Yellow Nutsedge
Cyperus esculentus
Washington State Classification
Class B — Control Required (Designated)
It is considered one of the world's worst weeds.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
Yellow nutsedge is a perennial plant growing from an extensive system of rhizomes, tubers and roots, with stems reaching 12 to 32 inches tall. With age, its rhizomes develop tubers and basal bulbs that bear aerial shoots.
Leaves
Leaves are narrow (4-9 mm wide) and grass-like, pointed at the tips and keeled, about equal to or longer than the flower stems. Leaves are 3-ranked and mostly clustered at the base of the stem.
Flowers
Flowers are straw colored to golden-brown, in spikelets 5-30 mm long. Spikelets are arranged in an umbel-like, open inflorescences. Leaf-like bracts occur at the base of the inflorescence, the longest being much longer than the inflorescence.
Fruit & Seeds
Seeds are yellowish-brown, three-angled and are about 1/16 inch long.
Impact
It is considered one of the world's worst weeds. It is highly adaptable to irrigated agricultural areas. It competes with crops for resources and reduces crop yield. Research suggests that this species may produce chemicals that are toxic to crops.
Ecology & Spread
Habitat
Yellow nutsedge grows in croplands as well as along margins of lakes, rivers, streams and marshes. Please click here to see a county level distribution map of yellow nutsedge in Washington.
Spread Mechanisms
Reproduction
Yellow nutsedge spreads by seed and by tubers, rhizomes, and corm like basal bulbs. Seeds and tubers are dispersed with agricultural and nursery activities, soil movement and by water. Seeds can also be dispersed by the wind.
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Control Methods
Mechanical
- Tillage at four week intervals depletes the energy reserves of the tubers.
Cultural / Prevention
- Maintaining a healthy planting or turf area to provide competition will prevent weed establishment.