Evil Weed

Have you seen this viney plant growing at the edges of mowed areas or sprouting in disturbed areas?

THIS IS EVIL WEED!!!

That's black swallow wart, an alien invasive from Spain / Italy that has taken root in the eastern United States over the last ten years.

This plant spreads by both rhizome and seed. It grows vigorously when in full sun, climbing and smothering other plants. And here and in the North East, it has no natural predator.

Black Swallow Wart is very difficult to destroy because of its vigor, ability to smother other plants and develop from cut roots.

Black Swallow Wart is in the same family as Milkweed, and has a similar toxin that discourages browsing animals from controlling it. Worse, it attracts native insects that do eat milkweed mistake it for milkweed and lay there eggs there, but the larva cannot survive eating Black Swallow Wart.

BSW has small dark flowers in July and develops seed pods in August. If those pods are allowed to mature, they will spread on the wind by the thousands.

Mowing the plants in late July helps to prevent the spread by seed, but it does not control the plant. It will spread by rhizome.

We are trying to control ours through weeding, smothering and cutting. We have not been at it long enough to know if we are having any success. I suspect that given the pervasiveness of this plant on our land, it will always be a problem for us that takes continual maintenance. But hopefully we can gain some control over it and recover some productivity of our land.