Pollination: GMO vs. non-GMO corn

COLUMBUS – With the production of genetically modified corn gradually increasing in Ohio, the risk of contaminating non-GMO corn through pollination is becoming more of a concern.

Peter Thomison, an Ohio State University Extension agronomist, said that growers who produce pure genetic lines or organic grain are at the forefront of the issue of “pollen drift.”

“It’s going to require a lot of coordination among growers to help minimize pollen drift between GMO and non-GMO corn fields,” said Thomison.

“Most of the corn growers in Ohio are not too concerned about whether their corn is contaminated because most of the grain elevators will accept GMO corn. It’s IP (identity preserved) or organic growers who might be concerned.”

Identity preserved growers represent people using conventional corn products or a GMO crop, but they are trying to grow a crop they can guarantee to an end user is free of GMO events not approved in certain overseas markets.

Organic growers, since GMOs are not approved in organic systems, have to prove to the end user that the organic crop is not contaminated.

GMO 10 percent in Ohio. Thomison estimates roughly 10 percent of the corn grown in Ohio is GMO, ranging from Bt corns that target the European corn borer to herbicide-resistant corn like Roundup Ready to the new Bt corn designed to control rootworms.

Since corn reproduces through cross-pollination, a certain percentage of a corn crop is pollinated by neighboring plants.

“Maybe 20 percent to 40 percent of the ovules on that ear of corn may have been pollinated from a neighboring plant, the result due mainly to wind and gravity,” said Thomison.

He said probably half of the pollen is going to be within the first 12 feet of the corn plants.

“At 40-50 feet away you are probably looking at around 1 percent of corn to be contaminated.”

Proving purity. Thomison said the issue of pollen drift is becoming a growing concern in Ohio, not only with growers looking for pure crops, but also with seed companies and grain elevators where GMO-contaminated seed and grain may not be acceptable.

“Seed companies are concerned for purity reasons. They’ll accept seeds that are 99.5 percent hybrid X and 0.5 percent Y, but they usually won’t accept contamination levels exceeding 1 percent.”

Some grain elevators won’t accept GMO corn if a percentage of the grain has been contaminated with a GMO event not approved by the European Union.

Confusing signals. There are varying levels of what’s acceptable, said Thomison.

Some grain elevators accept GMO corn regardless of what’s in it because it’s all going to animal feed, but some grain elevators may decline a Bt corn if it’s been contaminated by an event not approved by the EU.

Growers plant corn with up to seven different GMO events, mainly Bt and Roundup Ready events. Less than half of these crops have been approved by the EU for use in Europe.

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