Hybrid Poplar Research Program
Barri Herman, Ph.D.
The WSU Poplar Research Program has been in existence for nearly 30 years. It began, and continues today, as a collaborative effort between researchers here at WSU-Puyallup and the University of Washington. The early success of the program was based on creating hybrid trees by breeding native black cottonwood (Populus trichocarpa) with eastern cottonwood (P. deltoides). The better hybrids out grew their parents by 40 to 50%, capturing the trait for rapid height growth from black cottonwood and the trait for rapid diameter growth from eastern cottonwood. Since the start of the hybrid breeding program, over 10,000 individual offspring have been tested for growth. Many of the original parents and their hybrids are archived in clone arboreta and in variety trials located at the R. L. Goss Farm at the WSU Puyallup Research and Extension Center and at other trial sites throughout the region.
Currently, there are nearly 100,000 acres of hybrid poplars growing in the Pacific Northwest, from southern Oregon into British Columbia, due primarily to the efforts of the WSU-UW poplar program. Most of these plantations are owned or are under lease to paper companies, that are growing the trees primarily for fiber. By applying agricultural methods to growing these trees, the plantations are extremely productive, producing 70 to 80 foot trees with eight to 10 inch diameter in six to eight years. More recently, the hybrid poplar wood has been used to make solid wood (molding, furniture core stock, and structural lumber) and engineered wood products (plywood, oriented strand board and fiberboard) that have excellent characteristics, comparable to or better than industry standards.
Other applications where the hybrid poplars are starting to be used include stream bed stabilization, riparian buffer strips to protect and enhance water quality from agricultural and industrial runoff, the removal and storage of carbon dioxide and other greenhouse gases, and clean up toxic chemicals from soil.
Future of the program is moving towards understanding the genetics of important traits like growth and disease resistance. In a global collaborative effort, we have started breeding the parents and the hybrid offspring with other poplar species from around the world to capture new traits in our best hybrids. We are also exploring adaptability in populations of black cottonwood for use on marginal agricultural and forest lands.