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Resistant alfalfas face challenges

Herbicide-resistant (Roundup Ready) alfalfa is expected to be offered for sale commercially this year.

So far it has not spawned an anti-biotech attack, but that does not mean there are no challenges associated with the herbicide resistant forage crop.

However, none seem insurmountable and researchers at the recent National Alfalfa Symposium in San Diego say the path seems clear for what one called the “landmark” movement into a new biotech crop that offers great potential to reduce weed control costs; produce cleaner alfalfa and be a possible solution to new water quality regulations facing western producers.

Roundup Ready alfalfa has not run into the opposition like herbicide-resistant wheat, a factor in Monsanto shelving Roundup Ready wheat. While Monsanto claimed officially that declining wheat acreage was the primary factor in pulling the plug on biotech wheat, it was actually opposition from countries importing U.S. wheat that postponed the introduction of herbicide-resistant wheat. Growers were concerned that world markets would be eroded for any country permitting herbicide-resistant wheat to be grown.

Japan, one of America's biggest agricultural trading partners, said it would not buy wheat — biotech or conventional — from any country that allowed biotech wheat to be grown. However, according to one of the speakers at the alfalfa symposium Japan is expected to approve the importation of biotech alfalfa. Japan is the biggest importer of U.S alfalfa, taking 75 percent of the alfalfa exported by the U.S. with a value of almost $500 million annually.

The difference is that wheat is imported primarily for human consumption and alfalfa is imported for livestock rations. Scientists said no one has documented a risk to humans consuming milk, meat or eggs from animals fed genetically modified hay.

Asked to certify

Nevertheless, Western alfalfa growers have already been asked by some foreign customers to certify that hay shipped to them is non-biotech. Easy-to-use protein-based test strips are being developed to detect the presence of the Roundup Ready gene in alfalfa hay and forage.

If herbicide resistant alfalfa is introduced commercially in 2005, it will be the fourth major U.S. biotech crop. Eighty-five percent of the 74 million acres of soybeans grown in the U.S. are herbicide-resistant; 13 percent of the 80 million acres of corn are biotech varieties; 60 percent of the 14 million acres of cotton are biotech varieties. About 60 million acres of wheat are grown in the U.S. annually, and U.S. farmers produce alfalfa from 22 million acres annually. Unlike the other crops, alfalfa is a perennial that once planted can have a harvestable lifespan from 3 to 10 years or more, depending on how often it is harvested each year.

Forage Genetics International will “likely” introduce Roundup Ready alfalfa varieties this year, according to its president Mark McCaslin.

Food and Drug Administration approval of the herbicide-resistant crop is expected to coincide with Japanese approval to import the hay, said McCaslin. Canada, Mexico, South Korea and Taiwan are expected to follow suit.

McCaslin acknowledges that some buyers of American hay will require testing to ensure that they are not getting biotech hay.

Forage Genetics, Monsanto, scientists from the University of California and the University of Washington and key alfalfa exporters are developing protein-based test strips to detect the Roundup Ready gene in hay.

First trait

McCaslin said herbicide resistance should be the first of many biotech traits in alfalfa. Others traits under development include traits to enhance yields, tolerance to other herbicides, insect resistance and stress tolerance. Output traits likely will be improved fiber digestibility and increased efficiency in protein utilization that will result in “significant increases” in milk and beef production, according to McCaslin.

This new biotech era for alfalfa could even reverse a nationwide alfalfa acreage decline trend by keeping the crop competitive, McCaslin said. “Genetic engineering offers potential breakthroughs in improving the efficiency of alfalfa forage and seed production and improving forage quality in a way not possible through conventional plant breeding,” said McCaslin, adding that Forage Genetics surveying has indicated a “strong demand” for new biotech alfalfa hay products that improve animal performance.

The hay export market is primarily a concern for Western forage producers who export virtually 100 percent of the 2.9 million metric tons of U.S. hay exported to Pacific Rim countries.

According to William T. W. Woodward of Washington State University, Japan is expected to set a low tolerance level for GMO alfalfa, however, the export hay customer may want zero tolerance.


This will pose a challenge from pollinator bees which can fly several miles. However, Woodward said the most likely contamination could be in purchased seed because seed production practices that may not allow adequate isolation distances.

“Although contamination is expected to be low, tests may unexpectedly detect the Roundup Ready gene. It is difficult to certify that a non-GMO will not be contaminated if grown in an area where GMO alfalfa cultivars are produced,” said Woodward.

Isolation will be critical in managing pollen flow in California as well, agreed Ron Vargas, weed control specialist and farm advisor in Madera and Merced counties in the San Joaquin Valley.

Since there are no sexually compatible food crops or weeds to alfalfa, outcross is of minimal concern. However, Vargas once again sounded the alarm about feral and volunteer herbicide-resistant plants. Volunteer alfalfa must be effectively controlled in rotational crops like cotton and corn with a herbicide other than glyphosate. Roadside and ditch bank feral alfalfa also will be a concern since Roundup has traditionally been used for weed control in those areas. Other herbicides will have to be used in those situations.

Herbicide substitutes

“Cutting schedules in hay also will have to be diligently adhered to so that the hay is cut at early bloom stage before pollen is produced,” added Vargas.

Vargas said 2,4-D and dicamba were the most effective herbicides to replace Roundup in taking out old alfalfa stands. He added control was 100 percent with all non-glyphosate herbicides evaluated when followed by cultivation.

As with any widely used herbicide, resistance is an issue. With the Roundup Ready technology in several crops, it is a growing concern with glyphosate. Glyphosate-resistance has already been identified in ryegrass and horseweed and reduced control has been validated in lambsquarter and barnyardgrass. Continued use of glyphosate on hard to control weeds such as stinging nettle, cheeseweed and hairy fleabane can be the cause of weed shifts.

Vargas said development of resistance to glyphosate is “thought to be less likely” than other herbicide because it has no soil residual activity and controls weeds with a unique mode of action. Nevertheless, Vargas and other researchers said rotating herbicides to manage resistance is good stewardship. This includes rotating with herbicides with different modes of action; using recommended glyphosate rates; monitoring and controlling escape weeds; using only certified planting seed; cleaning equipment and rotating crops to prevent resistance.

Vargas said it is “probably not” a good idea to rotate Roundup Ready cotton or corn with Roundup Ready alfalfa.

“Following Roundup Ready corn with Roundup Ready cotton has (already) caused problems with the control of corn in the cotton crop. Using Roundup Ready technology in the same field too frequently may result in weed species shifts or resistance.”

Still good option

Even with the challenges, Vargas and his colleagues believe Roundup Ready alfalfa will give growers a simply, broad spectrum weed control option.

It could even help in complying with California's new groundwater protection regulations which restricts the use of many herbicides. Roundup is not one of the products restricted in groundwater protection areas.

Of course, the bottom line for growers will be the economic benefits. Since no price structure or technology fee has been announced. That remains the biggest unanswered question about the new emerging biotech era for forage producers.


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