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Witchweed
What is it?
There are about 60 species of parasitic witchweeds (Striga). Striga asiatica and S. hermonthica are the most widespread and cause major economic losses to agriculture around the world.
Where is it found?
Witchweeds have been reported in Africa, India, other parts of Asia, North America, Indonesia and Papua New Guinea. Two native species of Striga are present in Australia but these species are not weedy in their own environment.
What are its effects?
Witchweeds are root parasites that damage cereal crops such as maize (corn), sorghum, rice and sugarcane, depriving them of water and nutrients.
Millions of tiny, dust-like seeds can be produced in a square metre of soil and are easily spread by wind or on the harvested crop, machinery or clothing.
What’s the risk to Australia?
Tiny witchweed seeds could enter Australia as contaminants in seed consignments or on clothing or machinery. AQIS officers inspect imported seed consignments for witchweed seeds.
Agriculture workers or tourists who have visited cereal-growing areas in countries with witchweeds should make sure they thoroughly clean their clothing before returning to Australia.