Background

Genetically engineered (GE) corn, cotton, and soybeans were commercially introduced in 1996. Adoption rates for these crops, especially those with herbicide tolerance (HT) traits, increased rapidly in the years that followed.

See Adoption of Genetically Engineered Crops in the U.S., a data product on the ERS website, for more information.

HT crops tolerate potent herbicides (such as glyphosate or glufosinate), which have the potential to damage non-GE crops. Insect-resistant (Bt) crops contain a gene from the soil bacterium Bacillus thuringiensis that produces an insecticidal protein. Although other GE traits have been developed (such as virus and fungus resistance, drought resistance, and enhanced protein, oil, or vitamin content), HT and Bt traits are the most commonly used in U.S. crop production. While HT seeds are also widely used in alfalfa, canola, and sugar beet production, most GE acres are planted to three major field crops: corn, cotton, and soybeans. 

Though GE seeds tend to be more expensive than conventional ones, planting them tends to increase crop yields, lower pesticide costs, and/or provide time and labor savings. The impacts of GE crops vary by crop, year, and location. Bt crops tend to have higher yields than non-Bt crops when insects are present. Insecticide costs also tend to be lower on fields where Bt crops are planted. Planting HT crops tends to simplify weed management decisions, which can lead to time and labor savings. HT adoption also tends to promote the use of conservation tillage technologies and often induces farmers to substitute the herbicide glyphosate for more toxic herbicides. However, large increases in glyphosate use have recently led to the development of glyphosate-resistant weed populations. The spread of resistant weed populations has the potential to erode the benefits associated with HT production systems.