By the first quarter of the twentieth century, field bindweed was proclaimed the worst weed in California and many other Western states. Field bindweed has been given many names including perennial morningglory, creeping jenny, bellbine, sheepbine, and cornbind.
Field bindweed is a hardy perennial found throughout California below the 5,000-foot elevation line. It spreads from an extensive rootstock and from seed. Most parts of the bindweed roots and rhizomes can produce buds that can create new roots and shoots.
Roots capable of budding are found to depths of 14 feet. Fragments of vertical roots and rhizomes as short as 2 inches can form new plants. Lateral roots serve another important function. About 15 to 30 inches from the parent plant, a lateral often turns downward, becoming a secondary vertical root, and sends out both roots and shoots from the turning point. By this means a single field bindweed plant can spread radially more than 10 feet in a growing season. This extensive underground network allows for overwintering without foliage, and it can persist for many years in the soil.
One to four dark brown seeds are produced in round, smooth, 1⁄4-inch capsules. An average plant produces about 550 seeds. Within one month after forming, the seed coat matures and becomes impervious to water. Seed that is 60 years old has been found to be viable. Once the seed coat is weakened, the seed will germinate at temperatures of 41° to 104°F.
Drought tolerance is a characteristic of field bindweed. In California, 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. 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.
Three practices can reduce the possibility of introducing field bindweed—purchase and plant clean seed and ornamental stock, remove any seedlings before they become perennial plants, and prevent any plants from producing seed. If topsoil is introduced to a site, it should be free of roots, rhizomes, seeds, and other bindweed propagules. It is important to control new infestations when they are small, because spot control is the least expensive and the most effective strategy.
Cultivation or hoeing has been partially effective in reducing established stands of field bindweed. Cultivate about every 2 to 3 weeks and repeat whenever necessary. In conjunction with cultivation, 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.
In other words, good luck! ■
