Curly Dock Control – How To Kill Curly Dock Plants In The Garden
We’ve probably all seen it, that ugly, reddish brown weed that grows alongside roads and in roadside fields. Its red-brown color and dried out, shaggy appearance makes it look like it’s been heavily doused with herbicides or burned. From the look of it, we expect it to wilt over dead or crumble to ash any second, yet it persists in this dead-looking stage, sometimes even poking its dried brown tips right through snow banks of winter. This ugly weed is curly dock, and when the plant is in its mature reddish brown phase, it isn’t dead; in fact, curly dock can seem nearly impossible to kill.
Curly Dock Control
Curly dock (Rumex crispus) is a perennial native to Europe, Asia, and parts of Africa. In its native range, different parts of curly dock are used as food and/or medicine. However, outside of this range it can be a problematic, aggressive weed.
Also known as sour dock, yellow dock, and narrowleaf dock, one reason controlling curly dock weeds is so hard is because plants may bloom and produce seeds twice a year. Each time, they may produce hundreds to thousands of seeds which are carried on wind or water. These seeds can then lie dormant in the soil for 50 years or more, before germinating.
Curly dock weeds are one of the most widely distributed weeds in the world. They may be found along roadsides, parking lots, pastures, hay fields, crop fields, as well as in landscapes and gardens. They prefer moist, regularly irrigated soil. Curly dock weeds can be a problem in pastures, as they can be harmful, even toxic, to livestock.
In crop fields, they can also be a problem but specifically in no-till crop fields. They are rare in tilled crop fields. Curly dock weeds also spread underground by their roots, forming large colonies if left unchecked.
How to Kill Curly Dock Plants in the Garden
Getting rid of curly dock by hand pulling is not a good idea. Any part of the root that is left in the soil will only produce new plants. You also cannot employ animals to graze on curly dock as a control because of the plant’s toxicity to livestock.
The most successful methods of controlling curly dock are mowing it down regularly, where applicable, and the regular use of herbicides. Herbicides should be applied at least twice a year, in spring and fall. For best results, use herbicides containing Dicamba, Cimarron, Cimarron Max, or Chaparral.
General description: Basal rosette of elongated leaves (up to 12 in long) with wavy margins. Leaves are a dull green. Flowering stem has a few leaves and reaches heights of 3 ft. Flowers have green sepals; mature into brown, 3-sided winged structure surrounding the achene.
Key ID traits: Rosette of wavy, elongated leaves. Leaves of rosette have large, ‘slimy’ ochrea usually positioned below the soil line. Flower stalk with clusters of winged achenes. Achenes turn dark brown when mature.
Similar species: There are several closely related Rumex species similar in appearance to curly dock. The wavy leaf margin is the key vegetative trait to identify curly dock. Pale dock (Rumex altissimus) has similar shaped leaves, but leaves are glossy and don’t have the wavy margin. Broadleaf dock (Rumex obtusifolius) leaves are approximately half was wide as they are long, whereas curly and pale dock leaves are much narrower.
Miscellaneous: A native of Europe, curly dock was first observed in North America in the 1700s.
Curly dock produces a rosette of elongated leaves with wavy leaf margins in the spring.
As the stem elongates large ochreas are visible surrounding the leaf petioles.
Curly dock produces dense panicles, seed have small wings and turn dark brown when mature.
Pale/sour dock has a similar growth habit as curly dock, but the leaf margins are smooth rather than wavy.
Curly dock, Rumex crispus L., is a robust perennial with a deep, fleshy taproot that is native to Europe and parts of Africa and Asia. The plant initially forms a basal rosette of lance-shaped leaves; it later bolts, sending up an erect flower stalk that can reach 5 feet in height. The flower stalk(s) may arise singly or in small groups from the root crown and are typically unbranched below the flower head; they are hairless, sometimes ridged, stout and hav e swollen joints (nodes). The leaves of curly dock are mostly basal; they are long and linear, hairless, petioled, alternately arranged, and have a prominent midvein and distinctly wavy or “crisped” margins. At each node at the leaf base is a characteristic membranous sheath (ocrea) that encircles the stem. Stem leaves become progressively smaller up the stem. The flowers of curly dock occur in panicles or clusters on the upper stems; the flowers are non-showy, without petals (apetalous), and consist of green sepals that, like the rest of the plant, turn reddish-brown at maturity and remain conspicuous through winter. Each flower matures into a dry fruit—a papery, 3-winged membranous structure with veins that encloses a single reddish-brown, triangular seed. The membranous wings of the fruit are readily dispersed by wind and water. Under good growing conditions, a single plant can produce up to 60,000 seeds, some of which germinate readily, while a large percentage remain viable in the soil for 3 years—and some much longer. While curly dock primarily reproduces and spreads by seed, it can also resprout from root fragments. While some plants flower and die in a single season, others live 3–5years.
Curly dock differs from Broadleaf Dock (Rumex obtusifolius), which has wider, broader leaves and normally has heart-shaped leaf bases. Also, the winged structure enclosing the fruit is irregularly toothed. Photos below for comparison.
Curly dock is found throughout the U.S. and across the rest of the World (all continents). It primarily occurs as a weed of pastures, agronomic crop fields (particularly perennial crops like alfalfa), ditches, roadsides, and waste areas. Curly dock favors wet soil and is often found in poorly-drained or low-lying areas of standing water or where overwatering has occurred.
While curly dock is a valuable food source for the caterpillars of many butterflies, its seeds and foliage can be toxic to animals. The plant is also an alternate host for a number of viruses, fungi, and nematodes. Its greatest impact, however, is its interference with native habitats and competitiveness with crops and native plants for nutrients, sunlight, and space.
Cultural Control: All exotic docks are difficult to control because of high seed production, long-lived seed banks and the ability to regenerate from root segments. They do not, however, tolerate crowding by more vigorous species or tillage. Infestations in perennial crops can be reduced by shifting to annual crops that need or tolerate a tilled cropping system.
Mechanical/Physical Control: For small populations of young plants, a spade or shovel can be used to dig out the plant—removing as much of the root system as possible. For more mature populations, plants can be eradicated by continually removing above-ground growth in order to exhaust the energy supply stored in the plants’ roots. Mowing before seed set will prevent seed production but will not control dock unless it is routinely repeated or is combined with another control option, i.e., chemical control. While curly dock does not tolerate regular tillage, tillage practices can result in root fragmentation and regeneration.
Chemical Control: Several chemicals (or combinations thereof) are available for control of curly dock: metsulfuron, chlorsulfuron, glyphosate, clopyralid, aminopyralid, triclopyr and 2,4-D. Post-emergent herbicides should be applied to actively growing plants in the spring and early summer; however, once curly dock becomes established, fall applications work best. Curly dock in alfalfa is difficult to control and must be treated when it is a seedling with different pesticides than those listed above (except glyphosate).
More information can be found in the PNW Weed Management Handbook