Ornamental woody plant breeding, selection and evaluations for cold climate conditions

The North Dakota State University (NDSU) Woody Plant Improvement Program (WPIP) has been servicing the Northern Great Plains for over 60 years with germplasm evaluation trials beginning in 1954. The program has evaluated 200+ genera and 3,000+ species and cultivars of trees and shrubs. In 1974, NDSU purchased land to develop a research arboretum near Absaraka, ND, USA and began trial plantings used for evaluation and selection of woody ornamental plants. The arboretum was named after Dr. Dale E. Herman in 2011, who developed this program and managed it for nearly 40 years. This research arboretum is the most extensive collection of woody ornamental plants in North Dakota and in the Northern Great Plains. There have been over 9500+ accessions obtained and evaluated since planting began in 1974 with focus on evaluating and selecting species suitable for planting within the USDA cold hardiness zones 3a/3b. Forty years later, with a notable shift in historic winter temperature lows, the focus of the program is on evaluation, selection and breeding of species suitable for planting in USDA cold hardiness zones 3b/4a. This shift has added a new emphasis of trialing plants that are typically an entire USDA cold hardiness zone lower to include species from USDA cold hardiness zones 4b/5a. Focus species include: Cercidiphyllum japonicum (katsuratree), Cercis canadensis (eastern redbud), Cornus mas (Cornelian cherry), Ginkgo biloba (Ginkgo), Magnolia acuminata hybrids (cucumber tree hybrids), hybrid maples (Acer pseudosieboldianum × A. palmatum) and Asiatic elms. The WPIP has introduced over 50 woody plants with increased tolerance and winter hardiness for landscapes for production and sale since 1986. Some of the most promising selections include: Royal Splendor^® Norway spruce, Northern Acclaim^® thornless honeylocust, Prairie Expedition^® American elm, Prairie Statesman^® Swiss stone pine, Northern Tribute^® river birch, Northern Empress^® Japanese elm and Cinnamon Curls^® dwarf Korean birch.