On GE and non-GE corn since 1996, the volume of insecticides applied has declined, because of the pesticide industry-wide trend toward more biologically active insecticides applied at incrementally lower application rates. A more recent study reports a 24% reduction. Analysts assessing the impacts of Bt crops on insecticide use report reductions, or displacement, in the range of 25% to 50% per hectare. Net reductions in pesticide use, encompassing changes in both herbicide and insecticide kilograms/pounds applied, are among the purported claims of GE crops. glufosinate HR, LibertyLink cotton and corn). bromoxynil HR cotton), or have been planted on relatively few hectares (e.g. From 1996 through 2008, HR crops resistant to herbicides other than glyphosate either disappeared from the market (e.g. RR crops were rapidly adopted because they provided farmers a simple, flexible, and forgiving weed management system, especially compared to systems reliant on the low-dose, persistent herbicide chemistries on the market in the late 1990s, such as imazethapyr (43% soybean hectares treated in 1996) and chlorimuron-ethyl (14% treated). Glyphosate-resistant, Roundup Ready (RR) crops now comprise the overwhelming majority of HR crops. In 2011, an estimated 94% of the soybean area planted, 72% of corn, and 96% of cotton were planted to HR varieties, respectively, while about 65% of corn and 75% of cotton hectares in the U.S. From 1996 through 2011, 0.55 billion hectares of HR corn ( Zea mays), soybeans ( Glycine max), and cotton ( Gossypium hirsutum) were grown in the U.S. The emergence of herbicide-resistant genetically engineered crops in 1996 made it possible for farmers to use a broad-spectrum herbicide, glyphosate, in ways that were previously impossible. There is a degree of irony in such recommendations, given that the purpose of Cry 3Bb1 corn was to eliminate the need for corn soil insecticides. To combat this ominous development, some seed and pesticide companies are recommending a return to use of corn soil insecticides as a resistance management tool. Stable reductions in insecticide use in Bt-transgenic corn are also now in jeopardy as a result of the emergence of corn rootworm (CRW) populations resistant to the Cry 3Bb1 toxins expressed in several corn hybrids. pesticide use trends are substantial and obvious, especially in recent years as a result of the growing number and geographical spread of glyphosate-resistant (GR) weeds. Moreover, the impacts of these traits on U.S. Department of Agriculture (USDA) pesticide use data are available and can be used to track changes in pesticide use on crops containing GE traits. Fortunately, high quality and publically accessible U.S. Still, many experts and organizations assert that GE crops have reduced, and continue to reduce herbicide, insecticide, and overall pesticide use.
Public debate over genetically engineered (GE) crops is intensifying in the United States (U.S.), driven by new science on the possible adverse health impacts associated with herbicide-resistant (HR) crop pesticide use, and the rapid spread of glyphosate-resistant weeds. 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. 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%. ConclusionsĬontrary 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. Overall, pesticide use increased by an estimated 183 million kgs (404 million pounds), or about 7%. Herbicide-resistant crop technology has led to a 239 million kilogram (527 million pound) increase in herbicide use in the United States between 19, while Bt crops have reduced insecticide applications by 56 million kilograms (123 million pounds). 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. 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.
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. Genetically engineered, herbicide-resistant and insect-resistant crops have been remarkable commercial successes in the United States.
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