Weeds — those pesky unwanted plants that keep popping up in the lawn and garden — seem especially difficult to control in late summer. One in particular, field bindweed, is blooming and flourishing right now in the Midwest, and gardeners who have it know the special challenge of fighting it.
Bindweed is a major problem because of its extensive root system with reproductive buds, the ability for roots and seeds to remain viable in the soil for decades, and the plant’s interference with the growth of more desirable plants.
Bindweed might be a small annoyance in a flower bed, but left unchecked could cover and shade out plants. It is a little more annoying in a vegetable garden, where cultivated soil only seems to turn up new roots and seeds, and vines stretch to great lengths before being seen among the squash and cucumbers. For commercial producers, bindweed can cause substantial crop loss or yield reduction along with significant costs for control on a large scale.
Bindweed is identified by its dark green, dull, half-inch to two-inch long arrowhead or heart-shaped leaves. Leaves grow opposite each other along long, tender, viny stems. Bindweed is related to the prettier and less aggressive morning glory and is sometimes confused with it or with milkweed vine. Bindweed leaves are smaller and more abundant than these related species.
Bindweed is also identified by the white to pale pink flowers that are shaped like a trumpet’s horn. They are produced in abundance throughout the summer.
In mowed areas or areas without other vegetation, bindweed grows flat along the ground, but as soon as it contacts a plant or structure, it will use that for support to grow up and over.
Bindweed is easy to control by pulling as a very small tender seedling, but once it is established, it can take years of work to remove. Researchers suggest removing before the plant has 5 true leaves. After that, the roots begin producing reproductive buds and can re-sprout if the plant is pulled and roots break off. Root systems are reported to extend 30 feet deep or more in the right soil, and seeds can remain dormant in the soil for decades.
Repeated cultivation and pulling will eventually deplete the root system and is practical for a dedicated (stubborn) home gardener. Covering bindweed with black weed mat can be effective as long as light cannot penetrate — the University of Nebraska suggests the mat be left in place for three years to completely kill the plant. Solarization with clear plastic is ineffective as the bindweed will continue to grow even after weeks in the hottest part of the summer.
For gardeners or producers who need a larger-scale option, broadleaf-selective or broad-spectrum herbicides are the most popular choice. They are most effective in the fall when plants are storing resources in their roots, but may also make a dent on the plant in spring and early summer. Midsummer applications are largely ineffective. Also, one application may knock the plant back, but is unlikely to wipe it out completely. Plan to make multiple applications in the spring and fall each year for a few consecutive years at least.
— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation.