Branch Induction on Young ‘Delicious’ Apple Trees by Application of Growth Regulators

Application of BA, GA4+7, and Promalin (GA4+7 + BA) to 2-and 3-yearold spur ‘Delicious’ apple trees [Malus domestica(Borkh.)] resulted in an increased number of laterals (> 15 cm) and feathers (5-15 cm). Concentrations of 250 and 500 ppm were most effective. Application at 5 cm of terminal growth was most effective while application after 10 cm was ineffective. Use of the surfactants, Buffer X or Tween 20 (0.3%) with BA application, increased the branching response. Chemical names used: N-(phenylmethyl)-lH-purin-6-amine (BA), Gibberellins A4 + A7 (GA4+7).