Chemical thinning on Delicious apples in the Stanthorpe district, Queensland

Abstract

Thinning trials with the Delicious variety of apple at Stanthorpe were conducted from 1960 to 1963, using naphthalene acetic acid (NAA), naphthalene acetamide (NAD) and 1 naphthyl N methyl carbamate (carbaryl). NAA gave variable results and sometimes severely overthinned the trees. NAD proved a more consistent thinner but treated trees retained an excessively large number of small, non-commercial fruit. Carbaryl was the best of the three materials under trial. It partially corrected the biennial bearing habit of the trees and increased yields over a two-year period.