Evaluation of Growth Regulator Effects of Embark, Atrinal, Blazer, and Bayleton on Container-Grown Azaleas

Abstract

Three chemicals that are not normally used to promote branching were evaluated for their abilities to increase shoot production of containerized outdoor-grown azaleas and compared with Atrinal (dikegulac sodium) and manual shearing. In an initial experiment, spray applications of Embark (mefluidide) at 0.38% ai (active ingredient) promoted more new shoots than the sheared only controls and slightly more than Atrinal (0.5% ai) for most azalea cultivars. In subsequent experiments, applications of Embark at 0.3 and 0.4% ai generally promoted fewer new shoots than Atrinal (0.5% ai) and, in most cases, smaller plants. Applications of Blazer (acifluorfen, 4 mg ai per pot) as a soil drench consistently promoted more new shoots than Atrinal (0.5% ai), however, plant size was also smaller. Lower levels of Blazer (1 to 3 mg ai per pot) resulted in larger plant sizes, but inconsistent shoot production. Spray applications of Bayleton (triadimefon) at 0.06% ai had no significant effect on azalea shoot production or plant growth.