Ten-year performance of elms in the National Elm Trial
Ulmus americana (American elm) was an important urban tree in North America prior to the introduction of the Dutch elm disease (Ophiostoma ulmi and O. novo-ulmi) pathogen in 1930. Subsequently, urban and community forests were devastated by the loss of the large canopies. Disease tolerant elms (Ulmus spp.) of various species were later developed; however, consumer acceptance of these trees was slow. The goal of the National Elm Trial was to evaluate newer cultivars of elm across the United States. Trees were monitored for survival and growth for 7 to 10 years at 16 different locations. LSQUOMortonRSQUO elm had GROTERDAN90% survival, while 13 cultivars averaged 70 to 90%, and five cultivars ranged from 25 to 69% survival. Trunk diameter growth by location ranged from 0.5 cm year-1 at Colorado to more than 2.0 cm year-1 at Iowa. By taxa, trunk diameter growth ranged from a low of LSQUOJFS BieberichRSQUO elm (0.7 cm year-1) to a high of LSQUONew HorizonRSQUO elm (1.7 cm year-1). The fastest height growth was found with the American elm cultivars LSQUONew HarmonyRSQUO and LSQUOPrincetonRSQUO (0.63 and 0.61 m year-1, respectively).
Griffin, J.J. and Jacobi, W. (2018). Ten-year performance of elms in the National Elm Trial. Acta Hortic. 1191, 31-36
disease resistance, Dutch elm disease, tree evaluation, urban forestry