Effect of Plant Growth Regulators on Apple Fruit and Pedicel Abscission1

Abstract Lanolin bands containing 2, 3, 5-triiodobenzoic acid (TIBA) applied to the pedicel of apple fruits 2 to 3 weeks after bloom caused the fruits to drop. Naphthaleneacetic acid (NAA) applied to the cut end of defruited pedicels prevented pedicel abscission, but a band of lanolin containing TIBA at mid-pedicel caused most of them to abscise. Cytokinins did not prevent pedicel abscission. Indole-3-acetic acid (IAA) and gibberellins A 3 and A 4,7 more effectively prevented pedicel abscission of ‘Delicious’ than ‘Golden Delicious’.