Alternate cropping of the Delicious apple: the effect of 2, 3, 5-triiodobenzoic acid spray on blossom bud initiation in the on year

Abstract

Alternate-cropping trees of the Delicious variety of apple were treated with a single post-bloom spray containing 75 p.p.m. of 2,3,5-triiodobenzoic acid (TIBA). The TIBA treatment caused more blossom buds to be formed in the 'on' year, with consequent increases in crop in the following 'off' year. The effect was more pronounced in unthinned limbs than in limbs blossom-thinned prior to treatment. Evidence is presented of reduction in fruit-set and of fruit size following TIBA treatment in the on year. The results are discussed in relation to the anti-auxin properties of the chemical applied.