Description:
Cutting back of Andean pampas grass (Cortaderia jubata) Weed.
Cortaderia jubata is a large tussock grass (tussock grasses grows in mounded tufts) with most of its leaves near the base and narrow, attenuated blades. The panicles (loosely branched, pyramidal flower clusters) are large, terminal, and plume-like. Spikelets are several-flowered, with internodes of the rachilla jointed, the lower part glabrous (smooth), and the upper part bearded. Glumes (the empty bract at the base of a grass spikelet) extend beyond the lower florets. C. jubata possesses a breeding system termed agamospermous apomixis which allows plants to asexually produce seeds, i.e. without fertilisation, despite the fact that all plants are female. Distinctive features of C. jubata are huge, nodding pinkish or purplish flower plumes (later turning creamy white), and dark green, 1-cm-wide, drooping leaves with razor-like margins. Flower stems rise up to 3 times higher than the clump of foliage.
Occurs in:
Coastland, estuarine habitats, range/grasslands, ruderal/disturbed, urban areas, wetlands.
Habitat description:
Cortaderia jubata becomes established most easily in wet, sandy soil without existing vegetation. However, it has broad habitat requirements and will grow vigorously in nearly any soil, under low or high moisture regimes, and in full sun or dense shade. Cortaderia flourishes mostly in coastal areas and probably needs at least some summer moisture from fogs and freedom from freezing temperatures. Several consecutive nights of frost will generally not kill the plant, but can severely damage it. It colonises on foreshores, roadsides and wet areas. It grows best in full sunshine with adequate water, but can tolerate rather severe drought conditions once established.
Distribution of Andean pampas grass (Cortaderia jubata) shown in Green.
General impacts:
Cortaderia jubata is highly competitive with native plants once seedlings become established and is a substantial threat to the ecological quality of preserves, particularly in coastal and grassland sites. Its rapid growth and accumulation of aboveground and belowground biomass allow it to acquire light, moisture, and nutrients that would be used by other plants. It can be damaging even at low densities because of the amount of cover it can occupy. Particularly threatened habitats include coastal sand dunes and inland sand hills that contain a number of rare and endangered plant species.C. jubata can seriously hamper visibility, while its sharp leaves can cause serious cuts to humans. It is also a fire hazard because of the large amount of dry matter it produces, and it harbors vermin such as rats, mice, possums, and rabbits. Additionally, C. jubata seeds stick to fruit such as kiwifruit, seriously degrading fruit quality.
Geographical range:
Native range: Native to South America.
Known introduced range: C. jubata is now found in New Zealand, Australia, the United States, and South Africa.
Management information:
There is good opportunity for recovery of native plant populations if Cortaderia jubata is controlled with a strict management program.
Preventative measures:A Risk assessment of Cortaderia jubata for Australia was prepared by Pacific Island Ecosystems at Risk using the Australian risk assessment system. The result is a score of 22 and a recommendation of: reject the plant for import (Australia) or species likely to
Single Andean pampas grass (Cortaderia jubata) Weed Stalk.
be a pest (Pacific).
Physical:Physical removal of the plants is effective if they are small enough, but this method can be quite labour intensive. Good success has
been obtained by physically removing the plants whereby a rope or chain is tied around plants and they are pulled out of the ground with a vehicle. Although effective, this is labor intensive. Fire has also been suggested as a method to eliminate foliage for the later mechanical removal or chemical treatment of the plant.Fire will not kill pampas grass, but makes it unhappy.It is found that the high silica content in the leaves of pampas grass acted as a fire retardant and fire was not very effective in eliminating the foliage.
Chemical: A number of chemical treatments are also effective and may be more practical for severe infestations. Monitoring is definitely needed to document population trends in and adjacent to preserves. The effects of the weed on native plants should be monitored as well as the effectiveness of management efforts to eradicate it. If populations are found to be increasing rapidly, an intensive effort to control its spread is necessary. If an eradication program using an herbicide (Roundup) is initiated, treatments should be followed by evaluations of effectiveness. The emphasis of most programs has been to eliminate the largest plants first to reduce the potential for seed dispersal.
Biological: In New Zealand pine plantations Cortaderia is controlled by cattle grazing.
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