In 2001 normal non-GMO dent corn hybrids yielded above the trial average less frequently than what was observed in previous years. Generally, we would expect 50% of any group of corn hybrids to yield above the trial average and 50% below the trial average. In the UW Corn Hybrid Performance Trials from 1973 to 1998, the distribution of normal dent corn hybrids in relation to the trial average was 50:50; that is 50% of the hybrids yielded above the trial average and 50% below. Beginning in 1999, the frequency with which normal non-GMO hybrids were yielding above the trial average has steadily decreased so that in 2001 normal non-GMO corn hybrids yield above the trial average only 44% of the time (Figure 1).

The UW trials have seen an increase in the number of specialty hybrids entered by seed companies. For example, specialty hybrids that have the Bt trait yield above the trial average 66 to 72% of the time. Is the Bt trait protecting yield and allowing better performance with no genetic gain for yield? Or, are seed companies incorporating specialty traits into their best genetics and thus the combination of superior genetics and yield protection through the GMO trait allows specialty hybrids to perform in the top half of the trial more frequently?

It is very clear that specialty hybrids are displacing normal non-GMO hybrids in the upper 50% of hybrids in a trial. Certainly there are still many good, high performing normal non-GMO corn hybrids, but as a group normal dent corn is yielding above the trial average less frequently. How long will this trend continue?