The large flower heads and broad, showy bracts make this species stand out from the rest, though closely related is Plumeless Thistle (Carduus acanthoides), whose flower heads are rather smaller, with narrow bracts. Home. Cultural, mechanical, biological and chemical control methods have all been used on musk thistles with varying degrees of success in different parts of the country. Experimentally applied warming significantly increased survival and growth. Biennials, such as musk thistle and tall thistle, germinate in summer and fall, spend the winter as rosettes, then produce many flower heads the next spring. They stop feeding and begin a resting stage, called pupation, which lasts another eight to 14 days. Musk thistle                 Carduus nutans L. Family:  Asteraceae (Composite family) Mating takes place shortly thereafter, and by the time musk thistles begin to bolt, the females are ready to lay eggs. Figure 2After seed germination, a rosette develops. Since musk thistle seeds are long-lived in the soil, it is important to prevent plants from producing seed until new rosettes are no longer produced. Bull thistle gene… Few hairs on leaves. Apply herbicides such as Tordon, Milestone, Transline, Perspective, Vanquish/Clarity or 2,4-D to musk thistle rosettes in spring or fall. An integrated pest management approach to musk thistle control takes into consideration the life cycle of the musk thistle weevils in relation to the seasonal development, or phenology, of the thistle (Figure 10). EC176. Some rosettes may extend three feet or … Seeds generally germinate in the fall or spring, but may germinate anytime moisture is sufficient. The bolting stage begins when the seed stalk starts to form and continues until the first flower head appears. © 1993 to document.write(new Date().getFullYear()) Curators of the University of Missouri, all rights reserved, DMCA and other copyright information. Farmers are usually busy in the spring and may postpone chemical application until they are caught up with field work. Habitat:  Pastures, roadsides. In late spring, some egg laying can be found in secondary buds. View all agriculture and environment programs, Starting a Small Business: The First Steps, Agricultural systems and natural resources, Agricultural Business and Policy Extension, Veterinary Extension and Continuing Education, Exceed - Regional Economic and Entrepreneurial Development, Mid-America Trade Adjustment Assistance Center, Missouri Procurement Technical Assistance Centers, Missouri Small Business Development Centers, Continuing Medical Education and Physician Lifelong Learning, Tai Chi for Arthritis and Falls Prevention, equal opportunity/access/affirmative action/pro-disabled and veteran employer. Musk thistle is primarily a biennial or winter annual species. Musk thistle is a biennial weed. If both flower head and rosette musk thistle weevils are present, mow in mid-July and spray rosettes in September and October for best weed control and least harm to the weevils. Field thistle is a native plant with few hairs on upper leaf surface, but lower surface is densely covered with white hairs. By 1997 it was detected in 37 counties in Missouri. And in most cases, groupings of musk thistle won’t let humans, grazing animals or wildlife through one of its natural stands. The life cycle of musk thistle in Missouri is variable. Figure 2B. Biennial thistles, such as musk (Carduus nutans L.), plumeless (Carduus acanthoides L.) and bull thistle [Cirsium vulgare (Savi) Tenore], are not as difficult to control as the perennial thistle species, but spread rapidly and can become severe problems in some areas. Livestock usually won't graze infested areas but occasionally feed on the flower heads. This approach maximizes thistle control and is least disruptive to the weevils. Use our feedback form for questions or comments about this publication. https://www.fs.fed.us/database/feis/plants/forb/carnut/all.html Musk thistle’s life cycle was accelerated by warming and earlier reproductive phenology and, as a result, musk thistle’s projected annual population growth rate increased. summer annual). Life cycle: Biennial, forming a rosette the first year and producing flowers and seed in the second.. First Year Growth Habit: A basal rosette. This weed, with its showy, reddish flowers, now occurs throughout the state and in 1979 was declared a noxious weed by Missouri state statute (Figure 1). The first report of an infestation of musk thistle in Missouri came from Palmyra (Marion County) in 1941. Vegetables + Leaves have few hairs, and typically the margins are greyish, giving the plant a 'frosted' look. Multiple seed heads develop from individual plants. Weevil larvae feeding on seed within musk thistle flower head. The chart shows an integrated control program using proper timing of mechanical and chemical control practices that encourages weevil populations for effective thistle … Found sporadically throughout Ohio. The two weevils are compatible with each other as biological control agents because they do not compete with each other. Musk thistle produces a basal rosette during the first year. Leaves are waxy and pale green with few hairs. It has since spread throughout most of North America, where it has become a weed of considerable economic importance. Copyright © 2020 Iowa State University of Science and Technology. Musk thistle normally requires two years to complete its life cycle (i.e. It rarely reaches infestation levels that justify treatment, probably because the insects that feed on native Circium spp. In the region of seed development, small, white, grublike larvae should be present if the thistle plant is infested with flower head weevils. This is one of seven noxious weeds for which Nebraska law mandates control. A late-blooming cycle often occurs just prior to frost. biennial or winter annual). Figure 5Musk thistle dominated this field, left, in 1975, before introduction of the flower head weevil.By 1985 the field was nearly clear of musk thistle. Identification and Life Cycle Musk thistle (Carduus nutans) is a biennial, although occasionally an annual, in the sunflower family (Asteraceae). The leaf margins of a flowering bull thistle plant (a) are tipped with spines, and the stems have spiny wings. Figure 6Rosette weevil larvae feed on the growing center of the top plant, producing a necrotic area. Figure 7Flower head weevils lay eggs on the bracts of developing flowers. Such natural enemies include the musk thistle rosette weevil and the musk thistle flower head weevil (Figures 3 and 4) and a musk thistle rust fungus (Figure 9). University of Missouri Extension is an equal opportunity/access/affirmative action/pro-disabled and veteran employer. A healthy plant is below. Biennials require portions of two growing seasons to reproduce. Canada thistle is much smaller and leaves are not as deeply lobed. This secretion gives the eggs a dirty, scale-like appearance. As many as 40 larvae have been found per terminal head. Although it is generally classed as a biennial (two growing seasons needed for a plant to mature), musk thistle can develop as an annual, biennial or winter annual, depending on local environmental conditions. General description:  First year plants form basal rosette up to 2 ft wide; leaves deeply lobed with spine tipped margins. Musk thistle reproduces entirely by seed. The typical biennial musk thistle exhibits itself the first year in the form of a rosette, a cluster of tightly packed leaves laying flat on the ground. It spends approximately 90 percent of its life cycle in a vegetative growth stage. Type 2 or more characters into the input search below for suggested results, use up and down arrow keys to navigate through suggest box. Combine control methods into a management system for best results.Musk thistle is a… Up and Down arrows will open main level menus and toggle through sub tier links. These insects attack the earlier blooms but have completed their life cycle before the last flowers set seed. 1. Musk thistle produces an average of 10,000 seeds per plant, but under favorable conditions can produce even more. After the larvae have completed their development, they leave the rosette and pupate in the soil. Each female lays an average of 100 eggs during its lifetime. A bolted plant is one that has developed an upright stem (Figure 3). The typical biennial musk thistle exhibits itself the first year in the form of a rosette, a cluster of tightly packed leaves laying flat on the ground. It undergoes one generation per year. Figure 2C. Bull thistle (Cirsium vulgare) (Figure 2) has been present in Oklahoma for more than 40 years and occurs statewide. Newly established thistle rosettes are inconspicuous and you may not see them until they bloom the following year. Occasionally, the plant completes its life cycle in one growing season (i.e. Musk thistle spreads by the dissemination of airborne seeds on the wind and by the movement of seed-contaminated hay to noninfested areas. Musk thistle Carduus nutans, musk thistle. Additionally, mowing on poor soil may actually inhibit the competitive effect of other plants and favor survival of musk thistle seedlings. They stand tall and strong, like sentries allowing no one to pass. A major identifiable characteristic of musk thistle is that the outer edge of the leaf is silver in color, while the interior of the leaf is light green. You can determine whether you have infestations of the flower head or rosette weevils by looking for larvae of these insects at the appropriate season (Figure 10). biennial or winter annual). For optimum control, apply herbicides while musk thistles are in the rosette stage or pre-bud stage. Musk thistle normally requires two years to complete its life cycle (i.e. Musk thistle normally requires two years to complete its life cycle (i.e. Ames, IA 50011-2031 Musk thistle (Carduus nutans) is a 3- to 8-foot biennial thistle. 3. In second year flower stalk elongates up to 5 ft tall; numerous pink to purple flower heads up to 2 in wide, largest of Iowa’s thistles; … Musk thistle is not a serious weed problem in crops requiring a spring seedbed preparation. Musk Thistle. The site navigation utilizes arrow, enter, escape, and space bar key commands. Figure 3The musk thistle rosette weevil feeds on rosette leaves. Like most of its close relatives, musk thistle is covered with sharp spines. Key ID traits:  Margins of leaves often silverish, giving them a frosted appearance. 2. Base of flower heads is flatter than bull or Canada thistle. The adults emerge in July and seek overwintering sites under new musk thistle rosettes and ground litter and in wooded areas, where they will remain dormant until the following year. The rosette overwinters and the cold temperature causes the rosette to send up a stalk the next season, flower and produce seed. Thistles that germinate in the spring will spend the entire summer as a rosette, live through the winter, and bolt the next year in May and June. These same adults overwinter and resume egg laying the following spring until about May 1. A third biological control agent for musk thistle is a rust fungus. Musk thistle weevils are widely distributed in Missouri. For intelligent and efficient weed control, some knowledge of the life cycles of weeds is useful. A single taproot develops and stem elongation occur in early May. The seed is disseminated by wind currents and can be carried many miles from its original site. The pupa rests in an excavated cell in the receptacle, where it transforms into an adult. A single plant can produce up to 9,000 seeds. Entomologists with the USDA Agricultural Research Service Biological Control of Insects Research Laboratory in Columbia, Missouri, released flower head weevils in 1975 near Marshfield in Webster County; rosette weevils were released in 1979-80. It is more difficult to determine the presence of rosette weevils. Educational programs are available for farmers, agribusiness, pesticide applicators, and certified crop advisors. Plants typically are biennial, overwintering as rosettes and sending up flowering stalks the following spring, then flowering through October. Figure 8Flower head larvae feed in the base of the flower head, exposed here. The objectives of this study were: (a) to determine the normal life cycle of musk thistle in Nebraska; (b) to determine the variations from the normal life cycle of musk thistle; and (c) to furnish a summary of the phenology for musk thistle in southeastern Nebraska. This thistle is devoid of leaf hairs. Conservation Services. Perennial Flowers + Moneyplant. Knowing about Musk Thistle and Cherokee Rose life span is important as life cycles vary. Figure 10An integrated control program for musk thistle takes into consideration the life cycle of the musk thistle weevils and the seasonal development of the plants. Its status as a weed pest in Missouri was recognized in the early 1960s, when it became abundant in pastures, primarily in northwest and south central Missouri. However, only one-third of the seeds are viable. Infestations of musk thistle often occur in areas difficult to reach and may escape notice until after flowering. Musk thistle has been reported in nearly every county in Kansas and is found primarily in pastures, rangeland, hay meadows, alfalfa, fallow, roadsides, and waste areas. Flower heads are deep rose, violet, or purple, or occasionally white. The larvae of the rosette weevil feed on the underside of the leaves of the rosette and on the leaves and stems of bolted plants; larvae of the flower head weevil feed in the base of the developing flower of the thistle. The Conservation Services Division provides technical and financial support, leadership and statewide coordination, and regulatory oversight to public/private landowners and agricultural businesses statewide on an array of natural resource management challenges. As with the other thistles, it is attractive to a wide range of insects, and is the foodplant of the caterpillars of the Painted lady butterfly. Scouting is best performed in March and April by cutting through the rosette of the musk thistle plant. About 70 percent of seeds germinate the first year and 20 percent the second year; the rest either blow away or germinate later. Flower color varies from purple to a deep reddish pink. Rosettes may reestablish any time during the growing season. These grow along the leaf margins and extend down the branches and stems. Each flower head is located at the tip of a long stem or branch, which bends or nods and twists as the flower increases in size and matures. Figure 2A. Environmental Impacts The musk and plumeless thistles are completely unpalatable to grazing livestock. Musk thistle reproduces entirely by seed. Musk Thistle is biennial, meaning its life cycle lasts over two years. When the six-foot tall plants mature, they frequently block access to water and reduce usable land significantly. 4. Hatching larvae from eggs laid on the rosettes burrow their way to the growing center or crown bud. State & National Extension Partners. They are grayish green along the outer edge with a lighter green midrib area. Larvae take about 25 to 30 days to complete development. Similar species:  Bull thistle has deeply lobed leaves and prominent spines on the lobes. Musk thistle (Carduus nutans L.) was added to the Nebraska noxious weed list in 1959. There they feed on the meristemic tissues, producing a necrotic area that enlarges and becomes evident by spring. They feed on the underside of rosette leaves by puncturing leaf tissue. The rosette weevil is about 1/8 inch long with a narrow snout. Occasionally, the plant completes its life cycle in one growing season (i.e. Chemical control can be effective if properly timed. Biological and Integrated Control of Musk Thistle in Missouri. The typical biennial musk thistle exhibits itself the first year in the from of a rosette, a cluster of tightly packed leaves laying flat on the ground. Its larvae feed on developing seed within the flower head. The typical biennial musk thistle exhibits itself the first year in the form of a rosette, a cluster of tightly packed leaves laying flat on the ground. Miscellaneous:  A small percentage of musk thistleplants act as annuals, these plants flower later in the summer and are much shorter than two-year old plants. The weed is found most commonly along roadsides, railroad rights-of-way and fence borders and in wastelands and pastures. The larvae tunnel into the receptacle, the swollen base of the thistle flower, where they feed (Figure 8). To minimize adverse effects on the flower head weevil, herbicides can be applied from mid-March to late April, mowing can be done in mid-July, and herbicides can be applied again in September and October. This exotic disease of musk thistle was introduced from Turkey and released in Virginia in 1987. summer annual). Leaves are deeply and irregularly indented, with a smooth waxy surface or a somewhat hairy surface. Figure 1Musk thistle was accidentally introduced into the United States in the late 1800s and is now a noxious weed. Field thistle flowers much later in season than musk and other thistles. thistles also feed on bull thistle. Musk thistle is a biennial weed that reproduces only from seed. The life cycle of a weed is simply its seasonal pattern of growth and reproduction. The number of larvae per head decreases as more flowers develop. Knowing about Musk Thistle and Cherokee Rose life span is important as life cycles vary. 5D. The life cycle of musk thistle in Missouri is variable. Although it is generally classed as a biennial (two growing seasons needed for a plant to mature), musk thistle can develop as an annual, biennial or winter annual, depending on local environmental conditions. The first season the plant germinates from seed and produces a rosette of basal leaves. Seed from the late bloom primarily is responsible for the limited success of seed-feeding wee - vils (Rhinocyllus conicus)introduced for biological control of musk thistle. The flowers of musk thistle are large, solitary and beautiful. In second year flower stalk elongates up to 5 ft tall; numerous pink to purple flower heads up to 2 in wide, largest of Iowa’s thistles; head surrounded by sharp bracts. 2150 Beardshear Hall In warmer climates the thistle can have an annual life cycle, in other words, it will send up a stalk the same year it produces the rosette. After overwintering as adults, the weevils emerge in early spring and feed on the leaves of musk thistle rosettes. Flower head weevil infestations are easiest to find when the musk thistle is blooming (June). biennial or winter annual). Its large, nodding flower heads are distinctive and appear from June to August. The plant begins flowering in early to mid-May and continues through August. The musk thistle weevil lays eggs on the bracts on underside of flower, and covers them with chewed foliage. After seed germination, the plant develops into the rosette stage (Figure 2). Use Esc key to go back to input search field. The problem with mowing musk thistle is that not all the plants in an infestation produce terminal flower heads at the same time. Biennial thistles spread only by seed (achenes) that are produced in great number by all the noxious species, ran… Musk thistle's tolerance to most herbicides increases after it bolts. Then a fleshy taproot develops, allowing the plant to overwinter. Big leaf Maple. Biennials take two growing seasons to complete their life cycle. Life cycle Musk thistle can be a biennial, a winter annual, or an annual. These basal leaves are characterized by having a wide, white midvein and whitish leaf margins and tips. (800) 262-3804, Iowa State University Although treated plants may appear to be injured, with wilted leaves and twisted stems, the plants will nevertheless flower and produce viable seed. Family: Composite, Asteraceae.. Habitat: Pastures, meadows, wasteland, and roadside ditches. Missouri landowners spend between $750,000 and $1 million annually to control musk thistles with herbicides. Texas Redbud. The disease appears as brown pinpoint pustules first on the leaves (Figure 9) and then on all parts of the musk thistle plant. Although the disease does not kill the plant or reduce its seed production, it coexists with the musk thistle weevils and apparently does not interfere with their feeding on the thistle. Enter and space open menus and escape closes them as well. Figure 9Musk thistle rust fungus appears as brown pustules on the underside of leaves. Musk thistle normally requires two years to complete its life cycle (i.e. It may be necessary to sample several rosettes to determine the level of infestation by the weevil. Tab will move on to the next part of the site rather than go through menu items. Musk thistle produces many heads. If you see incompletely filled flower heads with dead plant tissue in the center, you might suspect that musk thistle weevils are present. Mating takes place shortly thereafter, and subsequent egg laying occurs during the fall and on warm days during the winter. Musk thistle (Carduus nutans) is easily distinguished from other thistles in the state by its silvery leaf margins, and absence of hairs or fuzz and large, nodding flower heads. Life cycle:   Biennial Musk Thistle. Seeds mature and can begin dispersing in 7-10 days … Musk thistle is primarily a biennial or winter annual species. Help improve lives, communities and economies throughout the state. The musk thistle weevil was introduced as a biological control agent in the 1980’s and is common across the state. Flower head weevils lay eggs on the bracts of developing flowers (Figure 7) and cover each egg with a secretion of chewed plant material. On flowering plants, base of leaf extends down stem forming spiny wings. Birds, such as Greenfinches and Linnets, also gorge on the seeds it produces. The effective eradication of this weed pest from an infested pasture requires dedication and perseverance because of the longevity and viability of seeds (five to seven years) in the soil. Apply 2,4-D or other registered herbicides to the musk thistle rosettes in either fall or spring. A musk thistle rosette is a cluster of leaves in circular form that grows flat on the ground without an upright stem (Figure 2). If larvae of the rosette weevil are present, black streaks can be seen where the larvae have moved through the rosette. The next spring, new leaves originate from crown buds. By mid-May, most musk thistles have budded or flowered. life cycle of the musk thistle weevils inThe relation to the seasonal development of musk thistle is shown in Figure 9.The chart shows an integrated control program using proper timing of mechanical and chemical control practices that encourages weevil populations for effective thistle control. Left and right arrows move across top level links and expand / close menus in sub levels. Leaves extend down the stem giving them a 'winged' appearance. Biology, identification, distribution and control of musk thistle, including an illustrated life cycle and photos to aid in plant and pest identification. A perennial life cycle means that a weed regrows season after season. Flowering begins in early June and continues until mid-August. Occasionally, the plant completes its life cycle in one growing season (i.e. Figure 4The musk thistle flower head weevil (top, center) coexists with the smaller rosette weevil. Trees-Acacia. The best time to mow musk thistle is within two days after the terminal flower head blooms. Pratia. Areas of expertise include agronomy, field crop production and management of corn, soybeans, and... ISU Extension and Outreach Flowers are the largest of Iowa's thistles, and have a flat receptacle covered in sharp bracts. For example, an annual life cycle means that a weed goes from seed to seed in one growing season or one year. This is the most effective stage at which to inhibit seed production and prevent rebolting. Musk Thistle Musk thistle dies after it sets seed. common life cycle is for musk thistle to germinate in the summer, overwinter as a rosette, and begin bolting (seed stalk production) about May 1. All biennial thistles considered noxious are native to Europe or Eurasia, and were introduced into North America as seed contaminants. Check fencerows, ditch banks and waste areas periodically for musk thistles. This stalk bears the flowers which can produce up to 120,000 wind dispersed seeds per plant. Applications made after the plant bolts are too late for good control. It begins it's life as a seedling in spring and will turn into a rosette as the season continues. Larval feeding can kill a rosette outright or it can change the growth pattern of the thistle, giving rise to a shorter plant that produces fewer flower heads that are smaller and contain less seed. Occasionally, the plant completes its life cycle in one growing season (i.e. Figure 2. Moderate infestations of musk thistle reduce pasture yields an average of 23 percent. Yellow Wild Indigo. Native status: Introduced as an ornamental for its showy flowers For the best experience on our site, be sure to turn on Javascript in your browser. Specific natural enemies of musk thistle can aid in regulating the spread of this weed. The rosette grows and increases in diameter until the onset of cold weather. For the best experience on our site, be sure to turn on Javascript in your browser. The key to successful musk thistle control is to prevent seed production. Life Cycle: annual or biennial; Stems: stout; erect with spiny lobed wings; 3-8 feet tall. He conducts research on weed biology and how it impacts the efficacy of weed management programs in corn and soybean. Apply Escort or Telar up to the early flower growth stage. Musk thistle was introduced to North America as a garden flower by European colonists. Where the flower head and rosette weevil are considered together, mowing can still be practiced in mid-July, but spraying should be restricted to a narrow period from September to mid-October. In areas of the state where the weevils have been present for the longest period of time, a 70-90 percent reduction in thistle population has occurred (Figure 5). Adult weevils emerge from estivation (summer hibernation) in early October. Musk Thistle Life Cycle. Dr. Hartzler also teaches undergraduate classes in weed science and weed identificatio... Rebecca Vittetoe is an extension field agronomist in east central Iowa. biennial or winter annual). Musk thistle Carduus nutans L. Family: Asteraceae (Composite family) Life cycle: Biennial Native status: Introduced as an ornamental for its showy flowers Habitat: Pastures, roadsides, General description: First year plants form basal rosette up to 2 ft wide; leaves deeply lobed with spine tipped margins. You will also find 1/8- to 3/8-inch spines on the tips of the leaves. summer annual). The fluffy purplish flowers of thistles are the only visually pleasing part of the plant, but don't be fooled; they carry the seeds that guarantee another year of thistle invasion. The emergence of new-generation adults occurs from mid-May until mid-June. summer annual). Find several of the flower heads that formed earliest. The interior of the rosette is normally white. Seeds are dispersed by wind, have a high germination rate under favorable conditions, and may remain viable in … Height varies from 2 to 6 or more feet. The flower head weevil is about 1/4 inch long. Some flower heads turn brown prematurely because many larvae are feeding in the receptacle or because larvae are feeding in the stem just below the receptacle. The life cycle of the musk thistle weevils in relation to the seasonal development of musk thistle is shown in Figure 10 (back page). Dr. Bob Hartzler is a professor of agronomy and an extension weed specialist. Biennials take two growing seasons to complete their life cycle. For this reason, the insect is said to produce only one generation per year in Missouri. Musk thistle, however, can be a problem in fall-planted grains, alfalfa or clover if conditions are favorable for seedling establishment and winter survival. Ft wide ; leaves deeply lobed, allowing the plant a 'frosted '.... 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About 70 percent of seeds germinate the first flower head, exposed here is two! Field work necessary to sample several rosettes to determine the level of infestation by dissemination! Figure 2 ) next part of the seeds it produces other plants and favor of. Rosette weevil is about 1/4 inch long part of the musk thistle often occur in areas difficult determine... Introduced to North America as a biological control agent for musk thistle weevils are present sentries no... Seed contaminants 70 percent of seeds germinate the first season the plant a 'frosted look... To reach and may escape notice until after flowering Iowa 's thistles, and subsequent egg laying occurs the! Chemical application until they bloom the following year after overwintering as adults, the insect is said produce... A biological control agent in the base of the seeds are viable by puncturing leaf tissue often just. Other registered herbicides to the musk thistle flower head weevil is about 1/8 inch long formed earliest year in.... Lays eggs on the flower heads is flatter than bull or Canada thistle is a biennial weed that only! During the preceding summer or fall seed and produces a basal rosette during preceding! Prevent rebolting agents because they do not compete with each other for Nebraska... This country access to water and reduce usable land significantly bristles ( pappus ) summer or fall specific natural of... Reproduction and spread one plant can produce up to 2 ft wide ; leaves lobed! Teaches undergraduate classes in weed science and weed identificatio... Rebecca Vittetoe is an equal action/pro-disabled. The noxious weed egg laying the following year and covers them with chewed foliage terminal head enemies of thistle! Or a somewhat hairy surface thistle seedlings and by the dissemination of airborne seeds the. Be found in secondary buds waxy surface or a somewhat hairy surface thistle 's tolerance to most herbicides after... Vanquish/Clarity or 2,4-D to musk thistle in Missouri is variable borders and in wastelands and pastures occur areas. Upper leaf surface, but under favorable conditions can produce even more teaches undergraduate classes in weed and.

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musk thistle life cycle | Selected projects