Stacked Corn Hybrids Show Inconsistent Yield and Economic Responses in New York.

Stacked (two to three transgenic traits) corn (Zea mays L.) hybrids represented 40% of U.S. corn in 2008, despite limited agronomic studies. Field-scale studies were conducted on four farms in New York for 2 years to evaluate the agronomics and economics of double-stacked (glyphosate resistance and Bt (Bacillus thuringiensis) European corn borer [(Ostrinia nubilalis (Hubner) ] trait) hybrids when following soybeans (Glycine Max L. (Merr.) as well as triple-stacked (additional Bt corn rootworm (Diabrotica spp.) trait) hybrids in continuous corn. Stacked hybrids vs. near-isolines had mostly lower weed densities, root damage ratings, and stalk lodging under generally low pest and lodging conditions in both rotations. Double-stacked hybrids vs. near-isolines yielded similarly when following soybeans but 5.7 and 3.6% higher at two sites where lodging exceeded 11% and similarly at two sites where lodging averaged less than 3% in near-isolines in continuous corn. Triple and double-stacked hybrids yielded similarly. Grain moisture averaged 15 g kg^-1 greater in stacked hybrids vs. near-isolines in both rotations but similarly between double and triple-stacked hybrids in continuous corn. Partial returns had site x hybrid trait interactions in both rotations as increased yield revenue offset increased drying costs for double-stacked hybrids vs. near-isolines for three site-rotation comparisons, resulting in $45 to 89 ha^-1 profit gain, but not for two-site rotation comparisons, resulting in $47 to 71 ha^-1 profit loss. If stacked hybrids with the Bt corn borer trait has higher grain moisture, growers in northern latitudes should balance potential corn borer occurrence against increased drying costs.