By Barbara Fahs, Garden Guides Contributor
Wild buckwheat (Polygonum convolvulus) is an annual weed with heart-shaped leaves and angular, 3-foot-long stems that vine on the ground or twine around other plants. It is native to Europe. This weed can be very destructive when it takes root in large commercially cultivated fields of such crops as flax. Wild buckwheat grows everywhere in the United States; but it presents more problems in areas with cooler climates. Often confused with another weed, the field bindweed, it is all too common in many areas.
Controlling wild buckwheat in commercial agricultural fields is important because in addition to competing for nutrients, light and moisture, it makes harvesting crops difficult due to its vines, which tangle around the moving parts of swathers and combines, often causing mechanical problems. When grains are stored, wild buckwheat seeds can cause spoilage because their moisture content causes the temperature in the grain bin to elevate high enough to deteriorate the grain and allow fungi to grow. Wild buckwheat is also a host for several plant diseases, which affect beets, cucumber, alfalfa and tobacco.
Like many weeds, wild buckwheat grows in many different environments. Seeds normally sprout in the late spring, and the resulting plants can quickly choke valued neighboring plants.
Cultivation and Care
Because each wild buckwheat plant can produce upwards of 1,200 seeds and because it thrives under most soil conditions, it can be tricky to eradicate. It prefers cultivated fields, commercial cereal crops and undeveloped areas. In fields growing flax, reduced harvests of up to 20 percent can occur when wild buckwheat exists in densities of five to 15 plants per square yard.
Weed Control Techniques
Pull young wild buckwheat plants when you first start noticing them, or cultivate with a hoe. Be sure to get the entire taproot, which can be rather long. Spraying with organic herbicides that contain clove oil (eugenol) or acetic acid can be most effective. Try to get rid of plants before they form seed, but if a few plants escape your efforts, mulching around cultivated plants helps to keep down the incidence of re-sprouting weeds. When found in lawn areas, mowing is an effective short-term remedy for wild buckwheat; but be sure to dispose of the clippings in an area where seeds will not be able to sprout. Covering with black plastic is a good way to kill plants and prevent seeds from sprouting. If you use a chemical herbicide, it is important to apply it early in the growing season.