Ever heard of kudzu vine? It’s often referred to as “the invasive vine that ate the south” and the “mile-a-minute” plant. Once established, kudzu grows at a rate of one foot per day with mature vines growing up to 100 feet long. We have a smaller, somewhat less aggressive type of weed – field bindweed. This plant, native to Eurasia, showed up 150 years ago in San Diego, and by the 1920’s was considered the worst weed in California and many other Western states.
Common names for bindweed are perennial morning glory, creeping jenny, bellbine, sheepbine, and cornbind. Mature field bindweed plants have arrowhead-shaped leaves that can be one half to two inches long, with trumpet-shaped flowers, white to pink, and about an inch wide. It’s a ground hugging plant unless it climbs on an object for support. It often is found growing on upright plants, such as shrubs or grapevines, with its stems and leaves entwined throughout the plant and the flowers exposed to the light.
Extremely drought tolerant, it seems to prefer heavy clay soils rather than sandy soils. When water is withheld, bindweed competes better than most other plants. If an area is well watered, some ornamentals might compete better than the bindweed; however, in most cases, bindweed will flourish and twine up plants potentially choking them out. In the landscape, field bindweed will survive with sprinkler or drip irrigation. If there is no summer water, the plant reduces its seed production first and then reduces growth and leaf size, but it still will produce some flowers and seed.
One of the main challenges of managing this weed is the root system. It has both deep vertical and shallow horizontal lateral roots. The vertical roots can reach depths of 20 feet or more. However, 70% of the total mass of the root structure occupies the top two feet of soil. Most of these lateral roots are no deeper than one foot.
Seedlings of field bindweed are easy to control with cultivation, but only for about three to four weeks after germination. After that, perennial buds are formed, and successful control is much more difficult. Manual removal of bindweed can be modestly successful, but it’s important to get all the roots, as one tiny remaining piece can continue to grow. Withholding water to dry the site might help to reduce the perennial population in a summer season, assuming the roots have not tapped into deep moisture.
Cardboard covered by mulch may be effective if no light is allowed to reach the soil and the plant. The edges of the cardboard must overlap so that the bindweed stems can’t grow between the sheets and into the light. It might take more than three years of light exclusion before the bindweed dies.