Crown Vetch is not native, and it’s been extensively planted along roadsides for erosion control.  It spreads quickly, and overwhelms native plants.

 

One good thing about Crown Vetch is that it supports a native butterfly.  Wild Indigo Duskywings were becoming less common because of loss of their caterpillar food plants: shrub legumes including Wild Indigo and Lupine.  Now the caterpillars have adapted to eating Crown Vetch, and the butterflies are becoming more common.

Still, I’d like to get rid of it here.  Fortunately we don’t have it in very many places.  The worst infestation is a former crop field near the creek, just south of Willow Bend, that we call Crown Vetch Meadow.  When we first saw that field it was dominated by Crown Vetch.

Crown Vetch Meadow – July 2023

 

There are also a few nearby spots – next to the creek – where there are a few Crown Vetch plants growing up through the Reed Canary Grass.

The other bad spot we have is at the south end of Western Prairie – a much drier site.  There’s a circle of Crown Vetch that’s about 25 feet (very approximate) in diameter.  I don’t often see that area when the plants are blooming, so it’s been easy to ignore.

I’ve tried several approaches to Crown Vetch Control, but I’ve never worked very hard at it so it still grows in all those places.

— I (foliar) spot spray with Milestone + water + surfactant.  That kills the plants, but there are so many of them, and so many seeds still in the ground that they keep coming back.  And Milestone persists in the soil for a long time, so I suspect it prevents natives from growing.

— We mowed Crown Vetch Meadow in 2023 and had it sprayed with glyphosate later in the fall.  That winter I planted wet prairie seeds.  Crown Vetch has still come up, but there’s less of it, and it’s less dense, so I think it’s been somewhat crowded out by the natives.

— I’ve tried squirting the roots of each plant with Garlon + bark oil, then cutting off and removing the plants.  This method is very slow, but seems to work well.  I did some of this on the steep banks of Crown Vetch Meadow that go down to the creek – since I couldn’t foliar spray there.  And I’m trying it on the circle in Western Prairie.

I think control will require more careful surveillance and follow-up than I’ve done so far.  I hope eventually I’ll be able to get rid of it.