As the commodity price for corn has dropped during the past two years, there has been greater interest among some growers in producing non-GMO corn for a premium. According to the USDA-ERS (http://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-us.aspx#.Ud1p1b95m5S) 86% of Ohio’s corn acreage in 2014 was planted to transgenic (GMO) corn. With GMO corn plantings so prevalent across the state, corn growers interested in obtaining non-GMO corn premiums need to develop plans to minimize pollen contamination of non-GMO corn. Pollen from corn containing transgenic traits may contaminate (by cross-pollination) nearby non-GMO corn. Ohio growers of identity preserved (IP) non-GMO corn should become more familiar with planting practices that limit pollen drift from nearby GMO corn fields. Several methods, including isolation and border rows, planting dates, and hybrid maturity, are effective in limiting exposure of non-GMO corn fields from pollen of GMO fields. For more details concerning these methods, consult Extension Fact Sheet AGF-135, Managing "Pollen Drift" to Minimize Contamination of Non-GMO Corn; it’s available online at http://ohioline.osu.edu/agf-fact/0153.html.
Once released from the anthers into the atmosphere, pollen grains can travel as far as ½ mile with a 15 mph wind in a couple of minutes (Nielsen, 2003). However, most of a corn field's pollen is deposited within a short distance of the field. Past studies have shown that at a distance of 200 feet from a source of pollen, the concentration of pollen averaged only 1% compared with the pollen samples collected about 3 feet from the pollen source. The number of outcrosses is reduced in half at a distance of 12 feet from a pollen source, and at a distance of 40 to 50 feet, the number of outcrosses is reduced by 99%. Other research has indicated that cross-pollination between corn fields could be limited to 1% or less on a whole field basis by a separation distance of 660 ft., and limited to 0.5% or less on a whole field basis by a separation distance of 984 ft. However, cross-pollination could not be limited to 0.1% consistently even with isolation distances of 1640 ft.
For more on growing non-GMO corn successfully, check out the following references:
Brittan, K. 2006. Methods to Enable the Coexistence of Diverse Corn Production Systems. University of California Cooperative Extension Agricultural Biotechnology in California Series Publication 8192. Online at http://anrcatalog.ucdavis.edu/pdf/8192.pdf [URL verified 2/22/15]
Nielsen, Bob. 2010. Tassel Emergence & Pollen Shed. Purdue Univ. Online at http://www.agry.purdue.edu/ext/corn/news/articles.03/Tassels-0716.html [URL verified 2/22/15]
Riddle, J. 2012. GMO contamination prevention - What Does it Take? Univ. of Minnesota SW Research and Outreach Center. online at http://www.extension.umn.edu/garden/master-gardener/volunteers/teaching-tools/docs/minimizing_gmo_contamination.pdf [URL verified 2/22/15]
Thomison, P. 2002. Managing "Pollen Drift" to Minimize Contamination of Non-GMO Corn. Extension Fact Sheet AGF-135. online at http://ohioline.osu.edu/agf-fact/0153.html [URL verified 2/22/15]