|Botanical Name||Carduus nutans|
|Origin||Europe and Asia, NW Africa|
DescriptionAnnual or biennial thistle, 1 m high or taller, with distinctive nodding flower heads.
Where is it found?Roadsides, pasture, wasteland, and amongst crops such as lucerne.
Why is it a problem?Strong pasture invasive.
How does it spread?Seed spread is the only means of dispersal. Although the seed has a pappus of bristles, this plays little part in spread as it readily detaches from seed. Studies have shows that 91% of seed falls within 1 to 2 metres of the plant and only a few were detected more than 10 metres away. Apart from localised wind dispersal seed can also be spread in mud, water, machinery, fodder and agricultural seed.
How do I get rid of it?
For scattered plants, grubbing is an effective method but at lease 50 mm of the taproot must be removed or plants will regrow.
Scattered plants can be treated with one of the following herbicides.
Gunspraying: 5 g to 100 litres water
Knapsack: 1 g to 10 litres water
Gunspraying: 500 ml to 100 litres water
Knapsack: 100 ml to 10 litres water
Wiper: 1 part to 1 part water
Glyphosate Wiper application only: 1 part to 2 parts water
In established pasture infestations, boomspraying in autumn/early winter with one of the following herbicides gives good control of smaller thistles, however follow-up spot treatment of individual plants will be needed of a number of years.
24-D, Ethylhexylester Ester 2 litres per hectare
MCPA 3 to 4 litres per hectare
MCPB 6 litres per hectare
Native of Europe and western Asia Nodding thistle receptacle weevil (Rhinocyllus conicus) was first imported in 1972, it is now common throughout the country.
Nodding thistle crown weevil (Trichosirocalus spp.) which is native of Europe was first imported in 1982.
Native of Europe Nodding thistle gall fly was first imported in 1989.
Good pasture management is the key to control as young seedlings are very susceptible to pasture competition. Stock management should aim at preventing overgrazing, especially in summer.