Hello everyone,

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
field bindweed
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.  

field bindweed 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. 









field bindweed
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.

field bindweed

In the image above, notice the two small leaf bracts that occur about 1 inch below the flower.


Control

field bindweed 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 herbicides.

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.


Look alikes

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

Literature

Appleby, A.  1999.  Field bindweed (Convolvulus arvensis).  http://www.css.orst.edu/newsnotes/9903/weed.html#Field Bindweed

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.