Impacts of genetically engineered crops on pesticide use in the U.S. -- the first sixteen years

Abstract

Background: Genetically engineered, herbicide-resistant and insect-resistant crops have been remarkable commercial successes in the United States. Few independent studies have calculated their impacts on pesticide use per hectare or overall pesticide use, or taken into account the impact of rapidly spreading glyphosate-resistant weeds. A model was developed to quantify by crop and year the impacts of six major transgenic pest-management traits on pesticide use in the U.S. over the 16-year period, 1996-2011: herbicide-resistant corn, soybeans, and cotton; Bacillus thuringiensis (Bt) corn targeting the European corn borer; Bt corn for corn rootworms; and Bt cotton for Lepidopteron insects. Results: Herbicide-resistant crop technology has led to a 239 million kilogram (527 million pound) increase in herbicide use in the United States between 1996 and 2011, while Bt crops have reduced insecticide applications by 56 million kilograms (123 million pounds). Overall, pesticide use increased by an estimated 183 million kgs (404 million pounds), or about 7%.Conclusions: Contrary to often-repeated claims that today's genetically-engineered crops have, and are reducing pesticide use, the spread of glyphosate-resistant weeds in herbicide-resistant weed management systems has brought about substantial increases in the number and volume of herbicides applied. If new genetically engineered forms of corn and soybeans tolerant of 2,4-D are approved, the volume of 2,4-D sprayed could drive herbicide usage upward by another approximate 50%. The magnitude of increases in herbicide use on herbicide-resistant hectares has dwarfed the reduction in insecticide use on Bt crops over the past 16 years, and will continue to do so for the foreseeable future.

Use of genetically modified crops and pesticides in Brazil: growing hazards

“…The results obtained in this study agree with similar studies in the US, Argentina, and other parts of the world 9,10,35,36 . Data from these studies strongly suggest that the adoption of GM crops increased pesticide use, specifically herbicides sprayed on soybean, as shown by the present study for Brazil.…”

“…In the US, Benbrook 10 revealed that between 1996 and 2011, GM crops led to a 183,000-ton increase in pesticides, which is equivalent to 7% of the overall pesticide use for all crops. Between 1995 and 2002, the use of the herbicide glyphosate in soybean production increased from 2,500 to 30,000 tons/year 8 .…”

Impact of phosphate on glyphosate uptake and toxicity in willow

“…Agricultural soils are subjected to frequent fertilization with PO 4 -3 and application of glyphosate-based herbicides [45]. The influence of soil P content on glyphosate uptake by plants has been investigated previously [20][21][22].…”

Are Ready for Market Genetically Modified, Conventional and Organic Soybeans Substantially Equivalent as Food and Feed?

“…Seven out of the 10 GM-soy samples we tested surpassed this "extreme level" of glyphosate + AMPA residues, reflecting the increased use of glyphosate on Roundup Ready soybeans in the US (Benbrook 2012). …”