Year: 1989
Type: article
Abstract: Thinning trials were carried out with various chemical compounds on Golden Delicious and Granny Smith apple trees over a period of three years in the Elgin area in the western Cape. The scorching agents dinoseb (2-sec-butyl-4,-6-dinitrophenol) and paraquat (1,1'-dimethyl-4,4′-bipyridinium ion) caused over-thinning and excessive russeting while ethephon (2-chloroethylphosphonic acid) gave erratic results. Application of 1-naphtylacetic acid (NAA) plus 6-benzyladenine/gibberellins (GA 4/7) as a tank mix on Golden Delicious, 18 days after full bloom, gave the best results with respect to fruit size, production and gross income. Naphtylacetamide (NAD) with and without GA 4/7, resulted in smaller fruit and did not improve yields over the three-year period when compared with a hand-thinned control. A carbaryl (1-naphtyl-N-methylcarbamate) spray on Granny Smith 18 days after bloom resulted in the same fruit size but an increase in gross income of 40% when compared with the hand-thinned control, while trees sprayed with ethephon and NAA did not produce fruit of an acceptable size.
Author: A. F. Lourens
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: bronze
OpenAlex ID: W2003807870