This goes against decades of advice from researchers like Gray who argue for integrated pest management the careful assessment of bug populations to determine what, if any, treatments are needed, and the use of changing tactics against adaptable pests such as the western corn rootworm and the European corn borer, either of which could devastate corn yields.
"We ask growers to consider rotation with soybeans, to spray only when insects are present at levels that are likely to affect yield, and to not use Bt every season, or if they do, to get a different type of Bt corn, one that expresses a different Bt protein," Gray said.
But instead of using integrated pest management, growers are relying on what he calls "insurance pest management," throwing everything in their arsenal at the bugs to protect their crop, year after year.
"For corn in central Illinois, the average non-land costs things like fertilizer, seed, crop insurance and machinery come to about $513 an acre," Gray said. Cash rent can add another $325 an acre for high-yield ground, he said. "So I think a lot of the growers see $20 to $25 dollars to apply a soil insecticide as pretty cheap insurance to protect that $850 investment."
Landowners are raising rents in this competitive arena, some lenders encourage growers to do everything in their power to protect their yields, and federal incentives have lowered the cost of crop insurance for growers who use Bt corn, Gray said. So there are a lot of reasons for farmers to keep doing what they have been doing.
Most growers are not likely to be alarmed by the low number of bugs, but will instead see it as proof that their strategy works, Gray said. Other evidence, however, suggests that the short-term benefits will lead to unanticipated and undesirable consequences.
Researchers are already finding failures of Bt corn against the western corn rootworm
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign