In the past few years, some herbicide manufacturers have put a herbicide class number on the product labels.
Increased concern about resistant weeds is the main driver behind the addition of the herbicide class numbers on the label, say Gregory Armel, herbicide technical market manager for BASF, and Ray McAllister, senior director of regulatory policy at CropLife America.
Armel says the development of multiple resistances in waterhemp, Palmer amaranth, Kochia and Italian ryegrass also drive the concern about the site of action and mode of action for herbicides.
In meetings with farmers, he is being asked more about site and mode of action about herbicides.
The idea of the herbicide class number system is products with the same site of action or mode of action are given the same number.
Most of the site of actions for herbicides are known, Armel explains. However, there are some herbicides where the mode of action is known but not the site of action.
"The purpose is to aid growers and applicators in rotating among different modes of action pesticides to delay or avoid the development of resistance," says McAllister.
Armel says the herbicide class number also is designed to be user friendly by being quick and accurate.
The idea of the herbicide class numbers has been around for 10 years, he says. Companies are not required to put herbicide class numbers on their product labels, but it is encouraged by the EPA, Armel adds.
The herbicide class number system was developed through the Weed Science Society Association over several years.
Many companies have a policy of putting the herbicide class numbers on the label the next time they update the herbicide label, McAllister says.
Armel expects to see more companies in the future put the herbicide class numbers on the label.
However, putting the information on the label is one step. The next step is helping farmers and applicators understand what they mean.
Many companies are making education of how to use the herbicide class numbers a higher priority in their producer meetings, McAllister says.
Armel says industry, university and retailers are working to educate farmers and applicators about the system.
