How to Identify and Remove Yellow Dock

Invasiveness of Yellow Dock

While the plant’s hardiness range is commonly listed as USDA zones 4 through 8, it is found almost anywhere in the United States even in warmer climate zones and in Alaska. This widespread distribution is not surprising, as yellow dock is native to Africa, temperate and tropical Asia, as well as Europe.

Yellow dock often tolerates poor, disturbed soils although it prefers to grow in rich, loamy soils in full sun and with adequate water. It often grows in overwatered soils or areas of standing water and in irrigation ditches. It is equally found along roadsides and in wasteland, on cultivated farmland, and in pastures, creating a problem because yellow dock is not only toxic to pets but also toxic to cattle and sheep.

Each plant produces between 40,000 and 60,000 seeds depending on the source, and they are dispersed from late summer through the winter. This huge number of seeds is combined with their extreme viability—seeds survive in undisturbed soil for more than 50 years. Where yellow dock spreads, it chokes out crops and native plants, depriving them of nutrients, sunlight, and space.

Another problem of yellow dock is that the plant is an alternate host for several crop diseases caused by viruses, fungi, and nematodes.

What Does Yellow Dock Look Like?

Yellow dock belongs to the buckwheat family, which is identified by the nodes that punctuate the plant’s stems. Young seedlings are either entirely green or take a red tinge in cooler months. Mature plants have dark green leaves or bluish-green leaves. The bottom leaves are quite long, ranging from 1/2 foot to 1 foot in length. Look, in particular, for the sword-like shape and the curled or wavy edges of the foliage. As the leaves age, they become reddish-purple.

The distinct flower head of the plant that remains after the blooms have dried and turned reddish-brown is helpful for the identification of yellow dock. The flowers start out a much less distinctive light-greenish color (they sometimes have a reddish tinge, too). Blooming occurs in clusters in the form of multiple, long, skinny flower stalks at the top of the plant.

Another aid in identifying the plant is its height. The plant reaches as much as 4 feet tall at maturity.

The fleshy, smooth stems with a reddish color die back in the fall. Yellow dock has a large, deep taproot that is yellowish-orange in color.

How to Get Rid of Yellow Dock

As long as the plant is small, you can dig it out with a shovel or a spade. Hand-pulling is not a good option because the long taproot will likely rip and the plant regrows from any root segments.

Removing mature plants with their entire tap root is challenging. Instead of trying to dig it out, cut any vegetative growth repeatedly starting in the spring in order to gradually exhaust the plant’s energy reserves. Once the plant is weakened, it will still need to be treated with an herbicide such as glyphosate, clopyralid, triclopyr, or 2,4-D to eradicate it. If you are dealing with a large infested area, mowing it repeatedly weakens the plant. 

Yellow dock does not do well when it has to compete against other vigorously growing plants so after you remove it, replant the area promptly. Given the large number of seeds of yellow dock and their long viability, there will likely still be seeds in the soil but the presence of other plants or crops will make the reemergence of yellow dock less likely.

How to Prevent Yellow Dock from Spreading

Cutting down yellow dock before it starts its long flowering period, which stretches from June into September, is the most important thing you can do to prevent its spread.

How to Tell the Difference Between Yellow and Broadleaf Dock

Broadleaf dock (Rumex obtusifolius) is a related weed that also grows to be as much as 4 feet tall. It is easy to tell the two apart: True to its name, the broadleaf type has bottom, or “basal” leaves that are very wide (4 inches across, versus 1 inch across for yellow dock plants). Curly dock has basal leaves shaped like swords, the basal leaves of its broadleaf dock are shaped more like shields.