[Convolvulus arvensis L.][CONAR][CDFA list: C] Photographs Map of Distribution
SYNONYMS: small bindweed, field morningglory, small-flowered morningglory,
wild morningglory, European morningglory, orchard morningglory, creeping jenny,
creeping charlie, cornbind, greenvine, lovevine
DESCRIPTION: Viny perennial with
an extensive system of deep creeping roots and rhizomes. Field
bindweed is considered one of the most noxious weeds of agricultural
fields throughout temperate regions of the world. Plants typically develop
large patches and are difficult to control. It is troublesome in numerous
crops, but is especially problematic in cereals, beans, and potatoes. Heavy
infestations in cereal crops can reduce harvest yields 30-40% or more. In
California, it is estimated that 770,000 hectares of agricultural land was
infested in 1981. Plants can harbor the viruses that cause potato X disease,
tomato spotted wilt, and vaccinium false bottom. Foliage contains tropane
alkaloids and can cause intestinal problems in horses grazing on heavily infested
pastures. Two biocontrol agents, the bindweed gall mite (Aceria malherbae)
and bindweed moth (Tyta luctuosa), are cleared for release in the U.S.
However, these biocontrol agents are not registered for use in California
since uncommon native morningglory (Calystegia) species may also be
susceptible to attack. Introduced from Europe.
SEEDLINGS: Cotyledons unequal, +/-square to kidney-shaped,
indented at the tip, ~ 8-20 mm long, 3-10 mm wide, glabrous, dull green
with whitish veins, on stalks ~ 10-20 mm long. First leaves +/- arrowhead-shaped,
blunt at the tip, similar in size to the cotyledons. Subsequent leaves increasingly
larger, +/- resemble mature leaves. New leaves loosely creased along the main
vein in bud. Taproot grows deep rapidly. By 6 weeks, creeping lateral roots
have developed, typically in the top 30 cm of soil.
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PLANT: Stems twine around and over
other plants or trail along the ground. Leaves alternate, short-stalked, arrowhead-shaped
to +/- oblong or round, tips often rounded, typically 2-4 cm long, glabrous
or sparsely covered with short hairs, dull green, sometimes covered with a
whitish powdery bloom. Basal lobes +/- pointed, often flared outwards
(hastate). Leaf size and shape vary greatly depending on environmental conditions
such as light intensity, soil moisture, and frequency of cultivation or defoliation.
and UNDERGROUND STRUCTURES: Roots cord-like,
white, fleshy, brittle. Root systems consist of a vigorous, extensive network
of primary and secondary taproots, numerous short-lived lateral feeder roots,
and long-lived horizontal creeping roots that develop rhizomes from endogenous
buds. Rhizomes grow to the soil surface and produce new shoots. Roots can
penetrate soil to a depth of 3 m or more depending on the availability of
soil moisture. Most horizontal creeping roots develop in the top 60 cm of
soil. Root systems competitively extract soil moisture and can survive extended
periods of drought and repeated cultivation.
FLOWERS: April-October or until the first frost. Flowers axillary,
solitary or in cymes of 2-4, on stalks (peduncles) ~ 2-6 cm long. Corolla
white or pinkish, funnel-shaped, 1.5-3 cm long, pleated
and spiraled in bud. Calyx +/- bell-shaped, usually less than 5 mm long.
Stigmas 2, linear, cylindrical, not flattened. Bracts 2, linear to
narrowly lanceolate, 1-10 mm long, attached ~ 10-25 mm below flower.
Flowers open for 1 day. Insect-pollinated. Self-incompatible.
and SEEDS: Capsules spherical, +/- inflated,
+/- 8 mm in diameter. Seeds few per capsule, variable in shape, but typically
obovate, slightly compressed, +/- 3-sided in cross-section, 3-4 mm long, dull
dark gray-brown, covered with small, rough, irregular tubercles.
CHARACTERISTICS: Shoots typically die-back
during the cool season.
HABITAT: Cultivated fields, orchards, vineyards, gardens, pastures,
abandoned fields, roadsides, waste places. Grows best on moist fertile soils.
Tolerates poor, dry, gravelly soils, but seldom grows in wet soils. Inhabits
regions with temperate, Mediterranean, and tropical climates.
DISTRIBUTION: Abundant throughout California. To 1500 m (4900 ft).
PROPAGATION/PHENOLOGY: Reproduces by seed and vegetatively from deep creeping
roots and rhizomes. Most seeds fall near the parent plant, but some seeds
may disperse to greater distances with water, agricultural activities, and
animals. Seeds are hard coated and can survive ingestion by birds and other
animals. Most seeds can imbibe water and germinate 10-15 days after pollination.
However, seed coats mature 15-30 days after pollination, and ~ 80% of seeds
become impermeable to water. Impermeable seeds require scarification or degradation
of the seed coat by microbial action to imbibe water and germinate. Seeds
germinate throughout the growing season, but peak germination usually occurs
mid-spring through early summer. Germination can occur under various temperature
regimes, from 5-40º C, but is highest and most rapid when temperatures
fluctuate from 35-20º C. A 3-6 week period of chilling to ~ 5º C
appears to increase germination. Light is not required. A large portion of
the seed bank remains dormant from year to year. Under field conditions, seed
can survive for 20 years or more. A high percent of seed under dry storage
can survive for at least 50 years. Seed production is highly variable. Dry,
sunny conditions and calcareous soils favor seed production. Frequent cultivation,
rain, or heavy, wet soils can inhibit seed set. One plant can produce up to
500 seeds. In the field, young plants seldom produce seed the first season.
Root starch reserves are highest from mid-summer through early fall, but then
decline rapidly with conversion to sugars. Root carbohydrates are lowest in
mid-spring before flowers develop. Maximum translocation of carbohydrates
from shoots to roots occurs from the bud to full flower stages. Conditioned
roots can survive temperatures as low as 6º C. Most new shoots
appear in early spring. Undisturbed patches can expand their radius up to
10 m per year. Root fragments as small as 5 cm can generate new shoots.
FAVORING/DISCOURAGING SURVIVAL: Deep cultivation
before flowering and repeated cultivation when new shoots appear for 1-several
years, followed by rotation to competitive crops such as winter wheat or alfalfa,
can control troublesome infestations in agricultural fields. Where practical,
flooding fields with water to a depth of 15-25 cm for 60 to 90 days can effectively
eliminate most field bindweed plants. Cultivation to a depth of at
least 10 cm (4 in.) within 3 weeks after emergence can control seedlings.
Stems and leaf surfaces have a texture that is difficult to wet. The addition
of a wetting agent to certain herbicides may make them more effective. Some
field bindweed biotypes are less susceptible to certain herbicides.
SPECIES: Western morningglory [Calystegia
occidentalis (A. Gray) Brummitt] is a native perennial that closely resembles
field bindweed. It is a desirable component of the vegetation in natural
communities, but is sometimes weedy in agricultural or managed forest systems.
Unlike field bindweed, western morningglory typically has flowers
2.5-4 cm long, calyxes greater than 7 mm long, stigma lobes flattened,
and bracts mostly attached less than 10 mm below the flowers. In addition,
western morningglory is hairy throughout, and the basal lobes
of leaves are often squared to slightly indented or 2-lobed. Western
morningglory grows on dry slopes in chaparral and pine forests throughout
California, except the Mojave and Sonoran deserts, to 2700 m (8900 ft). Hollyhock
bindweed [Convolvulus althaeoides L.][Bayer code: none] is a showy
perennial with purple to deep pink flowers introduced from the
Mediterranean region. Hollyhock bindweed is distinguished by having
some upper leaves deeply lobed. It grows in localized populations
on disturbed sites in the northern Sierra Nevada foothills (Nevada Co.), Transverse
Ranges, Peninsular Ranges, and Southwest region, to 1000 m (3300 ft).
Biology and Prevention:
Field bindweed is a very serious perennial vine that may reduce crop yields,
increase irrigation costs, and interfere with harvesting. Field bindweed is
an excellent competitor for soil moisture and thrives in dryland agricultural
systems. Its extensive root system utilizes deep soil moisture and allows
the plant to withstand serious drought. Additionally, the plant is capable
of summer dormancy and new shoots emerge from adventitious buds on vertical
and lateral roots when rainfall returns.
Field bindweed also occurs in disturbed rangelands and wildlands. In these
areas it may establish in open grasslands above riparian areas where frequent
disturbance occurs such as that caused by feral pigs. It may form small patches
but generally does not constitute a serious threat. It is also frequently
found in conservation or restoration areas that were historically farmed.
These previously established patches are extremely difficult to eliminate
and inhibit restoration efforts. In rangelands, field bindweed rarely overlaps
with winter and spring grazing systems due to its emergence in late spring.
It provides very little green summer forage, as sheep and cattle generally
Field bindweed is also a serious weed of many irrigated crops, young orchards
and vineyards. It establishes along irrigation drip lines in vineyards and
uses soil moisture and nutrients applied for the crop. It is strongly competitive
with many seedling vegetables and establishes in perennial crops such as alfalfa
or asparagus. Field bindweed is also a frequent problem in landscaping and
ornamental areas. Rootstocks and seeds are often transported in soil and mulch
to new areas.
When dealing with field bindweed, the farmer, land manager or home owner must
recognize that there are no "quick fix" solutions to eliminate it.
It is possible to bring bindweed to a manageable level, but it requires intensive
effort and a watchful eye. Additionally, even when infestations are reduced
to a minimal level, care must be take to prevent reestablishment from seed,
which are capable of persisting in the soil for 30-50 years. There are several
keys for field bindweed management.
1. Use tillage cautiously around patches to avoid spreading it. Always clean
tillage equipment before moving to new fields.
2. Always follow good production practices to get a competitive, healthy,
crop stand established, i.e. fertilize according to soil testing recommendations,
plant at optimum row spacing, plant populations, and planting dates.
3. A severe infestation of field bindweed will be very difficult to control
in broadleaf crops, due to a lack of selective herbicides. Incorporating winter
annual cereals into the rotation will increase competitive suppression and
allow for better herbicide selection for field bindweed control.
4. Any lax in management for even one year may allow field bindweed to rapidly
recover. A long-term plan should be developed if sustainable control is desired.
5. Additionally, severe infestations of field bindweed may suppress the germination
of other weed seeds in the seedbank. When field bindweed is controlled, several
other species may "suddenly appear." Knowing the field history may
assist in preparing for this potential problem.
Mechanical: Tillage systems
have generally provided negative results for field bindweed control. Field
bindweed responds to plowing, discing, and rod weeding by increasing bud formation
just below the tillage layer. New shoots rapidly emerge and carbohydrate reserves
are replenished in a few weeks. Tillage is clearly effective on seedlings.
However, plants may form perennial buds within six weeks of emergence. Tillage
used for seedling control should be conducted within the first few weeks to
prevent plants from surviving.
Infrequent tillage used in fallowed fields or within orchards may actually
promote field bindweed infestations by eliminating annual weed competition
and spreading root fragments around. If field bindweed patches are evident,
avoid tilling them to prevent spread of the rootstocks. In this case, spot
treatment herbicide applications will be more effective.
Intensive cultivation was historically used for field bindweed control. This
entailed cultivating at least every two weeks to exhaust carbohydrate supplies
in the roots. This type of tillage strategy is not recommended, due to the
increased potential for erosion and soil moisture loss. Other intensive mechanical
strategies include hand pulling or grubbing. These must be done repeatedly
to be effective.
Biological: There are currently no registered biological control agents
for field bindweed in California. However, there are two insects that are
used in the Great Plains: the bindweed moth (Tyta luctuosa) was released in
Arizona, Iowa, Missouri, Oklahoma, and Texas and the bindweed gall mite (Aceria
malherbae) was released in Texas. Registration of these insects in California
Chemical: Chemical control of field bindweed generally requires a multiple
year approach. There are few herbicides that provide effective control. Always
refer to the herbicide label for specific instructions and plantback restrictions.
These treatments work best when
applied to actively growing, healthy bindweed with 6-18 inch runners. When
bindweed is under drought stress, the effectiveness of these treatments will
likely be significantly reduced. Finally, it cannot be stressed enough that
field bindweed management must be practiced on a continuous, year to year
basis, even with the above recommended herbicide applications. No single treatment
will eradicate field bindweed. However, these treatments will suppress bindweed
populations to a manageable level.