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Ministry of Agriculture, Food and Rural Affairs

Wild Buckwheat

Scientific Name: Polvgonum convolvulus L.

Other Names: renouée liseron, Black bindweed, Climbing bindweed, Corn bindweed, faux liseron, sarrasin sauvage

Family: Pink Family (Caryophyllaceae)

General Description: Annual, reproducing only by seed.

Habitat: Wild buckwheat is a common weed in cultivated fields and gardens throughout all of Ontario and its "seeds" frequently contaminate small grains.

Seedlings

  • Seedling cotyledons oblong and entire

Stems

  • 5 cm (2 in.) to more than 2 m (80 in.) long
  • Slender
  • Prostrate or twining vine-like over other plants or any available support
  • Short ocrea (membranous sheath) (a) at each node (joint)

Leaves

  • Alternate (1 per node)
  • Arrowhead-shaped with
  • Elongated slender tips (c)

Flowers and Fruit

  • Flowers (d) small, 5 mm across
  • 5 greenish to whitish sepals (no petals), in small clusters at tips of short branches or from axils of leaves (C)
  • Seeds:
    • Dull black
    • 3 mm (1/8 in.) long
    • Pointed at both ends but sharply triangular in cross-section
    • Often partly or wholly enclosed by the dry sepals even after shattering from the plant
  • Flowers from July to August

Roots and Underground Structures

Fibrous root system

Often Confused With / Distinguishing Features
It is often confused with field bindweed and hedge bindweed. It is distinguished from all other weedy members of the Smartweed Family by its twining stems, its arrowhead-shaped leaves, and its seedling usually having longer cotyledons (e) (7 - 33 mm) long. It is distinguished from field bindweed by its annual root system with thin, downward-tapering taproot (f), the presence of an ocrea (a) around the stem at each node (joint), its very small, short-stalked greenish flowers (d), borne in the axils of leaves (C) or in clusters along short branches, and its dark, sharply triangular seeds.

Management

Wild buckwheat is persistent, tenacious, resilient, and relentless despite many effective control strategies. Cultural practices, such as crop rotation, mowing, delayed seeding, post-seeding harrowing, or post-harvest cultivating, can reduce wild buckwheat stands, but have not been effective in control. This is because seedling emergence is not restricted to any specific period, so seedlings can emerge throughout the growing season.
Wild buckwheat is most sensitive to herbicides in its early stages. Wild buckwheat and related smartweed species have some natural tolerance to glyphosate. Wild buckwheat control from glyphosate is reduced when applications are made at lower than labelled rates, when only one glyphosate application is made, when plants are stressed from adverse environmental conditions, or when runners are more than 3 to 4 inches long. Glyphosate has no soil residual activity to control later weed flushes throughout the growing season.
The most effective herbicides on wild buckwheat are atrazine, bromoxynil (Pardner), clopyralid (Lontrel), dicamba (Banvel), glufosinate (Ignite / Liberty), and some sulfonylurea products. Using these herbicides or mixtures with these ingredients will ensure the most effective wild buckwheat control. Atrazine, clopyralid, dicamba, and some sulfonylurea herbicides may persist in the soil and carry over for more than one growing season, especially in soils with high pH.

References

http://www.ontarioweeds.com/weed.php?w=POLCO
http://www.extension.purdue.edu/extmedia/GWC/GWC-10-W.pdf
wild buckwheat leaves wild buckwheat plantWild buckwheat seedling Wild buckwheat
Click to enlarge.