Revised Classification of Herbicides by Site of Action for Weed Resistance Management Strategies¹

The classification of herbicides by site of action, published in 1997, has been revised. The classification system uses a numbering system for a herbicide's site of action, chemical family, and common name. Regulatory agencies in the United States and Canada have published labeling guidelines based on the classification to aid in herbicide resistance management.Abbreviations: EPA, Environmental Protection Agency; HRAC, Herbicide Resistance Action Committee; PMRA, Pest Management Regulatory Agency.