Nutgrass (Cyperus rotundus): Weed management guide for Australian vegetable production

Abstract

Nutgrass (Cyperus rotundus) is a highly variable perennial sedge.Although not a grass species, the name 'nutgrass' is commonly used for this plant in Australia. It is also sometimes called 'nutsedge'. It usually grows to between 20 and 50cm tall, and occasionally taller under favourable conditions. Stems are erect, smooth, not branched, and triangular in cross-section. Leaves are dark to bright green, glossy, up to 2-6 mm wide and 20cm in length, grass-like, and have a prominent vein on the underside. They are slightly serrated, and generally shorter than the plant stems. There are up to 20 leaves per plant, mostly emerging in three rows near ground level.The flowers are a cluster of brown to reddish-brown/purplish-brown narrow flattened spikelets of varying lengths. These tend to emerge from a common point on several slender flower stalks. Beneath the ground, the plant features a network of bulbs, roots, rhizomes, and multiple tubers in chains (over six per chain in some circumstances). Tubers are dark brown to black, irregularly shaped and up to 2 cm in length when fully grown. Each tuber has multiple buds, most of which remain dormant and are available as a reserve in the event the active shoot is destroyed. Dormant tubers can commonly persist in the soil for 3-4 years, but remain viable for up to 10 years in ideal conditions. Individual plants form a basal bulb, mostly within 7-18 cm of the soil surface. This basal bulb contains the plant growing point. The fibrous root system can extend up to 1.2 metres below the soil surface. Because the growing point remains in the basal bulb, leaves can regrow easily after being severed at the soil surface.