Improved vegetative propagation of Scouler willow

Demand has exceeded supply for conservation plantings of Scouler willow (Salix scouleriana Barratt ex Hook.). To test possible ways to improve propagation, we treated 8- to 10-cm-long (3.2- to 4.8-in-long) hardwood cuttings with 0.0, 0.1, 0.3, 0.8, and 1.6% indole-3-butyric acid (IBA), and 5- and 10-cm-long (2- to 4-in-long) softwood cuttings, with 0.0 and 0.3% IBA. Best rooting (73% and 87%) occurred after treatment with 0.3% IBA in the hardwood and 10-cm-long softwood cuttings, respectively. Microshoots were tested with the antibiotic cefotaxime and calcium gluconate to control bacterial contamination and shoot-tip necrosis. Microshoots, with or without naphthaleneacetic acid (NAA), rooted up to 92% both in and ex vitro without NAA. Similar micropropagation options may improve production of other difficult to propagate willows.