This week's article will focus on one of the most difficult to control
weeds in Oregon (and the rest of the U.S.). Field bindweed's (Convolvulus
arvensis) aggressive vine habit makes it imperative to control, while
its deep root system makes it extremely difficult to control. Its name
is derived from the Latin word convolvo which means "to twine", and arvense
which means "of the field" (Clark, 1998).
Field bindweed (Convolvulus arvensis) is a deep-rooted perennial
in the Morningglory family (Convolvulaceae). It spreads by seed and a deep,
extensive root system. Reports indicate that seed can persist in soil
for up to 60 years, and that roots can grow up to 30 feet deep (Appleby,
1999). It is obvious why this plant is such a problem.
Field bindweed grows prostrate along the ground until it comes in contact
with other plants or structures. It grows up and over anything in
its path. Much like pole beans, stems rotate in a circular patter
until it makes contact with a solid structure (fence posts, other plants,
etc.), then it wraps around the structure as it grows.
Foliage is arranged oppositely along the stem and is arrow shaped.
Most of the field bindweed I see looks consistently the same, although some
references describe it as variable. When juvenile stems are broken,
they exude a milky sap.
Flowers are trumpet shaped, pink to white in color, with 5 fused petals.
Field bindweed has two leaf bracts that grow from ½ to 1 inch
below the flower, and is a key identification characteristic. Flowering is indeterminate, so flowers will continue
to develop along growing stems until first frost.
In the image above, notice the two small leaf bracts that occur about 1
inch below the flower.
Because of its prostrate growth habit, field bindweed is generally unaffected
by mowing. Cultivation works with persistence and dedication.
Once cultivated, the plant will regenerate its shoot system in about 3 weeks.
Thus cultivation should occur every 3 weeks (Ross and Lembi, 1999).
Repetitive cultivation throughout the growing season for at least 2 years
should deplete the root system and provide control. Use the deepest
cultivation implements available. This may not be financially practical for
many agricultural production systems.
Herbicides can be used when a nursery crop is in the field as long as weeds
can be sprayed without making herbicidal contact with the crop. Applications
of glyphosate containing herbicides (like Roundup) or 2,4-D are effective.
These two herbicides are absorbed by foliage and moved throughout the plant
to kill roots and shoots. Repeated applications will be necessary, as
the root system on this plant can be so immense that insufficient herbicide
is absorbed with a single application. Use repeated applications, but
allow the plant to grow and produce flowers before each subsequent application.
More translocated herbicide will be moved to the root system when the
plant is flowering than when vegetatively growing.
If using contact herbicides like Finale (glufosinate), Gramoxone (paraquat),
or Scythe (pelargonic acid), reapply immediately after plants re-emerge from
the soil. Do not allow plants to develop flowers. This process,
even when done correctly, will take longer compared to tillage or using translocated
For the safest and most effective control, apply herbicides during the fallow
season when nursery crops are not present. Consider using a grass cover
crop along with 2,4-D, or a Roundup Ready crop with a glyphosate-containing
herbicide. This will control erosion and improve soil structure, while
killing field bindweed.
Hedge bindweed (Calystegia sepium), wild buckwheat (Polygonum
convolvulus), and sharppoint fluvellin (Kickxia elatine) are other
vine weeds that could be confused with field bindweed. It's important
to distinguish these weeds from field bindweed because controlling them requires
different strategies. Next week's email will detail these weeds and
provide clues for distinguishing one from the other (and a few words on how
to control them!).
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James Altland, Ph.D.
Oregon State University
North Willamette Research and Extension Center
Appleby, A. 1999. Field bindweed (Convolvulus arvensis). http://www.css.orst.edu/newsnotes/9903/weed.html#Field
Clark, L. 1998. Wild Flowers of the Pacific Northwest. Harbour
Publishing, Madeira Park, BC.
Ross, M.A. and C.A. Lembi. 1999. Applied Weed Science. Prentice
Hall Inc., Upper Saddle River, NJ.