Bigtooth maple (Acer grandidentatum) has potential as a small, water conserving landscape tree in western landscapes. This potential has been hindered in part by the difficulty in asexually propagating superior accessions. The ability of etiolation to enhance rooting of softwood cuttings of selected wild accessions was determined by grafting six accessions onto seedling rootstocks to use as stock plants. Etiolation was applied to stock plants by placing open-ended, black, velour, drawstring bags over the end of pruned shoots at bud swell allowing new shoots to develop and grow out the end of the bag while leaving the base of the shoot covered. In 2009 and 2010, cuttings from etiolated and nonetiolated shoots were treated with 4000 ppm indole-3-butyric acid (IBA) + 2000 ppm naphthaleneacetic acid (NAA), stuck in a premoistened 3 perlite:1 peat (by volume) rooting substrate and placed under intermittent mist. After 4 weeks, 89% (2009) and 85% (2010) of the etiolated cuttings rooted and only 47% (2009) and 17% (2010) of the nonetiolated cuttings rooted. Etiolated cuttings produced on average 11.3 (2009) and 7.2 (2010) roots per cutting and nonetiolated 2.1 (2009) and 0.5 (2010) roots per cutting. Etiolation, and its application through the use of black cloth bags, can be an effective way to increase the rooting of bigtooth maple cuttings and the availability of these plants for use in water conserving landscaping.
Melody Reed Richards and Larry A. Rupp
Melody Reed Richards, Larry A. Rupp, Roger Kjelgren, and V. Philip Rasmussen
The potential of bigtooth maple (Acer grandidentatum) as a small, water-conserving landscape tree for the western United States is limited by the selection of superior accessions from a morphologically diverse gene pool and the ability to propagate wild plants in a nursery environment. Superior accessions were selected based primarily on red fall color. Aerial digital images taken during peak fall color in 2007 and 2008 were synchronized with flight global positioning system (GPS) track files using digital image editor software and visually compared with corresponding satellite images to determine the exact latitude and longitude of selected trees on the ground. Trees were physically located using GPS technology then visually evaluated for initial selection. Criteria included fall color, habitat, relative disease and insect resistance, bud quality, and plant form. From 56 observed trees of interest, six were selected for propagation. Through time-course experiments using multistemmed, bigtooth maple seedling rootstocks in a coppiced stoolbed, the optimum time for chip budding scions of wild accessions in northern Utah was determined to be July through mid-August. Further evaluation of accessions for use in the landscape industry is required.