Seth James Wechsler

Genetically Engineered Crops in the United States

More than 15 years after their first successful commercial introduction in the United States, genetically engineered (GE) seeds have been widely adopted by U.S. corn, soybean, and cotton farmers. Still, some questions persist regarding the potential benefits and risks of GE crops. The report finds that, although the pace of research and development (measured by the number of USDA-approved field tests) peaked in 2002, other measures show that biotech firms continue to develop new GE seed varieties at a rapid pace. Also, U.S. farmers continue to adopt GE seeds at a robust rate, and seed varieties with multiple (stacked) traits have increased at a very rapid rate. Insecticide use has decreased with the adoption of insect-resistant crops, and herbicide-tolerant crops have enabled the substitution of glyphosate for more toxic and persistent herbicides. However, overreliance on glyphosate and a reduction in the diversity of weed management practices have contributed to the evolution of glyphosate resistance in some weed species.

Pesticide Use in U.S. Agriculture: 21 Selected Crops, 1960-2008

Pesticide use has changed considerably over the past five decades. Rapid growth characterized the first 20 years, ending in 1981. The total quantity of pesticides applied to the 21 crops analyzed grew from 196 million pounds of pesticide active ingredients in 1960 to 632 million pounds in 1981. Improvements in the types and modes of action of active ingredients applied along with small annual fluctuations resulted in a slight downward trend in pesticide use to 516 million pounds in 2008. These changes were driven by economic factors that determined crop and input prices and were influenced by pest pressures, environmental and weather conditions, crop acreages, agricultural practices (including adoption of genetically engineered crops), access to land-grant extension personnel and crop consultants, the cost-effectiveness of pesticides and other practices in protecting crop yields and quality, technological innovations in pest management systems/practices, and environmental and health regulations. Emerging pest management policy issues include the development of glyphosate-resistant weed populations associated with the large increase in glyphosate use since the late 1990s, the development of Bt-resistant western corn rootworm in some areas, and the arrival of invasive or exotic pest species,such as soybean aphid and soybean rust, which can influence pesticide use patterns and the development of Integrated Pest Management programs.