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Agricultural Economists' Brief Assessment Of NYT 'Doubts About the Promised Bounty of GM Crops'

This post was originally published on Forbes on November 7, 2016.

Post written by Graham Brookes and Justus Wesseler. Graham Brookes, agricultural economist & Justus Wesseler, professor of Agricultural Economics & Rural Policy, Wageningen University

GMO Answers is launching a two-part response to recent claims regarding the benefits of GMOs and GM technology. This post is our first installment.

GMOs provide ample benefits to our environment, food system and farmers. (Image Credit: GMO Answers)

The New York Times article, ‘Doubts About the Promised Bounty of Genetically Modified Crops,’ claims to have extensively examined the impacts of GM crops in the U.S. and Canada and concluded that the technology has not ‘accelerated increases in crop yields or reduced use of chemical pesticides.’

The author also implicitly suggests that U.S. farmers did not gain from using the technology.

The article is, however, far from ‘extensive,’ is inaccurate and thoroughly misleading. Let’s look briefly at the two main claims:

The claim that GM crops have not increased yields

Any discussion about crop yields should acknowledge that there are numerous factors that affect yield such as weather, soil quality, husbandry practices, use of inputs such as fertilizers, pesticides and seeds, knowledge and skills of farmers, price of inputs, effectiveness of existing technology to control pests, diseases and weeds, and more. The genetic capability of seed and its ability to withstand yield reducing effects of pests, diseases and weeds are but two of these factors. GM crop technology widely used to date has largely offered:

  • Insect resistance technology (IR: found mostly in corn and cotton) to provide farmers with alternative and better levels of pest control (relative to insecticides). Where used, by farmers that suffer yield loss from the specific pests targeted by the GM IR technology, the technology has been shown to consistently deliver higher yields through improved pest control (References 1,2).
  • Herbicide tolerance (HT) technology – which makes weed control easier and typically cheaper for farmers. This GM technology does not target increased yields as a primary benefit to farmers unless they were getting poor levels of weed control with existing methods.

The NYT article mainly uses a comparison of aggregate canola (GM HT) yields in Canada and non-GM rapeseed yields in Western Europe (also GM HT sugar beet from the U.S. with non-GM sugar beet in Europe). It is not surprising therefore that claims about a lack of evidence of yield gains can be seen relative to Western European yields, given the main aim of GM HT technology is not necessarily to increase yields. It is also not surprising that average yields are higher in Europe than Canada as the agro-climatic conditions are different between the two regions – in Canada spring canola is the main crop compared to winter oilseed rape in Europe (winter crops typically yield better than spring crops).

In sum, the NYT article is making spurious comparisons that lack context and will mislead readers. A more critical and balanced assessment would have examined the crops of corn and cotton, where the GM technology aims to reduce pest-related yield losses, to see if the farmers using this technology had made yield and income gains. There are numerous such studies available (see for example those cited in references 1 and 2) and these have consistently identified yield gains for most users of GM IR technology. In addition, detailed examination of real farm income levels and factors that affect income between countries of the European Union (Belgium, France, Italy, Finland, Sweden and the United Kingdom) and the U.S. observed significant and substantial differences, suggesting that EU farmers have been losing out from their lack of access to technologies available to U.S. farmers [reference 7].

The claim that GM technology has not reduced pesticide use

Any discussion about pesticide use in agriculture should provide readers with context. This article provides no such relevant context.

Firstly, the amount of pesticide used is a poor measure of environmental impact of pesticide use because it is the toxicity of a pesticide that impacts on the environment (and on the health of humans, animals, exposed to them).

Secondly, any examination of pesticide use changes with GM crop technology should also explore the ‘alternative’ – what has happened or would reasonably be expected to have happened if this technology had not been used.

The NYT article fails on both counts and therefore misleads. The consistent evidence identified in GM crop studies (references, 2, 3, 4, 5, and 6) shows that:

  • the volume of insecticide used (per acre) has fallen and the associated impact on the environment has improved with the use of GM IR technology (largely in corn and cotton);
  • whilst the volume of herbicides used (per acre) with GM HT crops has increased in the last ten years (after falling in the initial years of adoption), so has the volume of herbicides used on non-GM conventional ‘equivalent’ crops;
  • the associated environmental impact of herbicides used with GM HT crops has been and continues to be better than the associated environmental impact of herbicides used with conventional alternative crops;
  • the use of GM HT crops has also facilitated the wider adoption and maintenance of no and reduced tillage production systems generating additional environmental benefits (eg, carbon emission savings, reduced soil erosion) and has contributed to reduced herbicide use in following crops.

Overall, there is a considerable body of consistent evidence, in peer reviewed literature that quantifies the impacts of crop biotechnology and provides insights into the reasons why so many farmers around the world have adopted and continue to use the technology – in 2014 for example, for every extra $1 spent on GM seed, farmers earned an extra $3.59 in additional income (reference 1). Sadly, the author of the NYT article largely ignored this substantial literature.

Readers are encouraged to read the peer reviewed papers cited, and the many others who have published on this subject (and listed in the references below) and to draw their own conclusions.


  1. Brookes G and Barfoot P (2016) Global income and production impacts of using GM crop technology 1996-2014. GM Crops and Food, 7, p38-77. Both papers are available on open access at
  2. Klumper W and Qaim M (2014) A meta-analysis of the impacts of genetically modified crops. PLoS ONE 9: e111629
  3. Brookes G (2014) Weed control changes with GM HT crops in the U.S. 1996-2012, GM Crops and Food, vol 5, Issue 4, 321-332
  4. Brookes G and Barfoot P (2016) Environmental impacts of GM crop use 1996-2014: impacts on pesticide use and carbon emissions. GM Crops 7: p84-116
  5. Perry E et al (2016) GE crops and pesticide use in U.S. maize and soybeans, Sci Adv, 2016, 2, e1600850, 31/8/2016
  6. Wesseler J, Scatasta S, Fall EH (2011). Environmental Benefits and Costs of GM Crops. In “Genetically modified food and global welfare” edited by Colin Carter, GianCarlo Moschini and Ian Sheldon, pp 173-199. Volume 10 in Frontiers of Economics and Globalization Series. Bingley, UK: Emerald Group Publishing.
  7. Wesseler J, Ihle R, Zilberman D (2016). Does Biotechnology Make a Difference? Paper presented at the XXth ICABR Conference, Ravello, Italy, June 26 – 29, 2016.