The Wisconsin Department of Natural Resources Invasive species law (NR40) established a classification and regulatory system for invasive species restricting actions such as sales, transportation, planting, or releasing listed species to the wild without a permit. While none of these plants classified by the rule have any direct agronomic value as a crop, producers will need to ensure that they are not transporting viable propagules (seeds or perennial tissue that can resprout) of prohibited and restricted species as this is illegal (unless a permit is obtained). While the rule exempts people who incidentally or unknowingly transport, possess, transfer or introduce a listed invasive species, knowledgeable producers must demonstrate that they took reasonable precautions to prevent movement of listed species. An example of this situation would be haying a field filled with listed plants like spotted knapweed or Canada thistle and transporting the bales to another location off farm. Producers can transport plant tissue of these species, but they must be incapable of reproducing/propagating. So harvesting these fields before any viable seeds are produced would be considered an adequate practice to prevent spread by DNR as the producer took steps to prevent movement of propagules of known listed plants.
Soil Science Extension
University of Wisconsin Madison