Understanding modes of action
In 1997, herbicides were organized into different Groups based on their mode of action, or the way they kill weeds. Today, according to the Weed Science Society of America, there are 29 different Groups.
"Tried and true"
methods aren't working like they have in the past.
Herbicide groups often contain several products or brands. Products within the same Group have similar or even identical modes of action. Some groups have many products, others only a few, and some may contain only one herbicide because it has a unique mode of action. A product may contain more than one Group if it contains more than one active ingredient.