E-mail this article to
yourself or a friend.
Enter address:


Report points out problems with Roundup Ready soybeans

(May 3, 2001 -- Cropchoice news) -- Contrary to the promises of Monsanto, farmers are applying more herbicides to Roundup Ready soybean plants and reaping lower yields from them compared to conventional varieties, according to a new report by Dr. Charles Benbrook of the Northwest Science and Environmental Policy Center in Sandpoint, Idaho.

The study, "Troubled Times Amid Commercial Success for Roundup Ready Soybeans: Glyphosate Efficacy is Slipping and Unstable Transgene Expression Erodes Plant Defenses and Yields," available at www.biotech-info.net/troubledtimes.html, uses recent USDA and university research to update the Center's 1999 report on the same subject.

Many farmers have told Cropchoice about the extra herbicides and lower yields that go along with growing Monsanto's herbicide-resistant beans. Despite this, they're planting more Roundup Ready soybeans -- 60 percent of this year's crop -- because the technology makes weed management relatively easy.

But what farmers may not want to hear, and what this study reveals, is that relying on Roundup to kill weeds in Roundup Ready soybean fields has led to their becoming herbicide resistant.

Increased herbicide use

One must look at the amount of herbicide growers apply per acre of soybeans to see that Monsanto's transgenic varieties require more applications, according to the executive summary of the report.

"More than a dozen soybean herbicides are applied at an average rate of less than .1 pound active ingredient per acre. Roundup, on the other hand, is usually applied on soybeans at about .75 pound per acre in a single spray and most acres are now treated more than once," Benbrook writes. "...Total herbicide use on RR soybeans in 1998 was 30 percent or more greater on average than on conventional varieties in six states, including Iowa where about one sixth of the nation's soybeans are grown. RR soybean herbicide use was 10 percent or more greater in three more states. Use on RR soybeans was modestly lower in five states."

Benbrook predicts that farmers will apply about .5 pounds more herbicide (active ingredient) to the average acre of Roundup Ready beans than they will to conventional varieties in 2001. "As a result over 20 million more pounds of herbicides will be applied this crop year."

Yield drag in Roundup Ready beans

The report highlights research linking the 5 to 10 percent yield drag in Roundup Ready soybeans to the interaction of their genetics with environmental factors, including the application of Roundup.

Herbicide resistance in weeds

"There are two major factors on the plus side of RR soybean trade-offs -- weed management is simplified and soybean crop injury is avoided. But troubled times lie ahead for RR soybeans because the efficacy of glyphosate is clearly slipping in managing weeds and because unanticipated yield penalties are surfacing in some RR fields...," Benbrook writes.

To see the full report, go to www.biotech-info.net/troubledtimes.html