GM crops show mix of benefits, concerns: USDA


Weed and insect management made easier | Study says yield benefits elusive with GM crops and can sometimes lower yields

(Reuters) — U.S. farmers are continuing to see an array of benefits after more than 15 years of using genetically modified crops, says a report issued by the U.S. Department of Agriculture.

However, it said the impacts on the environment and on food production are mixed, and high farmer use of a popular herbicide on GM crops is a cause for ongoing concern.

“We are not characterizing them (GMO crops) as bad or good. We are just providing information,” said Michael Livingston, a government agricultural economist and one of the authors of the report, which was prepared by the USDA’s Economic Research Service.

The report, released online Feb. 20, comes at a time when GM crops are under intense scrutiny: 

  • Consumer groups are calling for tighter regulation of crop research and production and seeking mandatory labelling of food made with GMOs.

  • Environmentalists are reporting increasing concerns about weed resistance and insect resistance to the crops and the chemicals used on them.

  • Some scientific studies are reporting that the chemicals used on the crops are linked to disease and illness.

As well, the report comes as the USDA and the Environmental Protection Agency are in the final stages of approving the commercialization of a new GM crop and chemical product package developed by Dow AgroSciences.

GM crops have become wildly popular with U.S. farmers since Monsanto introduced herbicide tolerant Roundup Ready soybeans in the mid-1990s. Since then, Monsanto and other seed and chemical companies have introduced corn, soybeans, cotton, canola and others crops that tolerate being sprayed with herbicide or resist insects.


GM crops were planted on 169 million acres in the U.S. last year, which is about half the total land used for crops, the report said.

The seeds are patented and cost more than conventional seeds. The report said the price of GM soybean and corn seeds increased by 50 percent between 2001 and 2010.

However, the companies that sell them say they make weed and insect management easier for farmers and can help increase production.

In their report, the ERS researchers said GM seeds have not been shown to definitively increase yield potentials over the first 15 years of commercial use.

“In fact, the yields of herbicide-tolerant or insect-resistant seeds may be occasionally lower than the yields of conventional varieties.”


Several researchers have found “no significant differences” between the net returns to farmers who use GM herbicide tolerant seeds and those who use non-GM seeds, the report said.

GM crops that prevent yield losses to pests are more helpful to farmers financially because they increase yield potential and monetary returns. 

As well, insecticide use on corn farms was down to .02 pounds per acre in 2010 compared to .21 lb. per acre in 1995.

However, while insecticide use has gone down, herbicide use on GM corn is rising, the report said.

Herbicide use on GM corn in-creased from 1.5 lb. per planted acre in 2001 to more than two lb. in 2010. Herbicide use on non-GM corn has remained stable during that same time frame, the ERS said.


As well, the over-reliance on glyphosate has translated into an increase in weed resistance, which makes crop production much harder.