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Abstract Detail



Agronomy

Cox, Bill [1].

Field-Scale Studies Indicate that Seed-Applied Insecticide (Neonicotinoids)/Fungicides on Soybean Consistently Increase Plant Populations but not Yield or Partial Returns.

Cool conditions after soybean [Glycine max (L.) Merr.] planting may increase soil pest incidence and reduce emergence. Consequently, many soybean growers in northern latitudes use seed-applied insecticide (neonicotinoids)/fungicides, despite a possible link between neonicotinoids and honey bee die-offs. Field-scale studies (5-10 ha) 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. Treated vs. untreated varieties had 16 to 22% plant density increases but only 0 to 4% yield increases at the three locations. 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), however, were similar because seed treatment cost offset lower seed cost. Field-scale studies were also conducted at four locations in New York in 2012 and 2013 to evaluate agronomic and economic responses to rhizobia (Bradyrhizobium japonicum), biological, fungicide, and insecticide seed treatments. Rhizobia, biological, and fungicide seed treatments vs. untreated seed increased plant populations by 22 and 8% but not yield at two locations. Rhizobia, biological, fungicide, and insecticide seed treatments vs. untreated seed increased plant populations (20 and 10%) and yield (7 and 4.5%) at two other locations, along with partial returns (US$155 ha–1) where yield increased by 7% but not where yield increased by 4.5%. Growers who are risk averse to poor plant establishment will probably apply biological, fungicide, and insecticide seed treatments, whereas growers who are risk averse to additional inputs without a high probability of increased profit will probably not apply seed treatments or rhizobia inoculant, especially if low market prices prevail. Nevertheless, results of both studies indicate that soybean seed treatments consistently increase early plant populations but show only small or no yield increase or partial returns. If neonicotinoids were banned, soybean growers in northern latitudes could increase seeding rates by 15-20% and probably see no effect on yield or partial returns in most incidences.


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1 - Cornell University, Soil and Crop Sciences, 620 Bradfield Hall, Ithaca, NY, 14853, USA

Keywords:
Soybean
seed-applied insecticide/fungicides
neonicotinoids.

Presentation Type: Oral Paper:Papers for Topics
Session: 62
Location: Salon 8/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 9:30 AM
Number: 62006
Abstract ID:126
Candidate for Awards:None


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