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Thistle infestation
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Alternative Names: blue thistle, cotton
thistle, heraldic thistle, woolly thistle
Background
Scotch thistles, Onopordum acanthium, and Illyrian
thistles, O. illyricum, were probably introduced from
Europe in the early 1800s as ornamental plants. By 1850 Scotch
thistle was recorded as a weed in Victoria and today both
species are serious pasture weeds in South Eastern Australia.
These plants have a tendency to form dense stands, smothering
desirable vegetation with their rosette leaves, thus reducing
pasture socking rates. Plants may produce up to 20,000 seeds,
a proportion of which become incorporated in a long-lived
soil seed bank. Such seeds may remain viable for more than
twenty years.
The Project
Biological control of these thistles commenced in France
in 1987.
There have been seven biological control agents released
since 1992. Four agents are established and form part of the
redistribution program. The first seed fly released failed
to established. More recently a rosette fly and another seed
fly have been released but have failed to establish.
Biological control agents:
Key People
Anthony Swirepik
CSIRO Entomology
GPO Box 1700
Canberra ACT 2601
AUSTRALIA
Ph: +61 2 6246 4252
Email: firstname.lastname@csiro.au
More Information
Scotch thistle biocontrol
attack (PDF 48Kb)
National Weeds Stategy
Release of the Onopordum
Rosette Weevil Trichosirocalus briesei (PDF 1.36MB)
Release of the Onopordum
Seed Weevil Larinus latus (PDF 1MB)
Release of the Onopordum
Stem Boring Weevil Lixus cardui (PDF 1.20MB)
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