2019 ASHS Annual Conference

The objective of these experiments was to evaluate the response of two hard to propagate herbaceous perennials, Salvia pachyphylla ‘Mojave Sage’ and Osteospermum ‘Avalanche’, to repeated foliar applications of three plant growth regulators (PGR). The PGR were applied at two rates: 1) Ethephon (2-chloroethyl Phosphonic Acid) (200 and 400 mg·L^–1 (ppm)) (Verve, Nufarm Americas, Inc., Alsip, IL), 2) 6-benzylaminopurine (250 and 500 mg·L ^–1) (Configure; Fine Agrochemicals Limited, Worcester, U.K.), and 3) Gibberellins A4A7 (GA) & N-(phenylmethyl)-1H-purine 6-amine (50 and 100 mg·L^–1) (Fascination; Valent USA Corp., Fresno, CS). Data collected to evaluate PGR efficacy: vegetative growth (height and width index), vegetative cutting numbers, fresh weight and dry weight of the harvested vegetative cuttings were assessed. A secondary propagation study was conducted in synchronization to determine the PGR treatments effects on the rooting of vegetative cuttings taken from the treatments. No significant differences in propagation material, fresh or dry weights was observed in the first of two experiments for Salvia pachyphylla between treatments. Fascination significantly increased vegetative propagation material production for Salvia pachyphylla when compared to all other treatments in the second experiment. In the propagation study with Salvia pachyphylla, no significant difference in rooting percentage was observed after four weeks. Vegetative cutting harvested resulted in an 26% and 27% increase in number of vegetative cuttings with Fascination (50 or 100 ppm) treatments with Osteospermum ‘Avalanche’ when compared to the control. Fresh and dry weights of vegetative cuttings harvested resulted in no significant differences. Rooting experiments for Osteospermum ‘Avalanche’ resulted in no significant differences with all treatments, including the control; possessing high rooting percentages over 95%.