Foliar Application of Auxin for Rooting Stem Cuttings of Selected Ornamental Crops

Abstract Research was conducted to determine whether a foliar spray application of the commercial root-promoting formulation Dip 'N Grow® [10,000 ppm indole-3-butyric acid (IBA) and 5,000 ppm 1-naphthaleneacetic acid] or the potassium (K) salt of IBA (K-IBA) would be as effective as a basal quick-dip for rooting stem cuttings of selected ornamentals. Cuttings of Chrysanthemum pacficum sprayed with Dip 'N Grow® at 50 + 25 ppm IBA + NAA or K-IBA at 0 to 50 ppm showed generally similar root development measures compared to a basal quick-dip; an exception was 10 ppm K-IBA which produced greater total root length. Cuttings of Forsythia x intermedia ‘Lynwood Gold’ typically did not differ in root development under the two application methods, but cuttings sprayed with Dip 'N Grow® at 0 + 0 to 10 + 5 ppm IBA + NAA exhibited greater shoot growth 80 days after sticking (insertion into the rooting substrate) than cuttings receiving a basal quick-dip. Root and shoot development measures were similar or lower for cuttings of Abelia x grandiflora, Hydrangea paniculata, and Lagerstroemia (indica x fauriei) ‘Natchez’ sprayed with auxin compared to a basal quick-dip.