It's a long journey between GM and non-GM plants coexisting and the potential cross-pollination you're concerned about:
- First, a plant can only pollinate another closely related plant. So, for example, corn can pollinate corn, but not soybeans.
- Also, pollen movement varies by crop. Corn and soybeans are the most widely planted GM crops in the United States, so we’ll focus there. Soybeans are nearly 100 percent self-pollinating, meaning there is little risk of cross-pollination or pollen flow from a field of GM soybeans to non-GM soybeans.
- Corn pollination occurs during a short, approximately one-week period, and that period would have to overlap between two fields for there to be any potential for cross-pollination.
- In addition, corn pollen is relatively large and heavy compared with the pollen of other crops, which limits its movement.
- Local environmental factors, such as natural wind blocks, also may impact pollen movement.
- And, finally, after corn pollen is shed from the tassel, the viability of that pollen declines rapidly.
Since our business began in 1926―decades before the development of GM technology―we've been studying and documenting pollen movement and flow so that we could successfully develop new corn hybrids, maintain the purity of parent seed and research plots and produce seed crops each year.
Thanks to this work, a long history of published science, firsthand farmer experience and more, there is a great deal of understanding about where, how and at what rate pollen flow occurs. That knowledge translates into best management practices, such as planting at recommended separation distances or timing the planting so that pollination of the two fields occurs at different times.
For more information about cross-pollination, there are a number of university and extension publications that provide recommendations to farmers, including materials from Ohio State University and University of California, Davis.