The National Elm Trial was an American volunteer effort to evaluate a range of newly developed elm cultivars as replacements for elms destroyed by Dutch elm disease. The Colorado State University College of Agricultural Sciences coordinated the trial.[1]
The trial began in 2005, but was restricted to elm cultivars commercially available in the United States, unlike the trial conducted by Iowa State University in the 1970s which included the most recent European developments. The trial was conducted for 10 years, with annual assessments of each tree for height, diameter, crown characteristics, and fall color, as well as response to vascular diseases, canker diseases, foliar diseases, insect infestations, bark beetle infestations, and abiotic damages.[1] Stated goals of the trial were as follows:
As of 2007, 19 distinct cultivars were being evaluated in regional trials taking place under the scientific supervision of Auburn University, University of California at Davis, Colorado State University, Purdue University, Iowa State University, Kansas State University, Michigan State University, University of Minnesota, Rutgers University, State University of New York, North Dakota State University, Ohio State University, Utah State University, University of Vermont, Washington State University, and West Virginia University.[2]
Based on the trial's final ratings, the preferred cultivars of the American elm (Ulmus americana) are ‘New Harmony’ and ‘Princeton’. The preferred cultivars of Asian elms are the Morton Arboretum introductions and ‘New Horizon’.[1]
Based on the ratings, the preferred cultivars of American elm were 'New Harmony' and 'Princeton', and the preferred cultivars of Asian elm were The Morton Arboretum introductions and 'New Horizon'.
Consumers need to also be aware that a nursery trade mix-up a dozen years ago still plays out in the marketplace, and 'Princeton' elms continue to be sold as 'Jefferson' unknowingly by reputable nurseries from New York to Minnesota. .... National Elm Trial (NET) results were inconclusive and provided no data on 'Jefferson' due to the cultivar mix-up..
"American Elm Renaissance" (PDF). United States Department of Agriculture: United States Forest Service. Archived (PDF) from the original on July 16, 2014.
