Nut grass is a nuisance weed that often appears in lawns, gardens and around moist areas. It is not actually a true grass, but a member of the sedge family and more accurately referred to as nutsedge. Unlike grasses, it does not spread or grow from roots, but a nut-like tuber, hence its name.
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Nutsedge is difficult to control with most commercial herbicides. It has a tough, smooth, waxy outer coating which repels most weed killers. Its biology also is an added challenge as most herbicides are formulated to kill broadleaf weeds or grasses. Nutsedge is neither. Nutsedge can store more nutrients in its tuber than other weeds and as such even if one is successful spraying with a weed killer, quite often the nutsedge will grow back.
Regardless of which herbicides are used for nutsedge control, it is likely that multiple applications will be required to be effective. Herbicides containing the active ingredients bentazon, halosulfuron, imazaquin can be used with some success for nutsedge control. A non-selective herbicide such as those containing glyphosate can be used as well, but they will kill anything that they contact in addition to the nutsedge. Make sure to add a spreader sticker to the herbicides you use to help them stick to the surface of the nutsedge.
Other Preventative Measures
The best way to control nutsedge is to create an environment that is not conducive to its development. Start by ensuring that any soil or plants purchased are free of the nutlet tubers. Keep an eye on irrigation practices. Do not water lawns and gardens any more than is needed as nutsedge likes wet areas. This can also help to control unwanted fungus problems. Nutsedge do not do well in shade. Planting trees shrubs and flowers in areas where they have been a problem before can help to eliminate them as well.
Before attempting to eradicate nutsedge, make sure you have accurately identified the plant. Nutsedge can be distinguished from other grasses in a variety of ways. Grass stems are round or flat and hollow. The stems of all sedges, nutsedge included, is solid and triangular. Grass leaves appear in pairs at the base of their stems. Sedge leaves occur in three's. Sedges are also much sturdier and thicker than most grasses.