Repeated use of herbicides with the same site of action can result in the development of herbicide-
resistant weed populations.
Simplify the chore of rotation by using the numbers that are conveniently located on most herbicide labels. Look for the box labeled "herbicide group." Generally, rotating these groups and using multiple target site groups delays the selection of herbicide-resistant weeds.
Premixes containing more than one site of action will have multiple numbers listed. It’s an easier way to keep track of what is included in those premixes, too.