Earlier this year, FMC released a supplemental label for Anthem® Flex herbicide that includes additional uses for potatoes and mint. Anthem® Flex is a premix product containing pyroxasulfone (the active ingredient in Zidua® SC) and carfentrazone (the active ingredient in Aim® EC). Carfentrazone, a postemergence contact herbicide, is registered for use in Indiana for both potatoes and mint. Pyroxasulfone, a soil-applied preemergence herbicide, is registered for use in both potatoes and mint, but its use in mint is restricted to the Northwestern states of Idaho, Montana, Oregon, and Washington. In Indiana, this supplemental Anthem® Flex label represents the first registered use of a pyroxasulfone product in peppermint and spearmint.
In 2021 and 2022, we applied 4.5 fluid ounces of Athem® Flex per acre to dormant peppermint on mineral soils with no meaningful injury to the crop. Weed control varied from 79 to 90% control 1 week after treatment but increased to 95 to 98% by 6 weeks after treatment (Figure 1). In those trials, Anthem® Flex provided significantly greater weed control than Zidua® SC alone. In our trials, Athem® Flex applications included spray-grade ammonium sulfate (AMS) and methylated seed oil (MSO).
Figure 1. Peppermint 6 weeks after being sprayed with 4.5 fl oz/a of Anthem® Flex herbicide (bottom) compared to a non-treated control (top) at Fair Oaks, IN (Photos by S.L. Meyers).
The new supplemental label allows for a single application of 3.5 fl oz/a of Anthem® Flex to dormant, healthy, established mint. The label prohibits its use on mint grown on soils classified as sand. Anthem® Flex may be applied to potatoes after planting and before emergence at rates of 3.5 to 6.0 fl oz/a, depending on soil texture. Do not apply Athem® Flex on soils with less than 1% organic matter. Before the supplemental label, plant back interval restrictions were 4 months for mint and 0 months for potatoes.
This is not an endorsement of Anthem® Flex herbicide or its component herbicides. As with any new product or practice, adoption on the farm should be gradual until you have a sense of how it fits with your individual production system. The supplemental Anthem® Flex label can be found here: https://www.cdms.net/ldat/ldC07001.pdf. To explore other weed management options for potato and mint, visit the Midwest Vegetable Production Guide website at https://mwveguide.org/.