Chondrilla juncea (rush skeletonweed)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Biology and Ecology
- Air Temperature
- Soil Tolerances
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Economic Impact
- Environmental Impact
- Threatened Species
- Risk and Impact Factors
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Chondrilla juncea L.
Preferred Common Name
- rush skeletonweed
Other Scientific Names
- Chondrilla acanthophylla Borkh.
- Chondrilla angustissima Hegetschw
- Chondrilla gaudini Hegetschw.
- Chondrilla glomerata K.Koch
- Chondrilla graminea var. graminea
- Chondrilla graminea var. kashmirica Hook.f.
- Chondrilla hispida Desf.
- Chondrilla juncea subsp. acanthophylla (Borkh.) Arcang.
- Chondrilla juncea subsp. glabrescens Iljin
- Chondrilla juncea subsp. juncea
- Chondrilla juncea subsp. macrocarpa Chrtek
- Chondrilla juncea var. acantholepis (Boiss.) Boiss.
- Chondrilla juncea var. graminea (M.Bieb.) Schmalh.
- Chondrilla juncea var. juncea
- Chondrilla juncea var. latifolia (M.Bieb.) K.Koch ex Iljin
- Chondrilla laciniata Steven
- Chondrilla latifolia M.Bieb.
- Chondrilla rigens Rchb.
- Chondrilla vallisoletana Pau
- Chondrilla viminea Bubani
International Common Names
- English: devil’s grass; gum succory; hogbite; naked weed; skeleton weed; succory
Local Common Names
- Argentina: yuyo esqueleto
- France: chondrille à tige de jonc; chondrille effilée
- Germany: Binsenknorpellattich; großer Knorpellattich; großer Krümling
- Italy: condrilla; lattaiola; lattugaccio
- Netherlands: knikbloem
- Portugal: leituga-branca
- Spain: achicoria juncal; alotxa; mastec
Summary of InvasivenessTop of page
C. juncea is a herbaceous biennial or perennial plant native to parts of Western Europe, north Africa and central Asia. It was accidentally introduced into a number of regions around the world as a contaminant of plant material, seed and fodder. C. juncea is invasive in Australia, Argentina, Canada, New Zealand, South Africa and a number of states in the USA. C. juncea produces a large tap root which can compete with native plant species for nutrients and water. In Australia and Argentina it is a major problem of wheat fields and can reduce yields by 80%. In the USA, C. juncea is one of the invasive species impacting on the threatened species Silene spaldingii. A number of distinct genotypes of C. juncea exist which makes control of this species difficult. In addition to this, C. juncea is resistant to a large number of herbicides.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Asterales
- Family: Asteraceae
- Genus: Chondrilla
- Species: Chondrilla juncea
Notes on Taxonomy and NomenclatureTop of page
Chondrilla is a genus of flowering plants, belonging to the daisy family or Compositae (formerly Asteraceae). The genus has 106 scientific plant names of species rank, of which, 41 are accepted species names (The Plant List, 2013). C. juncea was first described by Linnaeus in 1753 and is the most well-documented species in the genus. C. juncea is known by several common names including the rush skeletonweed, gum succory, devil's grass and nakedweed.
Distinct genotypes of C. juncea have been identified which differ in branching and the appearance of the rosette leaves (USDA-FS, 2014). In the USA three morphologically different genotypes are most common but molecular studies have identified more (Van Vleet and Coombs, 2012). A study by Gaskin et al. (2013) revealed a total of 13 different genotypes from Australia, Argentina and North America and 682 genotypes from the native range.
DescriptionTop of page
C. juncea is a thin, spindly, herbaceous perennial. In addition to a deep (2 m) taproot, it has lateral roots that produce daughter rosettes. Plants also grow from buds on root fragments cut by cultivation or other equipment. It has a basal rosette of dandelion-like leaves, up to 20 cm long, glabrous. They are rush-like in appearance, up to 150 cm bright green or yellow-green with multiple, slender, leafless branches and reddish downward-pointing hairs near the base. Rosette and stem leaves are deciduous. Flowers 1-2 cm across have yellow, daisy-like capitulae, borne singly or in small clusters, almost sessile on the virtually leafless stem. Fruits are achenes, white to dark, 3-4 mm long, with pappus of white toothed bristles 5-8 mm long on a beak of similar length. The leaves, stems and roots exude milky latex when damaged (Parsons and Cuthbertson, 1992).
Plant TypeTop of page Biennial
DistributionTop of page
The origin of C. juncea is thought to be near the Caspian Sea, from where it spread to the Mediterranean and Central Europe. Its native range is considered to be between 35° and 55° N latitude from Western Europe and North Africa to central Asia (McVean, 1966). The plant is known throughout most temperate regions of the world as an introduced species and is usually considered a noxious weed. C. juncea is reported to be invasive in Argentina, Australia, Canada, New Zealand, South Africa and the USA.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|China||Present||Present based on regional distribution.|
|Georgia (Republic of)||Present||Native||USDA-ARS, 2015|
|South Africa||Present||Introduced||Invasive||Invasive Species South Africa, 2015|
|Canada||Present||Present based on regional distribution.|
|-British Columbia||Present||Introduced||Flora of North America Editorial Committee, 2015; GBIF, 2015|
|-Ontario||Present||Introduced||Flora of North America Editorial Committee, 2015; GBIF, 2015|
|USA||Present||Present based on regional distribution.|
|-Delaware||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; GBIF, 2015|
|-District of Columbia||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; USDA-ARS, 2015|
|-Georgia||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; GBIF, 2015|
|-Idaho||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; GBIF, 2015|
|-Illinois||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; GBIF, 2015|
|-Maryland||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; GBIF, 2015|
|-Michigan||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; GBIF, 2015|
|-Montana||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; GBIF, 2015|
|-New Jersey||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; USDA-ARS, 2015|
|-Oregon||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; USDA-ARS, 2015|
|-Pennsylvania||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; USDA-ARS, 2015|
|-Virginia||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; USDA-ARS, 2015|
|-Washington||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; USDA-ARS, 2015|
|-West Virginia||Present||Introduced||Invasive||Flora of North America Editorial Committee, 2015; USDA-ARS, 2015|
|Brazil||Present||Present based on regional distribution.|
|Albania||Present||Native||Not invasive||GBIF, 2015|
|Andorra||Present||Native||Not invasive||GBIF, 2015|
|Austria||Present||Native||Not invasive||GBIF, 2015|
|Belgium||Present||Native||Not invasive||GBIF, 2015|
|Bosnia-Hercegovina||Present||Native||Not invasive||USDA-ARS, 2015|
|Bulgaria||Present||Native||Not invasive||GBIF, 2015|
|Croatia||Present||Native||Not invasive||USDA-ARS, 2015|
|Cyprus||Present||Native||Not invasive||Meikle, 1985|
|Czech Republic||Present||Native||Not invasive||GBIF, 2015|
|Czechoslovakia (former)||Present||Native||Not invasive||GBIF, 2015|
|France||Present||Native||Not invasive||GBIF, 2015|
|-Corsica||Present||Native||Not invasive||USDA-ARS, 2015|
|Germany||Present||Native||Not invasive||GBIF, 2015|
|Gibraltar||Present||Native||Not invasive||GBIF, 2015|
|Greece||Present||Native||Not invasive||GBIF, 2015|
|Hungary||Present||Native||Not invasive||GBIF, 2015|
|Italy||Present||Native||Not invasive||GBIF, 2015|
|Luxembourg||Present||Native||Not invasive||GBIF, 2015|
|Macedonia||Present||Native||Not invasive||USDA-ARS, 2015|
|Moldova||Present||Native||Not invasive||USDA-ARS, 2015|
|Montenegro||Present||Native||Not invasive||USDA-ARS, 2015|
|Netherlands||Present||Native||Not invasive||GBIF, 2015|
|Poland||Present||Native||Not invasive||USDA-ARS, 2015|
|Portugal||Present||Native||Not invasive||GBIF, 2015|
|Romania||Present||Native||Not invasive||USDA-ARS, 2015|
|Russian Federation||Present||Native||Not invasive||USDA-ARS, 2015|
|Serbia||Present||Native||Not invasive||USDA-ARS, 2015|
|Slovakia||Present||Native||Not invasive||GBIF, 2015|
|Slovenia||Present||Native||Not invasive||USDA-ARS, 2015|
|Spain||Present||Native||Cirujeda et al., 2011|
|-Balearic Islands||Present||Native||Not invasive||GBIF, 2015|
|Switzerland||Present||Native||Not invasive||USDA-ARS, 2015|
|Ukraine||Present||Native||Not invasive||USDA-ARS, 2015|
|Australia||Present||Introduced||Flora of North America Editorial Committee, 2015|
|-Australian Northern Territory||Present||Introduced||Invasive||GBIF, 2015|
|-New South Wales||Present||Introduced||Invasive||GBIF, 2015|
|-South Australia||Present||Introduced||Invasive||GBIF, 2015|
|-Western Australia||Present||Introduced||Invasive||GBIF, 2015|
|New Zealand||Present||Introduced||Invasive||USDA-ARS, 2015|
History of Introduction and SpreadTop of page
C. juncea has been known in the USA since 1872 (McVean, 1966) and it is thought to have been introduced with contaminated plant material, contaminated seed, or with animal fodder or bedding from Europe (Piper and Coombs, 1996). It is currently present in California, Delaware Georgia, Idaho, Indiana, Maryland, Michigan, Montana, New Jersey, New York, Oregon, Pennsylvania, Virginia, Washington and West Virginia. In 2012, it was estimated that C. juncea occupied approximately 2.5 million hectares of rangeland in the Pacific Northwest and California (Van Vleet and Coombs, 2012).
In Canada, the weed is only present in British Columbia and Ontario (USDA-FS, 2015).
C. juncea was accidentally introduced into Australia around 1910. It was known near Waga Wagga in 1913 but was not formerly identified until 1917. C. juncea spread rapidly throughout the wheat belt of southeastern Australia. It is currently recorded in New South Wales, Northern Territory, Queensland, South Australia, Tasmania, Victoria and Western Australia (McLellan, 1991; Parsons and Cuthbertson, 1992).
In South Africa, C. juncea was introduced for ornamental purposes but in 2003 it was recorded in a maize field in Mtati village in the Eastern Cape (SANBI, 2015).
A molecular study by Gaskin et al. (2013) revealed that few introduction events into Australia, North America and Argentina took place. As a result there are fewer genotypes of this species present within its introduced range when compared to its native range; 13 and 682 genotypes respectively.
IntroductionsTop of page
Risk of IntroductionTop of page
C. juncea can produce a large number of seeds asexually which are dispersed over long distances by the wind. It can also spread more locally from vegetative growth from root fragments. This species is unlikely to be intentionally introduced into new areas as it has little economical/environmental importance. It may however, be accidentally introduced as a contaminant of hay or machinery for example.
HabitatTop of page
C. juncea favours disturbed land such as those weakened by drought, overgrazing, cultivation and wildfires. As such it is found on wasteland and in fallow and abandoned fields, along disturbed roadsides and eroded ground (USDA-FS, 2015). It also grows well along riverbanks and dry river beds and sand dunes. C. juncea prefers coarse-textured, well-drained soils such as sand dunes and granite outcrops but can be found on a wide range of soil types except heavy clay soils. In its native range it grows on calcareous or mildly acid soils (McVean, 1966). It can also grow on croplands, semi-arid pastures and rangelands (CAL-IPC, 2015).
Habitat ListTop of page
|Terrestrial – Managed||Managed forests, plantations and orchards||Present, no further details||Harmful (pest or invasive)|
|Managed forests, plantations and orchards||Present, no further details||Natural|
|Disturbed areas||Present, no further details||Harmful (pest or invasive)|
|Disturbed areas||Present, no further details||Natural|
|Rail / roadsides||Present, no further details||Harmful (pest or invasive)|
|Rail / roadsides||Present, no further details||Natural|
|Terrestrial ‑ Natural / Semi-natural||Riverbanks||Present, no further details||Harmful (pest or invasive)|
|Riverbanks||Present, no further details||Natural|
|Scrub / shrublands||Present, no further details||Harmful (pest or invasive)|
|Scrub / shrublands||Present, no further details||Natural|
|Arid regions||Present, no further details||Harmful (pest or invasive)|
|Arid regions||Present, no further details||Natural|
Hosts/Species AffectedTop of page
In Australia and Argentina, C. juncea is a major problem of wheat fields and can reduce yields by 80%.
Biology and EcologyTop of page
The genus Chondrilla has a basic chromosome number of five. C. juncea is triploid (2n=15) (McVean, 1966). A number of distinct biotypes have been recognised, these are of particular concern in respect to control of this weed using biological methods.
C. juncea can establish vegetatively by adventitious buds on both vertical and lateral roots and new shoots can also form from tiny fragments of root (USDA-NRCS, 2015). In addition to this, it produces a large number of seed asexually (an obligate apomict); 15,000-20,000 seeds per plant (USDA-FS, 2014). Some sexual reproduction may occur in the native range (Gaskin et al., 2013). Seeds of C. juncea do not remain viable for long (6-18 months) and have very little dormancy; their germination is dependent on moisture (Jacobs et al., 2009). Cuthbertson (1970) recorded that white seeds tend be non-viable, yellow seeds may have about 25% viability while olive-green to brown seeds had greatest viability. Alebrahim et al. (2010) found some benefit from light and an optimum temperature of 20°C. Differences in the number of seeds and viability have been recorded between the different genotypes of this species. Although flowers may be visited by a number of insects this serves no purpose for the plant.
Physiology and Phenology
In Europe, summer temperatures of at least 15°C are required for flowering and seed formation (Jacobs et al., 2009). Individual flower heads bloom for just one day but flowering continues during the summer until a frost in late autumn (Van Vleet and Coombs, 2012). Overwintering occurs as rosettes and new growth begins in the spring. Germination of seeds occurs over a wide range of temperatures from autumn to spring (7-40°C) (Van Vleet and Coombs, 2012). Valuable information on phenology, ecology and germination are available in Parsons and Cuthbertson, (1992) and in USDA-FS (2016).
In its native range, C. juncea is often described as a biennial or short-lived perennial (3-4 years). In Australia, its invasive range, it is described as a perennial living up to 20 years (USDA-FS, 2015).
C. juncea can grow on disturbed soils and is not tolerant of shade. It is able to tolerate a wide temperature range. In Australia, Panetta and Mitchell (1991) document a temperature range of 4-30.7°C for C. juncea. However optimal conditions include cool winters with warm summers (Jacobs et al., 2009). It is present in areas with precipitation ranging from 23-150 cm and from sea level to 6,000 m. The growth of C. juncea is limited by the availability of calcium and phosphorus in the soil (McVean, 1966). In Australia it has been recorded on soils with pH ranges from 4.5-8.
ClimateTop of page
|BS - Steppe climate||Tolerated||> 430mm and < 860mm annual precipitation|
|BW - Desert climate||Tolerated||< 430mm annual precipitation|
|Cf - Warm temperate climate, wet all year||Tolerated||Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year|
|Cs - Warm temperate climate with dry summer||Tolerated||Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers|
|Cw - Warm temperate climate with dry winter||Tolerated||Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)|
|Df - Continental climate, wet all year||Tolerated||Continental climate, wet all year (Warm average temp. > 10°C, coldest month < 0°C, wet all year)|
|Ds - Continental climate with dry summer||Tolerated||Continental climate with dry summer (Warm average temp. > 10°C, coldest month < 0°C, dry summers)|
|Dw - Continental climate with dry winter||Tolerated||Continental climate with dry winter (Warm average temp. > 10°C, coldest month < 0°C, dry winters)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Mean annual temperature (ºC)||4||30.7|
RainfallTop of page
|Parameter||Lower limit||Upper limit||Description|
|Mean annual rainfall||230||1500||mm; lower/upper limits|
Soil TolerancesTop of page
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
|Aceria chondrillae||Herbivore||Leaves/Stems||Julien et al., 2012||Australia, USA|
|Adonisea cognata||Herbivore||Lecheva and Stantcheva, 2003|
|Bradyrrhoa gilveolella||Herbivore||Julien et al., 2012; Lecheva and Stantcheva, 2003||Argentina, Australia, USA|
|Chondrillobium blattnyi||Herbivore||Julien et al., 2012|
|Coptocephala scopolina||Herbivore||Lecheva and Stantcheva, 2003|
|Cystiphora schmidti||Herbivore||Julien et al., 2012; Lecheva and Stantcheva, 2003||Australia, USA|
|Ensina sonchi||Herbivore||Seeds||Julien et al., 2012|
|Golovinomyces orontii||Pathogen||Leaves||Julien et al., 2012|
|Leveillula taurica||Pathogen||Stems||Julien et al., 2012|
|Neomargarodes chondrillae||Hyperparasite||Roots||Julien et al., 2012|
|Ophiomyia cunctata||Herbivore||Leaves||Julien et al., 2012|
|Oporopsamma wertheimsteini||Herbivore||Leaves/Roots||Julien et al., 2012|
|Puccinia chondrillina||Pathogen||Leaves||to species||Julien et al., 2012||Argentina, Australia, USA|
|Sphenoptera clarescens||Herbivore||Julien et al., 2012|
|Tephritis neesii||Herbivore||Seeds||Julien et al., 2012|
|Tephritis rasa||Herbivore||Seeds||Julien et al., 2012|
Notes on Natural EnemiesTop of page
C. juncea has been the target of biological control since 1966 and as a result a number of natural enemy surveys have taken place in the native range. According to Julien et al., (2012) the following natural enemies have been reported and investigated; Dastneura sp., Ensina sonchi, Tephritis nesii, T. rasa, Melanagromyza cunctata [Ophiomyia cunctata], Puccinia chondrillina, Erysiphe cichoracearum [Golovinomyces orontii], Leveillula taurica, Eriophyes chondrillae [Aceria chondrillae], Chondrillobium blattnyi, Cystiphora schmidti, Bradyrrhoa gilveolella, Oporopsamma wertheimsteini, Sphenoptera clarescens and Neomargarodes chondrillae.
Surveys for natural enemies were conducted by Lecheva and Stantcheva (2003) in Bulgaria between 2000 and 2002 also revealed Mordellistens sp., Schinia cognata [Adonisea cognata], Coptocephala scopolina, Cytiphora schmidtii, Bradyrrhoa gilveollela, Mylabris sp. and A. chondrillae and fungi belonging to the genera Alternaria, Leveilulla and Fusarium.
Means of Movement and DispersalTop of page
C. juncea produces large quantities of seed. Potential seed production has been estimated in the order of 70,000 seeds per m² in a dense infestation in Australia (Panetta and Dodd, 1987). The seeds are readily dispersed due to their small size and the pappus facilitates wind dispersal (USDA-NRCS, 2015). Local dispersal occurs as a result of vegetative regeneration (Van Vleet and Coombs, 2012).
The pappus also facilitates transportation of seeds by animals (Zouhar, 2003).
Seeds of C. juncea may accidentally be introduced into new areas by contamination of agricultural equipment and products such as hay for example (Zouhar, 2003).
Pathway CausesTop of page
Pathway VectorsTop of page
Impact SummaryTop of page
Economic ImpactTop of page
Wiry stems and latex produced by C. juncea can clog and break harvesting equipment (Jacobs et al., 2009).
Additionally, C. juncea is a major problem of wheat and a reduction in crop yeilds of up to 80% have been recorded (Panetta and Dodd, 1987; Van Vleet and Coombs, 2012).
Environmental ImpactTop of page
C. juncea colonises areas of disturbed land where it produces a large tap root which enhances its competitive ability over other native plant species for water and nutrients, in particular nitrogen (Van Vleet and Coombs, 2012). In Argentina and Australia, C. juncea is reported as a major weed in wheat fields (Kashefi et al., 2007). It is said to be “the most serious weed of Australian wheat growing regions” (Panetta and Dodd, 1987) and reductions in crop yields of up to 80% were recorded causing a shift from cultivated land to pasture (Panetta and Dodd, 1987; Van Vleet and Coombs, 2012). C. juncea can form dense stands which decreases the available forage causing losses to the cattle industry and decreasing native biodiversity.
In the USA, C. juncea is one of the invasive species named as difficult to control in the recovery plan for the threatened species Silene spaldingii (ECOS, 2007).
Threatened SpeciesTop of page
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Has a broad native range
- Highly adaptable to different environments
- Pioneering in disturbed areas
- Highly mobile locally
- Reproduces asexually
- Damaged ecosystem services
- Reduced native biodiversity
- Threat to/ loss of endangered species
- Threat to/ loss of native species
- Competition - monopolizing resources
- Highly likely to be transported internationally accidentally
- Difficult/costly to control
UsesTop of page
C. juncea is both palatable and nutritious for livestock in the rosette and early bolting stages and makes good sheep and goat fodder. It is also a source of nectar for honey bees (USDA-NRCS, 2015). The leaves and the tender shoots of Greek varieties of C. juncea are eaten raw in salads or boiled by locals on the island of Crete. The plant is also traditionally consumed by ethnic Albanians in southern Italy (GBIF, 2015).
Uses ListTop of page
Animal feed, fodder, forage
- Fodder/animal feed
Human food and beverage
- Honey/honey flora
Similarities to Other Species/ConditionsTop of page
Taraxacum officinale and Cichorium intybus are both similar in appearance to C. juncea at the rosette stage. However after bolting it is readily distinguished by brown, downward-pointing hairs near the base of the stem (USDA-FS, 2014). It is also similar in appearance to Centaurea solstitialis, Lactuca serriola and Lygodesmia juncea, similarities and differences between these species can be found in Van Vleet and Coombs (2012).
Prevention and ControlTop of page
C. juncea is listed as noxious, prohibited, or banned in nine western states in the USA and is targeted for control or eradication (USDA-NRCS, 2015). Once a new infestation of C. juncea has been identified effort should be made to eradicate the weed before seed production (Van Vleet and Coombs, 2012).
Cultural Control and Sanitary Measures
Certified seed, soil, gravel, hay and manure etc. that is weed-free should be used where possible. All machinery and equipment used in an infested area should also be cleaned down before taken into a new area to prevent spread. In Australia it has been suggested that leguminous forages can provide competition which reduces the problem over a period of years (Parsons and Cuthberston, 1992).
Small infestations of C. juncea can be controlled by hand pulling when the soil is wet. This must be done several times per year for several years. Regular mowing is partially effective for control of C. juncea as it can reduce aerial and root biomass and reduce seed production. However, mowing is not effective at eliminating rosettes as these are close to the ground (USDA-FS, 2015). Cultivation may be counter-productive as regrowth can occur from quite small root fragments.
A number of biological control agents have been studied for control of C. juncea in Australia and USA. Studies were initiated by CSIRO in the 1960s and to date, a total of four biocontrol agents have been trialled with variable success.
A blister-forming gall midge, Cystiphora schmidti, can feed on the rosettes, stem leaves and stems, causing damage and reduction in seed production. It was first released in California in 1975 and is available for collection in California, Idaho and Oregon (USDA-NRCS, 2015).
The gall-forming mite, Aceria chondrillae, can infest vegetative and floral buds creating galls which if severe, can stunt the growth of the plant and reduce seed production. It is the most effective agent in the Pacific Northwest (Van Vleet and Coombs, 2012).
A root moth, Bradyrrhoa gilveolella, was released in Argentina and Australia but was not successful. This agent was most recently introduced in Idaho, USA in 2002 but establishment has not been confirmed (Horner, 2002).
A rust fungus, Puccina chondrillina, was researched as a potential biological control agent for C. juncea by Hasan and Wapshere (1973) and was first released in North America in 1978. As a result of extreme host-specificity of this rust fungus, one of the three genotypes in the USA and two in Australia are not controlled and very little control has been recorded in Argentina (Gaskin et al., 2013). Although it was the most successful agent released in Australia, the two rust-resistant genotype of C. juncea have since expanded their range to replace the rust-susceptible genotype (Gaskin et al., 2013).
The effectiveness of a biocontrol agent is dependent on factors such as climate, the genotype of C. juncea and interactions with native parasites and predators.
The deep and extensive roots of C. juncea make it difficult to control with chemical herbicides and successful control can only be achieved with multiple applications. This is because herbicides do not persist well in the poor soil types favoured by this weed and because herbicides are not easily translocated in plants with a limited leaf area such as C. juncea. Herbicide treatment is most effective on young plants. Repeated application of herbicides such as picloram or 2, 4-D (or a combination of both) can be applied to rosettes and will provide some control in autumn. In cereals, the phenoxy-acid herbicides can provide a useful degree of suppression and 2, 4-DB can be used in cereals sown with legumes (Parsons and Cutthbertson, 1992). Picloram, clopyralid, aminopyralid and dicamba can also be used and translocate into the roots (USDA-FS, 2015; Parsons and Cuthbertson, 1992). Mixtures of clopyralid with 2,4-D have proved especially useful (Heap, 1993).
Once C. juncea has been removed from an area it is important to reseed with native perennial plants. This provides competition and therefore reduces the density of C. juncea; legumes such as clover and Medicago sativa (alfalfa) have been shown to be effective for this (Zouhar, 2003).
ReferencesTop of page
Alebrahim MT; Majd R; Mohammaddust H, 2010. Seed germination behavior of Rush skeletonweed (Chondrila juncea). In: Proceedings of 3rd Iranian Weed Science Congress, Volume 1: Weed biology and ecophysiology, Babolsar, Iran, 17-18 February 2010. Tehran, Iran: Iranian Society of Weed Science, 163-166.
Cal-IPC (California Invasive Plant Council), 2015. California Invasive Plants Council. www.cal-ipc.org. Berkeley, California, USA: California Invasive Plants Council.
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ContributorsTop of page
11/12/2015 Original text by:
Sarah E. Thomas, CABI-UK
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