Wisconsin Corn Agronomy

June 1999
Field Crops 28.34-24

Unapproved Corn GMO's: How should they be handled?

Joe Lauer, Corn Agronomist

The announcement that some corn processors will not accept corn hybrids that have been genetically modified has caused some confusion among farmers as corn is planted this spring. Some farmers have returned seed. Others, due to late notification and the excellent planting conditions experienced around the state, have gone ahead and planted the seed and are now wondering what can be done. Current estimates are that about 7 percent of the corn seed now in farmers’ hands for planting is not approved for export to the European Union (EU). The main areas of concern are with pollination and marketing genetically modified organisms (GMO) corn that is not approved.

Corn hybrids that DO NOT include GMO events are high-oil corn, IMI corn, white corn, and waxy corn. Below are some comments regarding GMO and things to watch for during the growing season.

1. Correctly identifying the events used in the GMO hybrids planted on your farm is key to understanding potential problems when marketing corn.

2. All local markets and uses of GMO corn should not be affected. All GMO seed sold in the U.S. is approved for sale and use in the U.S. The problem is with exported GMO corn. For a complete listing of events approved by different countries, please see the Table 1.

3. Unapproved GMO hybrids should be the first to be made into silage or otherwise stored for feeding and only approved hybrids should be taken to the elevator or stored for later sale to the elevator. Elevators accepting GMO corn will in some cases only sell it as feed for use in the U.S. Such corn can also be exported to most Asian countries, which represent a much larger fraction of the export market than does the EU.

4. The decision to return unapproved GMO seed in exchange for approved hybrids should not be made lightly, especially if it means giving up yield protection. Many of the non-GMO hybrids are outstanding in yield potential and general agronomics. Backcrossing into non-GMO hybrids originally produced many GMO hybrids. Selection of replacement hybrids should be done as carefully as time permits. In some cases it may be better to keep an unapproved hybrid and find an alternative market than to substitute a substandard or unknown one.

5. Pollen from a field with a GMO hybrid can "contaminate" a non-GMO hybrid in a neighboring field. The amount of contamination will probably be very low, only a few kernels. Even though the percentage of these kernels in an approved field is very low, the very sensitive tests for the presence of such genes could result in unexpected positives. This is not only a problem for unapproved GMO corn for export to the EU this year, but is also an issue for organic and other non-GMO corn that is being marketed. Most corn pollen falls within 50 feet of the plant. However, isolation requirements for certified corn hybrid seed production are 660 feet. If contamination problems are suspected, some things to keep in mind are:

• The greatest contamination occurs in the 165 to 248 feet nearest contaminating corn,

• Pollen from border rows in the non-GMO field dilutes contamination,

• Natural barriers (e.g. tree lines) may reduce contamination,

• An abundant supply of non-GMO corn pollen at the right time reduces contamination,

• The direction of a field from contaminating pollen influences the amount of contamination, and

• "Depth of field" in the direction of the contamination source is important.

6. If a producer delivers all of his corn to an elevator, then it depends on what the elevator does with the corn it purchases. Unapproved GMO events will need to be identity preserved and handled separately. Trying to "sneak" corn into commercial elevators will probably not work because ELISA tests have been developed for specific GMO events. These test kits are sensitive, quick and easy to use, and each truckload could be potentially tested and checked. Test kits so far only detect approved Bt events and thus won’t be of much help to prevent the entry of unapproved GMO hybrids. Development of new kits to find unapproved hybrids may happen quickly.

There is still time before harvest, and approval could come at any time for unapproved GMO events. Those who sell, produce or buy corn should take seriously the risk and consequences of GMO events not approved by the EU. Hopefully the negotiation process will be complete and favorable by harvest. It is wise to check on the policy of both your seed company and the place where you sell corn, if you have any concerns.

If you would like to subscribe to updates during the growing season, click here.

©  1994-2008 Board of Regents of the University of Wisconsin System, Division of Cooperative Extension of the UWEX.