IR-4 Efficacy of Plant Growth Regulators on Branch Architecture of Container-Grown Trees and Shrubs

Objective: Evaluate the effectiveness of several plant growth regulators (PGR) on branch architecture for select ornamentals (/lex, Hydrangea and two tree species). Experimental Procedures: In April, well rooted liners of at least 2 selected ornamental shrubs (azalea, holly, rose, Hydrangea, and Raphiolepsis), and two tree species (Oxydendron arborea, and Tilia cordata Shamrock®) will be transplanted into Barky Beaver Professional Grow Mix in 1 or 3 gallon containers. Irrigation will be applied with micro emitters. Controlled release fertilizer will be top-applied at transplant. Plants will be hand weeded for the duration of the experiment. Thirty to sixty days following transplanting, while plants are in active growth, treatments will be applied. Applications will be made using an Atomist sprayer. Initial and final plant height, width, caliper, number of shoots, and days until first flower and length of flowering (if applicable), and phytotoxicity (if applicable) will be recorded. For phytotoxicity the following ranking will be used: 0 being no phytotoxicity and 10 being plant death. Final assessments will be made 3 to 6 weeks after the last application. The experiment will be a factorial design with 10 replications of each treatment. Research will be conducted on a gravel pad at the Horticulture Research Farm in Lexington, KY. At the conclusion of the experiment an electronic report will be submitted which will include a summary of results, materials and methods, experimental design, statistical analyses, raw data, pertinent records and observations, and digital images documenting the efficacy of the products and phytotoxicity, if applicable. Results will be presented at the Southern Nursery Association Research Conference and the Kentucky Landscape Industries Winter Trade Show and Conference, and other venues upon request.