Evidence of the magnitude and consequences of the Roundup ready soybean yield drag from University-based varietal trials

Over half the soybeans planted in the United States in 1999 are varieties genetically engineered to tolerate applications of the broad-spectrum, contact herbicide glyphosate manufactured by Monsanto Company (Trade Name, Roundup). Just a small fraction of soybeans produced in 1996 were “Roundup Ready ” -- varieties able to tolerate direct applications of glyphosate herbicide. The rapid adoption of Roundup Ready (RR) soybeans has been unprecedented in the history of American row-crop agriculture. No new genetic trait, nor any pesticide has so dramatically gained market share in such a short period of time. Roundup Ready soybeans have proven so popular with farmers because they greatly simplify the task of managing weeds and help farmers avoid a variety of problems associated with other herbicide-based weed management systems. They have proven especially popular among farmers who must complete weed management practices on a timely basis over hundreds to thousands of acres of soybeans. The success of RR soybeans is remarkable in light of the magnitude of the so-called Roundup Ready “yield drag. ” Under most conditions extensive evidence show