Yellow nutsedge is very difficult to control and sticks out like a sore thumb in well maintained turf areas. It is not a broadleaf weed or a grassy weed, but a sedge, and requires specific control measures.
Yellow nutsedge grows in full sun and prefers moist areas of lawns.
The leaves are light green to yellowish in color, wide (up to 1/2”) with a thick mid-vein and a very waxy covering. I find the easiest way to distinguish yellow nutsedge from grasses is the triangular shape of the stem. Roll the stem of the plant in your fingers; you should be able to feel the three sides of the triangle. Flowers of yellow nutsedge are a yellowish-brown color and look like a series of spikes.
Yellow nutsedge has a shallow root system that produces rhizomes and tubers. Rhizomes (underground stems) allow the plant to spread over an area producing “daughter plants” and forming a mass of nutsedge. The nut-like tubers that also develop serve as underground storage organs (think bulb). Each tuber can produce a new plant. During a good growing season each plant can produce up to 7,000 tubers. Also, the flowers of yellow nutsedge can produce seed. When you introduce soil into your landscape either as topsoil or from containers of trees or perennials the tubers and seed are in the soil.
In a lawn situation, a healthy, dense, vigorous stand of turf can compete with yellow nutsedge. This is achieved by mowing at the proper height, providing fertilizer in the right season and adjusting the pH as indicated by a soil test. When this is done correctly only a few weeds may be present, in which case, hand pulling will be the best way to eradicate this pest.
When large patches of nutsedge are present, treatment with a post-emergence herbicide may be the only option. Homeowners have three products available that will control yellow nutsedge in lawns. Look for new sedges in late spring/early summer and spray when they are discovered. Herbicides are most effective on young, actively growing plants. Products available for control include:
- MSMA (methane arsonate)
- Basagran T/O; Sedge Hammer (bentazon)
- Manage (halosulfuon)
Submitted by Kelly Jackson, Agent for Horticulture, Christian Co. Cooperative Extension Service