Navua sedge

• Vigorous, grass-like perennial sedge, generally 30–70cm tall, occasionally reaching 2m.
• Continuously growing underground stem produces shoots at regular intervals along its length, which can then develop an extensive, shallow, fibrous root system.
• Leaves are 5cm long, 3cm wide, in drooping clusters at base of stem.
• Flowers are white, at apex of triangular stalk.
• Seeds are brown to black, egg-shaped, with hook at one end.

• Prefers areas with annual rainfall exceeding 2,500mm and no distinct dry season.
• In areas with substantially less rain and distinct dry season, generally restricted to damp, low-lying pastures or disturbed areas.

• Found in scattered populations in North Queensland and South East Queensland.

• Seedlings develop quickly and flower 10 weeks after emerging. At flowering, underground stem produces new shoot. New shoot then grows as seedling did, producing flower 10 weeks after seedling emerges and producing another new shoot from underground stem.
• Seeds can germinate at any time of year but highest germination occurs when temperatures alternate between 15˚C and 25˚C. Seeds also require exposure to light for germination.
• Seed heads on each shoot generally produce about 250 seeds each.
• Longevity of seeds has not been determined.

Environmental

• Competes strongly for nutrients, light and moisture.

Economic

• Invades and replaces pastures.
• Problem in sugar cane where crop is light with poor canopy cover.
• Forms dense stands that smother tropical pasture species.

• Spread occurs through normal extension of rhizome system, by seed and by dispersal of viable rhizome fragments during cultivation.
• Seed can be dispersed in animal and bird faeces, and in mud on hooves, pelts, footwear and machinery.

• Find out how farmers can prevent weed spread.
• Find out how gardeners and outdoor enthusiasts can prevent weed spread.

Physical control

• Dig out with spade and turn entire plant over, exposing root system and completely covering all aerial parts of plant.
• For large infestations, may be possible to bring underground roots to surface by discing and allowing them to dry out. Effectiveness will depend on weather, because damp conditions are likely to encourage considerable regrowth.

Mechanical control

• Mechanical control of large infestations has been achieved in Fiji using heavy rollers at intervals of 8–12 weeks to repeatedly break stems at ground level and allow grass to out-compete sedge. This is impractical in hilly country.
• Mechanical control methods are generally not a long-term solution and require repeated applications.

Herbicide control

• Limited to use of herbicides registered for control of sedges (Cyperus spp.) in general. These herbicides are registered for control of sedges in certain situations specified on herbicide label. Most of these herbicides are non-selective in pastures and have withholding periods.
• See the Navua sedge fact sheet (PDF, 1.7MB) for herbicide control and application rates.
• Watch the video on Navua sedge control in pastures with Nufarm Sempra herbicide.

Biological control

• No known biological control agents. However, the department is currently researching potential agents.

• Navua sedge is not a prohibited or restricted invasive plant under the Biosecurity Act 2014. However, by law, everyone has a general biosecurity obligation (GBO) to take reasonable and practical steps to minimise the risks associated with invasive plants under their control.
• Local governments must have a biosecurity plan that covers invasive plants in their area. This plan may include actions to be taken on Navua sedge. Some of these actions may be required under local laws. Contact your local government for more information.