Efficacy of BA For the Promotion of Lateral Bud Formation on Douglas-fir and Colorado Blue Spruce

Abstract

A whole-tree foliar application of BA at a concentration of 1000 ppm increased lateral bud density on douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] but not on Colorado blue spruce (Picea pungens Englm.) when treated ≈6 weeks after budbreak. A single BA application made at the same time, but only to the terminal leader, was not effective in increasing overall lateral bud density on either the terminal or lateral branches of either species. Lammas shoots formed on all trees that received whole-tree applications of BA. Bud formation on lammas shoots appeared normal for douglas-fir but uncharacteristic for Colorado blue spruce. Chemical names used: N- (phenylmethyl)-lH-purin-6-amine (BA).