HPIPM:Wild buckwheat

Taxonomy

Domain	Eukarya
Kingdom	Plantae
Phylum	Magnoliophyta
Class	Magnoliopsida
Superorder	Caryophyllanae
Order	Caryophyllales
Family	Polygonaceae
Genus	Fallopia

Scientific Name

Fallopia convolvulus

Scientific Name Synonyms

Polygonum convolvulus var. convolvulus

Polygonum convolvulus var. subulatum

Polygonum convolvulus

Common Name

wild buckwheat

Wild buckwheat (Polygonum convolvulus)

Compiled by Terry Angvick, Montana State University, Sheridan County Extension

and Marjolein Schat, Montana State University from the following sources:

www.glyphosateweedscrops.org.

http://plants.usda.gov/java/profile?symbol=POCO10

Identification and Life Cycle

Wild buckwheat (Polygonum convolvulus) is an annual in the buckwheat or smartweed family (Polygonaceae) that has several common names including black bindweed, climbing buckwheat, cornbind, and dullseed cornbind. Wild buckwheat is a summer annual that grows from a hard, black, triangular seed about 1/8 of an inch long. The cotyledons are narrow with a rounded tip and base. The plant has long, slender, creeping stems that trail along the ground or climb any plants or objects they contact. The leaves are alternate, heart- or arrowhead-shaped, pointed at the tip, and have widely separated lobes at the base. The flowers are small and have no petals, but have five greenish or pinkish sepals. Flowers are located in short-stemmed clusters in the axils of the leaves or at the end of stems. Like other smartweeds, wild buckwheat possesses an ocrea (thin membrane) around the stem at each node. It can be confused with field bindweed because of its vining growth habit and arrowhead-shaped leaves. Field bindweed, however, is a perennial, has an extensive underground root system, does not possess an ocrea, and has large funnel-shaped flowers that are white or pink. Also, wild buckwheat’s lower leaves are usually much wider than bindweed leaves.

Habitats

Wild buckwheat grows everywhere crops are cultivated in Europe and North America and is common in more than 40 other countries.

Impacts

Wild buckwheat has become widely distributed in temperate regions via grain transport. Wild buckwheat is also one of the most common contaminants in seed stock. Its seed is similar in diameter to wheat seed and is often planted with the grain. At harvest, many seeds do not thresh completely from the seed coat and are especially difficult to clean from wheat. Yield losses may range from 15 to 66 percent depending on wild buckwheat density, environment, and type of crop. Wild buckwheat causes difficulty in harvesting crops. Its vines tangle around the moving parts of swathers and combines, often causing mechanical failures. In stored grain, large amounts of wild buckwheat seed can cause spoilage because the weed seed’s moisture content raises the temperature in the grain bin high enough to deteriorate the grain and allow fungi to grow. Furthermore, wild buckwheat is a host for several crop plant diseases, including virus yellows of beets and cucumber, alfalfa mosaic virus, and tobacco rattle virus.

Biology and Ecology

Wild buckwheat begins germinating early in the spring during the first prolonged warm period. The majority of wild buckwheat seed emergence occurs by mid-June. The majority of germination takes place in the top 2 inches of soil, but emergence has been observed from as deep as eight inches. After that, intermittent seed germination occurs throughout the growing period until September. Stem growth increases as temperature increases, but growth is slowed under hot, dry conditions and when plants enter the reproductive phase. Flowering is indeterminate and all stages, from new buds to ripe seeds, can be found on one plant. Flowering may begin in late June in warmer regions. A single wild buckwheat plant can produce 12,000 seeds over the course of a single growing season, although only 3 percent of the seeds germinate after reaching physiological maturity and shedding from the plant. The other 97 percent remain dormant and can germinate if they are exposed to temperatures ranging from 37°F to 41°F for eight weeks. About 75 percent of all seeds are initially viable, and seeds can remain viable in the soil for five years.

Biological Control

There are currently no biological control agents available for wild buckwheat.

Mechanical and Cultural Control

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.

Chemical Control

There are a number of effective herbicides for control of wild buckwheat.

For herbicide recommendations for specific grain rotations and weeds in Montana, please see the MSU Herbicide Chooser Tool.

Examples of herbicides that can be used to manage wild buckwheat

Consult herbicide labels for additional rate, application, and safety information. Additional herbicide information can be found at http://www.greenbook.net.

Herbicide Active Ingredient trade name	Mode of Action	Product per Acre	Application Time or Growth Stage
Alfalfa
Imazethapyr	Inhibition of acetolacetate synthase ALS (acetohydroxyacid synthase AHAS)
*Pursuit		4 - 6 ounces	Apply post-emergence only to seedling or established alfalfa grown for forage, hay or seed. Apply when the seedling alfalfa is in the second (2nd) trifoliate stage or larger and when the majority of the weeds are 1 to 3 inches. When applied to alfalfa grown for seed, apply before bud formation. Can be applied to established alfalfa or clover in the fall, in the spring to dormant or semi-dormant alfalfa or clover or between cuttings when there is less than 3 inches of regrowth
Dry Peas
Imazamox	Inhibition of acetolacetate synthase ALS (acetohydroxyacid synthase AHAS)
*Raptor		4 ounces	Apply post-emergence prior to bloom stage but after dry peas have at least 3 pairs of leaves. Delay application until the majority of the weeds are at 3 inches tall.
Grass grown for seed
Clopyralid	Action like indole acetic acid (synthetic auxins)
*Curtail		2 - 4 pints	Apply only to established grasses before the boot stage of growth. Applications in the boot stage and beyond will result in increased potential for injury. Do not apply to bentgrass unless injury can be tolerated.
Wheat
Metasulfuron; thifensulfuron; tribenuron	Inhibition of acetolacetate synthase ALS (acetohydroxyacid synthase AHAS)
*Ally Extra		0.3-0.4 ounce	Make applications after the crop is in the 2-leaf stage, but before the flag leaf is visible. For Durham and Wampum varieties of spring wheat, apply after the crop is tillering but before boot. Applications to durum and wampum varieties should be made in combination with 2,4-D.For best results, use 0.3-0.4 ounces per acre and apply ALLY® EXTRA plus 2,4-D, MCPA, or bromoxynil containing products when plants have no more than three true leaves (not counting the cotyledons).
Wheat and Barley
Thifensulfuron; tribenuron	Inhibition of acetolacetate synthase ALS (acetohydroxyacid synthase AHAS)
*Affinity BroadSpec		0.8 ounce	For best results add a surfactant. Apply when crop is in the 2-leaf stage but before flag leaf is visible.
Dicamba	Action like indole acetic acid (synthetic auxins)
*Banvel		2 – 4 ounces	Use 2 to 4 ounces in wheat, and fall seeded oats and barley, and 2 to 3 ounces in spring seeded barley. Apply, before, during, or after planting when weeds are in the 2-3 leaf stage.
Wheat, Barley, and Oats
Fluroxypyr	Action like indole acetic acid (synthetic auxins)
*Starane		0.5 – 0.66 pint	Apply as a broadcast post-emergence treatment to actively growing wheat, barley, or oats from the 2-leaf stage up to and including flag leaf emergence stages of growth. Apply before weeds reach 8 inches tall.
Fluroxypyr; dicamba	Action like indole acetic acid (synthetic auxins)
*Rave		2 – 4 ounces	Apply in spring wheat at the 6 leaf stage, and in winter wheat up to the jointing stage. In spring barley apply at 2 ounces/acre up to the 4-leaf stage. In winter barley apply up to the jointing stage. Apply after buckwheat has produced true leaves and is 1 to 4 inches tall.
Clopyralid; fluroxypyr	Action like indole acetic acid (synthetic auxins)
*WideMatch		1 – 1.33 pints	Apply broadcast post-emergence to actively growing crops from the 3-leaf stage up to and including flag leaf emergence stage. Apply when buckwheat is in the 1-3 leaf stage and before vining.
Wheat, Barley, Winter Oat, and Triticale
Thifensulfuron; tribenuron	Inhibition of acetolacetate synthase ALS (acetohydroxyacid synthase AHAS)
*Harmony Extra		0.6 – 0.9 ounce	Apply after crop is in the two leaf stage, but before the flag leaf is visible.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

References

For more images please visit IPM Bugwood. http://www.ipmimages.org/search/action.cfm?q=wild%20buckwheat&Start=1&results=17