A decade of herbicide-resistant crops in Canada

Abstract

-J. 2006. A decade of herbicide-resistant crops in Canada. Can. J. Plant Sci. 86: 1243-1264. This review examines some agronomic, economic, and environmental impacts of herbicide-resistant (HR) canola, soybean, corn, and wheat in Canada after 10 yr of growing HR cultivars. The rapid adoption of HR canola and soybean suggests a net economic benefit to farmers. HR crops often have improved weed management, greater yields or economic returns, and similar or reduced environmental impact compared with their non-HR crop counterparts. There are no marked changes in volunteer weed problems associated with these crops, except in zero-tillage systems when glyphosate is used alone to control canola volunteers. Although gene flow from glyphosate-HR canola to wild populations of bird's rape (Brassica rapa L.) in eastern Canada has been measured, enrichment of hybrid plants in such populations should only occur when and where herbicide selection pressure is applied. Weed shifts as a consequence of HR canola have been documented, but a reduction in weed species diversity has not been demonstrated. However, reliance on HR crops in rotations using the same mode-of-action herbicide and/or multiple in-crop herbicide applications over time can result in intense selection pressure for weed resistance and consequently, greater herbicide use in the future to control HR weed biotypes. History has repeatedly shown that cropping system diversity is the pillar of sustainable agriculture; stewardship of HR crops must adhere to this fundamental principle. L'adoption rapide du canola et du soja RH laisse croire que les agriculteurs y trouvent un net avantage économique. Les cultures RH ont souvent facilité la lutte contre les mauvaises herbes, accru le rendement ou les revenus tout en ayant un impact similaire voire plus faible que les cultures qui ne le sont pas sur l'environnement. On ne remarque pas de changement marqué au niveau de la repousse spontanée des adventices avec ces cultures, sauf dans les systèmes de non-travail du sol où l'on n'utilise que du glyphosate pour combattre la repousse spontanée du canola. Bien qu'on ait mesuré la transmission de gènes du canola résistant au glyphosate aux populations sauvages de navette (Brassica rapa L.) dans l'est du Canada, l'enrichissement de ces populations par des hybrides ne survient que si l'herbicide accentue la pression sélective. La littérature scientifique cite des cas où la population d'adventices change consécutivement à la culture de canola RH, mais on n'a pu démontrer l'appauvrissement de la diversité des espèces. Employer des cultures RH dans les assolements où l'on recourt à des herbicides ayant le même mode d'action ou applique une multitude d'herbicides peut néanmoins déboucher avec le temps sur une intense pression sélective qui favorisera les adventices plus résistantes, ce qui nécessitera éventuellement un usage plus intense d'herbicides pour lutter contre les biotypes RH. L'histoire a montré à maintes reprises que la variété des systèmes agricoles est la pierre angulaire ...

Monitoring the occurrence of genetically modified oilseed rape growing along a Japanese roadside: 3-year observations

“…Spontaneous occurrence of GM oilseed rape in Japan Beckie et al (2006) estimated that in 2005 over 80% of the oilseed rape area in Canada was devoted to herbicideresistant crops, most of which was the glyphosate-and glufosinate-tolerant varieties. Hence, it has been estimated that over 60% of the oilseed rape seeds imported into Japan have one of two herbicide-resistance genes (for glyphosate and glufosinate).…”

Nonconventional Weed Management Strategies for Modern Agriculture

“…Major transgenic traits introduced in crops are herbicide resistance, insect resistance, virus resistance, and stress resistance. However, HT crops comprise the vast majority (83%) of genetically modified (GM) crops (Beckie et al 2006). The reason behind the introduction of HT crops and their rising acceptance is primarily due to the effective weed control.…”

“…However, about 90% of the global GR canola production is in Canada (Gianessi 2005). HT soybean is the most prevalent, where around 60% of the total production is transgenic crops (Beckie et al 2006). Nontransgenic HT corn, canola, wheat, soybean, sunflower, and sorghum developed in the past were tolerant to imidazolinones, photosystem II inhibitors, and sulfonylureases (Green 2012).…”

“…Biotechnology has provided successful HT crops that are tolerant to glyphosate, glufosinate, bromoxynil, imidazolinone, and dicamba (Gealy et al 2003;Givens et al 2009). HT crops like cotton, corn, canola, rice, sugar beet (Beta vulgaris L.), alfalfa (Medicago sativa L.), brassica, and soybean (Gealy et al 2003) have revolutionized weed management in the United States (Givens et al 2009), Canada (Beckie et al 2006), Australia (Duke and Powles 2009) and many other countries.…”

“…The practical implications, latest scenario, future research needs, and the scope of allelopathy in integrated weed management strategies have been thoroughly discussed in this review. Different reviews have concluded that the development of herbicide-tolerant crops has revolutionized the crop production in many regions (Beckie et al 2006;Dill et al 2008;Duke and Powles 2009;Green 2012). Although biological weed management is not a panacea under prevailing conditions, it has a great potential (Ash 2010;Charudattan 2001Charudattan , 2005Hallett 2005).…”