Field Bindweed Convolvulus Arvensis L.: Convolvulaceae

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PNW 580 Field Bindweed Convolvulus arvensis L.: Convolvulaceae

ield bindweed (Convolvulus arvensis L.: F Convolvulaceae) is one of the most common noxious weeds in the Pacific Northwest (PNW) and one of the most difficult to control. It was introduced from Europe to Virginia in 1739, and even before 1900 the U.S. Department of Agriculture recog- nized the weed as a national menace. By 1900 field bindweed was established in all western states. By 1955 it was present in every Idaho county, occupying 140,000 acres of cropland. It is estimated to occupy more than 500,000 acres Figure 1. Field bindweed climbs upright plants, binding together all plants of Idaho cropland plus an equiva- within a colony or patch. Creeping in every direction, it grows in circles. lent acreage of pasture and range- Pink to white floral petals fuse into a funnel shape. land. In Oregon and Washington, it is estimated to infest approximately 500,000 acres in each state. The only noxious weed that infests more crop acreage is Canada this- tle (Cirsium arvense (L.) Scop.). Field bindweed is known as morningglory, wild morningglory, corn-bind, and creeping Jenny, but to avoid confusion with other species, it should be called field bindweed. Crop yields often are reduced 50 percent or more where field bindweed infestations are dense. Field bindweed has a deep root system that competes with crop plants for water and soil nutrients. Figure 2. True seedlings, at left and lower Figure 3. Crop yields can Field bindweed vines climb on right, emerged from seed. Upper right seedling be reduced 50 percent or comes from a root stock so it doesn’t have more where field bindweed plants and shade them. They com- cotyledonary (seed) leaves. infestations are dense. plicate tillage and harvesting by clogging machinery and entan- ______Authors—Don W. Morishita, Robert H. Callihan, Charlotte V. Eberlein, Joseph P. McCaffrey, and Donn C. Thill

A Pacific Northwest Extension Publication University of Idaho • Oregon State University • Washington State University gling plants. Agricultural land prohibit certification of crop seed Leaves—Although field bindweed infested with field bindweed is that contains field bindweed seeds leaves vary in size and shape, they reduced in resale value. or that comes from fields in which always are shaped like an arrow- Field bindweed also is common field bindweed was found during head with two pointed basal lobes around home landscapes, frequent- the field inspection phase of the that usually extend at right angles ly infesting shrubs, gardens, and certification process. This means to the leaf midvein. This is an iden- other ornamental plantings. As that for control, aboveground tifying characteristic of many new homes are built on land that growth must be destroyed and pre- plants in the Convolvulaceae once was farmland, field bindweed vented from producing seed. (morningglory) plant family. Field can continue to trouble homeown- bindweed leaves have no stipules ers, interfering with garden pro- Description and have a petiole (leaf stalk). duction and competing with orna- Field bindweed and weed The leaf blade is usually blunt- mental plants. It is not frequently species resembling it differ in leaf tipped with a tiny point at its end. found in range or forest land size and shape, flower color, and In some biotypes, the blade is unless the soil has been disturbed growth habit within and between sharply pointed. Leaves are dark and seed or plant parts have been populations (Fig. 6). However, they green, vary from smooth to slightly introduced. all share the following characteris- hairy, and are usually 1/2 to 1 inch tics: long, but vary in size depending upon the biotype and growing con- State Laws Growth habit—Field bindweed is ditions. Field bindweed is a noxious a perennial species with creeping weed species under the noxious roots and slender green, twisted, weed laws of many states. In and vining stems that may grow as Idaho, Oregon, and Washington long as 6 feet. When other plant field bindweed is considered nox- species are absent, field bindweed ious, although each state has a stems lie on the ground. Field slightly different categorization of bindweed will climb upright plants, noxious. Currently, Idaho uses a binding together all plants within a single designation of noxious colony or patch. Field bindweed weeds while Oregon and normally grows in circular patches Washington have multiple cate- because it creeps in every direc- gories of noxious weeds depending tion. Cultivation or other types of on established criteria. Field mechanical or physical control bindweed in Oregon is a Class B may change this pattern by physi- noxious weed, which means that it Figure 5. Field bindweed flowers, cally moving creeping roots. faintly scented, are about 1 inch in is a weed of economic importance diameter and l/2 to 1 inch long. in areas of the state in which it is regionally abundant. In Flowers—The flowers originate Washington, field bindweed is a and grow from the leaf axils (at the Class C noxious weed, which junction of leaf and stem). See fig- means that it is widespread in the ures 1, 6, and 9. They have pink to state and long-term control pro- white petals that are fused into a grams are a county option. funnel shape. The funnel shaped Field bindweed also is designat- flowers are another identifying ed as a “primary noxious weed” in characteristic of many plants in the the Idaho, Oregon, and Washington Convolvulaceae family. Two tiny Seed Laws, which prohibit the sale bracts are located 1 1/2 to 2 inches of desirable plant seed containing below each flower, and secondary seeds of any primary noxious flowers can grow from buds in the weed. All crop seed offered for bracts' axils. sale in all three states must be Flowers are faintly scented and tagged to show it is free of these about 1 inch in diameter and 1/2 to pests. The tags also give the per- 1 inch long. The exterior of each centage of purity and germination flower has five lengthwise, thick- of the crop seed. Clean seed of ened strips that may be light green adapted crop varieties is always a or pink. Flowers fold at night to good investment. Figure 4. Leaves shaped like an form a 5-part twisted tube and The Idaho, Oregon, and arrowhead have two pointed basal lobes that extend at right angles to the leaf open during the day. Flower Washington seed certification laws midvein. blooming starts about 4 weeks

2 after emergence in mid-spring and deeper than 2 feet. Studies have across. At the flower base, two continues until the plant foliage is shown that root systems increase large but not overlapping bracts killed by frost. in vigor and regenerative ability as enclose the flower calyx (green Seeds—A pure stand of field root diameter increases and as the protective covering of a bud). bindweed can produce 22 million root gets older. Buds on broken Hedge bindweed has been seeds (about 3/4 ton) per acre. root segments as short as 1 inch reported in the Idaho counties of Seeds are mature about 3 weeks can produce new shoots. Gem and Bingham in 1989 and after flowers bloom, but have been Another factor affecting the abil- 2001, respectively. It is more com- known to germinate within 10 days ity of a root segment to re-grow is mon in western Oregon and after the flowers open. Field the depth from where the root seg- Washington. Several other bindweed seeds have a hard, ment originated. Fragments taken bindweed or morningglory species impervious seed coat that enables from below the plow layer are occur in the United States, but some seeds to remain dormant, yet much more likely to grow than none has been reported in the PNW. viable in the soil for many years. fragments taken from the top 2 to Annual morningglory— Bindweed seed germination has 4 inches, due to the lack of buds Ipomoea purpurea (L.) Roth, occurred in a field even after no above the plow layer. another member of the morning- bindweed seed production was Seedlings—Field bindweed seed glory family, is a related, commer- allowed for 28 years, and seeds germinates in the fall and spring. cially available ornamental species have been documented to survive See figure 2. The optimum germi- that is rarely weedy in the PNW. 50 years. nation temperature is 86°F and can Varieties of this species have much Field bindweed seeds are con- range from 34°F to 104°F. larger, showy flowers of various tained in two-sectioned capsules, Bindweed seedlings can be identi- colors. Because it is an annual, it is each with one to four (usually fied easily by their two cotyledons more easily controlled by mechani- four) seeds. Seed shape is deter- (seed leaves) shaped like kidneys cal means such as cultivation. This mined by the number of seeds in or hearts. species is also a weed in many each capsule, but is typically egg- As soon as the plant begins pro- other parts of the country. shaped with one or two flat sides ducing true leaves, their outline is Wild buckwheat—Polygonum and a squared-off tip at the tapered the same arrowhead shape as convolvulus L., is a member of the end. When four seeds form, each leaves on a well established plant. Polygonaceae or buckwheat fami- one has two flat sides and one Seedlings develop a deep taproot ly, and is sometimes called black rounded side. When two seeds about 6 weeks after emergence. bindweed. This annual weed form, they have only one flat side. More importantly, at approximately occurs throughout the PNW and Occasionally, capsules have single the same time—6 weeks after often is mistaken for field seeds; these seeds have no flat- emergence—these plants can also bindweed. Wild buckwheat has a tened side. Seeds are grayish begin producing underground root- twining growth habit and leaf sizes brown to black and have a rough, stocks capable of producing new and shapes similar to those of field pebbly surface. plants from vegetative buds. bindweed, which is why the Seeds are about 1/8 inch (3 mm) Therefore, mechanical control species are often confused. long. This, combined with their such as tillage or hoeing can be Buckwheat is distinguished easily variable shape, makes them very effective for seedlings only during by the following characteristics: difficult to separate from wheat, the period from emergence to 6 (1) untwisted, often red or white barley, and other seeds in seed weeks after emergence. After this stems, (2) tiny, inconspicuous flow- cleaning equipment. As a result, period, when field bindweed plants ers in groups at the leaf axils, (3) field bindweed seeds are common develop lateral roots, the plants an inconspicuous papery sheath contaminants in these crops. resist mechanical control, but usu- that encircles the stem at the base Roots—Field bindweed spreads ally are not difficult to control with of each leaf petiole, (4) leaf blades primarily by roots when weed con- herbicides until they are two to with basal lobes that point down- trol practices suppress flowering three years old. ward and (5) long, very pointed and where tillage implements carry leaf tips that do not vary in shape. roots to uninfested areas. Buds at Similar species Each wild buckwheat flower has various intervals along the roots Hedge bindweed—Calystegia a single seed that is distinctly trian- send up shoots creating new plants sepium (L.) R. Br. is in the same gular in cross-section, with sharp aboveground. Roots spread out family and occurs in waste areas angles and sharply pointed ends. belowground laterally from a field and fencerows. It is nearly identi- The plant is not unusually hard to bindweed and also can penetrate cal to field bindweed, but has control and seldom occurs outside 20 feet deep in soil, but normally much larger, hairless leaves and of cropland, gardens, or ornamen- do not send up shoots from any flowers that measure 1 1/2 inches tal plantings.

3 Silver lace vine—Polygonum Many other species have leaf occur when field bindweed contam- aubertii Henry, also in the shapes similar to field bindweed, inated soil is moved or when field Polygonaceae family, has woody but lack twisted, vining stems. bindweed root sections are trans- stem bases and may climb as high ported by agricultural or construc- as 30 feet on trees and poles. Its How Field Bindweed tion equipment from one location to leaves have nearly the same size Spreads another. and shape as field bindweed leaves, Field bindweed seeds can pass but they have sharp, narrow tips The primary means of long-dis- through animal digestive systems more like those of wild buckwheat, tance spread is by seed, but once a with little or no damage. Grains or and distinctively ruffled edges, espe- seedling becomes established, a forages containing mature field cially when young. The flowers are patch or colony forms and spreads bindweed seeds should not be fed small and in showy bunches. Silver by extending lateral roots. The to animals unless the feed is ground lace vine is uncommon in the PNW. spreading root system enables or otherwise processed to destroy It is sold as an ornamental and undisturbed patches in crops to the seeds. sources can easily be found on the enlarge 6 to 10 feet in diameter per Internet. It is described as a ram- year. As previously mentioned, such Effects on Livestock pant, twining vine that produces a patches tend to be circular. cloud of white flowers and is valued Under favorable soil moisture Although field bindweed is not for its adaptability, not its refinement. conditions, new infestations can productive forage, sheep have grazed and eaten it in the United

Figure 6. See ﬁeld bindweed and species resembling it. Distinctive differences in ﬁeld bindweed compared to similar weeds are labeled. Growers will want to eliminate all of these from crop, pasture lands, and from home landscapes.

Field bindweed Small bracts well below ﬂower Leaf: Arrowhead shaped, up to 2 l/2 inches long, tiny point in rounded leaf tip. Basal lobes point at nearly right angles to midrib. No stipules. One leaf per node. Flower: Funnel-shaped, up to 2 l/2 inches long, 3/4 to 1 inch across. White to pink. Stalk has 2 bracts l/2 to 2 inches below the ﬂower. Flower folds at night. Stem: Twisted, green.

Hedge bindweed Large bracts enclose ﬂower base Leaf: Sharply pointed. Blade up to 8 inches long. No stipules. One leaf per node. Flower: 1 l/2 to 2 inches across. 2 to 3 inches long. White to pink. Bracts are large at base of petals. Distinct points on calyx lobes. Stem: Green, very slight twist.

Russian vine Rufﬂed edge Leaf: Sharply pointed, up to 2 l/2 inches long. Rufﬂed edges. Rounded basal lobes. Sheathing stipules. Two or more leaves per node. Flower: Small, white, in profuse bunches. Stem: Brown woody lower part. Green upper part, not twisted.

Wild buckwheat Narrow, sharp point Sheathing stipule Leaf: Arrow shaped. Sharply pointed. Basal lobes point opposite to leaf tip. Up to 3 inches long. Sheathing stipules. One leaf per node. Flower: Small, green to white, inconspicuous, one triangular seed per ﬂower Stem: Red to white, not twisted.

4 States with no reported ill effects. Continuous, intensive sheep grazing over a period of several years can temporarily suppress field bindweed. Afterward, however, it will recover fully if undisturbed. More importantly, grazing that is intensive enough to control field bindweed usually destroys desirable grass species as well, opening the way for erosion and more weed invasion. Cattle do not readily graze field bindweed, and hog poisoning from field bindweed consumption has been reported. Other members of the Convolvulaceae family have been reported to possess purgative properties and have caused cattle, goats, and sheep to become ill, although the illness has not been clearly defined. As a result, even Figure 7. A pure stand of field bindweed can produce 22 million seeds (about though small amounts (5 to 10 per- 3/4 ton) per acre. Seeds mature about 3 weeks after flowers bloom, but have cent by weight) of field bindweed in been known to germinate within 10 days after flowers open. an animal's diet have produced no reports of adverse effects, heavy control strategies will provide the from any cropping method, grow grazing on dense stands of field greatest chance for success. healthy, vigorous crops. For maxi- bindweed appears to be risky. mum crop yield, test the soil to Allowing livestock to eat field Biological control determine crop nutrient needs, and bindweed after seed maturity can Competition—Perennial grasses apply the necessary fertilizer. This result in weed spread since seeds can compete well with field will improve the crop’s competitive can pass through livestock and ger- bindweed. Most of these grasses ability and help suppress bindweed. minate. Any transport of noxious begin growth much earlier in the Insects and Mites—Organisms weed seeds, even in animals, vio- season than field bindweed does, for biological control are under lates many states' noxious weed and can take early advantage of lim- investigation, but have not yet laws. ited soil moisture and establish a resulted in substantial field canopy that competes with field bindweed control. Several insect Control and bindweed for light. and mite species attack field Bindweed will persist in range- bindweed in its native European Management land, pasture, and lawns in a sup- and Asian habitats. Some of these Since field bindweed seeds can pressed condition and will grow vig- species already exist in the United survive in the soil for many orously if competitive species are States and Canada. However, many decades, total eradication is not a absent, overgrazed, or mismanaged. insects that feed on field bindweed realistic short-term goal where Enhance competition from desir- also damage native and ornamental seeds lie dormant. However, with able grasses by avoiding early and morningglories (Ipomoea and diligence you can eliminate field mid-spring grazing or by grazing all Calystegia spp.) as well as sweet bindweed root systems by integrat- plants in a short duration high potato (Ipomoea batata). The U.S. ing the use of biological, mechani- intensity system, applying nitrogen Department of Agriculture will cal, and chemical control agents fertilizer, and reseeding where approve the release of those insect into certain cropping or land man- needed. and mite species that damage field agement practices. When only the Alfalfa can be used to contain a bindweed only. The single imported more easily controlled seedlings field bindweed infestation, but will insect that has been tested success- growing from seed remain, a field not crowd it out. Alfalfa may, how- fully and approved for release in bindweed infestation causes negligi- ever, be used as a soil-building crop parts of the United States is the ble economic losses. The best con- in a rotation designed to control European moth (Tyta luctuosa). trol methods and materials depend bindweed by other means. This may Caterpillars of this moth defoliate on the size of the infestation and the be especially useful under dryland bindweed, usually in the later part conditions under which the weed is conditions. of the growing season. This is growing. Using a combination of To obtain maximum benefits

5 unlike the other moths, Bedellia bindweed—The two-spotted spider ture content in the soil will and Emmelina, which feed early. mite (Tetranychus urticae) and decrease the probability of root This moth has not been released on other mites can cause considerable fragment survival. Tillage performed a large scale to date; thus, its biolo- damage to bindweed foliage. in dry soil will help break the roots gy and impact under U.S. conditions Unfortunately, this damage sup- into pieces that are too small to are unknown. presses the plant little because it grow and will leave the root seg- A gall-forming mite, Aceria mal- occurs late in summer. These mites ments loose from soil particles, herbae, has become established in have a broad host plant range that allowing them to dry out. Field Texas, and has had greater success includes many important crop bindweed root fragments, which in the southern U.S. Its feeding plants and are not considered valu- have been disturbed recently by deforms field bindweed buds and able for field bindweed suppression. other tillage methods, are less likely leaves. The insects and mites to grow than root segments from described here are unlikely to pro- Mechanical Control undisturbed areas. As previously vide satisfactory control unless they Fallow tillage works when mentioned, segments in the top few work together with other agents. consistent 3 to 5 years inches are less likely to grow than Field bindweed control with segments from greater depths. Field bindweed control by tillage insects and mites is not promising This type of tillage program requires 3 to 5 years of consistent, in an annual cropping system, gar- requires 3 to 5 growing seasons frequent tillage. Field bindweed dens, or turf. The extensive root without cropping. Consistency is stores its food reserves in the roots system, which limits control by crucial. A month's lapse can set the and will yield only to a thorough, other methods, also limits the abili- program back a year or more. This well-timed tillage program. The best ty of insects and mites to control fallow program may increase ero- time to start a tillage program is this weed. In conventional annual sion on slopes. Erosion can be immediately after harvest. It is best cropping systems and gardens, bio- reduced by planting an alfalfa-grass to keep equipment out of isolated logical control agents do not control crop or green manure crop to add bindweed patches except when field bindweed because they are organic material to the soil before weed control operations are in seriously damaged by insecticides, tillage and by spreading organic progress. tillage, and other farming and gar- materials. After harvest, plow 6 inches dening practices. Eventual use of deep. Then, beginning 12 days after Cultivation in row crops biological control agents is expect- the bindweed re-emerges, perform a Cultivation in row crops will sub- ed to be limited to range, pasture, tillage operation with an implement stantially suppress field bindweed forest, and other noncrop areas. that cuts off all of the plants such as growth, especially between rows, Insects that occasionally dam- a rod weeder or a sharp, duckfoot- but will not prevent the weed from age field bindweed—A leaf-min- type field cultivator. Make an ade- causing significant crop loss. Even ing moth (Bedellia somnulentella) quate overlap of the sweeps every though young stems emerging with- and a defoliating moth (Emmelina 14 days until the bindweed shoots in crop rows may be covered with (= Oidaematophorus) are killed by freezing. Cultivate no soil thrown by the cultivator early monodactyla) occur in the PNW deeper than necessary to complete- in the season, many will continue to and other parts of the United States. ly cut off all of the shoots, usually 2 grow. Cultivation can transport These insects may attack bindweed to 4 inches. roots and stems resulting in consid- early in the season and can some- Clean roots and stems from erable weed spread from localized times cause significant damage. equipment before moving out of patches. Use other control methods Parasitism and predation of these each bindweed patch. Resume during times in the rotation when moths by other insects limit their tillage in the spring 12 days after the cultivated crops are not grown. effectiveness. These moths have a bindweed emerges. Repeat this Mowing, pulling, and burning broad host range that includes tillage operation every 14 days until Removal of all field bindweed top sweet potato, discouraging their use bindweed no longer appears. growth by pulling or burning can or further distribution for biological Research shows that root segments eliminate all but the weed seed if control in the United States. in the early summer are less likely repeated at least every 14 days over The golden tortoise beetle to grow than segments from late 3 to 5 years. Mowing is inadequate (Metriona bicolor) and other tor- summer. Presumably roots from the because it misses stems lying flat as toise beetles are commonly found late summer have a higher amount well as low leaves and flowers, and on native morningglories and some- of food storage built up than do the the plants can reproduce. Mowing is times on field bindweed in the west- roots in early summer. effective only when combined with ern United States. Feeding by adults Root segments are much less other control methods such as her- and larvae generally results in likely to grow if tillage operations bicide treatment. Burning is most minor damage to weed foliage. are performed in dry soil, when no effective during the summer Mites occasionally damage field rain is predicted, since low mois- because damaged stem tissue

6 allows less water to leaves, stunting conduct heat and stimulates weed quinclorac (Paramount or Drive), growth of field bindweed. Burning seed germination. The heat trapped and triclopyr (Crossbow, which also must be repeated like mechanical under the polyethylene will kill the contains 2,4-D). The translocated cultivation. Any lapse in the fre- seeds or seedlings. Soil solarization herbicide glyphosate (Roundup and quency of these types of control can suppress field bindweed top many other names) is not selective, methods will set back progress growth for as long as 6 weeks. Soil but can be used selectively with toward eradication. solarization also will reduce the precise application and protection number of seedlings, but field of desirable plants. Composting bindweed will not be eradicated Many translocated herbicides Applying manure to fields is a totally. move within plants along with sug- common practice in many places; Field bindweed along with some ars produced from photosynthesis. however, there is great concern other perennial weeds are hard to Best perennial weed control is with the amount of weed seed that control because their underground achieved when the herbicide appli- is being applied with the manure. vegetative structures, like rhizomes, cation coincides with maximum High temperature composting can tubers, and bulbs, enable them to sugar movement to the roots. In a be an effective way to help elimi- survive soil solarization and other perennial plant newly emerged from nate viable field bindweed seeds in non-chemical control methods. Soil a root bud in spring, most sugar is manure. Studies prove that field solarization of seedling and/or annu- moving upward to help produce bindweed seed will be killed if the al weeds can be an effective alterna- new vegetative growth. When the temperature of the compost reaches tive to chemical control. plant reaches the bud or early 180°F or higher for 7 consecutive bloom stage, vegetative growth days. If the temperature is not main- Herbicides slows or stops. After that time, most tained at 180°F or higher for at least For current herbicide informa- sugar produced in the leaves begins 7 days, seed viability will only be tion, consult the Pacific Northwest to move toward the roots. partially reduced. For instance, Weed Management Handbook or The bud or early bloom stage is compost temperatures reaching other publications including the the best time to spray field 180°F for only 3 days will reduce labels of specific herbicides. An bindweed provided that the plant is the seed viability to 30 percent. Be online version of the handbook can not water stressed. Sugar move- aware that since the outer edges of be found on the Internet at ment to the roots is also high in fall a compost pile may not reach tem- http://weeds.ippc.orst.edu/pnw/ as nighttime temperatures decline, peratures high enough to complete- weeds. This bulletin mentions only so herbicide treatment of fall re- ly reduce viability, turning or mixing those herbicides that are commonly growth after harvest or tillage has the compost is essential. With small used and currently registered for resulted in long-term control of field amounts, the use of compost bins specific site uses. New herbicides bindweed. No herbicide will be enable reaching and maintaining the may become available, and current effective if the plant has gone into necessary compost temperature label details will change over the dormancy or semi-dormancy due to more easily. Smaller composting years. Be sure to read the label drought, a killing frost, or other operations that do not meet these before using any herbicide. adverse growing conditions. temperature and time requirements Selective herbicides may kill most soft-coated weed A selective herbicide is one that seed, but not seed with hard seed does not normally harm desirable coats like field bindweed. plants while it injures the target plant. When hormone-type herbi- Soil Solarization cides are used at low dose rates Soil solarization uses the sun's according to label directions, they solar energy to kill soil pests. Clear do not harm grasses such as grain polyethylene tarps may be used crops or lawn or pasture grasses. singly to cover pre-formed beds in Long-term chemical control of field small or large areas. Weed control is bindweed depends on sufficient her- most effective when prepared beds bicide moving into the root system are irrigated before covering with to kill roots and root buds. This polyethylene. To prepare a bed for requires the use of a translocated or soil solarization, the surface area systemic herbicide (a herbicide that should be tilled and leveled. moves from one plant part to anoth- Irrigation also should be done after er). Examples of selective, translo- the polyethylene has been installed cated herbicides are 2,4-D, dicamba Figure 8. Blooming begins about 4 if irrigation drip lines are installed (Banvel or Clarity), picloram weeks after emergence in mid-spring first. Moisture under the tarps helps and continues until frost kills plant (Tordon), dichlobenil (Casoron), foliage.

7 Table 1. Ten ways to control ﬁeld bindweed are summarizd on pages 8 and 9. With diligence, ﬁeld bindweed root systems can be eliminated by integrating the use of biological, mechanical, and chemical control agents.

Control type Strategies to ﬁght bindweed plant & seeds Success notes Cautions/Problems

Biological control- Perennial grasses compete well with ﬁeld To enhance competi- Bindweed will persist competition bindweed. tion from desirable in rangeland, pasture, Alfalfa can compete with a bindweed infesta- grasses: and lawns in a sup- tion, but will not crowd it out. It can be used as • Avoid early and mid- pressed condition and a soil building crop in a rotation designed to spring grazing; or will grow vigorously if control bindweed by other means (especially • Graze all plants in a competitive species under dryland conditions). short duration, high are absent, over- intensity system, grazed, or misman- • Apply nitrogen fertil- aged. izer, as needed • Reseed where needed.

Biological control— The USDA approves the release of insects and Caterpillars of this This moth has not insects and mites mite species that damage field bindweed only. moth defoliate been released on a By 2005, the only one was European moth (Tyta bindweed, usually in large scale, as of fall, luctuosa). the later part of the 2005. A gall-forming mite, Aceria malherbae, is estab- growing season. Control with insects lished in Texas and shows success in the south- Aceria malherbae and mites is not prom- ern U.S. deforms field bindweed ising in annual crop- buds and leaves. ping systems, gardens, or turf. Extensive root systems limit abilities of insects and mites to control this weed. Many insects that feed on field bindweed also damage native and ornamental morningglories.

Mechanical FALL: Begin tillage after harvest. Plow 6 inches Fallow tillage program A month’s lapse in this control—fallow deep. works when consistent tillage program can set tillage • Twelve days after bindweed re-emerges, till over 3 to 5 years, eradication back a with an implement that cuts off all plants—a preferably in dry soil year or more. rod weeder or sharp, duckfoot-type ﬁeld culti- and without cropping. vator. Mechanical controls • Overlap sweeps every 14 days until bindweed (tillage, hoeing) can be shoots freeze. effective for weed • Cultivate to cut off all shoots—usually 2 to 4 seedlings only from inches deep. emergence to 6 weeks SPRING: Resume tillage 12 days after after emergence. After bindweed emerges. Repeat every 14 days until that, lateral roots cause bindweed no longer appears. them to quickly spread. • Keep equipment out of bindweed patches except during control operations. Roots have less food • Clean roots and stems from equipment before reserves after spring leaving bindweed patch. emergence than in the fall.

Mechanical Cultivation in row crops will substantially sup- Use other control Cultivation in row control—cultivation press field bindweed growth, especially methods, such as her- crops will not prevent in row crops between rows. bicides, in combination the weed from causing Once the crop becomes too large to cultivate, with cultivation and significant crop loss. the crop must be healthy and competitive with during times in the Cultivation can trans- field bindweed. rotation when cultivat- port roots and stems, ed crops are not spreading weeds. grown. Many young stems covered with soil thrown by the cultivator early in the season will continue to grow.

8 Table 1. Continued.

Control type Strategies to ﬁght bindweed plant & seeds Success notes Cautions/Problems

Mowing, Removing all field bindweed top growth by Mowing is effective only Mowing alone is inade- pulling, pulling or burning can eliminate all but the when combined with other quate because it misses burning weed seed if repeated at least every 14 days control methods such as stems lying flat, low leaves, over 3 to 5 years. herbicide treatment. and flowers, so plants can Burning, which must be reproduce repeated, is most effective Any lapse in repeated during summer because burning or mowing will set damaged stem tissue back eradication. allows less water to leaves, stunting field bindweed growth.

Composting Heat compost to 180°F for at least 7 days to kill Smaller composting opera- Field bindweed seed com- hard coated seeds such as ﬁeld bindweed. tions that do not meet tem- posted less than 7 days at Mix compost so edge materials also heat up. perature and time require- 180°F will survive. ments may kill soft-coated weed seed, but not ﬁeld bindweed seed with hard coats.

Soil Use polyethylene tarp over tilled, leveled, Can suppress top growth Reduces number of solarization irrigated bed. for 6 weeks. seedlings, but does not totally eradicate them. Deep reproductive roots will not be killed.

Herbicides, Consult PNW weed management handbook Time applications to coin- Carefully follow label selective online at http://weeds.ippc.orst.edu/pnw/weeds. cide with maximum sugar instructions. (doesn’t • Systemic herbicides include 2,4-D, dicamba movement to the roots harm desir- (Banvel or Clarity), picloram (Tordon), (late summer or early fall able plants) dichlobenil (Casoron), quinclorac (Paramount before killing frost). or Drive), and triclopyr (Crossbow). Selective herbicides enable • Use translocated herbicide glyphosate desirables plants to be (Roundup and many others) with precise more competitive. application and protection of desirable plants. See guidelines for speciﬁc crops on pages 10 and 11.

Herbicides, Examples: glyphosate, a systemic or translocat- Contact herbicides Contact herbicides only nonselective ed herbicide; paraquat (Gramoxone Max), a (paraquat) kill only tissue affect short-term control of (kills or contact or non-systemic herbicide. Revegetate contacted directly; can kill ﬁeld bindweed top growth. injures all with desirable competitive plants such as peren- seedlings in the cotyledon New shoots can develop plants) nial grasses. stage. from unaffected roots. Nonselective herbicides can kill all vegetation.

Chemical Use soil sterilants only on noncrop sites and as Use in areas where vegeta- Most prevent growth of soil a last resort. Soil sterilants do not sterilize soil; tion creates a ﬁre or safety shallow-rooted weeds only, sterilants they kill or inhibit growth of plants that absorb hazard such as electrical so their use may result in them. utility areas, remote gas more bindweed growth. Apply in late fall or winter (not on frozen soil), pumping stations, etc. Do not use where erosion so winter moisture moves materials into the Inspect areas treated each could occur after vegeta- bindweed root zone. Follow label directions. year for bindweed emer- tion loss. gence, and treat again Soil fumigation can pro- when appropriate/neces- vide substantial suppres- sary. sion, but does not penetrate deeply enough to kill the entire root system. Fumigants cannot kill dormant ﬁeld bindweed seeds.

9 Selective herbicides by /restrictions for follow crop planting dicamba (Distinct) in many vari- after dicamba application in the fall eties of field corn. Dicamba may be crop, location since residues from high rates of applied until the fifth leaf stage or Small grains—In irrigated areas, dicamba can persist in soil to injure corn is 8 inches tall, whichever spring-planted barley or wheat com- sensitive crops the next year. comes first. Corn from 8 to 36 inch- petes well with field bindweed. Glyphosate has no soil activity, so es tall may be treated with dicamba Most varieties may be sprayed with any labeled crop may be planted or diflufenzopyr + dicamba, but 2,4-D. Apply the herbicide after the after a glyphosate application. drop nozzles should be used to grain has tillered but before the Glyphosate alone has not consis- reduce dicamba drift. Do not use boot stage. If weather conditions tently controlled field bindweed and either herbicide if susceptible crops prevent this application during this in some tests has been no better such as potatoes, sugar beets, dry time period, make the application than 2,4-D. However, combining beans, alfalfa, etc., are nearby. after the dough stage. glyphosate and 2,4-D or dicamba In corn 3 to 8 inches tall, 2,4-D Under non-irrigated (dryland) usually improves bindweed control may be used. As with sweet corn, conditions in winter wheat or bar- compared with using any of these when field corn is taller than 8 inch- ley grown east of the Cascade herbicides alone. Glyphosate may es, reduce injury by using drop noz- Mountains, 2,4-D is less effective be best for spot treatment in situa- zles to keep 2,4-D off the upper because the fall-planted crop usual- tions requiring a nonresidual treat- leaves and whorl. Avoid using 2,4-D ly reaches the boot stage before the ment or when a field also is infested esters and do not make any 2,4-D bindweed is advanced enough for with quackgrass or other applications on windy or hot days. most effective spraying. If possible, glyphosate-sensitive perennial Do not allow 2,4-D to contact any apply 2,4-D before the small grain weeds. plant for which there is no label crop starts to boot; 2,4-D can be Quinclorac (Paramount) is a rela- provision. applied to winter wheat or barley tively new herbicide that is used in Some corn varieties will not tol- after the dough stage if the first wheat cropping systems. It should erate selective spraying with 2,4-D. application timing is missed. For be applied in the fall just prior to Refer to the label or consult a long-term selective control on dry- the first killing frost. Field knowledgeable crop adviser or uni- land, use a crop rotation that bindweed plants should be actively versity extension specialist for vari- includes at least three consecutive growing, and the above-ground ety tolerance information. years of wheat or barley, and apply growth should be at least 4 inches Pasture and rangeland—In estab- the selective treatment each year. long. In winter wheat cropping sys- lished grass pasture, apply 2,4-D, After small grain harvest in irri- tems, it is best to allow a minimum dicamba, imazapic plus glyphosate gated fields, remove excess straw to of 30 days for field bindweed to re- (Journey), and picloram (Tordon) expose the bindweed, then irrigate grow after tillage prior to applica- according to label directions when the field to stimulate active weed tion. Quinclorac can be mixed with field bindweed starts to bloom. growth. In dryland areas, bindweed 2,4-D, dicamba, or glyphosate. Some of the herbicides have restric- regrowth after harvest will depend Spring or winter wheat or grain tions for returning livestock to on adequate fall rain before a killing sorghum are the only crops that can treated areas. The limitations of frost. be planted earlier than 10 months individual herbicides are specified When bindweed stem regrowth in after application. Refer to the quin- on each label. clorac label for other follow crop the late summer/early fall is 10 to 14 Potatoes, sugar beets, peas, dry restrictions. inches in fields where no crop is beans—Apply 2,4-D and/or growing, apply 2,4-D, dicamba, Sweet corn—Field bindweed glyphosate the season before plant- glyphosate, quinclorac, or commer- growing in sweet corn may be sup- ing potatoes, sugar beets, beans or cial premixed combinations such as pressed with 2,4-D. However, some other sensitive crops. Allow glyphosate plus 2,4-D. The herbicide varieties may be injured severely by bindweed stems to grow an average labels will specify rates and applica- 2,4-D, so consult the label, a knowl- of 12 inches before 2,4-D and/or tion methods. 2,4-D is less expen- edgeable crop advisor, and/or your glyphosate application. These crops sive than dicamba or glyphosate, corn dealer or contractor before cannot be planted in the same sea- but residual bindweed control the applying 2,4-D. When corn height is son 2,4-D is used. season after a single 2,4-D applica- more than 8 inches tall, corn injury If field bindweed has stopped tion averages only 30 to 40 percent. can be reduced by using drop noz- growing in irrigated fields, irrigate Dicamba is more costly, but is usu- zles to keep 2,4-D off the upper the infested area(s) at least a month ally more effective than 2,4-D. Fall leaves and whorl. before herbicide application. Spray application of dicamba results in 70 Field corn—Field bindweed can be when weed growth resumes and to 85 percent control the next sea- treated with dicamba, 2,4-D, a com- produces 12- to 14-inch stems. Wait son. Follow label recommendations bination of both, or diflufenzopyr + 2 days after treatment for herbicide

10 uptake and movement within the appear. This application must be pumping stations, and other areas plants, then irrigate the sprayed done consistently over a period of where the presence of vegetation area as soon as possible to maintain several years in order to destroy all creates a fire or other safety hazard. the translocation of herbicides as roots. If the roots are successfully Apply soil sterilants in late fall or completely in the plant as possible. killed, seedlings emerging each year winter (but not on frozen soil) so Re-treat whenever new bindweed can be controlled with these herbi- that winter moisture will move the growth reaches 10 to 14 inches in cides within 6 weeks of germination material into the bindweed root length. or before the seedling produces six zone. Follow label directions to pre- Do not plow for at least 2 weeks leaves, whichever occurs first. vent undesirable side effects such after herbicide application. Ornamentals—Glyphosate and as off-site movement of the herbi- Orchard floors (apple, blueber- some brands of 2,4-D are permitted cide. Areas treated with soil steri- ry, cherry, grape, nectarine, as long as no spray mist, droplets, lants should be inspected each year peach, pear, prune, plum)—Field or other forms of the herbicide con- for bindweed emergence and treat- bindweed can be a major problem tact desirable plants. Extreme care ed again when appropriate/neces- in fruit production areas, especially must be taken to avoid injuring sary. in young orchards. In addition, the desirable vegetation. Herbicide Soil fumigation can provide sub- 20-year cycle from planting to application can be combined with stantial suppression, but will not removal in fruit tree crops such as hand-weeding for more effective completely kill field bindweed those listed above, usually allows control. plants since the fumigant does not penetrate deeply enough in the soil field bindweed to increase unless Nonselective Herbicides profile to kill the entire root system. intensive control is practiced. Nonselective herbicides typically Deep roots unaffected by the fumi- In most orchards, maintain bare kill or injure all plants. Selectivity gant can produce new shoots. soil under trees and grass sod in the however, is sometimes based on the Fumigants also cannot kill dormant row middles. The use of dichlobenil use rate. Examples of nonselective field bindweed seeds. as a selective residual herbicide can herbicides include glyphosate, effectively maintain bare soil while which is a systemic or translocated Folair nonselective herbicides a planting is becoming established. herbicide, and paraquat In noncrop, industrial, recreation- Soil-active herbicides should not be (Gramoxone Max), which is a con- al, and public areas where soil steri- applied around trees younger than tact or non-systemic herbicide. lants have been applied and field 1 year old nor should they be Contact herbicides such as paraquat bindweed is emerging, glyphosate applied to shallow, coarse, sandy, kill only the tissue contacted direct- may be applied nonselectively. or gravelly soils. Competition from ly. They can kill seedlings in the Certain crops can be planted after established sod will minimize field cotyledon stage, but only short-term glyphosate application in these bindweed growth in the middles. control of field bindweed top areas. Refer to the label for restric- In older plantings where growth can be achieved since new tions/recommendations. Picloram, bindweed is a problem in bare shoots can develop from unaffected dicamba, or 2,4-D also are labeled areas, a paraquat/glyphosate mix- roots with root buds. Other types of for use in such areas at much high- ture can be a successful nonselec- nonselective herbicides are called er, less selective doses than their tive "burn down" treatment. Follow soil sterilants. use rates for weed control in crops. label instructions. Do not let the Chemical soil sterilants herbicide contact immature (green Use soil sterilants only on non- Prevention or thin) bark or tree foliage. crop sites and as a last resort. Soil 1. Plant seed that is free of field Roadside, fencerow, and non- sterilants do not sterilize the soil; bindweed seeds. cropped areas—Maintain an they kill or inhibit growth of plants 2. Ensure that roughage or grain for adapted, competitive grass. Apply that absorb them. Most soil steri- feed contains no field bindweed labeled herbicides as soon as field lants prevent growth of shallow- seeds. bindweed begins to bloom, and rooted weeds only, so their use may 3. Buy nursery stock only from nurs- reapply within 2 weeks of the actually result in more bindweed eries that guarantee soil around appearance of new growth. growth. Soil sterilants may be used the roots to be free of field Picloram, dicamba, or 2,4-D may be in noncrop areas where high rates bindweed roots and seeds. used. may be effective, but only should be 4. Avoid mature field bindweed Lawns and turf—Apply 2,4-D, tri- used where erosion will not occur patches when harvesting as har- clopyr, a mixture of the two after vegetation loss and where the vest operations may distribute (Turflon D), quinclorac (Drive), or herbicide will not move to sensitive, seeds. Transport of field other labeled systemic broadleaf nontarget areas. Examples of where bindweed seeds in crops or on herbicides to fully expanded field soil sterilants are used include elec- vehicles or equipment violates bindweed leaves whenever they trical utility areas, remote gas

11 Idaho, Oregon, and Washington state noxious weed laws. 5. Treat all field bindweed infestations appropriately in order to kill roots, prevent shoot growth from root buds, and to prevent seed production. Use effective methods to control seedlings (growing from seed) in subse- quent years. 6. Be sure tractors, tillage implements, harvest equipment, and other machinery are clean before allowing entrance onto your land, especially if they have been used in field bindweed-infested areas. 7. Support laws and ordinances that are intended to prevent field Figure 9. Flowers originate and grow from leaf axils at the junction of leaf bindweed spread. and stem. Two tiny bracts are located l l/2 to 2 inches below each flower.

______The Authors—Don W. Morishita is a University of Idaho extension weed scientist at Twin Falls; Robert H. Callihan is a UI professor emeritus; Charlotte V. Eberlein is associate vice president and director of UI Extension at Twin Falls; Joseph P. McCaffrey is an entomologist at the UI in Moscow, and Donn C. Thill is a weed scientist at the UI College of Agricultural and Life Sciences in Moscow.

PESTICIDE STATEMENT ALWAYS read and follow the instructions printed on the pesticide label. The pesticide recommendations in this UI publication do not substitute for instructions on the label. Due to constantly changing pesticide laws and labels, some pesticides may have been cancelled or had certain uses prohibited. Use pesticides with care. Do not use a pesticide unless both the pest and the plant, animal, or other application site are speciﬁ- cally listed on the label. Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock. Trade names are used to simplify the information; no endorsement or discrimination is intended.

Paciﬁc Northwest extension publications are produced cooperatively by the three Paciﬁc Northwest land-grant universities: Washington State University, Oregon State University, and the University of Idaho. Similar crops, climate, and topography create a natural geographic unit that crosses state lines. Since 1949, the PNW program has published more than 550 titles, preventing duplication of effort, broadening the availability of faculty specialists, and substantially reducing costs for the participating states.

Published and distributed in furtherance of the acts of Congress of May 8 and June 30, 1914, by University of Idaho Extension, the Oregon State University Extension Service, Washington State University Extension, and the U.S. Department of Agriculture cooperating.

The three participating extension services offer educational programs, activities and material without regard to race, color, religion, national origin, gender, age, disability, or status as a Vietnam-era veteran as required by state and federal laws. University of Idaho Extension, Oregon State University Extension Service, and Washington State University Extension are equal opportunity employers.