Wild buckwheat (Polygonum convolvulus) is a summer annual plant that grows in a vine-like nature. It is a host of many many crop diseases and has many characteristic similarities to bindweed, another weed.
Wild buckwheat infestation
Photo by Joseph M. DiTomaso of University of California – Davis, via Bugwood.org
Identification
Seedlings: Cotyledons of wild buckwheat are oblong and rounded at the apex with a waxy surface. The cotyledons are 20 mm (4/5’’) long and 3 mm (1/10’’) wide. Leaves of the young plant are bluish green on the upper surface and reddish on the lower side and stem. The leaves alternate, are heart-shaped, pointed at the apex, with entire to shallowly toothed margins. On leaves just emerging, the margins curl under the leaf blade. A mesh-like cylindrical sheath (ocrea) wraps around the stem at the base of each leaf.
Wild buckwheat seedling
Photo by Phil Westra of Colorado State University, via Bugwood.org
Leaves: Leaves of the mature plant are triangular to heart-shaped, alternate, and hairless. The leaves are 2-6 cm (0.8’’-2.7’’) long. The leaf margins are entire and leaf blades taper toward the apex. Similar to the young leaves, cylindrical sheath (ocrea) wraps around the base of the stalk that connects the leaves to the main stem (petiole).
Wild buckwheat msture leaves.
Photo by Lynn Sosnoskie of University of Georgia via Bugwood.org.
Mature wild buckwheat plant
Photo by Bruce Ackley of Ohio Stae University, via Bugwood.org.
Mature plant: The stems of the mature plant, like the leaves, are hairless. They are erect initially and then growing in an intertwining, creeping shape. The vines can be 0.2-1.5 m (8’’-60’’) long and can grow over other plants or surrounding objects.
Wild buckweed vine growing up a stick
photo by Lynn Sosnoskie of University of Georgia via Bugwood.org
Mature wild buckwheat plant
Photo by Bruce Ackley of Ohio State University, via Bugwood.org.
Flowers/Fruit: Flowers emerge and preside from July through October. They are greenish-white and approximately 4 mm (⅕’’) long. The flowers are clustered in unevenly spaced groups (groups of 3-6) on 2-6 cm (0.8’’-2.4’’) long elongated flower stalks (racemes).
The fruits (achenes) are composed of 3-angled, dull, and black. The fruits are enclosed in the remains of the leaf-like structures that grow under the flower (sepals). These sepals are green, flat, and winged.
Wild buckwheat flowers
Photo by Carl Dennis of Auburn University, via Bugwood.org
Management
Chemical control
Click above for the chemical control of Wild buckwheat from the Cornell Weed ID site
Non-chemical control
Wild buckwheat seedlings emerge throughout the growing season, not during any particular period. As they are an annual weed, wild buckwheat is easier to control at the seedling stage. Consequently, many cultural practices, including mowing, crop rotation, and delayed seeding, are not effective in controlling this weed. One method of management that has shown to be effective is planting crop seeds.
References
Uva R H, Neal J C, DiTomaso J M. 1997. Weeds of the Northeast. Book published by Cornell University, Ithaca NY. The go-to for weed ID in the Northeast; look for a new edition sometime in 2019.
Cornell University’s Turfgrass and Landscape Weed ID app. Identification and control options for weeds common to turf, agriculture, and gardens in New York; uses a very simple decision tree to identify your weed.