Tests to compare sources of com seed grown by Iowa farmers have been conducted in Iowa since 1920. In 1960, 351 corn hybrids were tested. The presentation of the data obtained, however, does not imply approval or endorsement of any of the hybrids tested by the authors or by the agencies sponsoring and conducting the 1960 testing.

The state was divided into 12 districts, and two test fields were planted in each district as shown on the map (fig. 1). Table A lists the name and address of each cooperator in 1960 and also the planting and harvesting dates for each field for the past 4 years.

Each hybrid was entered by districts. In district 3, separate entries were made in subdistricts 3A and 3B. A total of 44 different individuals or companies made application for entry of hybrids to be tested in the 1960 test.