Evaluation of Various Traits of 40 Selections and Cultivars of Red Maple and Freeman Maple Growing in Maryland

Abstract

Abstract Thirty-seven red maple (Acer rubrum L.) and three Freeman maple (A. x freemanii E. Murray) selections and commercial cultivars were evaluated for six years in a replicated field plot at Glenn Dale, MD. Significant differences among clones occurred for growth rate; for time, intensity, and duration of autumn color; for time of growth initiation in the spring; and for injury sustained from potato leafhopper (PLH) [Empoasca fabae (Harris)] feeding. The red maple cultivars showing the best red color over three years time were ‘Autumn Flame,’ ‘Brandywine,’ ‘Cumberland,’ ‘Red Rocket,’ ‘Somerset,’ ‘Sun Valley,’ and ‘Van.’ The cultivar ‘Bowhall’ was the least reddish. Of the three Freeman maples evaluated, ‘ Jeffersred’ and ‘Indian Summer’ manifested the best red color and also low PLH injury; whereas ‘Armstrong’ consistently showed the least reddish color of all 40 clones tested, and intermediate PLH injury. Those cultivars and selections from northern seed sources reached their peak color the earliest, but often dropped their leaves more quickly after showing their best color, compared to clones originating in more southerly locations. The clones showing the least PLH injury over several years included the Freeman maples ‘Jeffersred’ and ‘Indian Summer,’ and red maple clones and cultivars selected by the U.S. National Arboretum either from full-sib progenies (e.g., ‘Brandywine,’ ‘Somerset,’ ‘Sun Valley’) or from an Ohio provenance-progeny test (e.g., ‘Cumberland,’ ‘Red Rocket’). Those clones initiating growth (or “flushing”) earliest in the spring generally showed the least PLH injury; correlations between lateness of flushing and degree of PLH injury were highly significant.