Yellow nutsedge

Image: James Altland, USDA-ARS
Yellow nutsedge is very problematic once established in a field production system.
Image: James Altland, USDA-ARS
Image: James Altland, USDA-ARS
Leaves of yellow nutsedge radiate out from the base of the plant.
Image: James Altland, USDA-ARS
Image: James Altland, USDA-ARS
Nutsedge emerges from small, brown “nutlike” tubers.
Image: James Altland, USDA-ARS
Cyperus esculentus
Life cycle: 
Yellow nutsedge grows upright to form dense clumps. Its habit resembles that of many grasses. Their thick, stiff leaves are arranged in sets of three at their bases. A cross section of their stems shows a solid, triangular shape in contrast to grass stems which are hollow and round, and in cross section are almost flat or oval shaped.
Yellow nutsedge produces numerous small yellowish to tan flowers arranged in narrow spikelets originating from a single point. Directly below each inflorescence, or at the base of each flower head, there are three long, leaflike bracts. Flowering occurs with the longer days of summer, usually July to September.
Favorable environments: 
Favorable environment notes: 
Yellow nutsedge is predominantly found in cultivated, irrigated agricultural field sites, such as field nurseries and row crops. It can be found in landscapes and turf areas as well. Yellow nutsedge prefers areas with full sun and plentiful moisture. It does not do well in shaded areas. Once established, yellow nutsedge is extremely difficult to control and is more tolerant to drier conditions.
Yellow nutsedge does produce small yellowish-brown seeds; however, reproduction by seed is minimal. The species spreads primarily by rhizomes and tubers, sometimes referred to as “nutlets”. The rhizomes, or underground stems, can grow as deep as 8 to 12 inches below the soil surface. A single, darkish colored, ½ inch tuber, grows at the end of each rhizome. Buds on the tubers sprout and grow to form new plants. In the Northwest, this occurs usually sometime in late spring or early summer, when the soil temperatures have warmed sufficiently. The majority of the tubers are in the top 6 inches of soil. They can survive there for up to 3 years.