ST. LOUIS, Dec. 8 /PRNewswire/ -- Studies at nearly 200 locations across the Corn Belt demonstrate that Bt insect-protected corn provides significant economic benefit and that hybrids with season-long protection against European corn borers outperform Bt brands that target primarily first-generation corn borers.
Comparisons conducted by several leading seed companies showed that Bt corn produced higher yields than non-Bt corn, and that YieldGard(R) insect-protected corn provided significantly higher yields than other Bt brands. YieldGard is the only product on the market that expresses the Bacillus thuringiensis (Bt) gene throughout the plant with season-long protection against multiple generations of corn borers. Other Bt products lose effectiveness as the season progresses and do not effectively control second-generation corn borers that infest fields. In some regions, up to three generations of corn borers may attack fields in a season.
The research data show that YieldGard hybrids outperformed non-Bt corn by an average of 15.7 bushels per acre. YieldGard outperformed other Bt brands by an average 9.8 bushels per acre. In Iowa, where second-generation infestation was high, YieldGard hybrids outperformed the same non-Bt hybrids by an average of 21.6 bushels per acre. Across the Corn Belt, the overall average YieldGard advantage was 14.9 bushels per acre over the non-Bt isoline, returning growers $27.25 per acre after they paid for the technology.
Even in areas with light infestations of European corn borer, Bt protection resulted in improved yields of six or more bushels per acre.
"The data clearly show that the yield loss from even a mild outbreak of corn borers more than justifies the cost of protection that comes from planting Bt-protected corn," says Monsanto (NYSE: MTC) entomologist Dr. Paula Davis. She points to data from Ohio, where corn borer infestation was light in 1997, but where YieldGard hybrids outperformed the identical hybrid without the Bt gene by an average of 6.3 bushels per acre.
"These results indicate that growers can expect similar yield protection and economic benefits from YieldGard hybrids offered by various seed companies," says Eric Sachs, YieldGard corn business director. Sachs adds that the grower's choice of YieldGard hybrid should be based on the hybrid best suited to the grower's operation.
Davis said the trials offer strong evidence that second generation infestations may be more significant than previously thought. Harvested corn plants were checked for stalk tunneling, an indication of second-generation infestation. In non-Bt fields, state averages ranged from 40 to 95 percent of the plants with corn borer tunnels at harvest. Bt products that target primarily first-generation corn borers averaged 23 to 57 percent tunneling. In the YieldGard fields, only 1 to 3 percent of plants had tunneling.
Plants also were examined for the presence of live corn borers. In Iowa, Nebraska and Illinois, where corn borer pressure was high, YieldGard sites averaged less than one corn borer per 100 plants, while other Bt products averaged 41 live corn borers per 100 plants.
"The data show a clear correlation between corn borer presence at harvest, tunneling damage, ear damage and yield," Davis says. "Growers who invest in Bt corn to preserve their yield are clearly not getting maximum protection unless they plant varieties with whole-plant, whole-season protection, like YieldGard hybrids."
Whole-plant protection also reduced by 71 percent the number of ears that dropped to the ground before harvest, a common problem that can occur when corn borers tunnel into ear shanks. The studies found non-Bt corn dropped 3.8 ears per 100 feet before harvest, while YieldGard hybrids dropped only 1.1 ears per 100 feet of planted corn.
The 1997 field trials were not the first indication that Bt expression throughout the plant, throughout the season is an advantage over other products. Results of a three-year study conducted by Iowa State University and the U.S. Department of Agriculture recently were featured in "Phytopathology," a publication of the American Phytopathological Society. The study showed that corn protected by the YieldGard trait had a lower incidence of fusarium ear rot than unprotected corn. Other Bt traits, which do not protect corn kernels from corn borers, did not produce healthier ears.
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