If you’ve really been unlucky, you might have looked at your yard, vegetable garden or raised bed and discovered that you had an abundance of a white-flowered vining plant just appearing all over. The white cup shaped flowers look a lot like morning glory, and like the flowers, the leaves are also similar to morning glory, but they’re smaller and narrower. They’re cousins, members of the same family, but you definitely don’t want this character. Once you’re certain that this isn’t something you placed in the ground, you may realize that this pretty thing is a very serious weed. Attractive it may be, but field bindweed ( Convolvulus arvensis) is indeed a problem.
People have planted it as a ground cover, in hanging pots, and climbing up trellises, since it is after all a pretty thing. Here’s an unfortunate example of an invasive plant that can establish itself and thrive, in part because it seems too pretty to pull out and put in the trash. If all weeds were ugly, they’d rarely be problems, now would they!
Field bindweed originated in Europe and Asia, but it’s been causing problems for North American gardeners and farmers since the mid seventeenth century. It’s a perennial, which means it can grow, produce flowers and drop seeds for years on end. Bindweed has root system that’ll grow as deep as 20 feet, if soil conditions permit it, so that’s at least one thing we don’t have to worry about. However, the roots can and will spread, sending out new shoots from nodes. As if that weren’t enough, it’ll also produce rhizomes, underground stems that can develop into robust plants.
When bindweed’s made itself at home, few other plants’ll successfully compete with it. The name “ bindweed” might be an indication of one of its most troublesome features. It’s not a parasitic plant; it creates its own food through photosynthesis. What it’s most like is a very rude, invasive neighbor. It forms dense mats that block light from tender young plants. It can become so tightly tangled with other landscape plants that it can injure them. Some reports say it can grow so thickly that it can break rose canes! As if that weren’t bad enough, being a robust invader, it draws large amounts of nutrients and water from the soil, weakening the plants you installed.
Once it’s established, getting rid of it takes a lot of effort, and nothing’s guaranteed to work. Simply pulling it from the soil, as if you were weeding a normal plant, only works for very young seedlings. In older plants, the roots and rhizomes spread throughout the planting bed. Removing a single weed, or even a few, only gives those underground structures the opportunity to produce new growth aboveground. Even the seeds are a problem; they’ve survived in the soil dormant for over 50 years.
A few methods have a measure of control, but no single one is completely effective. To get rid of it entirely, it’s essential to combine them and repeat them several times.
This plant thrives in full light, so if you can shade it, it becomes less of a problem. Planting other things really densely, such as strong ground covers, can block light from getting to it. That’ll help decrease the bindweed’s vigor.
Common herbicides, especially if you use them along with shade cloth, can also work be effective to a degree. If you elect to use an herbicide, choose one that’ll move through the plant, not just burn the leaves it touches. Herbicides alone can control part of the weed, but may not kill it entirely. And if you’re going to use herbicides, remember - they may be called “weed killers” but they’re designed to kill plants, so don’t let them get onto those lovely things you’d really like to keep.
It’s such a noxious thing that you’ll probably need to use several methods, even rototilling the area to break up its rhizomes. Most important, whatever you do, don’t let it stay and flourish.
For KNPR’s Desert Bloom, this is Dr. Angela O’Callaghan of the University of Nevada Cooperative Extension.