Carduus pycnocephalus
Encyclopedia
Carduus pycnocephalus (common name
s include Italian thistle, Italian plumeless thistle, slender thistle and Plymouth thistle) is a species of thistle
native to the Mediterranean region of Europe and Asia which has become a noxious weed in Australia
, New Zealand
, South Africa
, South America
, and North America
, especially in California
, where it is a C-listed weed by the California Department of Agriculture and a Moderate rating by the California Invasive Plant Council http://cal-ipc.org. It favors grasslands, woodlands, and chaparral
vegetation types, but is especially prevalent in oak woodlands in and around the Central Valley. It is found in disturbed areas, often with basaltic soils, fertile soils, or soils with a relatively high pH (> 6.5) (Bossard et al. 2000).
A winter annual, the plant stems range from 8 in to 6.6 feet (2-20 dm) and are glabrous to slightly wooly. Stems are winged with spines. Basal leaves are 4-6 in (10-15 cm) 4-10 lobed; cauline leaves are tomentose on the underside and contain spines on the lobe tips. Flower heads are 2-5 per cluster, densely matted with cobwebby hairs at the base of the phyllaries and spiny towards the tips. Corollas are pink to purple, approx. .4-.6 in (1-1.4 cm) long, and the fruits are brown to gold, with a bristly, minutely barbed pappus (Hickman 1993; Brossard et al. 2000).
in the winter, thereby preventing establishment of those plants. Its spiny leaves, stems, and phyllaries prevent animals from grazing on it and nearby forage (Parsons 1973). Its tendency to grow under the canopy of oaks increases the risk of fire damage to those trees, as fire can carry to the canopy easier.
Biological control agents have limited success with Italian thistle. Insects that tested host-specific by the California Dept. of Agriculture and caused significant damage to the reproductive structures of the plant have not been utilized due to concerns about possible predation of native thistles in California (Sheppard et al. 1991). Puccinia cardui-pycnocephali is a rust
apparently exclusive to Italian thistle; other rust species have been found on the plant as well (Olivieri 1984; Bruckart 1991). Grazing by sheep or goats (not cattle) in Australia has showed promise as well (Bendall 1973).
Chemical control can be achieved with a variety of products including: Clopyralid
, glyphosate, Diquat
, Picloram
, and 2-4 D ester. However, caution must be exercised when using these products and they are not always appropriate, especially near water surfaces or other sensitive natural resources (Brossard et al. 2000). Check with state, county, or regional regulations concerning these products.
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
s include Italian thistle, Italian plumeless thistle, slender thistle and Plymouth thistle) is a species of thistle
Thistle
Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles often occur all over the plant – on surfaces such as those of the stem and flat parts of leaves. These are an adaptation that protects the...
native to the Mediterranean region of Europe and Asia which has become a noxious weed in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, especially in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, where it is a C-listed weed by the California Department of Agriculture and a Moderate rating by the California Invasive Plant Council http://cal-ipc.org. It favors grasslands, woodlands, and chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
vegetation types, but is especially prevalent in oak woodlands in and around the Central Valley. It is found in disturbed areas, often with basaltic soils, fertile soils, or soils with a relatively high pH (> 6.5) (Bossard et al. 2000).
Biology
Problems
Italian thistle can grow densely, crowding out other vegetation with its rosettesRosette (botany)
In botany, a rosette is a circular arrangement of leaves, with all the leaves at a single height.Though rosettes usually sit near the soil, their structure is an example of a modified stem.-Function:...
in the winter, thereby preventing establishment of those plants. Its spiny leaves, stems, and phyllaries prevent animals from grazing on it and nearby forage (Parsons 1973). Its tendency to grow under the canopy of oaks increases the risk of fire damage to those trees, as fire can carry to the canopy easier.
Control
Mechanical methods can be effective but must be done before the plant sets seed. Additionally, the root must be severed at least four inches (1 dm) below the ground to prevent the plant from regenerating. Mowing and slashing are not reliable as the plant is able to regrow and produce seed even at a height of 3 inches (8 cm) (Tasmanina Dept. of Agriculture 1977; Brossard et al. 2000).Biological control agents have limited success with Italian thistle. Insects that tested host-specific by the California Dept. of Agriculture and caused significant damage to the reproductive structures of the plant have not been utilized due to concerns about possible predation of native thistles in California (Sheppard et al. 1991). Puccinia cardui-pycnocephali is a rust
Rust (fungus)
Rusts are plant diseases caused by pathogenic fungi of the order Pucciniales. About 7800 species are known. Rusts can affect a variety of plants; leaves, stems, fruits and seeds. Rust is most commonly seen as coloured powder, composed off tiny aeciospores which land on vegetation producing...
apparently exclusive to Italian thistle; other rust species have been found on the plant as well (Olivieri 1984; Bruckart 1991). Grazing by sheep or goats (not cattle) in Australia has showed promise as well (Bendall 1973).
Chemical control can be achieved with a variety of products including: Clopyralid
Clopyralid
Clopyralid is a selective herbicide used for control of broadleaf weeds, especially thistles and clovers....
, glyphosate, Diquat
Diquat
Diquat is a contact herbicide that produces desiccation and defoliation most often available as the dibromide, diquat dibromide. Brand names for this formulation include Aquacide, Dextrone, Preeglone, Deiquat, Detrone, Reglone, Reglon, Reglox, Ortho-Diquat and Weedtrine-D.Diquat is a non-selective...
, Picloram
Picloram
Picloram is a systemic herbicide used for general woody plant control, sold under the trade names Tordon and Grazon. It also controls a wide range of broad-leaved weeds, but most grasses are resistant...
, and 2-4 D ester. However, caution must be exercised when using these products and they are not always appropriate, especially near water surfaces or other sensitive natural resources (Brossard et al. 2000). Check with state, county, or regional regulations concerning these products.