Ask Mr. Smarty Plants

Mentha arvensis (wild mint) is one of the very few mints native to North America and the mints, can, indeed be invasive. Your sheep and goats are smart not to eat it. From the Conditions Comments on our Native Plant Database page on this plant:

"Warning: The fruit of this plant is toxic and may be fatal if ingested in large quantities. It is especially dangerous to children, who may mistake the fruit for grapes. Sensitivity to a toxin varies with a person’s age, weight, physical condition, and individual"

The plant is native not only to Ohio but to the area in and around Harrison County, so you are kind of stuck with it. It likes moist conditions and part shade. The Lady Bird Johnson Wildflower Center recommends neither for nor against herbicides, and in this case, that would be difficult. You would have to spray the whole field with a broad-leaf plant, or dicot, herbicide, hoping to preserve the grasses, or monocots, that the livestock could actually graze on. To do that, you would probably have to remove your stock to some other location, and you could never be absolutely sure you had eradicated the wild mint. This problem is the kind of thing that state agricultural universities are trained to handle, and you can contact some experts through the Ohio State University Extension Office-Harrison County. Since this plant is both native to your area and invasive, as well as having poisonous parts, this is surely not the first time the Extension Office has dealt with the problem. Hopefully, they will be prepared to offer you a solution you can work with.

From our Native Plant Image Gallery

Mentha arvensis

Mentha arvensis

Mentha arvensis