Mist Interval and K-IBA Concentration Influence Rooting of Orange and Mountain Azalea

Using a Mississippi source of orange (Rhododendron austrinum (Small) Rehd. [Ericaceae]) and mountain (Rhododendron canescens (Michx.) Sweet) azalea, we found that treating terminal softwood cuttings with 10 000 ppm K-IBA yielded the best rooting performance in terms of root number, length, and quality when misted 4 s every 6 min (4 s:6 min). Rooting percentage of orange and mountain azalea was similar from 0 to 10 000 ppm K-IBA. For orange azalea, cuttings treated with 7500 ppm K-IBA had more roots compared with plants treated with 0 ppm K-IBA. Cuttings treated with 7500 or 10 000 ppm K-IBA had greater average root length and higher root quality compared with the control. Cuttings placed under mist for 4 s:6 min had more roots compared with cuttings placed under mist for 4 s:12 min. For mountain azalea, cuttings treated with 10 000 K-IBA had more roots, greater average root length, and higher root quality compared with cuttings treated with 0 ppm K-IBA. Cutting growth was greater under 4 s:6 min than 4 s:12 min. Although information on vegetative propagation of native azaleas is limited, and other cultural practices may affect misting interval and K-IBA concentrations, these results should help growers produce more plants for market until additional discoveries are made.