Virginia buttonweed is a low-growing, spreading weed that is difficult to control in lawn and landscape situations. It commonly grows in moist sites, such as woods and marshes, but can be especially troublesome in turfgrass areas.
A spreading perennial weed with slightly hairy, branched stems. Leaves are opposite and lance shaped. Opposite leaves are joined across the stem by a membrane. Virginia buttonweed has white tubular flowers with four lobes that are found at each leaf axil along the stem. This plant produces a green fruit that is elliptical, hairy and ridged and is also found at each leaf axil. Virginia buttonweed reproduces by seed as well as root and stem pieces. Leaves often turn mottled yellow in summer as a result of a virus.
Control in Turf:
If only a few plants are present, spot treat with Roundup or physically remove by digging. Remove all plant parts and soil, and replace with weed-free soil.
Most herbicides only offer fair control(70-79%) and repeat applications are usually needed. Products containg 2,4-D, MCPP and dicamba, such as Weed-B-Gon and Weed Stop, are available at most garden centers and nurseries for use on bermuda, zoysia, centipede and fescue lawns. In centipedegrass and St. Augustinegrass, premergence applications of atrazine (Bonus S) will help to control Virginia buttonweed plants that arise from seed, but will not effectively control plants that regrow from the roots. Always read the label when using herbicides and follow all 'Directions for Use' instructions. Refer to labels for specific rates for each type of grass. Be sure to keep these products away from nearby ornamental plants and do not re-seed or re-sod for at least 3 weeks. Virginia buttonweed flourishes in wet conditions; therefore, try to control excess water. Provide good drainage to areas infested with this weed.
At this time, no pre-emergence controls have been effective.
Control in Ornamentals:
Roundup (glyphosate) provides good control(80-89%). Take special care to prevent drift of Roundup to nearby desirable plants and turf.