In a Garretson, S.D., field that has been continuous corn for 15 years, controlling corn rootworm resulted in a 47 bushel per acre yield increase.
That's according to SDSU research in 2006 conducted by entomologists Billy Fuller and Brad McManus. They compared several practices – genetically engineered hybrids, granular soil insecticides and seed treatments -- and recorded yield increases from 19.3 to 46.9 bushels per acre compared to unprotected corn.
In this trial, YieldGard Plus produced the most corn. But Force PG was a close second with a 34 bushel per increase.
Which was best depends on price – price of the harvested corn, the trait-stacked seed and seed treatment, and the insecticide, says Mike Catangui, SDSU Extension entomologist.
Corn rootworm pressure is a factor, too.
In a trial near Bryant, S.D., on third-year continuous corn, the yield advantages ranged from 3.2 to 39.2 bushels per acre. A combination of Poncho and Force insecticides on the seed and in the furrow turned in the top yield. YieldGard Plus posted only a 9.5 bushel yield advantage over unprotected corn.
Catangui concludes that in the first year of corn on corn, insecticides and seed treatments will be competitive with genetic traits.
As corn rootworm pressure grows, genetic traits become more important but they still may not always be the most profitable option.
"Don't get rid of the insecticide boxes yet," Catangui says.
To see all the results from the SDSU trials, go to plantsci.sdstate.edu/ent.