Umberger, D. E. (Department of Agriculture Columbia, MD, United States)
Proctor, M. H. (Department of Agriculture Columbia, MD, United States)
Clark, J. E. (Oregon State Univ. Corvallis, United States)
Eisgruber, L. M. (Oregon State Univ. Corvallis, United States)
Braschler, C. B. (Missouri Univ. Columbia, United States)