Influence of herbicide-resistant canola on the environmental impact of weed management.
The growth of herbicide-resistant canola varieties increased from 10% of the canola area in Canada in 1996, when the technology was first introduced, to 80% in 2000. From 1995 to 2000, the amount of herbicide active ingredient applied per hectare of canola declined by 42.8% and the Environmental Impact (EI) per hectare, calculated using the Environmental Impact Quotient for individual herbicides and the amounts of active ingredients applied, declined 36.8%. The amount of herbicide active ingredient per hectare applied to conventional canola was consistently higher than that applied to herbicide-resistant canola each year between 1996 and 2000. Similarly, the EI of herbicide use per hectare in conventional canola was higher than that of herbicide-resistant canola during the same time period. Since 1996, herbicide use has shifted from broadcast applications of soil-active herbicides to post-emergence applications of herbicides with broad-spectrum foliar activity. The decline in herbicide use and EI since the introduction of herbicide-resistant varieties was due to increased use of chemicals with lower application rates, a reduced number of applications and a decreased need for herbicide combinations.
Brimner
Theresa A
TA
Department of Botany, University of Guelph, Guelph, ON, Canada.
Gallivan
Gordon James
GJ
Stephenson
Gerald R
GR
D000383:Agriculture / Q000379:methods; D029688:Brassica napus / Q000187:drug effects*; D029741:Brassica rapa / Q000187:drug effects*; D002170:Canada; D004351:Drug Resistance; D004784:Environmental Monitoring; D006540:Herbicides / Q000494:pharmacology*; D013997:Time Factors
D006540:Herbicides