| One hundred "new" clones and 20 "check" clones of eastern cottonwood were established with unrooted cuttings during March--April 2003 in second-stage clonal trials in Missouri and Georgia. The "new" clones had been selected for three-year superiority in Melampsora leaf rust resistance, height growth, and diameter growth during first-stage rooted-cutting trials. The Georgia site had larger trees and less leaf rust infection than the Missouri site. The "check" clones were the top performers at the Georgia site, while the new select clones performed better at the Missouri site. Gains for height and diameter growth could be achieved through selection of individual clones; however, selection based on clone origin is sufficient for improving rust resistance. Although the top clones varied somewhat for each site, selection should still be based on the individual clone performance and the clone's ability to perform across a variety of sites. |
