For Release August 7, 2001

AGRI-VIEWS
by Chuck Otte, Geary County Extension Agent

I’ve started getting the calls about the funny green grassy stuff in yards. It is probably one of two plants. If it is starting to look a funny light green, and it seems to crawl all over the place, then it is probably crabgrass and there is not much you can do about it now anyway. Wait until next spring and use a crabgrass preventer.

If it is a darker green, stands very upright, has a coarse stiff leave and the stem, at the base, is triangular, it is a sedge, or nutgrass. If it’s a sedge, you have problems! Sedges are not a true grass. They are a group of plants that stand apart from others. Worldwide, sedges are considered to be the worst weed in crop production.

The best known member of the sedge family is the obscure species, with a name that I can’t pronounce, that originated in eastern China and is know grown extensively in Australia. The large corm of this sedge is harvested and sold as water chestnuts. And all this time you thought those were really a nut!

Sedges look very grass like. They can survive in full sun and all do much better than grass in heavier shade. They do not show moisture stress the same way that grass does. This probably explains why they become so visible during hot dry summers.

Sedges reproduce and spread in two ways. They have a seed head and will produce seed readily late in the season. They also can reproduce vegetatively. As a sedge plant grows and develops, it creates little bulblets or nutlets just under the soil surface. Think of wild garlic or bunching onions. As long as these bulblets are attached to the plant, they tend to remain dormant. When you pull up the main plant, these often dislodge and stay in the soil. The minute they do become detached from the mother plant, they also start growing. So when you think you’re doing a good thing by pulling them, you are really gaining nothing!

They are perennial, so crabgrass preventers will not affect them. Roundup will kill the main plant, and may even kill some of the bulblets. If you have sedges in a garden or flower bed, this is probably the best approach. After you spray the plant, just leave it alone. Even after it is dead, don’t pull it. This may trigger bulblets that are still alive into growing. If you see new sedge sprigs coming up, let them get several inches tall and then spray them again with Roundup.

In lawns we generally don’t want to be spot spraying Roundup as it will leave dead spots in the yard. There are products labeled as nutgrass killers. These are generally some of the arsenic based compounds and will control existing smaller sedges, but not the bulblets. However, if you stay on top of the sedge problem for three or four years you would probably get it under control.

A better treatment has become available in the past few years. A homeowner product called Manage is now available. It needs to be mixed with water and is specifically for controlling sedges in turf grasses. It can be used on all the standard turfgrass species except Buffalograss. While it can be safely sprayed across an entire lawn, I would recommend spot treating. The product is somewhat expensive, and a couple of applications at least four weeks apart will probably be needed. I would recommend treating now, when the sedges are easily seen, and then retreating next spring when you can find them again. Sedges will spread, and they can be very unsightly in your yard. But they are treatable!

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