1. Department of Agricultural and Resource Economics, University of Tennessee, Knoxville, TN 37996, USA
2. Department of Horticulture Sciences, North Carolina State University, Raleigh, NC 27606, USA
3. Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
4. Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843, USA