How Can I Control Nutsedge?

Do you want to try controlling nutsedge with cultural control methods?

Do you want to control nutsedge by removing its plants and tubers?

Do you want to control nutsedge by drying?

Do you want to control nutsedge by shading?

Do you want to try controlling nutsedge with nonselective post-emergent herbicides?

Do you want to try controlling nutsedge with selective post-emergent herbicides?

Tubers are key to nutsedge survival. If you can limit the production of tubers, you’ll eventually control the nutsedge itself. To limit tuber production, remove small nutsedge plants before they have 5 to 6 leaves, in summer this is about every 2 to 3 weeks. Up to this stage, the plant hasn’t formed new tubers yet. Removing as much of the plant as possible will force the tuber to produce a new plant, drawing its energy reserves from tuber production to the production of new leaves. Continually removing shoots eventually depletes the energy reserves in the tuber.

During the middle of summer, you can control purple nutsedge by cultivating the infested area and then withholding all moisture to allow the sun to dry the tubers. Repeated tilling and drying are required to give good control. This method is effective only in areas where other plants don’t need irrigation. Drying isn’t effective for controlling yellow nutsedge.

Nutsedges don’t grow well in shade, so changing landscape plantings might reduce their growth. For example, a highly infested, annually planted flower bed might be better off if you replant it with a tall, dense ground cover or shrub. Low-growing ground covers won’t shade out nutsedge.

The commonly used black polyethylene plastic mulches don’t control yellow or purple nutsedge, because the sharp points at the ends of their leaves can penetrate them. Landscape fabrics made from polypropylene polymers are available that effectively suppress nutsedge growth and have the added benefit of being water and air-permeable. For complete control, however, you still will need to remove any emerging nutsedge plants.

The only nonselective post-emergent herbicide currently available to help control nutsedge in the home landscape is glyphosate or glyphosate with nonaoic acid. This herbicide requires repeated applications, and its use will result only in limited suppression of these weeds. Apply glyphosate only when the plants are young, actively growing, and haven’t recently been mowed or cut. Be sure to read the label to determine how much time after application must occur before irrigation can resume. Don’t apply if rainfall is expected within 24 hours of application.

Postemergent herbicides that have some selectivity, particularly in turf, are halosulfuron and MSMA. These herbicides move through the plant rapidly, but to be effective, you must apply them to nutsedges before the fifth-leaf stage, when the plant is still building energy reserves by drawing energy from its leaves to the newly forming tubers. After this stage, this translocation to the tubers slows down or ceases, and the herbicide will kill only the aboveground portion of the plant, leaving the tubers unaffected.

Although no preemergent herbicides control purple nutsedge, those that reduce yellow nutsedge include dichlobenil, metolachlor, and dimethenamid-P. Metolachlor and dimethenamid-P are safer around many ornamentals than dichlobenil, but they are available only to professional pesticide applicators. No preemergent herbicides that effectively control nutsedge can be used on turfgrass, but you can use them on selected ornamental plants.