A subirrigation method for rooting softwood cuttings of seven woody taxa was compared to use of intermittent mist. Both methods resulted in >90% rooting of ‘Goldflame’ spirea (Spiraea x bumalda Burv. ‘Goldflame’). Averaged over two dates, >50% of ‘Pioneer’ elm (Ulmus L. ‘Pioneer’) cuttings rooted, and >70% of cuttings retained leaves and formed callus regardless of method. Subirrigation without mist was unsuccessful for rooting Lamarck serviceberry (Amelanchier lamarckii F.G. Schroed.), Amur maackia (Maackia amurensis Rupr. & Maxim.), or ‘Kwanzan’ cherry (Prunus serrulata Lindl. ‘Kwanzan’). Subirrigating cuttings without mist resulted in reductions in rooting percentage, leaf retention, and callus formation of >90% for Lamarck serviceberry and >50% for ‘Kwanzan’ cherry compared to misted cuttings. For misted cuttings of Amur maackia, percentage rooting, leaf retention, and callus formation were 23, 48, and 35%, respectively; in contrast, no subirrigated cuttings of Amur maackia survived. ‘Charles Joly’ and ‘Michael Buchner’ lilacs (Syringa vulgaris L. ‘Charles Joly’ and ‘Michael Buchner’) varied in response to the propagation methods. Sixty-one, 15, and 42% of ‘Charles Joly’ lilac cuttings rooted when misted, when subirrigated with tap water, and when subirrigated with a solution of complete fertilizer that contained N at 5.4 mM (75 ppm), respectively. For ‘Michael Buchner’ lilac, 48, 7, and 19% cuttings rooted under mist, when subirrigated with water, and when subirrigated with fertilizer, respectively. We recommend use of subirrigation without mist for rooting softwood cuttings of ‘Goldflame’ spirea, ‘Pioneer’ elm, and ‘Charles Joly’ lilac.
Journal Paper No. J-17476 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project No. 3229, and supported by Hatch Act and State of Iowa funds This research was supported in part by a grant from The Horticultural Research Institute, 1250 I Street, N.W., Suite 500, Washington, D.C. 20005. The authors wish to thank J. Frank Schmidt & Son Co., Sherman Nursery, and the Minnesota Landscape Arboretum for their generous support in supplying plant material for this study.
2Research Associate and Associate Professor, respectively