12.7 Classifying Herbicides: Mode of Action

Mode of Action is defined as how a particular herbicide acts on a plant. Currently there are ten modes of action, listed below.  Notice that most of these modes of action deal with regulation or inhibition of plant functions. The ‘Undefined’ herbicides do not fit into any of the other groups.   For these it is not yet known exactly how they injure plants. Fortunately, there are very few herbicides listed with an undefined mode of action.