Bindweeds

Images above: Upper left: Hedge bindweed climbing on corn (Antonio DiTommaso, Cornell University). Upper right: Hedge bindweed storage roots (Antonio DiTommaso, Cornell University). Bottom: Hedge bindweed (left) and field bindweed (right) leaf comparison (Antonio DiTommaso, Cornell University).

Image above: Field bindweed (left) and hedge bindweed (right) flower comparison (Antonio DiTommaso, Cornell Univeristy).

Identification

Visit this page for more information on bindweed identification.

Other common names:

• Field bindweed:  bindweed, European bindweed, lesser bindweed, corn-bind, possession bind, bear-bind, cornbine, barbine, European glorybind, field morningglory, orchard morning-glory, wild morning-glory, small-flowered morningglory, creeping jenny, green-vine, devil's-guts, corn-lily, laplove, hedge-bells
• Hedge bindweed:  great bindweed, bracted bindweed, wild morning-glory, devil's-vine, Rutland beauty, hedge-lily

Family:  morningglory family, Convolvulaceae

Habit:  Twining perennial herb spreading by thickened horizontal roots.

Description:  Vegetative sprouts arise from rhizomes, lack cotyledons, and have normal leaves, although the first leaves that form as the shoot is just pushing out of the soil are often deformed.  Seedlings are much less common than vegetative sprouts.

• Field bindweed:  Cotyledons are 0.35-0.87” (0.9-2.2 cm) long by 0.14-0.4” (0.4-1 cm) wide, long stalked, dark green with many white veins, square to heart or kidney shaped, with lobes pointing toward the stem and an indented tip.  Stems are red near the soil line.  First leaves are bell shaped with basal lobes pointing outward.
• Hedge bindweed:  Cotyledons are 1-2” (2.5-5.1 cm) long by 0.5-1” (1.3-2.5 cm) wide, have strong veining on underside, and concave or flat tips and backwards extending, rounded lobes at the base.  Stem may be red at the base.  First leaves are arrow or heart shaped.

Mature plants run along the ground and twine up other plants.  Stems may be hairy or hairless and smooth.

• Field bindweed:  Leaves are alternate, 1.5-2.5” (3.8-6.4 cm) long, spade or arrow shaped, and borne on a long stalk.  Lobes are triangular, with rounded ends.  Roots can extend over 20 ft (6.1 m) deep and run laterally up to 25 ft (7.5 m), forming large clones.
• Hedge bindweed:  Leaves are alternate, 1.5-6” (3.8-15 cm) long, heart or arrow shaped, and pointed at the tip.  Lobes are squarish when laid flat.  Roots extend up to 1 ft (30 cm) deep and run laterally up to 9 ft (2.7 m), forming large clones.

Flowers are white or pink and are petunia shaped in both species.

• Field bindweed:  Flowers are grouped 1-5 to a leaf axil and measure 0.5-1” (1.3-2.5 cm) across.  Leafy bracts at base of the flower are less than 0.1” (0.25 cm) long.
• Hedge bindweed:  Flowers are single in leaf axils, and measure 1.25-3” (3.2-7.6 cm) across.  Bracts are heart shaped, 0.25-0.75” (0.6-1.9 cm) long, they overlap and hide the flower base.

Fruit and Seeds:  Both field and hedge bindweed have round or egg-shaped capsules with two chambers, each containing 1-2 seeds.  Seeds are gray-brown to black, with two flat and one rounded side.

• Field bindweed:  Capsule is 0.31” (0.8 cm) in diameter.  Seeds are 0.12-0.16” (0.3-0.4 cm) long and coarsely bumpy.
• Hedge bindweed:  Capsule is 0.31” (0.8 cm) in diameter and is hidden by remnant flower bracts.  Seeds are 0.16-0.20” (0.4-0.5 cm) long and slightly rough.

Similar species:  Wild buckwheat (Polygonum convolvulus L.) has a papery covering extending up the stem from each leaf axil, long tapering leaf tips, and long clusters of small, greenish flowers.

A note on development:  The seedling develops a taproot from which thickened permanent lateral roots arise.  After growing laterally for 15-30” (38-76 cm) these bend downward to form secondary taproots.  At the bend, a vertical rhizome develops which grows to the soil surface to become a new shoot, and one or more new lateral roots continue the outward spread of the plant.  Occasionally, rhizomes and subsequent shoots also develop from buds on the horizontal thickened roots.  In undisturbed conditions, most of the thickened horizontal roots are in the top 6” (15 cm) of soil.  Feeder roots form on both horizontal roots and taproots.  In a deep silt loam soil in Kansas, a field bindweed plant spread laterally over 10 ft (3 m) from the point of germination in 7 months and had roots penetrating to nearly 4 ft (1.2 m).  By the end of a third growing season, the plant had spread outward more than 16 ft (4.9 m) and had roots penetrating as much as 23 ft (7 m) (Frazier 1943).

Management

The bindweeds cause severe problems in many crops.  The extensive and efficient root system of field bindweed can reduce soil water content to below the wilting point of most crops.  Hedge bindweed is more upright in its early growth than field bindweed and is quicker to climb up crop plants (Mohler, personal observation).  Both species are strong competitors and cause harvesting problems for grain, and for both hand-harvested and mechanically-harvested vegetables (Sosnoskie et al. 2020).

Winter grains and early planted spring grains suffer less from bindweed competition than summer crops because their primary period of water use occurs before bindweed is well established (Weaver and Riley 1982).  If a fallow period prior to planting suppresses the bindweed in the fall, winter grains will cast enough shade in the spring to effectively suppress field bindweed (Stahler 1948).  Similarly, if your soils do not allow early tillage, use a vigorous fall planted cover crop to compete with bindweed in the spring.  Alfalfa can suppress bindweed by dense shading and repeated mowing (Sullivan 2004).  Summer planted cover crops also can be effective, but choose species that develop a dense leaf canopy and plant them at high density.  In one study, forage soybean planted July 1 in Minnesota killed every shoot of field bindweed, whereas less shade-producing covers did not.  Sudangrass and German millet were also relatively effective (Stahler 1948).  For vegetable farmers that are not land-limited, a sequence of cover crops such as overwintered rye, oats plus peas, then buckwheat or sorghum-sudangrass, and finally overwintered rye plus hairy vetch with disking before planting each cover crop, will suppress bindweed and prepare the field for a good vegetable crop (Sullivan 2004).

Repeated shallow tillage during fallow periods between crops is also important for controlling bindweed.  Root reserves reach a minimum when the shoot is about 12-28” (30-70 cm) long and has 4-6 fully expanded leaves (Barr 1940, Rask and Andreasen 2007), and plants are probably most sensitive to cultivation at that stage of development.  Full eradication by tillage alone usually requires continuous fallow for two full growing seasons, with shallow tillage every 12 to 20 days (Timmons and Bruns 1951).  Usually such extreme measures are not economically feasible or environmentally desirable.  Shorter fallow periods, however, can be worked into the crop rotation either before late planted crops or after early harvested crops.  These will not eliminate bindweed but can greatly reduce its density and competitiveness.  Note that the amount of soil moisture (affected by rainfall or irrigation) plays an important role in the effectiveness of fallow and repeated tillage (R. Boydston, personal communication).  Untimely rainfall or poorly planned irrigation can allow bindweed to persist despite repeated tillage or fallow.

Begin inter-row cultivation of row crops as soon as possible since tine weeders and rotary hoes are ineffective against young bindweed shoots.  A tine weeder can be used, however, to comb larger bindweed shoots out of row crops, but at the cost of some damage to the crop and considerable labor cleaning the weeder.  Continue inter-row cultivation as long as you can get through the crop.  Use low-pitch half sweeps or vegetable knives set shallowly to cut bindweed off close to the row without damaging crop roots.  If bindweed stems are longer than about 8” (20 cm), avoid using rotary tillers, spyders or rolling cultivators as the vines will spool up on the implement and you will spend more time cleaning the equipment than actually cultivating.  Avoid spreading bindweed by scraping off tillage and cultivation implements after working in infested areas.  Grazing by sheep, cattle, and chickens will suppress above-ground growth and thereby help deplete storage reserves in the roots.  Pigs will grub out roots and rhizomes from the plow layer (Sullivan 2004).

Organic mulch is completely useless against these species: we have observed hedge bindweed shoots emerging through an 18” (46 cm) thick pile of bark mulch that was waiting to be spread!  Synthetic mulch can suppress field bindweed (Sullivan 2004), but it is relatively ineffective against hedge bindweed since the vines will follow light to the planting holes.  This puts the vines in an optimal position for twining up the crop plants and makes hand pulling difficult.  Interseeding clover into corn at last cultivation did not control hedge bindweed, but it reduced the height of climbing stems by half, and the length of creeping stems by 72% (Pfirter et al. 1997).

Although the bindweeds are difficult to manage, many growers keep them below damaging levels through good crop rotation and persistent cultivation.  An integrated program of non-chemical control tactics can provide equivalent control to that obtained using herbicides (Davis et al. 2018).  We know one vegetable farm that successfully eradicated a bad infestation of hedge bindweed over a three-year period by supplementing mechanical cultivation with consistent hand weeding.

Ecology

Origin and distribution:  Field bindweed probably originated in the Mediterranean region of Europe, Asia, and North Africa (Austin 2000), but now occurs widely on those continents and has been introduced into North and South America, Australia and the Pacific Islands (Holm et al. 1977).  It was probably introduced into the eastern U.S.A. as a seed contaminant and spread across North America during the 1800s (Sosnoskie et al. 2020).  Hedge bindweed is native to Eurasia, Africa and eastern North America (EFBI), and has been introduced into New Zealand (Cameron 1984).  Both species occur throughout the U.S.A. and southern Canada (USDA Plants).

Seed weight:  Field bindweed: 8-20 mg, mean 10 mg (Weaver and Rilery 1982, EFBI, Salisbury 1974), 11.5 mg (Xiong et al. 2018).  Hedge bindweed: 28-32 mg (Salisbury 1974), 34 mg (EFBI).

Dormancy and germination:  Both species have hard seed coats that prevent absorption of water (Steinbauer and Grigsby 1959).  Consequently, only 5-25% of freshly collected field bindweed seeds will germinate (Weaver and Riley 1982, Jayasuriya et al. 2008, Xiong et al. 2018) and no fresh hedge bindweed seeds will germinate (Jayasuriya et al. 2008).  Damage to the seed coat (scarification) leads to 100% germination in both species.  Cold, moist stratification at 41 °F (5 °C) for 4 to 8 weeks partially overcame dormancy (Xiong et al. 2018).  Overwintering in soil tends to soften the spot where the seed attached to the parent plant and increases the germination ability of hard seeds by 30%.  Scarified seeds of field bindweed germinate over a wide range of temperatures from 41-104 °F (5-40 °C) but percentage germination and speed of germination is greatest at 95/68 °F day/night temperature (35/20 °C).  The seeds do not require light for germination (Weaver and Riley 1982).  Similarly, 100% of scarified hedge bindweed seeds germinate within one week at day/night temperature regimens ranging from 68/50 to 95/68 °F (20/10 to 35/20 °C) and within 4 weeks at 59/43 °F (15/6 °C).  Unscarified hedge bindweed seeds germinated slowly, with 20-50% germinating within 6 months, depending on temperature.  Unscarified seeds germinate best at 77/59 °F (25/15 °C) (Jayasuriya et al. 2008).

Seed longevity:  These species form long-term persistent seed banks with some seeds remaining viable in the soil for at least 20 years (EFBI).  Burial of field bindweed seeds for a single growing season reduced number of intact seeds by 17-40% (Leishman et al. 2000).

Season of emergence:  Shoots from overwintering roots begin emerging in mid-spring and continue emerging throughout the growing season.  Seedlings of field bindweed are most abundant in late spring and early summer but continue to emerge throughout the growing season (Weaver and Riley 1982).

Emergence depth:  Shoots can emerge from roots that are as deep as 2 ft (60 cm) (Weaver and Riley 1982).  Seedlings of field bindweed emerge readily from anywhere in the top 2.4” (6 cm) of soil and 10% of seeds at 4” (10 cm) will produce seedlings.  Seedlings will usually not emerge from 4.7” (12 cm) (Benvenuti et al. 2001).  Hedge bindweed seeds are larger, and seedlings may emerge from even deeper in the soil.

Photosynthetic pathway:  C3 (EFBI).

Sensitivity to frost:  The above ground shoot dies back from frost, but the roots withstand temperatures as low as 21 °F (-6 °C) (Weaver and Riley 1982).

Drought tolerance:  Field bindweed can survive long periods of drought due to its deep root system (Weaver and Riley 1982).  When watering frequency was reduced from daily to once per week, shoot and root production by field bindweed seedlings was about halved; shoot production by plants grown from root segments was similarly about halved, but root production of plants grown from root segments was scarcely reduced (Dall’Armellina and Zimdahl 1989).  With its shallower root system, hedge bindweed may be more susceptible to drought than field bindweed.

Mycorrhizae:  Both species are mycorrhizal (Harley and Harley 1987).

Response to fertility:  The limited information available indicates that field bindweed is favored by additions of P and K but tends to be out-competed by N responsive species when N or a balanced nutrient source is used (Mamolos and Veresoglou 2000).  Weight of twining vines was about twice as great when hedge bindweed was grown in compost and loam as when grown in sand, but productivity of surface runners and below-ground parts differed little (Klimeš and Klimešová 1994).

Soil physical requirements:  Field bindweed can grow on a wide range of soils including fertile or infertile, low or high pH, and moist or dry (Sosnoskie et al. 2020).  It does not tolerate waterlogged soils (Weaver and Riley 1982).  In contrast, hedge bindweed is highly tolerant of water-logged conditions and invades wetlands (Gryseels 1989).

Response to shade:  The bindweeds are moderately sensitive to shade.  Reducing light by 55% reduced root growth by 35% and shoot growth 60% (Dall’Armellina Zimdahl 1988).  In 80% shade, field bindweed shoot dry weight was reduced by 25-30% but stem length about doubled (Gianoli 2004, González and Gianoli 2004).  Under heavy shade (95%), leaf weight decreased 39% but leaf area increased 36%, allowing the plant to continue growth (González and Gianoli 2004).  With dense shade from a competitive crop, however, field bindweed cannot climb (Stahler 1948, Weaver and Riley 1982).  The 98% shade cast by forage soybeans killed all shoots of field bindweed, and heavy shading cover crops of rye, oats and sudangrass suppressed growth substantially (Stahler 1948).  Both species overcome moderate shade by climbing on crop plants.

Sensitivity to disturbance:  These species are extremely resistant to soil disturbance because the root system penetrates below the plow layer and new shoots can emerge from as deep as 2 ft (60 cm).  Tillage implements fragment roots and vertical rhizomes, resulting in the propagation of these weeds.  Root reserves reach a minimum when the shoot is about 12-28” (30-70 cm) long and has 4-6 fully expanded leaves (Barr 1940, Rask and Andreasen 2007).  Plants are most susceptible to destruction of the shoots at this growth stage.  Under favorable growing conditions, clipped seedlings can resprout from the root 19 days after emergence (Weaver and Riley 1982).

Time from emergence to reproduction:  Field bindweed plants rarely flower during the first season.  In subsequent years, shoots emerge in mid-spring and typically begin flowering 6 to 9 weeks later (Weaver and Riley 1982, Degennaro and Weller 1984).  Seeds become viable 10 to 15 days after pollination, but the impermeable seed coat does not fully develop until 30 days after pollination.  Lateral storage roots, which are the source of new shoots, form on seedlings within 6 weeks of emergence (Weaver and Riley 1982).

Pollination:  Both species are insect pollinated.  Field bindweed sometimes self-pollinates (EFBI), but some populations are self-incompatible (Degennaro and Weller 1984).  Hedge bindweed has been reported to be self-incompatible (EFBI), but careful study has shown that it is self-compatible but requires insects to move pollen within the flower or between flowers of the same clone (Ushimaru and Kikuzawa 1999).

Reproduction:  Most reproduction occurs by shoots sprouting up from the spreading root system, and in field bindweed, clones can reach 20 ft (6 m) in diameter.  In tilled fields, reproduction is furthered by fragmentation of roots and rhizomes.  In one experiment, 5” (12 cm) segments of roots produced 0.4-9.8 shoots/g of root over the span of 12 weeks (Degennaro and Weller 1984).  A single 2” (5 cm) piece of field bindweed root planted in Saskatchewan produced 25 shoots over the following 4 months, and spread as far as 9.4 ft (2.85 m) from the parent plant within 15 months (Weaver and Riley 1982).  Seed production requires dry, sunny weather.  Capsules normally contain 1 to 4 seeds with an average of 2 (EFBI, Weaver and Riley 1982).  Single plants of field bindweed produce 25 to 300 seeds per year but determining the scope of an individual is often difficult.  Pure stands of field bindweed produce 0.5-180 seeds/ft2 (5-2,000 seeds/m2) (Weaver and Riley 1982).

Dispersal:  The seeds pass through the digestive tract of livestock and are dispersed when the animals are moved or when manure is spread (Harmon and Keim 1934, Wiese et al. 1998).  The seeds are more resistant to elevated temperatures during composting than other weed species and can persist in commercial compost (Wiese et al. 1998).  The seeds commonly contaminate seed grain and beans (Weaver and Riley 1982). We have twice found abundant bindweed seeds in rye sold for cover crop seed.  Seeds disperse in surface irrigation water (Kelley and Bruns 1975).  Migrating birds may disperse field bindweed long distances (Proctor 1968).  Tillage and cultivating machinery spread roots and rhizomes within fields (Sullivan 2004, Mohler and DiTommaso, unpublished data).  Crops that are vegetatively propagated (e.g., asparagus crowns, mint roots) can be a source of field bindweed rhizomes (R. Boydston, personal communication).

Common natural enemies:  Bindweed gall mite, Aceria malherbae, has been established as a potential biocontrol agent (Boldt and Sobian 1993), and is now widespread in western states (Schutte and Lauriault 2015).  The native Argus tortoise beetle (Chelymorpha cassidea) sometimes completely defoliates both bindweed species in the Northeast without damaging the associated grain crops (Weaver and Riley 1982).  The native seed feeding beetle Megacerus discoidus can cause substantial damage to seeds of hedge bindweed (Wang and Kok 1986) and the sweet potato plume moth Oidaematophorus monodactylus consumes flower buds (Tipping and Camporasso 1997). Tyta luctuosa, a noctuid moth whose caterpillars defoliate field bindweed, has been successfully established in several regions of the U.S.A. (R. Boydston, personal communication).

Palatability:  People do not eat any part of the plant.  Field bindweed shoots and roots are good fodder for cattle (Weaver and Riley 1982, Schutte and Lauriault 2015).  Sheep can consume field bindweed foliage, but horses and pigs may be sensitive to alkaloids in shoots and roots (Sosnoskie et al. 2020).

References:

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