Failure to Yield

The report concludes that genetic engineering has failed to increase the intrinsic yield of any major food or feed crops and has provided only minimal gains in operational yield, primarily through Bt corn. Most yield increases in U.S. agriculture are attributed to traditional breeding and improved agricultural practices rather than GE traits.

• Genetic engineering has not increased the intrinsic yield—the highest possible yield under ideal conditions—of any currently available transgenic crop varieties. Historical increases in intrinsic yields for corn and soybeans are attributed to traditional breeding.
• Herbicide-tolerant (HT) soybeans and corn have not increased operational yields on a per-acre or national basis when compared to conventional methods using other available herbicides. Some best-controlled studies suggest HT soybeans may even experience 'yield drag,' resulting in lower yields than conventional near-isogenic varieties.
• Bt corn provides an operational yield advantage of approximately 7–12 percent compared to conventional practices only when European corn borer infestations are high; it offers little to no advantage when infestations are low to moderate.
• The aggregate operational yield increase for the entire U.S. corn crop attributable to Bt traits (combining European corn borer and rootworm varieties) is estimated to be between 1.3% and 5.5%, with 3.3% as a reasonable intermediate value.
• The majority of yield gains in U.S. agriculture are due to non-GE approaches. For example, corn production per acre was 28 percent higher from 2004–2008 than from 1991–1995, but only 3–4 percent of that increase is attributable to Bt corn, leaving 24–25 percent to factors like conventional breeding.
• Experimental GE field trials have largely failed to produce commercialized yield-enhancing crops. Out of 3,022 approved field trials for traits such as disease resistance or abiotic stress tolerance (excluding HT and IR), only virus-resistant papaya has seen limited commercial success in Hawaii.
• Future GE yield-enhancing genes are likely to be more complex than current traits, potentially causing detrimental pleiotropic side effects that may hinder commercialization or cause environmental and health impacts.
• Agro-ecological and low-external-input (LEI) methods can produce yields comparable to conventional methods and have shown the potential to increase yields by over 100 percent in developing countries, particularly in Africa.

APA

Gurian-Sherman, D. (2009). Failure to Yield. Union of Concerned Scientists. https://www.ucs.org/sites/default/files/2019-10/failure-to-yield.pdf

Chicago

Gurian-Sherman, Doug. Failure to Yield. Union of Concerned Scientists, 2009. https://www.ucs.org/sites/default/files/2019-10/failure-to-yield.pdf.

Wikipedia

{{cite report |last1=Gurian-Sherman |first1=Doug |title=Failure to Yield |publisher=Union of Concerned Scientists |date=April 2009 |url=https://www.ucs.org/sites/default/files/2019-10/failure-to-yield.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{guriansherman2009failure, author = {Gurian-Sherman, Doug}, title = {{Failure to Yield}}, institution = {Union of Concerned Scientists}, year = {2009}, month = apr, url = {https://www.ucs.org/sites/default/files/2019-10/failure-to-yield.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }