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University of Missouri Extension agronomists share their RR alfalfa advice

Since USDA authorized resumption of the sale of Roundup Ready alfalfa in late January, University of Missouri Extension agronomists have fielded a few inquiries from farmers around the state.

Tim Schnakenberg, MU Extension agronomist at Galena, says there’s no doubt that Roundup Ready alfalfa provides a unique opportunity to grow quality forage. “Its recent USDA approval is a welcome decision by many producers, though not all,” he says.

“There are some who are skeptical about using a genetic engineered product that is proprietary to only a few companies. There are many who are also concerned about resistant weeds developing in a few years.”

There are a few Roundup Ready alfalfa fields in Missouri established when genetically engineered alfalfa was last on the market. Five years later, some of the fields Schnakenberg has visited are still productive. “They are some of the cleanest alfalfa fields around,” he notes.

“The producers often will incorporate their insecticide spray with the glyphosate in a one-pass system, saving money on applications.”

What are pros and cons of using this product? Agronomists say the positives include more broad-spectrum weed control, less expensive herbicide applications, potential for a higher-quality product, improved stand persistence, limited crop rotation restrictions, and no crop injury compared to some of the conventional herbicides.

“I can’t quote research on this, but it makes good sense that if weeds are kept at bay routinely in an alfalfa stand, that the persistence of the stand will be longer,” Schnakenberg says.

“This must be accompanied by good fertility. Since conversion from fescue fields to alfalfa is a common occurrence in Missouri, the use of glyphosate in-crop for alfalfa helps in keeping newly established fields from becoming inundated with regenerated fescue.”

Cost challenges

Leading the list of cons is cost. While MU Extension agronomists report that exact seed costs are not yet available, based on the last time RR alfalfa was deregulated, an estimate of $7 to $8 per pound is commonly quoted (including the technology fee).

“Establishment costs would be the same as for conventional alfalfa, except that the seed cost would add $30 to $50 per acre,” says Rob Kallenbach, MU Extension forage specialist, Columbia.

“The cost to establish any new alfalfa fields is high — it’s estimated at $340 per acre.”

Seed availability shouldn’t be a problem, since it has been stockpiled for a long time. However, this does create a challenge for suppliers to insure that the seed germ is still good.

Other negatives include no residual control, potential for weed resistance, and the weakness of glyphosate on specific weeds: curly dock, fleabane, morningglory, smartweed, nutsedge and henbit.

“Henbit is a common concern in alfalfa, and this could be an issue for some farms,” Schnakenberg says.

“The resistance issue has become huge in soybeans, and there is potential for the same concern in RR alfalfa. Farmers will need to break the cycle of glyphosate from time to time with different chemistries.”

For hay producers, another disadvantage of using glyphosate is not being able to use a grass mix in the alfalfa stand, such as orchardgrass. The horse-market trend is for an alfalfa-grass mix. Orchardgrass mixed in the stand also aids in a faster drying time and insect resistance.

Weigh risks, profits

“Fertility and hay-cutting management is still going to be a primary key for success,” Schnakenberg adds. “This technology is not for everybody, but provides another tool for alfalfa production.”

As for the cost, Schnakenberg reminds farmers that they can spread out the upfront cost of seed over several years — for this perennial crop makes it more palatable than paying the cost for an annual crop like corn or soybeans.

“Farmers often get hung up on the high cost of quality forage seed, but forget that it can be prorated out over several years,” he says.

“Just looking at a technology fee of $2.50 [assumed], multiplied by 15 pounds per acre seeding rate, the extra cost is $37.50 per acre. If the stand is managed well and is maintained for at least five years, that prorates to a $7.50 per-year, per-acre cost.”

This article published in the March, 2011 edition of MISSOURI RURALIST.

All rights reserved. Copyright Farm Progress Cos. 2011.