1. Dep. of Agronomy Univ. of Wisconsin–Madison Madison WI 53706 USA
2. Dep. of Crop and Soil Sciences NC State Univ. Raleigh NC 27695 USA
3. Dep. of Horticulture and Crop Science The Ohio State Univ. Columbus OH 43210 USA
4. Cooperative Extension Service Univ. of Arkansas System, Division of Agriculture Little Rock AR 72204 USA
5. Dep. of Agronomy Univ. of Florida, North Florida Research and Education Center Quincy FL 32351 USA
6. Dep. of Plant and Soil Sciences Univ. of Kentucky Princeton KY 42445 USA
7. Dep. of Plant and Soil Sciences Univ. of Kentucky Lexington KY 40506 USA
8. Dean Lee Research and Extension Center LA State Univ. Alexandria LA 71302 USA
9. Dep. of Plant, Soil and Microbial Sciences MI State Univ. Lansing MI 48824 USA
10. Dep. of Agronomy and Plant Genetics Univ. of Minnesota St. Paul MN 55108 USA
11. Dep. of Plant and Soil Sciences MS State Univ. Mississippi State MS 39762 USA
12. Division of Plant Sciences Univ. of Missouri Columbia MO 65211 USA
13. Dep. of Plant Sciences ND State Univ. Fargo ND 58105 USA
14. Dep. of Plant and Soil Sciences OK State Univ. Stillwater OK 74078 USA
15. Pee Dee Research and Education Center Clemson Univ. Florance SC 29506 USA
16. Dep. of Agronomy, Horticulture, and Crop Science SD State Univ. Brookings SD 57007 USA
17. Dep. of Crop and Soil Environmental Sciences Virginia Polytechnic Institute and State Univ., Tidewater Research Station Suffolk VA 23437 USA