Field bindweed (Convolvulus arvensis), also known as wild morning glory, creeping Jenny, corn bind, and devil’s guts, is one of the world’s worst weeds and among the most difficult to eradicate. A European native, it occurs throughout the United States, except in the extreme Southeast and Southwest. In Canada, field bindweed occurs in all the southern provinces from Nova Scotia to British Columbia.
A broadleaf herbaceous perennial, it reproduces both by seeds and from shoots arising from its roots and rhizomes. The seed, which can remain viable for 20 to 60 years, germinates sporadically in the spring and early summer. In six weeks, the seedlings develop a taproot and accompanying lateral roots. By the end of the first year these lateral roots can spread 10 feet in diameter, and twice that far by the end of the second year. New plants arise from adventitious buds on the fleshy, cordlike roots, from axillary buds on the underground crowns, and from rhizomes. This extensive root system contributes to this weed’s drought tolerance and its ability to cope with repeated removal of its aboveground parts.
SYMPTOMS: A pest of both edibles and ornamentals, field bindweed infests fields, pastures, home gardens, orchards, and vineyards. On bare ground, it forms a sprawling mat; elsewhere it climbs by means of its twining stems, which can reach 10 feet, creating a smothering tangle. Leaves are alternate and arrowhead-shaped. From June to September, plants produce white to pink funnel-shaped flowers that are followed by seedpods with up to four hard, triangular, gray-brown seeds. Seedlings can be recognized by the paired, nearly square to kidney-shaped cotyledons with a shallow notch at their tips.
CONTROL: Once established, this weed is difficult to eradicate. Seedlings can be killed with cultivation three to four weeks after germination. Cultivation or hand-pulling of new shoots will also eventually eliminate established plants, provided it is done every two weeks during the growing season. This may take two to three years, however. Field bindweed is intolerant of shade. Landscape fabrics placed on top of infested areas and then mulched will provide control if the fabric is left in place for two to three years. Because the seed requires light to germinate, a mulch layer will also keep it dormant. In ornamental plantings, preemergent herbicides such as trifluralin, oryzalin, and pendimethalin will control seedlings. Where field bindweed is already established, applications of a glyphosate-based herbicide can be made when plants are in flower. Spray or paint a 2% to 4% solution of glyphosate on the leaves of bindweed. As this is a nonselective herbicide, be careful not to let it touch desirable plants.