Generic “Zidua®”
Zidua® herbicide has been registered for use in numerous crops in the United States for over a decade. It is a soil-applied, residual Group 15 herbicide containing the active ingredient pyroxasulfone. When Zidua® was registered for use in U.S. mint, the herbicide registrant (BASF) decided to not allow its use in the Midwestern mint-producing states of Indiana, Michigan, and Wisconsin. In 2024, Anthem® Flex (pyroxasulfone plus carfentrazone) was labeled for use in dormant mint, allowing Midwest mint growers to legally apply a pyroxasulfone-containing product for the first time.
At the recent IR-4 Project Food Use Workshop in September, I spoke with the BASF representative about this topic, and she informed me of one newly registered generic formulation of pyroxasulfone. Upon further review, there are now at least five unique pyroxasulfone products on the market. However, not all of them are created equal. (Note: This article focuses on what this means for mint growers. If you use pyroxasulfone in other cropping systems, you will want to review each label to ensure it is registered for your intended crop — do not just assume that all label language from the Zidua® label will be the same on each generic product label.)
One important difference is that each product has different label restrictions related to the states where the product can be applied. The Zidua® SC label has always excluded Midwestern mint-growing states of Indiana, Michigan, and Wisconsin. Some of the newly available generics follow this same language. NovaliTM explicitly adds Indiana, Michigan, Utah, and Wisconsin, while ZannisTM adds Wisconsin but excludes Indiana and Michigan. The RedEagle pyroxasulfone product does not include any language restricting the use to certain states, allowing it to be used nationwide. I am hopeful the table below will help you sort all of this out.
Also note that there are now three different formulations of pyroxasulfone represented by these products. The RedEagle product is an 85% wettable granule (WG). The others are water-based suspension concentrates, containing either 4.17 or 6.97 pounds of pyroxasulfone per gallon of product. This matters because it affects the product use rate and the mixing order if you plan to apply these products in a tank mix.
Figure 1. Table of five pyroxasulfone herbicide products showing formulation, rate per acre, and availability in eight states (Photo by Steve Meyers).
Two “special” herbicide labels going away
Spartan® 4F received a 24c Special Local Needs label in 2024 for applications to mint after cutting. This “at renovation” 24c label was allowed to expire by the Office of the Indiana State Chemist because the use was recently added to the Section 3 (nationwide) label.
The Anthem® Flex supplemental label that allows for its use on dormant mint will expire in April 2027. As with Spartan® 4F, this supplemental use has been added to the new Section 3 label.
New containers of Spartan® 4F and Anthem® Flex should include the updated labels. For those using older products, the new labels should be kept on file until all old stock is used up.