Why diversifying herbicide sites-of-action is key to herbicide long-term effectiveness When weeds produce seeds, there is a chance through naturally occurring genetic mutations that some individuals may be better able to survive the label rate of a particular herbicide active ingredient, while individuals without that mutation do not survive. Herbicide-resistant individuals will consequently be the only ones in the emerged population exposed to the herbicide to survive to produce seeds of their own. Over time, if the same herbicide is repeatedly used without further diversifying the number of herbicide sites-of-action to which weeds are exposed, the field's population will shift from one that is primarily sensitive to (and able to be controlled by) the herbicide to one that is primarily herbicide-resistant. Tank mixing herbicides from multiple, still effective herbicide sites-of-action increases the chances that those individuals that are resistant to one site-of-action...
