1. School of Plant and Environmental Sciences Virginia Polytechnic Institute and State Univ. Eastern Shore Agricultural Research and Extension Center Painter VA 24324 USA
2. Dep. of Agronomy Univ. of Wisconsin‐Madison Madison WI 53706 USA
3. School of Plant and Environmental Sciences Virginia Polytechnic Institute and State Univ. Tidewater Agricultural Research and Extension Center Suffolk VA 23437 USA
4. Dep. of Plant and Soil Sciences Mississippi State Univ. Mississippi State MS 39762 USA
5. Dep. of Agronomy Horticulture, and Crop Science South Dakota State Univ. Brookings SD 57007 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. Dep. of Horticulture and Crop Science The Ohio State Univ. Columbus OH 43210 USA
9. Dep. of Agronomy and Plant Genetics Univ. of Minnesota St. Paul MN 55108 USA
10. Cooperative Extension Service Univ. of Arkansas System, Division of Agriculture Little Rock AR 72204 USA
11. Dep. of Plant, Soil and Microbial Sciences Michigan State Univ. Lansing MI 48824 USA
12. Dep. of Crop and Soil Sciences North Carolina State Univ. Raleigh NC 27695 USA
13. Dep. of Agronomy Univ. of Florida Gainesville FL 32611 USA