Weed du Jour – Yellow Nutsedge

Yesterday I saw a man sitting in his front lawn pulling weeds. The weeds he was pulling had grass-like leaves with a greenish-yellow color. They were growing in clumps and were about twice as tall as the surrounding grass. This man has yellow nutsedge in his lawn.

Yellow Nutsedge

Yellow nutsedge (Cyperus esculentus) is found throughout the US while its relative, purple nutsedge (Cyperus rotundus), is a weed of the southern US. Yellow nutsedge is an interesting weed. While it looks like a grass, it’s actually a sedge. Sedges are a large family of plants that include water chestnuts, papyrus, sawgrass and others. There are two specific things that are unique to a sedge: the stems are triangular and the leaves form in groups of three. Grasses have round or oval stems and their leaves usually form in alternate pairs.

Yellow Nutsedge Root System

Yellow nutsedge, sometimes called nutgrass, is a perennial weed that emerges from May to mid-July. This weed can spread by seeds, but this isn’t its primary way of propagating itself. Instead, nutsedge has a large root system with many rhizomes (underground stems) that can grow into new plants. This alone would make nutsedge a difficult weed to control but it has one more trick in its arsenal. Small tubers (1-2 cm long) form at the end of the rhizomes. They are first white, then brown and finally black in color. A single plant can produce hundreds or even several thousand (!) tubers in a single growing season. These tubers can’t sprout until they’ve experience a chilling period but they can stay dormant in the soil for more than 10 years. To make things worse, the rhizomes are fairly brittle so when you pull a nutsedge plant out of the ground, most of the tubers break off and remain in the soil.

Yellow Nutsedge Tuber

In some parts of the world nutsedge is grown as a crop and the tubers – called tigernuts – are harvested and eaten. This would certainly be an easy crop to grow since nutsedge will grow almost anywhere!

But if you’re like me and nutsedge is a weed and not a crop, there are a few things you can do to control it. If there are a few plants growing in your lawn or garden, pulling them and throwing out the plants is your best approach. You’ll never eradicate it from the ground but you can keep it under control if  you continue to pull the plants when they’re young.

If you have a lot of nutsedge in the lawn, there are various sedge herbicides that will control it. These herbicide works best for spot application and when the nutsedge plants are small. If you have large clumps of nutsedge in open areas, a glyphosate herbicide, i.e. Round Up, will kill the weed but be careful – it will also kill any other plant that comes in contact with it. The benefit of glyphosate is that it will kill the rhizomes and tubers as well.

Yellow nutsedge is a tough weed. If you see it in your yard, you can guarantee that there are plenty of little tubers in your soil just waiting for the right conditions to grow. This is one of those weeds that you can only control.

As far as the man I saw pulling the nutsedge out of his lawn, he’ll be able to control this weed for now. But if I go back next year at the end of July, I’m certain that I’ll see him sitting in his front lawn once again, pulling more nutsedge!


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