Description. Buttonweed is a warm season perennial with a sprawling, widely branched growth habit. Leaves are opposite, margins slightly serrated, oblong or nearly linear, generally 2 to 3 inches long and leathery in texture. Leaves often develop a purplish color. The plant has an extensive root system and develops underground rhizomes.
The plant produces small, white flowers during the summer and fall. Fruit develop along the stolons, or stems, in summer and fall. Fruit are oval shaped with vertical ridges and usually 6 to 10 mm long. The fruit develops into leathery pods in rows along the stolons and give the plant its name, buttonweed.
Plants develop in early spring from dormant rhizomes and seed. Emergence occurs about the time St. Augustine grass begins growth and continues throughout the spring. The above ground part of the plant is killed in the fall by the first frost.
Control. Preemerge herbicides are not effective since buttonweed emerges from dormant rhizomes as well as seed. Postemerge contol requires repeated treatments in the spring and summer. In bermudagrass turf, MSMA at 3 lbs. per acre will provide temporary control. Combinations of MSMA with Trimec (or similar products) have provided good control with only two applications (spring and summer). MSMA at 2 lbs. per acre plus Sencor at 1/8 lb. has also demonstrated good control. Sencor alone has not demonstrated satisfactory control of buttonweed.
In St. Augustine grass lawns, dicamba (Banvel) or products containing dicamba (Trimec) provides some control with two or more applications in spring and summer. If some discoloration of St. Augustinegrass can be tolerated, Confront at 2 pints per acre and Scotts DMC at 1 ounce per acre have demonstrated good control of buttonweed.