- Albert Ronald Merz, Auton William Skuderna, B. L. Wade, Bess Viemont Morrison, Chalmers Jackson King, Charles Frederick Clark, Charles W. Culpepper, Clark Frederick Clark, David A. Savage, Elmer Valentine Walter, Ernest Muchmore Mervine, Fred Corry Bishopp, George Washington Craddock, Helen Nebeker Hann, Joseph Stuart Caldwell, Joshua John Skinner, Leo Anthony Isaac, Loyd William Brannon, Oscar Roland Mathews, Paul A. Berry, Rufus King Helphenstine, Samuel Newton Dicken, United States. Department of Agriculture, Victor Rickman Boswell, Wilbur Clifford Edmundson, William Daniel Smith, Hazel Katherine Stiebeling, Arthur Otto Alben, Carroll Newton Smith, Frederick James Stevenson, Hubert Hill Moon, James Herbert Beattie, Lee Seaton, Lindsey Andrew Brown, Margaret Blanche Hays, Ralph Edwin Beckett, Stanley Ward McBirney, Adonis A. Mathewson, Earl Donald Fowler, John McDowell McCown, Orlan Parker
· 1939
- H. L. Person, Albert Ronald Merz, Burt Walter Heywang, Charles W. Culpepper, Clarence Elbert Clement, Colin Alexander Taylor, Edward Dougall Gordon, Edwin Richard Kalmbach, Floyd Franklin Smith, Glenn Kenton Rule, H. F. Willard, Harold Hall McKinney, Irving Wesley Dix, Ivan Claude Jagger, James Vernon Morrow, John Clifford Elmore, John Robbins Mohler, Lee Milo Hutchins, Marinus Westveld, Matthew James Culley, May Thacher Cooke, Randall Latta, Robert Claude Wright, Samuel Benton Nuckols, Stuart Bevier Show, United States. Department of Agriculture, Maurice S. Shahan, Arthur Charles Mason, Charles Cloyes Fletcher, Dudley Smith, Eddie Walter Bodine, Gilbert Weaver Scott, Hubert Hill Moon, Joe Roudolph Furr, John Robert Magness, Leonard Gordon Utter, Wilbur Magruder Hurst, Halbert Houston Thornberry
· 1937
- Albert Ronald Merz, Arnon Lewis Mehring, B. L. Wade, C. C. Plummer, Carl Rohwer, Clyde William Doran, George McMillan Darrow, Jacob Martin Lutz, James F. Bullock, James Munday Walter, Jesse Roy Christie, John Henry Zeller, John Ira Hardy, John Raymond Horton, Joseph Franklin Brandon, Lawrence Paul Batjer, Mark Matthew Regan, Michael Hendrix Langford, Robert Hibbs Peebles, Thomas Earle Smith, Thomas Elliott Snyder, United States. Department of Agriculture, Wylie Daniel Goodsell, Bailey Edgar Brown, Curtis May, Elmer Thomas Jones, Eugene Grissom Moss, Fred A. Clarenbach, Grace P. Vincent, H. O. Hetzer, Harold Jeffers Fulton, Harold William Wolf, James Zetek, John Thomas Cassady, Oscar Roland Mathews, Albert Rudolph Johnson, Charles Walter Collins, Francis Marion Wadley
· 1943