GM winter oilseed rape disrupts environment

GM winter oilseed rape disrupts environment

UK government-funded field trial plantings of genetically modified oilseed rape show adverse environmental effects, leading to more doubts on GM crops.

Chee Yoke Heong

THE latest and final findings of UK Farm Scale Evaluations of genetically modified herbicide-tolerant crops in March show that weed balance in the fields can be disrupted, causing harm to bees and butterflies1.

The FSEs were established because of concerns that the introduction of GM herbicide-tolerant crops could have negative impacts. The UK government funded the largest known field trials ever conducted in the world, and these were carried out over three years at a cost of US$11 million, to investigate the environmental impacts of GM herbicide-tolerant crops.

The results for three of these crops – spring-sown oilseed rape, beet and maize – were published in October 2003. Those trials found that growing GM spring-sown oilseed rape (also known as canola) and beet had a greater negative effect on wildlife than growing their conventional counterparts. The trials for maize showed the opposite, but those findings have since been called into question.

The final and fourth farm scale trials looked into the potential impact of commercial growing of genetically modified herbicide-tolerant winter-sown oilseed rape in the UK.

In the last FSE, the results of which were published in the Proceedings of the Royal Society B: Biological Sciences, researchers compared GM winter-sown oilseed rape with a conventional non-GM version of the crop. The research was conducted by an independent consortium of research institutes and the work overseen by a Scientific Steering Committee. Sixty-five fields were sown with winter oilseed rape. Each field was split, one half sown with a conventional variety managed according to the farmer’s normal commercial practice for weed control, the other half sown with a GM herbicide-tolerant variety, with weeds controlled by a broad-spectrum herbicide called glufosinate-ammonium. Comparisons in biodiversity were made by looking at the levels of weeds and invertebrates, such as beetles, butterflies and bees.

The latest findings showed that growing GM winter oilseed rape has a more severe impact on weed management and farmland wildlife than its conventional counterpart.

Effects on weeds

There were similar total weed densities in both GM and conventional winter oilseed rape fields, with little difference in the total amount of weeds. However, it was observed that there were significant differences in the abundance of different types of weed.

There were fewer broad-leaved flowering weeds, and their seeds, in fields where the GM herbicide-tolerant oilseed rape were grown.

At harvest time, the amount of broad-leaved flowering weeds and the number of their seeds in the GM crop were one-third of those in the conventional plots after farmers applied herbicide to the GM crop. Flowers of broad-leaved weeds are important because they provide food for insects while seeds are a crucial food source for other wildlife.

On the other hand, grass weeds were three times higher in the GM crop thanin the conventional plots, with five times as many of their seeds as in the conventional. These effects were observed in the year of cropping and persisted in the following two years that data were collected.

More grass weeds in the GM crop than in conventional plots and some soil insects were discovered in the GM fields. Although more grass weeds are beneficial for wildlife, they pose a problem to farmers.

Effects on insects

There were fewer bees and butterflies in the GM crop compared with the conventional oilseed rape. After the crop had flowered, there were half the number of bees and two-thirds the number of butterflies found foraging in the GM crop areas, compared to the conventional. There were more butterflies and bees in the conventional winter oilseed rape plots because there were more broad-leaved flowering weeds.

Also, consistent with previous FSE results reported for spring-sown crops, the yearly totals for springtails, a type of detritivore which feeds on dead and decaying weeds, were higher in the GM crop areas.

For the majority of other invertebrate species, there was no significant difference between the GM and conventional herbicide regimes.

The results on the winter oilseed rape have been passed to the UK Government’s statutory advisory body – the Advisory Committee on Releases to the Environment.

European governments already say ‘No’

Meanwhile, many European governments are also reported to have voiced their objections to the application by biotech giant, Bayer, to grow GM winter oilseed rape. Friends of the Earth (FOE) discovered that 23 out of 25 EU countries, including the UK, objected because of concerns about the impact on the environment and human health. Comments compiled by FOE are as follows:
* UK: ‘The UK Competent Authority agrees that on the basis of the information provided in the dossier [application] approval for cultivation should not be granted.’
* Austria: ‘No data/studies at all on possible effects on human health are provided.’
* Belgium: Controlling gene flow will be ‘impracticable, hardly workable, and hard to control’.
* France: ‘. the French Food Safety Agency considers that the safety of genetically modified rape Ms8xRf3 from the health point of view cannot be guaranteed.’
* Poland: ‘. granting any consent for growing this species in EU territory would be inappropriate.’
* Slovenia: ‘. the gene flow from a cultivation could not be managed satisfactorily, so [as] to ensure existence of all different agricultural practices in EU, including organic farming. In the same way the geneflow to wild relatives would be impossible to prevent.’
* ltaly: ‘The Italian National Competent Authority agrees that no authorisation should be granted for the cultivation of the product under notification C/BE/96/01.’
* Norway: ‘. we will not support consent for this notification if it is to cover cultivation.’
* ‘Sweden retains objection to the cultivation of this oilseed rape.’

FOE has also discovered that Bayer has told the EU that it wants to withdraw its application to grow the GM winter oilseed rape. The UK Department for Environment, Food and Rural Affairs has told FOE that Bayer applied to the European Commission to ‘reduce the scope of the application to import and processing’ for use in food and animal feed.

The UK is perhaps the country that has most actively engaged the public in the debate over GMOs due largely to a high level of concern from the public as well as the scientific community.


1 Effects on weed and invertebrate abundance and diversity of herbicide management in genetically modified herbicide-tolerant winter-sown oilseed rape by DA Bohan, CWH Boffey, DR Brooks, SJ Clark, AM Dewar, LG Firbank, AJ Haughton, C Hawes, MS Heard, MJ May, JL Osborne, JN Perry, P Rothery, DB Roy, RJ Scott, GR Squire, IP Woiwod and GT Champion. The report is freely available online at:



From weed management to weed creation

AS the debate over genetically modified crops continues, the commercial planting of herbicide-tolerant crops has increased the most over the last few years. Published figures show that more than 52 million hectares of GM crops are planted worldwide. Of these, 41 million hectares are herbicide-resistant crops, which include an estimated 33.3 million hectares of herbicide-resistant soybean alone. Other crops engineered for herbicide tolerance and commercially planted are maize, canola and cotton.

Sugarbeet, wheat, and 14 other crops with GM herbicide-resistant cultivars are reportedly available but applications for their commercialisation are expected to be mired in controversies.

Meanwhile the management of weeds remains trapped in the use of chemicals. The heavy use of chemical herbicides, and now GM herbicide-resistant crops with their continuing use of those same chemicals, creates a perpetual chemical trap with new problems.

There are many risks associated with the production of GM and herbicide-resistant crops including problems with grain contamination, segregation and introgression of herbicide-resistant traits, marketplace acceptance and an increased reliance on herbicides for weed control.

These were the findings of a comprehensive study by Michael Owen and Ian Zelaya of Iowa State University (US) and published in the journal Pest Management Science (2005).

They found, in particular, that the widespread adoption of herbicide-resistant cultivars, particularly glyphosate-resistant crops, has had a dramatic impact on weed communities. There are weed population shifts to naturally resistant species and to species with inherent biological characteristics that make the weed populations difficult to manage.

The evolution of herbicide-resistant weed populations is also real, and this can be linked to the herbicide-resistant crop/herbicide use programme. Examples of herbicide-resistant weeds include populations of horseweed resistant to glyphosate.

Another problem is that the herbicide-resistant crops themselves evolve into volunteer weeds.

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