How can I kill yellow nutsedge? I’ve tried landscape fabric, newspaper and various mulches without success, and the fire ants loved the mulches as much as the nutsedge. I even tried a sinful herbicide, and the nutsedge laughed it off. It’s not practical to dig up all the “nuts” (root nodules). What can I do?
We are truly sorry to hear that your garden has become infested with yellow nutsedge (Cyperus esculentus), which compares in scope to a plague of locusts. In the course of a growing season, a single healthy nutsedge plant can produce 1,900 new plants and up to 7,000 nutlets on their roots! Originally from Europe and India, yellow nutsedge and the less cold-hardy but equally aggressive purple nutsedge (C. rotundus) are commonly listed as noxious weeds around the world. On the bright side, the nutlets produced by these amazingly prolific plants are edible. C. esculentus roots taste like coconut and can be eaten raw, boiled or roasted. However, even if you like the taste of nutsedge, you don’t want it to completely take over your garden, so it’s time to consider drastic measures.
You are correct about the futility of sifting through your soil to physically remove all the nutlets. Although most are found in the top 6 inches of soil, some may be lurking as many as 14 inches deep. You will never collect them all. The herbicide you tried didn’t work because, after one sprout died, a second one grew from the mother nutlet to replace it. Individual nutlets can resprout three times — maybe more — so an effective control strategy is to do everything you can to encourage the colony to sprout itself into exhaustion. This nutsedge cleanup will require taking the infested space out of production for a year, and weeding, hoeing or tilling it every three weeks (innocent-looking little nutsedge plants start producing nutlets in about a month). Weed scientists estimate that a nutsedge tuber uses up 60 percent of its energy reserves on its first sprout, and 20 percent for the second, so the stand should get weaker and weaker after each cultivation. By the time the weather turns cold and the weeds stop sprouting, your garden should be looking pretty clean.
When your soil gets out of rehab and you’re ready to plant crops again, use tight spacing to keep the soil as shady as possible, pull out or hoe any nutsedge sprouts the minute you spot them, and limit watering to only where you’re actually growing your crops. If you haven’t tried pine bark mulch, see whether you can slip it by your fire ants. In a study done in Hammond, La., pine bark mulch reduced nutsedge in flower beds by 75 percent. Good luck!
Above: If nutsedge shows up in your garden, remove it immediately! Photo by Sue Day.
Contributing editor Barbara Pleasant gardens in southwest Virginia, where she grows vegetables, herbs, fruits, flowers and a few lucky chickens. Contact Barbara by visiting her website or finding her on Google+.
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