Carduus nutans (nodding thistle)
Identity
- Preferred Scientific Name
- Carduus nutans L.
- Preferred Common Name
- nodding thistle
- Other Scientific Names
- Carduus macrocephalus Desf.
- Carduus thoermeri Weinm.
- International Common Names
- Englishmusk thistle
- Spanishcardo almizclerocardo pendientecardo rojo
- Frenchchardon nuchardon penche
- Local Common Names
- GermanyNickende Distel
- Italycardo rosso
- Netherlandsknikkende Distel
- Swedennicktistel
- EPPO code
- CRUMA (Carduus macrocephalus)
- EPPO code
- CRUNU (Carduus nutans)
- EPPO code
- CRUTH (Carduus thoermeri)
Pictures
Distribution
Host Plants and Other Plants Affected
Host | Host status | References |
---|---|---|
Allium cepa (onion) | Unknown | Tahira and Khan (2017) |
Lolium perenne (perennial ryegrass) | Main | |
Medicago sativa (lucerne) | Main | |
Poaceae (grasses) | Main | |
Trifolium repens (white clover) | Main |
Prevention and Control
Cultural Control
As C. nutans is a biennial found mainly in pastures, a key to controlling it in such systems is to utilize its dormancy when covered by green vegetation, preventing it from germinating (Phung and Popay, 1981). Techniques to utilize this include sowing pastures in dry areas with drought-tolerant cultivars and avoiding overgrazing of pastures during dry times of the year by reducing stock numbers and growing supplementary crops (Harrington, 1996). Although sheep and cattle avoid grazing C. nutans plants, goats will graze them especially as seed-heads are forming (Holst and Allan, 1996). C. nutans is still spreading to new areas and increasing its density in presently infested areas. Declaring the species noxious and thus applying regulatory pressures to reduce its incidence is a common strategy for controlling the species (Skinner et al., 2000). Prohibiting the presence of any C. nutans seed within certified pasture and crop seed is a common strategy to reduce further spread of the species (Popay and Medd, 1990).
Mechanical Control
Hand grubbing is commonly practised for infestations of low density or as a follow-up operation after herbicide treatment of denser or larger infestations (Popay and Medd, 1990). Grubbing hoes must cut the plants 5-10 cm below ground level to prevent resprouting from dormant axillary buds. Mowing the plant during flowering can greatly reduce seed production, though a single mowing is seldom sufficient due to the wide differences in the maturity of plants in a natural population (McCarty and Hatting, 1975).
Chemical Control
Good control of C. nutans can be obtained using herbicides such as 2,4-D, MCPA, clopyralid, dicamba and picloram, though the favoured option in clover-based pastures is to use the less effective MCPB while seedlings are young and thus susceptible to this herbicide (Popay and Medd, 1990). MCPA or 2,4-D will successfully control larger rosettes without damaging the clover substantially, but application must occur before rosettes become too large, and plants need to be actively growing (Popay et al., 1989). Repeated application of phenoxy herbicides to C. nutans populations over several decades has led to resistant ecotypes developing in some parts of New Zealand (Harrington, 1990).
Biological Control
Of the organisms listed in the Natural Enemies section, some have been introduced widely throughout the world to control C. nutans whereas others have been only tentatively released thus far and several have been deemed unsuitable for use.Rhinocyllus conicus has been released in Canada, USA, New Zealand and Australia since the 1970s and is well established in all of these countries (Popay and Medd, 1990). Although R. conicus has been recorded as being successful against C. nutans in parts of the USA, it has generally been less successful in New Zealand where it has been estimated that 69% reduction in seed production is required to reduce C. nutans populations, more than is usually achieved by the weevil (Shea and Kelly, 1998).Trichosirocalus mortadelo is probably restricted to C. nutans, and was introduced from Germany to Canada and from there to New Zealand and then Australia, and from Italy to the USA. However, it remains a possibility that the original introductions for C. nutans also included T. horridus and examination of voucher specimens is required to clarify the issue (Julien and Griffiths, 1998). Cartwright and Kok (1985) found the response of C. nutans in the USA was dependent on plant size and growing conditions, though infested plants consistently produced more stems and larger crowns than uninfested individuals due to the destruction of apical dominance. However, small and medium infested plants were shorter and produced fewer seeds and heads than uninfested plants. In Australia, Woodburn (1997) found T. horridus killed some plants and reduced rosette growth of survivors by 50%. The reproductive potential of the attacked plants, measured as seeds per plant, was reduced by 67%.The third insect to be used quite extensively as a biocontrol agent is Urophora solstitialis (Julien and Griffiths, 1998). It has been used in Australia and New Zealand to destroy seeds produced late in the season which are not controlled by R. conicus. However, there have been some problems with competition between the two agents (Woodburn and Briese, 1996). There have been limited releases of Cheilosia corydon (=C. grossa), Psylliodes chalcomera and Puccinia carduorum in USA, but the impact of these species cannot yet be ascertained (Gassmann and Kok, 2002).Research has been underway for a number of years in New Zealand to develop a mycoherbicide for C. nutans and several other thistle species using the fungus Sclerotinia sclerotiorum (Lib.) de Bary (Bourdot and Harvey, 1996), but a commercial product has still not been released from this work. Although there has been limited success to date in controlling C. nutans with biological control agents, it is generally agreed that they are an important component in any integrated weed control programme for this weed rather than as a sole control method (Woodburn and Briese, 1996).
Integrated Control
As discussed by several authors, the most effective strategy for controlling C. nutans is to use a combination of regulatory, cultural, physical, biological and chemical techniques (e.g. Harrington, 1996; Huwer et al., 2002).
Impact
The main economic impact of C. nutans is in pastures where it reduces animal production by preventing animals from eating plants growing in the vicinity of the plant and by suppressing the growth of desirable vegetation (Desrochers et al., 1988b). In addition to competition with pasture plants, there is some evidence that the weed may have an allelopathic effect (Wardle et al., 1991). Dense, mature stands of C. nutans become obstructive to livestock and dried fragments and spines may cause physical injury or adhere to wool, lowering its value (Popay and Medd, 1990). A simulation model studying the effects of C. nutans on pasture losses and animal production suggested it was economically beneficial to apply herbicides in spring whenever ground cover exceeded 2.5% (Moore et al., 1989). Apart from effects on animal production, many millions of dollars are spent annually on controlling C. nutans, primarily because of its status as a noxious plant (Vere and Medd, 1979). It is considered a serious pasture weed in parts of New Zealand, Australia, USA, Canada and Argentina. It can also create some problems in arable crops and seed crops in all of these countries.
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Copyright © CABI. CABI is a registered EU trademark. This article is published under a Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
History
Published online: 16 November 2021
Language
English
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