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Philos Trans R Soc Lond B Biol Sci. 2003 November 29; 358(1439): 1819–1832.
PMCID: PMC1693279

Weeds in fields with contrasting conventional and genetically modified herbicide-tolerant crops. I. Effects on abundance and diversity.


We compared the seedbanks, seed rains, plant densities and biomasses of weeds under two contrasting systems of management in beet, maize and spring oilseed rape. Weed seedbank and plant density were measured at the same locations in two subsequent seasons. About 60 fields were sown with each crop. Each field was split, one half being sown with a conventional variety managed according to the farmer's normal practice, the other half being sown with a genetically modified herbicide-tolerant (GMHT) variety, with weeds controlled by a broad-spectrum herbicide. In beet and rape, plant densities shortly after sowing were higher in the GMHT treatment. Following weed control in conventional beet, plant densities were approximately one-fifth of those in GMHT beet. In both beet and rape, this effect was reversed after the first application of broad-spectrum herbicide, so that late-season plant densities were lower in the GMHT treatments. Biomass and seed rain in GMHT crops were between one-third and one-sixth of those in conventional treatments. The effects of differing weed-seed returns in these two crops persisted in the seedbank: densities following the GMHT treatment were about 20% lower than those following the conventional treatment. The effect of growing maize was quite different. Weed density was higher throughout the season in the GMHT treatment. Late-season biomass was 82% higher and seed rain was 87% higher than in the conventional treatment. The difference was not subsequently detectable in the seedbank because the total seed return was low after both treatments. In all three crops, weed diversity was little affected by the treatment, except for transient effects immediately following herbicide application.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Berger WH, Parker FL. Diversity of planktonic foraminifera in deep-sea sediments. Science. 1970 Jun 12;168(3937):1345–1347. [PubMed]
  • Buckelew LD, Pedigo LP, Mero HM, Owen MD, Tylka GL. Effects of weed management systems on canopy insects in herbicide-resistant soybeans. J Econ Entomol. 2000 Oct;93(5):1437–1443. [PubMed]
  • Champion GT, May MJ, Bennett S, Brooks DR, Clark SJ, Daniels RE, Firbank LG, Haughton AJ, Hawes C, Heard MS, et al. Crop management and agronomic context of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops. Philos Trans R Soc Lond B Biol Sci. 2003 Nov 29;358(1439):1801–1818. [PMC free article] [PubMed]
  • Dewar Alan M, May Mike J, Woiwod Ian P, Haylock Lisa A, Champion Gillian T, Garner Beulah H, Sands Richard J N, Qi Aiming, Pidgeon John D. A novel approach to the use of genetically modified herbicide tolerant crops for environmental benefit. Proc Biol Sci. 2003 Feb 22;270(1513):335–340. [PMC free article] [PubMed]
  • Hails RS. Genetically modified plants - the debate continues. Trends Ecol Evol. 2000 Jan;15(1):14–18. [PubMed]
  • Hawes C, Haughton AJ, Osborne JL, Roy DB, Clark SJ, Perry JN, Rothery P, Bohan DA, Brooks DR, Champion GT, et al. Responses of plants and invertebrate trophic groups to contrasting herbicide regimes in the Farm Scale Evaluations of genetically modified herbicide-tolerant crops. Philos Trans R Soc Lond B Biol Sci. 2003 Nov 29;358(1439):1899–1913. [PMC free article] [PubMed]
  • Watkinson AR, Freckleton RP, Robinson RA, Sutherland WJ. Predictions of biodiversity response to genetically modified herbicide-tolerant crops. Science. 2000 Sep 1;289(5484):1554–1557. [PubMed]

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