Shading and IBA Treatment Do Not Improve Rooting of Stem Cuttings of Quercus phillyraeoides ‘Emerald Sentinel’1

Shoot tip cuttings of Quercus phillyraeoides A. Gray ‘Emerald Sentinel’ (‘Emerald Sentinel’ oak), in a transitional growth stage between softwood and semi-hardwood, were collected from containerized plants growing under uniform fertility on June 4, 1998. Cuttings were treated with talc formulations of indolebutyric acid (IBA), ranging from 0 to 8000 ppm (0.8%), and placed under intermittent mist with shade levels excluding 0%, 30%, 60% or 90% of full solar irradiance. After 14 weeks, percent rooting averaged 18% and was unaffected by either IBA concentration or shading regime. Similarly, both mean root number per rooted cutting and mean root length were unaffected by IBA concentration or shading. Roots per rooted cutting and mean root length averaged 2.6 and 41 mm (1.6 in), respectively. Results suggest that shading stem cuttings of ‘Emerald Sentinel’ during propagation does not affect rooting. Index words: Fagaceae, indolebutyric acid, irradiance, oak, propagation. Significance to the Nursery Industry Application of shade is one method propagators use to moderate ambient temperature during rooting of stem cuttings. Frequently, a shading compound or shade cloth is applied to greenhouses to achieve this effect. Shading reduces solar irradiance entering the greenhouse, thereby maintaining cuttings at a cooler temperature and increasing humidity. A recent report (19) suggested that shading woody stem cuttings during propagation might stimulate rooting of difficultto-root taxa, such as Quercus L. spp. (oaks). In the current study, we were able to maintain similar temperatures [± 2C (3.5F)] throughout four shading regimes (0%, 30%, 60%, and 90%) when attempting to root stem cuttings of a difficult-to-root cultivar of Quercus phillyraeoides A. Gray (ubame oak), and observed no stimulatory rooting response to the varying levels of shade or indolebutyric acid (IBA) treatments. Percent rooting (18%), mean root number (2.6), and mean root length [41 mm (1.6 in)] were unaffected by shading or IBA treatments.