Herbicide-Resistant Crop Management: A Canadian Perspective

Introduction In 2014, the top five genetically modified (GM) or transgenic crop producers were the United States, Brazil, Argentina, India, and Canada, together accounting for 90% of the global area of these crops (James, 2015). The United States has 40% of the area; Brazil, 23%; Argentina, 13%; India, 6%; and Canada, 6%. Although GM cultivars of 11 crops have been released, 4 crops cover 99% of the GM crop area. Soybean (Glycine max L. Merr.), corn (Zea mays L.), and cotton (Gossypium hirsutum L.) are the main GM field crops grown in the US, whereas soybean dominates the cultivated area in Brazil and Argentina. In Canada, canola (Brassica napus L.), soybean, and corn are the main GM crops, while cotton is the only GM crop grown in India. Herbicide resistance (HR) is still the dominant trait in GM crops (86% of total), 20 years after their introduction. Single-trait HR cultivars account for 58% of GM crop area, single-trait Bacillus thuringiensis (Bt), for 14%, and stacked traits (HR+Bt), for 28%. In Canada, the adoption rates of GMHR canola, corn (grain), and soybean in 2014 were 98, 91, and 80%, for total cultivated areas of 8.08, 1.23, and 2.24 million ha, respectively. Canola is mainly grown in western Canada, in contrast to corn and soybean, which are mainly grown in eastern Canada.