Iowa farmers have over 500 name and numbers of hybrid corn varieties to choose from, according to a survey conducted in 1954 by the Iowa Crop Improvement Association.
Wengert, Gerald and Hutchcroft, Charles
"Farmers Plant Many Corn Varieties,"
Iowa Farm Science: Vol. 9
, Article 7.
Available at: https://lib.dr.iastate.edu/farmscience/vol9/iss9/7