Musk thistle flower with large brown bracts and the tendency to nod or lean because of the large size of the flower. Musk thistle and specific controls common weeds noxious. The oklahoma state legislature declared musk thistle a locally noxious weed northeastern oklahoma in 1994. Two biological control agents introduced for control of musk thistle are the thistle head weevil rhinocyllus conicus froelich and the rosette weevil trichosirocalus horridus panzer. These biological control agents aid in reducing populations of the thistle. Plumeless thistle left and musk thistle right in early. Once established it spreads rapidly because of the large number of seeds produced. Thistles in oklahoma and their identification oklahoma. A reassessment musk thistle and nodding thistle are names commonly used to describe old world thistles in the carduus nutans species group. In italy, larvae of the syrphid fly, cheilosia corydon harris grossa fallen, infest the flower buds, stems, and roots of carduus nutans l.
Canada thistle grows in dense patches and reduces the vigor and establishment of grassland plantings and riparian buffers that are planted to improve wildlife habitat. Bill will assume the lead role on the red gum lerp psyllid. The head weevil works best in isolated areas where disturbance by people or ani mals is restricted and use of herbicides or cultural control methods is limited. The plants you are most likely to confuse canada thistle with are other thistles. We are thrilled to welcome syed and pat to the biological control program. Combine control methods into a management system for best results.
Musk thistle rosette, which often grows 2 feet or more in diameter, with no pubescence on the underside of the leaf, which helps distinguish it from plumeless thistle rosettes. Musk thistle control missouri department of conservation. Typically, it takes 6 to 10 years after weevil release to see a significant impact on the thistle population. This weevil develops in the crown of the musk thistle rosette. University of nebraskalincoln extension ec176 revised march. Control options include mechanical, biological, cultural, and chemical methods. The first biocontrol release in south dakota was in the early 1970s when the musk thistle seed weevil, rhinocyllusconicus, was released to control musk thistle. A third biological control agent for musk thistle is a rust fungus. While they dont eliminate musk thistle, they have made it more like a native thistle. Biological control can be used to control targeted weed species. Pucciniaceae has been introduced and established for control of nodding thistle in virginia.
Classical biological control of nodding and plumeless. The first bio control release in south dakota was in the early 1970s when the musk thistle seed weevil, rhinocyllusconicus, was released to control musk thistle. Herbicides have been used to control this and other thistles for many. Evaluation of a biological control agent for musk thistle. The weevils lay eggs on the bracts of the developing musk thistle flowers. In addition, a rust fungus puccinia carduorum jacky uredinales. In areas of nebraska where the weevils are present an 80 to 90percent reduction in thistle population has occurred. Musk thistle is a biennial weed that reproduces only from seed. Biological control of musk thistle integrated crop management.
These include carduus macrocephalus desfontaines bigheaded thistle, c. By 1997 it was detected in 37 counties in missouri. In the early 1960s, staff of the usda intensively surveyed carduus spp. Any plan relying on the use of the musk thistle head or rosette weevil needs to be approved by the kansas department of agriculture. Flower heads have involucral bracts that are broadly triangular more than 2mm wide, have smooth margins, and a short spinetip. University of nebraskalincoln extension ec176 revised. Rosettes formed the first year and bolt early in may to june of the next year. Field evaluation of puccinia carduorum for biological control. This thistlehead weevil was the first insect introduced into north america for the biological control of musk or nodding thistle. The fly was studied as a candidate biological control agent of musk and italian thistle in north america. Biological control of musk thistle in the southeastern united. Origin, distribution, and life history of musk thistle. The common, weedy thistles in pa include bull thistle cirsium vulgare, musk thistle carduus.
The thistle head weevil can reduce musk thistle populations by 90 to. Information sheet pdf colorado list b control required in jefferson county. Refusing to buy hay that contains musk thistle seed can help prevent musk thistles from becoming established on your farm. Establishing a dense, wellmaintained pasture is effective in preventing a musk thistle infestation. Musk thistle weevils were released by isu personnel in the 1980s, and they can be purchased from companies involved with biocontrol. Control options include mechanical, biological, cultural, and. Mowing and removing seedheads will reduce populations of the musk thistle weevils. The first documented report of musk thistle in kansas was from a collection made in washington county ini 1932. From the united states national agricultural library. Biological control of musk thistle m usk thistle, carduus nutans, was introduced into the eastern united states in the 1800s. Russian thistle puncture vine musk thistle yellow and dalmatian toadflax bull thistle canada thistle russian knapweed purple loosestrife biological controls are most useful for reducing seed production or weakening plants. Herbicides are not as effective and there are no weevils or other insects available for biological control. Perennial and biennial thistle control w799 publications.
Researchers have investigated several insects and pathogens for the control of musk thistle and some have been introduced into the united. Musk thistle, carduus nutans, was introduced into the eastern united states in the 1800s. Classical biological control of nodding and plumeless thistles. In my random examinations of musk thistle patches over the past decades i would estimate that musk thistle weevil is present at more than half of the. In locations where the weevils can multiply rapidly, a dramatic decline in musk thistle may be possible in as little as 2 to 3 years. This paper addresses the benefits and risks of using biological control as a component of an ipm program directed against musk thistle in the southeastern u. L873 biological control of musk thistle in kansas ksre bookstore.
Cultivation in cropland will kill young musk thistle seedlings. A strain of puccinia carduorum jacky, an autoecious rust fungus from turkey, was evaluated for biological control of musk thistle carduus thoermeri weinmann in a 3year field trial. Musk thistle biocontrol south dakota department of agriculture. Integrated management of invasive thistles in oklahoma. It invades many types of habitats but is a serious threat to pastures as it is unpalatable to livestock. In order to reduce control costs and comply with state noxious weed laws and avoid costly fines, releases of biological control agents have been made at ioc. Herbicides have been used to control this and other thistles for many years. Successful biological control of the musk thistle in oklahoma using. The key to successful musk thistle control is to prevent seed production. Biological control of the musk thistle in kansas, biological control of musk thistle in kansas. It was first recorded in the united states in 1852 at harrisburg, pa. Supplemental risk evaluations and status of puccinia.
These weevils are increasing and continuing to disperse naturally. Larvae develop in the flower head and consume the seed as it develops. Musk thistle is continuous throughout the united states. Musk thistle is often a biennial herbaceous plant in south dakota and is a highly competitive plant, threatening many desirable forage species. Pdf successful biological control of the musk thistle in. Because the state of iowa classifies musk thistle as a. Both surfaces appear grayishgreen due to thick cottonlike hairs. Last, bill roltsch was transferred from imperial county to sacramento. This successful biological control of musk thistle is partly due to the good synchronization of.
A seed eating weevil, rhinocyllus conicus, is quite. Plumeless thistle left and musk thistle right in early bloom. Several nontarget native thistle species also supported populations of in t. 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.
Musk thistle whitman county washington state university. Apply ally or telar up to the early flower growth stage. Curculionidae introduced into north america for the biological control of asteraceous thistles. The introduction of the musk thistle head and rosette weevils has been very effective in reducing the population in southwest missouri.
Grows in all soil textures, but soils must be well drained. This successful biological control of musk thistle is partly due to the good synchronization of plant growth and insect activity. Musk thistle weevil egg masses on a musk thistle seedhead. Musk thistle is usually a biennial, requiring 2 years to. Request pdf classical biological control of nodding and plumeless thistles nodding musk thistle carduus thoermeri weinmann in the carduus nutans l. Species profile musk thistle carduus nutans lists general information and resources. Evaluation of a biological control agent for musk thistle background musk thistle carduus nutans l. Thus, the goal of any control program is to reduce andor eliminate seed production. Successful biological control of the musk thistle in oklahoma using the musk thistle head weevil and the rosette weevil. March 31, 2015 musk thistle control nebraska extension. Mechanical, biological and chemical methods are some of the effective methods available for control of musk thistle. Test plants in the current study were evaluated in support of a proposal to use the rust in the western united states, and particularly, in california. Musk thistle carduus nutans, exotic and undesirable flower heads are mostly solitary and have involucres of 24 cm tall.
Mechanical and manual hand pulling is most effective on small populations and can be done throughout the year, but is most effective prior to the. Jun 08, 2017 musk thistle weevil egg masses on a musk thistle seedhead. Musk thistle seeds are dispersed by wind blown pappus. The targeted species in southwest missouri is the musk thistle. It is widely distributed in alabama and is a serious weed in pastures, roadsides, and waste areas idle ground. Impact of biological control agents on musk thistle. This exotic disease of musk thistle was introduced from turkey and released in virginia in 1987. The thistle head weevil can reduce musk thistle populations by 90 to 95 percent in eight to 10 years after they have established. Kansas state university agricultural experiment station and.
Currently there is one biological control agent released by the insectary for control of musk thistle, the musk thistle rosette weevil or crown weevil, trichosirocalus horridus. Biological control is a longterm approach to musk thistle control. Recommended practices in natural communities of high quality. Musk thistle and nodding thistle are names commonly used to describe old world thistles in the carduus nutans species group family asteraceae. Negative ecological effects of the musk thistle biological. Nodding thistle biological control is achieved in about 56 years in virginia, missouri, and montana. I nsect biocontrol agents have been released on both musk thistle and canada thistle with limited success. Large, dense infestations where other control methods are not costeffective. The thistle seed head weevil, rhinocyllus conicus, is very effective in reducing seed production in this biennial weed. Musk thistle is an introduced invasive broadleaf weed native to europe, siberia, asia minor and north. Biological and integrated control of musk thistle in. This weed infests more than three million acres in the state. Without these natural checks, musk thistle is more prolific and competitive.
Apply herbicides such as tordon, vanquishclarity or 2,4d to musk thistle rosettes in spring or fall. Musk thistle was among the first 19 weeds selected for biological control when the usda overseas laboratory was established at rome, italy in 1959. Biological control biological control,the practice of using natural enemies,can reduce musk thistle populations and reduce the spread of musk thistles. Compositae, both serious weeds in the united states. Sud morishita, former bonneville county, idaho weed supervisor, estimates that biocontrol has reduced the countys use of chemicals to fight musk thistle by as much as 60 percent. Apply ally or \ telar up to the early flower growth stage. Biological control of musk thistle auburn university. Kansas department of agriculture, plant protection and weed control and others to work together to document, promote, and preserve musk thistle biological. Biological and integrated control of musk thistle in missouri. Ethological and genetic differences among three biotypes of rhinocyllus conicus coleoptera. Buds and flowers will soon redevelop and the infestation will become greater. Musk thistle is a noxious weed in all counties in kansas.
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