2019 ASHS Annual Conference

Crape myrtles provide a reliable source of color for many southern landscapes, often flowering for more than 100 days. Mississippi State University has released six new crape myrtle selections, including Sequoyah™. Sequoyah™ is a hybrid resulting from the cross of Lagerstroemia ‘Arapaho’ and an unknown pollen donor. Sequoyah™ has a clear, true red flower color and medium to large growth habit. Three-year-old plants in a research setting are 4.5+ meters and have flowered from early June through late August. The objective of this research was to evaluate ease of rooting and determine optimal commercial auxin formulation and concentration and stem position for softwood and semi-hardwood cutting propagation of Sequoyah™. Medial cuttings (12.7 cm) were harvested and stuck to a depth of 2.6 cm on 9 April 2018. Medium was 100% perlite in 6.4-cm containers. Treatment factors included auxin formulation [Hortus; Hortus IBA Water Soluble Salts™ (IBA only), Dip’N Grow® (DNG; IBA + NAA with NAA at one-half the rate of IBA), or nontreated control], IBA rate (0, 500, or 1000 ppm), and stem position along the harvested shoots [1 (most proximal), 2, 3, or 4 (most distal)]. Auxin solutions were applied using a basal quick-dip. Experimental design was a randomized complete block design with five replications per treatment combination. Data collected included rooting (Y/N), length of new shoots, cutting quality rating (0-5), root count, average root length (length of three longest roots/3), and root quality rating (0-5). Results showed that number of roots and average length of the three longest roots were similar among treatment combinations. Percent rooted was greater for cuttings dipped in Hortus IBA Water Soluble Salts™ (Hortus IBA) compared to cuttings that received no auxin. Cuttings dipped in Hortus IBA exhibited better cutting quality and larger growth indices compared to cuttings dipped in Dip’N Grow^® (DNG). Hortus IBA at a concentration of 1000 ppm IBA resulted in better root quality and growth indices compared to Hortus IBA at 500 ppm IBA, which resulted in higher rooting percentages. In preparing cuttings from a shoot, a cuttings at position 1 was located at the site of attachment to the parent plant (most proximal) and positions 2-4 continued toward the branch tip with position 4 being the most distal. Stem positions 1 and 2 would serve as semi-hardwood cutting types and positions 3 and 4 would serve as softwood cutting types. It was observed that semi-hardwood cutting positions (1 & 2) had higher rooting percentages, root quality, cutting quality, and growth indices compared to the softwood stem positions (3 & 4). Overall, the results suggested that dipping Sequoyah™ semi-hardwood cuttings in Hortus IBA at 1000 ppm resulted in a higher quality liner.