Hard to control summer lawn weeds

Steve Borel, LSU AgCenter

Common lespedeza (Lespedeza striata) is a small summer annual legume with a somewhat wiry prostrate growth habit. The weed develops a woody tap root as it matures during summer months. Leaves have a prominent mid-rib with veins that branch at 45 degree angles. Leaves are oval in shape and contain small flowers that are pink to purplish. Reproduces from seed. This one is often in centipedegrass or St. Augustine grass that’s not receiving enough nitrogen fertilizer applications. Do not confuse this weed with prostrate spurge. Unlike lespedeza, prostrate spurge will have milky sap coming out when a stem or branch that is broken.

Common lespedeza is very difficult to control.

Virginia buttonweed (Diodia virginiana) is a mat forming summer perennial with spreading branches that ranks as the #1 weed problem in southern turfgrass. It usually proliferates in moist to wet areas and can tolerate mowing heights as low as 0.5 inches. It has an opposite leaf arrangement. Virginia buttonweed reproduces by seeds, roots or stem fragments. Flowers are white with four star-shaped petals, which sometimes have pink streaks in the center and two sepals. Seed capsules (buttons) are green, elliptically shaped, hairy and ridged. Each seed capsule contains two extremely viable seeds.

Control Recommendation: In research trials conducted by LSU weed scientists Celsius Herbicide or metsulfuron (MSM Turf, Manor, Mansion, Top Shot) - safe for all southern turf - provided the best control. These are not restricted use herbicides. Always read and follow label directions when applying pesticides. Remember the label is the law. There are other chemicals that also control these two weeds but either did not do as good a job as these, or they are for professional use only.

Do not expect 100 percent control with one application of these products. You will probably have to make repeat applications for best results. Again follow the label as to how often you should apply these chemicals.