Management Information
Preventative measures: Native species should be replanted after C. nutans has been controlled to ensure that it won't recolonise. Preserving a healthy stand of desirable vegetation will help prevent or at least slow invasion.
Physical:Hand pulling can be effective for small populations, but plants should be disposed of in a landfill to prevent seed dispersal. Care should be taken to not disturb the soil so that seeds will have a lesser chance of germinating. Mowing can also be used, but timing is imperative; it should be done before the flowers appear and should be done on a regular basis. Chemical: Herbicides are effective on large populations. MCPA and 2,4-D are often used in New Zealand to control it in pastures, though a herbicide resistant biotype has now developed in some areas. Foliar spraying is effective on established populations of musk thistle. Apply a 2% solution of glyphosate (e.g., Roundup) or triclopyr (e.g., Garlon) and water plus a 0.5% non-ionic surfactant wetting all leaves and stems. Chlorpyralid (e.g. Transline) is effective at a concentration of 0.5% and is selective to Aster, Buckwheat, and Pea families. A low pressure and coarse spray pattern will limit drift and damage to non-target species. Treatments should be applied during the rosette stage or prior to flowering. glyphosate is a non-selective systemic (i.e., moves through the plant) herbicide that can kill non-target plants that are only partially contacted by spray. Triclopyr is selective to broadleaf species and is a better choice if native grasses are present.
Biological: The gall fly (Urophora solstitialis), the receptacle weevil (Rhinocyllus conicus) and the crown weevil (Trichosirocalus horridus) have been found to be effective in greatly reducing the number of seeds produced. A mathematical model developed, predicts that nodding thistle populations will decline if 65% or more of the seeds are destroyed. Biological control combined with good pasture management has been leading to declined populations in New Zealand. In the United States, weevils (thistlehead-feeding weevil and rosette weevil) introduced from Europe have been found somewhat effective for control, however, the unanticipated effect it has on native populations of thistle in the western U.S. has caused some debate in its continued use (Landcare, NZ).
Location Specific Management InformationAustralia
Biological control of nodding thistle in Australia started in 1987. There have been three biological control agents released. The first, thistle-head weevil Rhinocyllus conicus, has now spread on its own to most nodding thistle infestations. Whilst its impact is great in the early part of the season it does not control seed production later in the season. The remaining two agents Urophora solstitialis a gall fly and Trichosirocalus horridus a crown weevil were actively distributed and are now quite widespread. Colorado (United States (USA))
Noxious Weed Idaho (United States (USA))
Noxious Weed Illinois (United States (USA))
Noxious Weed Iowa (United States (USA))
Primary Noxious Weed Kansas (United States (USA))
Noxious Weed Kentucky (United States (USA))
Noxious Weed Minnesota (United States (USA))
Primary Noxious Weed Missouri (United States (USA))
Noxious Weed Nebraska (United States (USA))
Noxious Weed Nelson (New Zealand)
C. nutans has been designated as a 'Boundary control pest' by the the Tasman-Nelson Regional Pest Management Strategy. The strategy has its effect over the combined area that lies within the administrative boundaries of the Tasman District Council and Nelson City Council. A regionally co-ordinated control programme has been put into place which empowers Councils to be able to require an occupier of infested land to destroy plants an appropriate distance clear from the boundary between the two properties. The objective of the strategy is to control the spread of C. nutans from adjacent properties to land clear of C. nutans, or being cleared of C. nutans. Please see Hierarchy of Plant Designations for an explanation of designation terminology. Nevada (United States (USA))
Noxious Weed New Mexico (United States (USA))
Class B Noxious Weed New Zealand
Three biological control agents have been released in New Zealand a gall fly (Urophora solstitialis), which damages the seeds.
A receptacle weevil (Rhinocyllus conicus) which damages the seeds. A crown weevil (Trichosirocalus horridus), which attacks the rosette plants. The crown weevil kills many rosettes and any that do survive an attack are stunted, producing fewer flowering stems and fewer seeds. A mathematical model has been developed, which predicts that nodding thistle populations will decline if 65% or more of the seeds are destroyed. With biological control levels of seed predation greater than this have already been observed in New Zealand. Combined with improved pasture management, this model explains why many people report that nodding thistle is now declining throughout the country. Ohio (United States (USA))
Prohibited Noxious Weed Oklahoma (United States (USA))
Noxious Weed Oregon (United States (USA))
B Designated Weed South Dakota (United States (USA))
Regulated Non-Native Plant Species Taranaki Region (New Zealand)
C. nutans is classified as a 'Containment pest plant' in the The Pest Management Strategy for Taranaki. 'Containment pest plants'are pest plants that are abundant in suitable habitats in a region or part of a region and for which the long-term goal is to prevent the spread of the plant to new areas or to neighbouring properties.
Each pest plant has a management programme according to its designation. These programmes are summarised in the series of bulletins 'Pest Plant Facts'. Please see Thistles: C. nutans for pest plant facts and management programmes. Tasman District (New Zealand)
C. nutans has been designated as a 'Boundary control pest' by the the Tasman-Nelson Regional Pest Management Strategy. The strategy has its effect over the combined area that lies within the administrative boundaries of the Tasman District Council and Nelson City Council. A regionally co-ordinated control programme has been put into place which empowers Councils to be able to require an occupier of infested land to destroy plants an appropriate distance clear from the boundary between the two properties. The objective of the strategy is to control the spread of C. nutans from adjacent properties to land clear of C. nutans, or being cleared of C. nutans. Please see Hierarchy of Plant Designations for an explanation of designation terminology. United States (USA)
In North America proper identification of C. nutans should be determined, before any control measures are taken because many native thistle species bear a strong resemblance to the musk thistle. Weevils (thistlehead-feeding weevil and rosette weevil) introduced from Europe have been used in the United States and found somewhat effective for control, however, the unanticipated effect it has on native populations of thistle in the western U.S. has caused some debate in its continued use. Utah (United States (USA))
Noxious Weed Washington (United States (USA))
Class B Noxious Weed, Noxious Plant Quarantine Wyoming (United States (USA))
Noxious Weed
Management Resources/Links
3. Environment Waikato. 2002. Nodding Thistle (Carduus nutans) and Plumeless Thistle (Carduus acanthoides) 10. Shea and Kelly, 1998. Estimating Biocontrol Agent Imapct with Matrix Models: Carduus nutans in New Zealand. Ecological Applications, 8(3), 1998, pp. 824–832.
Summary: The use of matrix models to assess the impact of biological
control and other pest management strategies with a case study of Carduus nutans (nodding
thistle) in New Zealand. Results Page: 1
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