1. a USDA Agricultural Research Service , Northern Plains Area , 1500 North Central Avenue, Sidney, Montana 59270‐4202, USA
2. b USDA Agricultural Research Service , Exotic and Invasive Weeds Research Unit , 800 Buchanan Street, Albany, California 94710, USA
3. c Center for Assessment and Monitoring of Forest and Environmental Resources (CAMFER), 151 Hilgard Hall , University of California , California 94720‐3110, USA