The Navo plant (Cyperus aromaticus or Cyperus javanicus), also known as Navua Sedge or Javanese Flatsedge, is a perennial sedge. It is recognized for its vigorous growth and ability to form dense stands in tropical and subtropical regions. Its presence often signals a need for management, especially in agricultural areas and natural ecosystems where it can outcompete other vegetation.
Identifying Navo Plant
Accurate identification of the Navo plant involves recognizing its distinct physical characteristics. This sedge typically grows 30 to 70 centimeters tall, occasionally reaching up to 2 meters. A key feature is its robust, creeping underground rhizome, which produces new shoots, forming dense clumps. The stems are triangular in cross-section.
Its leaves are lance-shaped, 5 to 15 centimeters long and 3 to 5 millimeters wide, generally clustered at the plant’s base. Flowers appear as white, knob-like clusters at the apex of the triangular stalk. These flower heads are surrounded by six leaf-like bracts, three typically longer and three shorter. Seeds are small, brown to black, egg-shaped, often with a hook.
Habitat and Growth
The Navo plant thrives in high moisture and disturbed soils. It prefers areas with annual rainfall exceeding 2,500 millimeters and no distinct dry season. In regions with less rainfall or a pronounced dry season, it is often confined to damp, low-lying pastures, drains, or other disturbed sites.
Native to tropical Africa, Cyperus aromaticus has spread widely and naturalized in many tropical and subtropical areas, including Australia, Fiji, Vanuatu, Samoa, Tahiti, and the Solomon Islands. It reproduces by seeds and extensive rhizome systems, contributing to its effective colonization of new areas.
Ecological Role and Impact
Navo sedge significantly impacts natural ecosystems and agricultural productivity due to its aggressive growth. It forms dense stands that strongly compete with native vegetation and desirable pasture species for nutrients, light, and moisture. This competitive advantage can reduce biodiversity and alter plant communities.
In agricultural settings, Navo sedge is a concern for livestock grazing, particularly dairy and beef production. Unpalatable to cattle, it leads to reduced pasture yield and carrying capacity when it invades grazing lands. The plant also affects crops like sugarcane, bananas, and sweet potatoes, especially where crop canopy cover is light.
Management Strategies
Managing Navo plant infestations often requires an integrated approach. Manual removal is feasible for small, isolated clumps; each plant should be dug out completely and left to dry. For larger areas, mechanical methods such as discing can bring roots to the surface, though effectiveness depends on dry weather conditions to prevent regrowth. Repeated applications of heavy rollers can break stems, allowing other grasses to compete.
Cultural practices include maintaining vigorous and dense pastures to outcompete Navo sedge seedlings and prevent establishment. Avoiding overgrazing is important, as it can encourage the spread of the plant.
Chemical control options include herbicides like glyphosate and halosulfuron-methyl, effective on smaller plants. Multiple applications may be needed, and environmental impacts should be considered, as they do not always effectively control extensive rhizomes. Preventing the spread of seeds and rhizome fragments, particularly by cleaning farm machinery, is also important.