The international name for corn is maize; it is most widely grown crop in the Western hemisphere, used for cereals, animal fodder and increasingly for the production of ethanol alcohol used in biofuel mixes. The DeKalb Genetics Corporation developed Roundup Ready corn, a registered hybrid variety of field corn that is tolerant of Roundup, a herbicide with the active ingredient of glyphosate. DeKalb earlier marketed a hybrid soybean that also tolerates glyphosate.
Roundup was first marketed the Monsanto Corporation of St. Louis, Mo, in 1973 and is the most widely used herbicide in the U.S. The Monsanto patent expired in 2000 and other companies now market glyphosate-based herbicides. DeKalb Corporation, of DeKalb, Illinois, released its first Roundup Ready corn seeds on the market in 1999. The European Union has approved Roundup Ready 2 for the European market. Seventy to 80 percent of the corn grown in the U.S. is Roundup Ready.
Roundup Ready corn does not require traditional, expensive tilling to control weeds. The crop is seeded directly into soil that has not been tilled; instead of plowing, growers rely on Roundup and other herbicides with the active ingredient of glysophate to kill the weeds. The heavy use of Roundup Ready corn and Roundup has reduced the price of both Roundup Ready corn seeds and Roundup, adding to the savings of those who plant the hybrid corn.
In conventional farming, growers generally applied herbicides containing the active ingredient atrazine before they planted corn. With Roundup Ready corn, they can wait until later, knowing the corn will not be affected by Roundup. This led to worries that weeds competing with corn plants for nitrogen would reduced yields of corn. Researchers at the University of Wisconsin say if the Roundup is applied to weeds before the weeds get too large, there is no difference in the yield between Roundup Ready corn and conventional corn.
Roundup Resistant Weeds
The overuse of antibiotics caused the appearance of germs that resisted antibiotics. The same phenomenon has occurred with glyphosate herbicides. As weeds become more resistant to glyphosates, the amount of glyphosate needed to kill them rises, accounting for the appearance glyphosate-resistance superweeds.
According to a report in "The New York Times," superweeds were first discovered in a Delaware soybean field in 2000; 10 resistant species of weeds, including pigweed, horseweed and ragweed now infect fields of Roundup-resistant corn, cotton and soybeans in 22 states. Ian Heap, director of the International Survey of Herbicide Resistance to weeds, financed by the agricultural chemical industry, estimates that 7 to 10 million acres have been affected by superweeds.
Mike Owen, a weed scientist at Iowa State University says, "What we're talking about here is Darwinian evolution in fast-forward."
Weed scientists at Ohio State University and Purdue University generally advocate that a mix of herbicides be used along with Roundup in Roundup Ready corn fields. This will improve the control of glysophate-resistant ragweed, marestail and waterhemp that afflict cornfields in the Midwest and help delay the appearance of glysophate-resistant weeds.