Selection, Evaluation, and Introduction of Betula spp. By the NDSU Woody Plant Improvement Program

The North Dakota State University (NDSU) Woody Plant Improvement Program has been servicing the Northern Great Plains for over 60 years, beginning germplasm trial evaluations in 1954. The goals of the NDSU Woody Plant Improvement Program are selection, evaluation and introduction of hardy superior woody plants for the landscape industry. In 1974, NDSU purchased an 80-acre (~32 hectares) farm to be established as the NDSU Horticulture Research Farm near Absaraka, North Dakota, USA (Lat:46.9859, Long: -97.3549). Evaluation plantings began in fall of 1974. The main portion of this research farm is the center 35-acre (~14 hectares) plot dedicated as the NDSU Dale E. Herman Research Arboretum which includes an extensive Betula spp. collection with plantings beginning in 1974. Betula (Birch) is an important ornamental tree for the Northern climate. Betula is a small group of trees and shrubs found mainly in the cooler temperate regions of the northern hemisphere. Birches make beautiful specimen trees and also provide a light, filtered shade. Birch species vary in their susceptibility to insect attacks and cultivar selections should be resistant to insects such as bronze birch borer (BBB, Agrilus anxius Gory.) Since 1974, four different subgenera with 21 different birch species (seven native to the U.S.A.), five hybrids and numerous commercially available cultivars have been evaluated at the NDSU Dale E. Herman Research Arboretum. Each species, hybrid or cultivar were evaluated over multiple years with a minimum of three replicates of each for evaluation. Plants were evaluated for survivability, dieback, BBB susceptibility, habit, and foliage quality. Members of the subgenera Neurobetula (Costate birches; B. chinensis, B. costata, B. davurica, B. ermanii, B. nigra, and B. utilis), Betula (Typical birches; B. occidentalis, B. papyrifera, B. pendula, B. platyphylla, B. popuilfolia, B. pubescens, and B. pubescens var. litwinowii), and Chamaebetula (Dwarf birches; B. glandulosa, B. middendorfii, B. ovalifolia, and B. apoiensis) had mixed performances with several of the species and/or cultivars performing very well. The subgenus Betulenta (Wintergreen oil birches; B. lenta and B. grossa), with overall good performance in USDA hardiness zone 3b. Five cultivar releases have been made from birch evaluations by the NDSU Woody Plant Improvement Program including: B. platyphylla ‘Fargo’ (1996, Dakota Pinnacle^® Asian White Birch), B. papyrifera ‘Varen’ (2002, Prairie Dream^® Paper Birch), B. platyphylla ‘Verdale’ (2002, Prairie Vision™ Asian White Birch), B. nigra ‘Dickinson’ (2006, Northern Tribute^® River Birch), and B. costata 'CinnDak' (2014, Cinnamon Curls^® Dwarf Korean Birch).