P&PDL Picture of the Week for
November 8, 2004

Pollen Drift in Corn: Visual Evidence

Bob Nielsen, Extension Corn Production Specialist, Purdue University

Certain of today's transgenic traits for corn (aka GMOs) are not approved throughout the entire global marketplace. Consequently, some grain buyers in the U.S. will not accept grain from such non-approved hybrids or grain contaminated with that of non-approved hybrids. Growers who want to produce GMO-free corn understand that one of the difficulties in doing so is due to the fact that corn is a cross-pollinated crop. Corn pollen can "drift" from one corn field to another and potentially fertilize ovules on ears in the adjacent field, resulting in grain with many of the characteristics of the pollen source hybrid. Thus, pollen from a transgenic corn field can result in kernels in an adjacent field that express the same transgenic trait.

A visual example of pollen drift occurs when yellow dent corn is grown adjacent to multi-colored Indian corn. Pollen from the Indian corn that drifts to yellow dent corn plants often results in multi-colored kernels developing amongst the normally yellow kernels. The good news about pollen drift, relative to concerns about transgenic trait contamination of "normal" fields, is that much of a corn field's pollen settles within the field and only a small percent drifts away from the field.

These images illustrate Indian corn contamination of nearby rows of normal yellow dent corn. The level of contamination in the row immediately adjacent to the Indian corn is quite high, but drops off dramatically within the first 12 - 13 ft away from the Indian corn, and is almost not detectable on ears of plants 50 ft away from the Indian corn.

Click image to enlarge

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service