Dealing with burdock

We don't have a lot of burdock at Pleasant Valley Conservancy, but it is such a nasty plant that we give it careful attention.

Burdock, also called bardane, beggar's button, lesser burdock, wild burdock, or wild rhubarb, is Arctium minus. According to the UW-Madison Herbarium web site, it is an introduced and ecologically invasive biennial. It is found in every one of the 48 states, and in some of these states it is classified as a noxious weed. Some sources state that burdock may be native in some parts of its range.

Burdock forms a rosette of very large basal leaves. There is practically no root system in first-year plants so that digging is problematic at that time. Second-year plants have a thick tap root that runs deep into the ground. In its second year it sends up a long somewhat leafy flower stalk, with thistle-like flowers. Its fruits are large, sticky burs. According to one site: "Don't get to close to the plant as the fruiting heads grab onto nearly everything." (According to one source, these burs were the inspiration for Velcro!)

At Pleasant Valley Conservancy we have burdock in only two locations: the marsh south of the Barn Prairie; and on the small knoll among white oaks in Unit 13. These two sites are quite different ecologically and it is not clear why burdock has been only established here.

Some years ago we tried digging plants with a shovel but discovered that we never eradicated them in that way. Apparently, root fragments could send up new shoots the following year. We finally turned to herbicide. Presumably any broad-leaf-specific herbicide would work, but since we use Garlon 3A as a foliar spray for brambles, etc., we are using that.

Our goal is to deal with this plant in its first year, so that burs are never made. Occasionally, we miss one and find it only when pushing through tall foliage and find burs attached to a sock or pant leg.

Yesterday I spent about an hour spraying burdock plants in the wetland at the edge of the Barn Prairie. This was an area that had burned completely during the Fish & Wildlife Service burn of two weeks ago, and most of the surface vegetation had been consumed. About the first plant to reappear was burdock, and I counted over 200 plants, both small and large. This was ideal spraying, as there was practically nothing else present, so I did not have to worry about peripheral damage. The photo to the left shows two sprayed leaves.

The infestation in this area was extensive, with leaves of varying sizes, even including seedlings still at the cotyledon stage. I sprayed them all.

I am trusting that eventually we will be able to eradicate burdock, since the patch we had at the edge of the Barn Prairie, sprayed for the past 4-5 years, now seems to be gone.