1. P. W. Becraft, Departments of Zoology and Genetics, and Agronomy, Iowa State University, Ames, IA 50011, USA.
2. P. S. Stinard, U.S. Department of Agriculture, Agricultural Research Service, Urbana, IL 61801, USA.
3. D. R. McCarty, Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA.