Q: I have a weed in my yard that looks like fine grass, but I when I dig it up the root it has a small, round ball attached to it. It is so aggressive that it even pops up through the weed cloth I have put down in my flower beds. What is this weed?
A: Probably what you have is a yellow nut sedge and you are correct in stating it is aggressive. It is a rapidly spreading perennial that puts out a long stem and a yellow-brown seed head. Stems of sedges are triangular (“sedges have edges”) whereas grass stems are hollow and round. It reproduces mainly by tubers and is found throughout the United States.
Several herbicides can temporarily suppress yellow nutsedge populations; however, eradication of established nutsedge in lawn grass is extremely difficult. Some herbicides kill the yellow nutsedge plant tissue, however new plants can emerge from the tubers in the soil. Although it looks similar to grass the leaves of sedges are thicker and stiffer than most grasses. In addition, yellow nutsedge is a lighter yellow green color than St. Augustine grass.
Sedges in general prefer moist soils so their presence may be an indication of too much water or the area is lower than the rest of your landscape. If over watering is contributing to the problem, reducing the amount of water may be beneficial.