Managing Cone Formation and Leader Growth in Fraser Fir Christmas Tree Plantations with Plant Growth Regulators

Early cone formation is a consistent issue in Fraser fir Christmas tree plantations the eastern United States. Growers must remove cones by hand, resulting significant labor costs, as degrade aesthetic value of trees. In this study, we conducted two series experiments collaboration with several farms to determine effectiveness applying plant growth regulators (PGRs), specifically GA-inhibitors, reducing and shoot fir. first investigated paclobutrazol, applied soil injection or foliar spray formation. The highest rate application (300 mL paclobutrazol per tree) reduced cumulative coning approximately 38%. Leader control increased rate. second set experiments, compared four GA-inhibitors (paclobutrazol, chlormequat chloride, uniconazole-p, daminozide) sprays on leader growth. Overall, was most effective compound for results confirm earlier findings that can reduce, but not eliminate, coning. Likewise, PGR reduce possibly increase density will eliminate need shearing.