Classification of herbicides according to chemical family for weed resistance management strategies - an update

There are inaccuracies in the chemical families of the WSSA and HRAC herbicide classification systems which could limit their practical use in herbicide-based weed management strategies. In essence, these inaccuracies could be divided into four parts: (i) the nomenclature of many of the chemical families is not correct, (ii) distinct active ingredients are grouped in same chemical families, (iii) many chemical families have been repeated in at least two modes of action/herbicide groups, and (iv) many active ingredients have not been assigned to chemical family, herbicide group or mode of action. The aim of this study was to revise the current classifications and to propose corrections for the current ones. Detailed investigations on chemical structure of the active ingredients of the registered herbicides showed that some moieties have the same mechanisms of action. According to this study, these moieties have been assigned to the names of chemical families and active ingredients are then classified within the chemical families accordingly. This study has 119 chemical families, compared with 145 in the WSSA system and 58 in the HRAC system. A major priority of this study is the number of active ingredients covered; we included 410 active ingredients with known mechanisms of action and herbicide groups, more than 100 active ingredients more than the current classification systems. Overall, this study provides better opportunities for the management of resistance to herbicides through the application of improved pure and applied knowledge.