The article in the New York Times (D Hakim) claims to have extensively examined the impacts of GM crops in the USA and Canada and concluded that the technology has not ‘accelerated increases in crop yields’ or 'reduced use of chemical pesticides.'
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
There are numerous factors that affect yield such as weather, soil quality, husbandry practices, use of inputs such as fertilisers, pesticides and seeds, knowledge and skills of farmers, price of inputs, effectiveness of existing technology to control pests, diseases and weeds, etc. 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 (IR) technology (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.
Hakim mainly uses a comparison of GM HT canola (rapeseed) yields in Canada and non-GM rapeseed yields in Western Europe (also GM HT sugar beet from the US 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 crops 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, Hakim is making spurious comparisons that lack context and will mislead readers.
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, etc).
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 Hakim article fails on both counts and therefore misleads. The consistent evidence identified in GM crop studies (references, 2, 3, 4 and 5) 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
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 www.tandfonline.com
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 US 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 US maize and soybeans, Sci Adv, 2016, 2,
Agricultural Economist with PG Economics UK. www.pgeconomics.co.uk - he has been analysing the
impact of GM crop technology around the world for 18 years and is the author of 22 peer reviewed
papers on the economic and environmental impact of GM technology