Research Progress Report 398
December, 1971

1971 Performance of Commercial Dent Corn Hybrids in Indiana
Paul L. Crane and T. R. Stierwalt, Department of Agronomy

Following serious problems with a new race of southern corn leaf blight in 1970, the corn seed industry has moved rapidly to produce resistant hybrids. "Normal" cytoplasm strains were generally used in 1971 production of seed for 1972 planting. The hybrids were made by detasseling the rows being used as the female parent, rather than using "Texas" cytoplasmic male sterility.
The Indiana Agricultural Experiment Station specified that all hybrid seed used for planting its 1971 corn performance trials should be of the "normal" type, comparable to what all farmers should be able to obtain for their 1972 planting. We know that the relative yields of hybrids change somewhat with weather from year to year, and that caution is necessary in using one year's data as a guide. The 1971 data are being published by the Experiment Station as a service to farmers and corn seed companies who are heroically meeting the challenge of race "T" of southern corn leaf blight.

THE 1971 INDIANA GROWING SEASON
The winter was colder and drier than usual, with the dryness continuing through March and April. Corn planting started early and was completed earlier than normal by
many farmers. Germination was slow during the first half of May because of low soil temperatures, but by late May improved moisture levels and warmer temperatures boosted growth. Good rainfall and above-normal temperatures during June and the first week of July produced very rapid growth. The remainder of July and most of August was cooler than normal, providing excellent conditions for tasseling, silking and filling. The first half of September and all of October were warm, generally facilitating good maturity and prompt harvest.

EXPERIMENTAL METHODS
Each area, soil type or production level was represented by two sub-locations. All entries were replicated three times at each sub-location. After harvest, the sub-locations were combined to give an average for that "area".
The plots were planted mechanically with standard commercial planters modified to plant small plots and to be clear of remnant seed at the end of each plot. This was accomplished by substituting a cone-type seed distributor for the usual planter-plate mechanism. Plots were harvested by a picker-sheller without gleaning, and a

PURDUE UNIVERSITY • Agricultural Experiment Station • Lafayette, Indiana