Study Helps Establish Buffer Zone for Genetically Modified Crops Pollen Drift

A Colorado State University study takes a step towards finding solutions to pollen drift from genetically modified plants onto organic and traditionally grown crops, a concern raised by some members of the public. The study shows that in Colorado, about 150 feet may be a reasonable buffer zone between genetically modified corn plots and organic and traditional corn plots to prevent significant cross-pollination due to pollen drifting from one field to another.

The first round study was conducted in Morgan County in eastern Colorado, the state’s corn belt – and also a windy area in the region, and at a second location on a plot in Boulder County. Results showed that less than 1 percent of corn farther than 150 feet from test plots is cross-pollinated by pollen from the test corn. That means that very little of the pollen from the test corn fields drifted more than 150 feet.

"We realize that one year’s data is not sufficient for this type of study," said Patrick Byrne, Colorado State University crop sciences professor and researcher. "Given the year-to-year variability in weather conditions, we will repeat the research again during the 2003 growing season."

The study tracked drift of blue kernel corn pollen at one site in Boulder County and the drift of Roundup Ready corn, a genetically modified crop, at the Morgan County site. The corn was planted adjacent to corn varieties without those traits. When the corn was harvested, samples were collected from various distances away from the test plots. These samples were tested for traits from the test plots, which indicate the amount of cross-pollination. The farthest sample was collected 305 meters – about 915 feet — away from the edge of the test plots.

Cross-pollination was highest at the closest sampling sites — up to 46 percent at three-quarters of a meter south of the blue corn plot in Boulder County. However, cross-pollination dropped off in a short distance, with only 0.5 percent cross-pollinated kernels near the blue corn plot at 150 feet. At that same distance in the Morgan County plot, 0.75 percent of the corn showed cross-pollination with the Roundup Ready test plot. The farthest distance at which any cross-pollination was detected was 600 feet in Boulder County and 270 feet in Morgan County.

"The growth in U.S. acreage planted with genetically modified crops has been paralleled by growth in the demand for organically produced foods," said Byrne. "It can be argued that both genetically modified and organic agriculture are approaches to improving conventional farming methods, but the two forms of agriculture are in conflict because of U.S. organic standards that prohibit the use of genetically modified products and pollen drift from genetically modified crops to nearby organic fields. Given the growing importance of both the biotechnology and organic sectors of food production, co-existence between the two becomes a critical issue. We hope that this study will eventually help to establish protocols for co-existence of these two types of food production."

This study came out of discussions in Boulder County, where Byrne served on a committee to study the concerns of that county’s residents, particularly those who raise organic crops, with allowing the farming of genetically modified crops on county-owned open space land. The study was used to establish genetically modified crop protocols on county open space cropland.