Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN, 55108, USA. Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA. Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA. mhufford@iastate.edu. Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN, 55108, USA. cnhirsch@umn.edu.