By Darrell Blackwelder
For the Salisbury Post
Bermuda grass is an obnoxious weed, but there may be another weed just as bad.
Nutsedge or nutgrass has become a major weed problem for homeowners this summer. It is found in nearly every type of planting, from lawns to vegetable gardens, and on nearly all soil types.
Unfortunately, it is one of the most difficult weeds to control. There are actually two different types of perennial nutsedge, yellow nutsedge and purple nutsedge. But our focus will be on yellow nutsedge because it is the predominant sedge in our area. Fortunately, it is easier to control than purple nutsedge. Purple nutsedge is distributed throughout the coastal plain but is much less common in the Piedmont.
Sedges are sometimes confused with the grasses but are in a completely different family. These are easily distinguished from grasses by the triangular cross section of their leaves.In contrast, shoots of grasses are flat or round in cross section. Distinguishing between grasses and sedges is very important because the majority of herbicides for grassy weeds are not effective on sedges.
Yellow nutsedge tends to be light to yellow-green with a long, tapered point. It seems like this weed can grow several inches overnight, especially in wet areas or near irrigation heads. The weed has flowers that are yellow-green to tan, usually growing in clumps.
Unfortunately, yellow nutsedge forms tubers (nuts) at the tips of the rhizomes. During the growing season, plants spread by rhizomes or underground stems producing “daughter plants.”
Yellow nutsedge begins forming tubers at the tips of the rhizomes, maturing in late July to mid-August. Under optimum conditions, a single yellow nutsedge plant can produce as many as 7,000 tubers.
The tubers are just one method of reproduction. Most sedges spread by underground rhizomes. However, these nuts or tubers may remain dormant in the soil for up to 10 years.
Control of yellow nutsedge is not easy. Pre-emergence control of yellow nutsedge is possible in woody landscape beds with Pennant before bud break. After nutsedge has emerged, postemergence herbicides such as Basagran TO and Manage can be used to control yellow nutsedge and other annual sedges.
These herbicides are best used as a directed sprays, avoiding contact with ornamentals. It’s best to treat early in the season to prevent nutsedge spread and tuber formation.
When all else fails and you need a total makeover, directed and spot applications of Roundup and other herbicides containing glyphosate can be used for a total kill.
Obviously, this is a complicated weed to control. Yellow nutsedge was discussed here because it is the dominant nutsedge in our area. However, purple nutsedge was accidentally introduced in this area. If you have purple nutsedge, control and management is entirely different. Visit the Web at http://www.ces.ncsu.edu/ depts/hort/hil/pdf/hil-647.pdf for more detailed information on identification and control.
Darrell Blackwelder is an extension agent in charge of horticulture at the Rowan County Center of the N.C. Cooperative Extension. Call 704-216-8970.