Location, Variety, and Seeding Rate Interactions with Soybean Seed‐Applied Insecticide/Fungicides

Cool conditions after soybean [Glycine max (L.) Merr.] planting may increase soil pest incidence and reduce emergence. Field‐scale studies were conducted in 2009 and 2010 at three locations in New York on two varieties at four seeding rates (272,000, 346,000, 420,000, and 490,000 seeds ha−1) with and without seed‐applied insecticide/fungicides to determine if treated seed enhances plant establishment, allowing for lower seeding rates for maximum yield and partial return. Plant density and yield had location × variety × seed treatment interactions. A treated vs. untreated Asgrow variety had 16 to 22% plant density increases and 4% yield increases at two locations, whereas a Pioneer variety had a 16% density increase at one location but no yield increases. At a third location, the treated vs. untreated Pioneer variety had 19 and 4% increases, respectively, whereas the Asgrow variety had no increases. Yield, which had no seeding rate × seed treatment interaction, had quadratic responses to seeding rate and early plant densities (maximum yield at 478,300 seeds and 295,300 plants ha−1, respectively). Partial return, which had a seeding rate × seed treatment interaction, had quadratic responses to seeding rate with maximum values at 398,800 and 341,800 seeds ha−1 for untreated and treated seed, respectively. Maximum partial returns at these seeding rates ($1241–1245 ha−1, respectively) were similar because seed treatment cost offset lower seed cost. Maximum partial return occurred at early plant densities of 248,400 plants ha−1, but the variety × location × seed treatment interaction complicates selecting seeding rates for this plant density.