.65
https://doi.org/10.17660/ActaHortic.1998.463.65
Thinning, NAA, Ethephon, Lime sulfur, fruit set, yield, return bloom, Malus domestica Borkh.

Acta Horticulturae