Jordan. Gretzky. Favre.
These athletes are the best of the best. Known for their tenacity, resiliency and toughness, they dominated their competition.
In the weed world, nutsedge has that kind of reputation. Few others have the same durability and persistence. This grassy-looking weed will infest lawns, flowerbeds and gardens. Technically, it's not a grass and grassy-selective herbicides will not control it. The leaves are distinctly creased, shiny, and pointed. When viewed from above, they emerge from the base in three directions and the main stem is triangular. Roll it between your fingers and you'll feel three distinct sides.
Nutsedge will grow almost anywhere, but it thrives in wet soil. A nutsedge infestation can indicate drainage problems. Its only weakness is shade. Dense plantings that block sunlight, such as groundcovers, can reduce nutsedge. While weed block is often an effective barrier against most weeds, nutsedge can pierce the fabric.
Nutsedge is sometimes called nutgrass because it forms vegetative tubers called nutlets that can be as deep as 14 inches and remain viable for years. When the weed is pulled by hand, the tubers break off in the ground and stimulate new growth. Nutsedge with less than six leaves can be pulled before tubers begin forming. However, if left alone, one nutsedge plant can spread 10 feet via rhizomes.
Tilling a nutsedge infestation can cause more problems by spreading the tubers. Over time, however, it's possible that frequent tilling can exhaust the reserves of germinating tubers.
Propane flamers are often used to control annual weeds by burning down the topgrowth. This is a great herbicide alternative but has little effect on perennial weeds and, in the case of nutsedge, the tubers and rhizomes are unaffected. The weeds will return.
If you can leave an area fallow for six weeks, solarizing in the summer can reduce nutsedge. By tarping the area with clear plastic and sealing the edges with bricks, timbers or soil, a greenhouse effect can be induced to bake weed seeds, tubers and rhizomes. The tarp can be removed after six weeks. The plastic should be 4-mil thick to prevent nutsedge from piercing through it.
If you don't have nutsedge, prevention is advisable. Avoid introducing it from other plantings or topsoil. If it is introduced, hand-pulling early and often is important. However, herbicides may be required to get heavy infestations under control.
Purple nutsedge and yellow nutsedge are the two most common nutsedges in the Lowcountry. Knowing how to distinguish between the two can determine your herbicide choice and application.
Yellow nutsedge is more prevalent because of its cold tolerance. It produces a single tuber at the end of rhizomes and grows 12 to 16 inches tall. Purple nutsedge grows tubers in chains along rhizomes and only grows 6 inches tall.
Herbicides are most effective when weeds are actively growing. Avoid applying during drought. Do not mow or string trim before an application to allow foliage to absorb herbicide. Also avoid mowing two days after application to ensure translocation to tubers and rhizomes.
Contact herbicides, such as vinegar and soaps, will burn down only the top growth. The results will be similar to flaming or hand pulling. Roundup is not as effective on nutsedge as it is on other weeds. There are herbicides especially formulated for nutsedge control. As always, read the label and follow directions.
Image is the most accessible herbicide for homeowners to purchase. The application should be followed by a half inch of irrigation to wash the herbicide into the crown/root zone. The effects are slow, so be patient. Reapplication may be necessary in a month. Image also has pre-emergent activity, so do not use in areas you plan to seed.
The most effective nutsedge herbicide, and perhaps one of the best product names on the market, is SedgeHammer. It's more expensive and difficult to purchase for homeowners, but its effects are rated as good to excellent on both yellow and purple nutsedge.
Tony Bertauski is a horticulture instructor at Trident Technical College. To give feedback, email him at firstname.lastname@example.org.
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