Cyperus esculentus • Class B

Yellow Nutsedge is a fibrous-rooted perennial that grows 12 to 32 inches tall.

It resembles grass in that its leaves are narrow and grass like, but it differs from true grass in that it has triangular stems and is arranged in groups of three.

Its flowers are arranged in straw colored spikelets. At the base of each umbel-like  inflorescences.  Leaf-like bracts occur at the base of each infloresence.

The underground portion of this plant consists of roots, rhizomes, and tubers. A single plant may produce several thousand tubers in one season; each tuber can have 5 to 7 buds that may germinate anytime for about 4 years. 

Yellow Nutsedge is considered one of the world’s worst weeds; it is a particular problem in irrigated agricultural areas and row crops. It competes with crops for water, light and nutrients, reducing crop yields. 

It is commonly found along margins of lakes, rivers, streams and marshes. It generally occurs in disturbed habitats. 

There has been research to suggest that this species may possess allelopathic chemicals that are toxic to crops. 

• Control of this species is difficult once an infestation occurs, because of the large number of reproductive tubers it produces. It is estimated there are 12 million tubers per infested acre. 

• Yellow Nutsedge has been shown to be resistant to many herbicides. Control with herbicide is difficult because herbicide translocation is complicated by the relationships within and between dormant tubers and germinating tubers and the growing plant. Most herbicides used affect only the shoots and/or roots and do not kill the tubers. 

• Manual control, hand pulling, hoeing, digging, etc. is possible only when infestations are small, or lightly scattered plants. Take care to remove all the root systems. If only the plant is removed some of the roots will leave the tubers, which in turn will be the source of new infestations. 

• Once nutsedge becomes established, control may be achieved only through a long term effort integrating cultivation, crop competition, and herbicide application. 

• Glyphosate products can be used to treat individual plants or small patches, by spot foliar application. Glyphosate will not prevent future nutsedge seed or nutlet germination. The infestation should be treated before the nutsedge plants reach the 4 to 6 leaf stage, if application is delayed beyond this stage, new tubers will develop. Keep in mind glyphosate products will injure any plant it comes in contact with. 

• Herbicide products containing the active ingredient Halsofuron are also recommended for use on Yellow Nutsedge plants. This herbicide is selective and will not affect the surrounding grasses. 
   
• Whenever using herbicides read and follow all label instructions and obey all label precautions. (Note: pesticide product registration is renewed annually and product names and formulations may vary from year to year.) 
   

 Download our Flyer or visit Washington State Noxious Weed Control Board Here. Photo by Leo Michels