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 yr 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 soybean [GlycineMax (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 soybean, but 5.7 and 3.6% higher at two sites where lodging exceeded 11%, and similarly at two sites where lodging averaged <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 have higher grain moisture, growers in northern latitudes should balance potential corn borer occurrence against increased drying costs.