Identification and Reproduction

Identification:

• Purple nutsedge is a perennial sedge that can reach up to 1 m tall. 
• Stems are smooth, triangular and long. 

• Leaves are attached at the basal portion of the stem. They have a distinct mid-rib and taper to a point. 

• Flowers are found in a umbel-like cluster and are purple to brown in colour. There are also short leaf-like bracts under the flower clusters. 

Reproduction: 

• Reproduces from tubers that store food that will help it complete its life cycle the following year. 
• Tubers can also remain dormant in the soil and then when conditions are favourable they will establish new plants. 
• Any tubers that are left in the ground will resprout. 

Habitat & Ecology

• It is well adapted to moist and sandy conditions, but prefers drier conditions. 
• Shade intolerant. 
• Purple nutsedge has been observed a various sites including cultivated fields, roadsides, pastures, riverbanks, sandbanks, irrigation channels and wastelands. 
• Currently it has yet to be found in BC, but purple nutsedge nutlets have been found in imported ornamental nursery stock. 

Impacts

Social: 

• They invade turf, landscape areas, pastures and cultivated fields. 
• Reduces crop yields. 
• Extremely competitive and will take up space and nutrients rapidly. Crop species will be negatively impacted. 

Ecological: 

• Displace native vegetation. 
• Will deplete nutrients from the soil and store them in its tubers. 

Management

Prevention is a high priority for this plant. 

• Use clean seed, hay, grain and straw.
• Maintain a healthy pasture and good crop cover to reduce ground exposure. 
• Contact the Canadian Food Inspection Agency (CFIA) if you think you have seen this plant. 

Mechanical/Manual Control:

• Mechanical removal will need to be repeated in order to deplete tubers of resources. 
• Do not cut stems as this will trigger tubers to form new rhizomes. 
• Soil cultivation can be effective only if the tubers are destroyed. Should be repeated every 2-3 weeks to distrupt plant growth. 

Chemical Control: 

• Many herbicides will kill the foliage of the plant but it is most important to kill the tubers. Currently glyphosate can be used on purple nutsedge. Applications should be applied 3-4 times in a growing season to effectively control it. 
• Please carefully read product labels prior to application. 

Resources

Download A Guide to Weeds in British Columbia for Purple Nutsedge here. 

For more details check out the Invasive Species Compendium datasheet on Cyperus rotundus (purple nutsedge). 

Header photo (Jeevan Jose)