Parthenium (Parthenium hysterophorus)
Mature parthenium with flowers
Parthenium is declared a Class A (to be eradicated) and Class C (not to be introduced to the Northern Territory) weed in accordance with the NT Weeds Management Act 2001. Parthenium is also a Weed of National Significance.
Parthenium weed is a native of Central and South America. It was first recorded in Australia in 1955. It has since spread through central Queensland and New South Wales where it is now well established.
In 1977 parthenium was discovered in the NT along Elsey Creek in the Mataranka district. The infestation had spread 8 km downstream from the Roper Highway. The Weed Management Branch has since conducted an intensive eradication program, involving aerial and ground spraying as well as manual removal. The plant has been successfully eradicated from this area. Smaller infestations have been reported and controlled in the Katherine and Borroloola areas.
There are currently no known parthenium plants in the NT. If you believe that you have seen this plant please contact the Weed Management Branch immediately.
Parthenium spreads rapidly and can quickly colonise large areas. Parthenium is capable of invading grazing land, as well as roadsides and other disturbed areas. It produces large quantities of seeds, which readily contaminate harvested material, vehicles, machinery and livestock facilitating spread. Over-grazing can lead to parthenium invasion. Once present, parthenium degrades pastures, increasing production costs and decreasing productivity.
Parthenium can cause allergic skin reactions in people who come into direct contact with the plant. Symptoms include swelling of the skin and itching, especially on the forehead and eyelids.
