Ask Mr. Smarty Plants

You have our sympathy, Solanum elaeagnifolium (silverleaf nightshade) is a real problem. It is invasive, poisonous, difficult to eradicate and native to North America. What it is NOT, according to this USDA Plant Profile, is native to Michigan. But we believe you, those profile maps are probably not updated very often, and an invasive plant like this can move faster than the research on it. From the page on this plant in our Native Plant Database:

"The lavender, star-shaped flowers with yellow centers are beautifully set off by the silvery foliage, and large patches of the plant in full bloom are striking. However, the plant is an aggressive, poisonous weed, spreading steadily from deep rootstocks; in a few states it is classified as a noxious weed."

According to this University of California Integrated Pest Management website Silverleaf Nightshade, it is reproduced by seed and creeping roots that give rise to bud shoots. That means mowing down the plant before it has a chance to flower and make seeds doesn't mean it can't survive from its roots. And, if it is in your horse pasture, you need to be even more concerned about its poisonous properties. Not knowing what kind of grass you have, we have no idea if it can crowd out the weed, but we wouldn't be optimistic. You might want to read some of the comments from Dave's Garden from people who are already fighting the plant.  One comment said they had "heard" grass would choke it out.

We read through several really mind-bending research papers on this plant, most of them from other countries where they are not welcoming the weed imported from the United States. This article from the Washington State Noxious Weed Control Board is even more discouraging.

We would suggest you contact the Michigan State University Extension office for Allegan County. Our thinking is that no matter what the USDA Profile says, if you have this weed on your property, you can bet other people around you do, too. Possibly the staff at the Extension Office have come up with some sort of plan. We hope so.

From our Native Plant Image Gallery: 

Solanum elaeagnifolium

Solanum elaeagnifolium

Solanum elaeagnifolium

Solanum elaeagnifolium