1. Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, Oregon 97330, USA;
2. Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA
3. Department of Forest Engineering, Resources, and Management, Oregon State University, Corvallis, OR 97331-5704, USA
4. Department of Forest and Conservation Sciences, Faculty of Forestry, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
5. Faculté de Foresterie et de Géomatique, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec G1V 0A6, Canada