January 27, 2011

Now that Roundup Ready® alfalfa has been approved again for planting, Nebraska growers need to determine what value this genetic trait may have for their operation. To aid this decision-making process, I’ve listed some of the opportunities and risks provided by the Roundup Ready trait.

Opportunities

Obviously, the Roundup Ready trait will provide another weed control option, including helping with some problems commonly experienced by Nebraska alfalfa producers.

1. Weed control during establishment when new alfalfa seedlings are most sensitive to competition. Roundup has been shown to cause less crop injury than other herbicides labeled for establishment.
2. Mid summer control of grassy weeds for high-value harvests.
3. Control of especially troublesome weeds like waterhemp.
4. Control of winter annual weeds, especially after spring alfalfa green-up when other herbicides cause crop injury.

Risks

1. Extra seed cost and extra herbicide use without a simultaneous increase in crop yield or value. Weed control in alfalfa often fails to increase total yield, but it does increase the percentage of the yield that comes from alfalfa.
2. Potential to hasten the development of glyphosate-tolerant weeds.
3. Reduced marketability to customers opposed to GMO crops.
4. Potential to contaminate conventional alfalfa hay or seed crops being grown to take advantage of specialty markets.
5. Yield-drag potential. Developers of Roundup Ready alfalfa varieties have claimed that the trait is only in varieties with elite germplasm with no yield drag; however, independent field testing has been limited due to previous GMO restrictions and regulations.

Bruce Anderson
Extension Forage Specialist