TY - JOUR T1 - Evaluation of Elm Clones for Tolerance to Dutch Elm Disease JF - Arboriculture & Urban Forestry (AUF) JO - JOA SP - 179 LP - 184 DO - 10.48044/jauf.2004.022 VL - 30 IS - 3 AU - A.M. Townsend AU - L.W. Douglass Y1 - 2004/05/01 UR - http://auf.isa-arbor.com/content/30/3/179.abstract N2 - Rooted cuttings of ten hybrid elm (Ulmus) clones, including one named ‘Patriot’, and all derived from various crosses of ‘Homestead’, ‘Prospector’, ‘Urban’, and Selection 970, were established along with a randomly selected American elm clones and three disease-tolerant cultivars (‘Frontier’, ‘Homestead’, and ‘Prospector’) in a replicated field plot. When the rooted cuttings were 3 years old, they were inoculated with a mixed spore suspension of Ophiostoma novo-ulmi and O. ulmi, the fungi that cause Dutch elm disease. Analyses of variance and regression showed significant variation among clones in crown dieback, survival, and height growth over a 7-year time period following inoculation. The American elm clone and selection 15-87 (an ‘Urban’ × ‘Prospector’ clone) showed the most crown dieback and lowest survival rate and were among the slowest in growth rate, 7 years after inoculation. Selections and cultivars showing the least dieback and highest survival were most hybrids from parentages of ‘Urban’ × ‘Prospector’, those from ‘Homestead’ × ‘Prospector’, and ‘Homestead’ × 970; and cultivars ‘Patriot’, ‘Homestead’, and ‘Prospector’. Many of the same disease-tolerant clones and cultivars also showed the greatest height growth after inoculation. Significant variation in disease symptoms occurred among clones from the ‘Urban’ × ‘Prospector’ cross. Results of this study emphasize the importance of selection and testing of specific clones within full-sib families. ER -