1. USDA-ARS Sunflower and Plant Biology Research Unit, Edward T. Schafer Agricultural Research Center, Fargo, ND 58102
2. Seed Science Center, Iowa State University, Ames, IA 50011
3. USDA-ARS Sunflower and Plant Biology Research Unit (retired), Edward T. Schafer Agricultural Research Center, Fargo, ND 58102
4. Department of Plant Sciences, North Dakota State University, Fargo, ND 58102
5. Department of Plant Pathology, North Dakota State University, Fargo, ND 58102