Nov 11, 2012 previous work, using an activated carbon experiment, suggests allelopathic effects by spotted knapweed on native bunchgrasses ridenour and callaway 2001. Knapweed utilizes allelopathy to inhibit neighboring plant communities. The importance of analytical techniques in allelopathy. Spotted knapweed is a biennial or shortlived perennial. Alaska plant materials center division of agriculture. It grows up to 122 cm 48 inches tall and its leaves and stems are similar to that of russian knapweed in its greygreen color. Carney4 summary understanding the origins and basic biology of nonindigenous invasive plants can help lay a strong. Spotted knapweed scholarworks montana state university. The four modes of release of allelochemicals from plants. Unless there is a high degree of similarity between areas where exotic plants are newly discovered and areas where they have already proven problematic, it is probably not safe to assume the exotic species will be highly problematic in the newly discovered area. This species is common throughout western north america but is not actually native to the north american continent, but to the eastern mediterranean.
The general effects of competition and allelopathy are. And although pollinators do use this species, it replaces native species that are typically higherquality food sources. Spotted knapweed report alaska plant materials center. An allelopathic compound, cnicin, has been isolated from spotted knapweed leaves and shoots. Knapweeds are allelopathic, inhibiting the establishment and growth of surrounding vegetation whitson et al. Studies indicate that this species negatively affects the growth of grassland species in the rocky mountains e.
Distribution, biology, and management of diffuse knapweed centaurea diffusa and spotted. Origins, hybridization and allelopathy of spotted and. Sustainable control of spotted knapweed centaurea stoebe. West of the cascades and the aridinterior scablands appear to be the upper and lower climatic limits for spotted knapweed. Spotted knapweed has allelopathic toxic properties, also reducing the native plant communities. Spotted knapweed washington state noxious weed control. It tends to grow to a height of 3 foot and has a single tap root that can go as deep as 18 inches.
We propose that native north american species that are resistant to knapweed allelopathy may be used to detoxify knapweed allelochemicals and facilitate establishment of diverse native communities in knapweed infested sites. Geographic and ecologic distribution spotted knapweed was located in 19 counties in washington in 1987 roche and roche 1988. Centaurea stoebe spotted knapweed is a noxious weed known for outcompeting. Spotted knapweed often forms dense stands in natural communities decreasing diversity of native vegetation, and degrading the forage quality for wildlife habitats. Mowing does not kill knapweed nor will it prevent propagation, therefore, it is an insufficient means of control when used alone. Species which have been noted to produce phenolic acids include. Brush management invasive plant control spotted knapweed. Depending on soil fertility and moisture conditions spotted knapweed plants are typically between 30 to 125cm tall and produce 1 to 10 flowering stems annually. As a result, allelopathy received considerable attention as an important competitive mechanism. Pdf role of allelopathy in plant invasion and control of invasive. Pdf allelopathy plays important role in many aspects of plants invasion plant.
In the western united states, yellow starthistles are an invasive species. In seasonally dry areas, spotted knapweed s taproot allows it to access water from. Members of the genus are found only north of the equator, mostly in the eastern hemisphere. Repeated measures anova results showing the response of spotted knapweed cover. Spotted knapweed is considered a noxious weed under north. Allelopathic native species were selected based on evidence for allelopathy in the literature. Table 8publications from 1999 to 2020 on allelopathy of diffuse knapweed. Bracts on diffuse knapweed may have darker coloration on the tips, but lack fringe present on spotted knapweed.
The possibility also exists that both allelopathy and positive feedbacks from. Outside of alaska knapweed is known to create dense stands that crowd out native and desirable plant species in both natural and farm ecosystems. It starts out as a rosette and can remain that way for several years before bolting and dying in a subsequent season. Spotted knapweed centaurea biebersteinii dc response to.
Comparing susceptibility of eastern and western us grasslands. Origins, hybridization and allelopathy of spotted and diffuse. This allelopathy inhibits germination and growth of other species. The competitive advantages that spotted knapweed has over other species includes heavy seed production, 20,000 seeds or more royer and dickinson 1999, and the use of allelopathy. Centaurea maculosa spotted knapweed spotted knapweed is an erect shortlived perennial or biennial that reproduces only by seed.
In laboratory experiments cnicin has been shown to reduce the germination of crested wheatgrass agropyron cristatum, bluebunch wheatgrass elymus spicatus, and rough fescue festuca campestris kelsey and locken. Most of the spotted knapweed acreage in washington is located in the northeast corner of the. Chapter 11 sustainable control of spotted knapweed. Centaurea diffusa, knapweed, allelopathy, seed bioassays, ryegrass. Graygreen, covered in rough hairs, and deeply divided. Allelopathy, as the theory is known, has had its ups and downs among. The flowers are light purple, aromatic, and found individually or in clusters on the stems. A rhizosecreted racemic mixture from spotted knapweed. The case against catechin involvement in allelopathy. It makes and secretes chemicals into the soil that kill surrounding plants allelopathy. The effects of flavonoid allelochemicals from knapweeds on. Comparing susceptibility of eastern and western us grasslands to competition and allelopathy from spotted knapweed centaurea. One potent allelopathic flavonoid called catechin is produced by the roots of spotted knapweed centaurea maculosa syn. Early reports showed that spotted knapweed produced an allelopathic compound, cnicin, which inhibited plant growth and seed germination.
Pdf comparing susceptibility of eastern and western us. Spotted knapweed centaurea stoebe, hereafter knapweed is an invasive plant that is both an ecological and economic concern in rangeland management. Seeds are prolific and hardy and are readily dispersed by people and. Chapter 11 sustainable control of spotted knapweed centaurea. Density results suggestdelayed development of spotted knapweed.
Sunflower family asteraceae native range central europe, east to central russia, caucasia, and western siberia description spotted knapweed is a biennial or shortlived perennial. Goats and sheep can be trained to graze spotted knapweed and can be an effective treatment option, especially if utilized when the knapweed is underseeded with a less desirable plant. University of nebraskalincoln extension ec173 revised. The stems and leaves are covered with fine hairs, giving the plants a light colored, almost white appearance at times. Progress 010105 to 123105 outputs we are exploring the origins of diffuse and spotted knapweed, allelopathy of spotted knapweed and the consequences of hybridization for biological control. Spotted knapweed, centaurea stoebe, is targeted for eradication in alaska because. Spotted knapweed is native to central europe and east to central russia. The identified allelopathic agent for spotted knapweed may not occur in high enough concentrations to have impacts on. North american insect herbivores do not grow as well on knapweed as they do on native plants schaffner et al.
Knapweed does not compete well in moist areas, such as near wet inicrosites. Thurston county noxious weed fact sheet spotted knapweed. Spotted knapweed is capable of producing flower buds until frost, but. In particular, allelopathy has been implicated as a mechanism of invasion for spotted, diffuse, and russian knapweed. After showing the photo on the front, read and discuss the information on the back of the card.
Allelopathy has also been suggested as a mechanism by which spotted knapweed restricts native plants and facilitates its success as an invader bais et al. Spotted knapweed produces chemicals that inhibit nearby plant growth, forming own habitat highly competitive with native vegetation, reducing forage for livestock and large game an hybridize with diffuse knapweed native to eurasia always read herbicide labels and follow instructions for use and ppe. The manual of montana vascular plants lesica et al. Diffuse knapweed can be distinguished from spotted knapweed by their bracts. Both species contain at least one phytotoxic flavonoid. The highly invasive spotted knapweed centautea stoebe uses an allelochemical within the flavonoid group of compounds. Spotted knapweed centaurea stoebe is an aggressive, perennial plant that can live up to 9 years. Through secreting allelochemicals, shifting microbial mechanism and. Developing rigorous analytical techniques to detect and quantify compounds of interest from soil or liquid media lays the foundation for designing ecologically relevant experiments that incorporate candidate allelochemicals. Comparing susceptibility of eastern and western us. Allelopathy and exotic plant invasion springerlink. Perhaps more challenging than the abundant seed production is the fact that spotted knapweed is allelopathic, meaning it exudes chemicals from its roots that are toxic to other plant species. Spotted knapweed infests a variety of natural and seminatural habitats including fields, forests, prairies, meadows, pastures and rangelands.
The relative importance of allelopathy in interference citeseerx. Spotted knapweed is driving out native plants and destroying rangeland, costing. Furthermore, diffuse knapweed s bracts have a rigid terminal and lateral spines. Russian knapweed acroptilon repens and spotted knap weed centaurea maculosa are allelopathic weeds invasive in north american grasslands. Allelopathic toxic chemicals cause it to choke out native vegetation. Ask students if they recognize the plant and if they have ever seen knapweed infestations. Infestations of spotted knapweed have been shown to increase the erosion of topsoil. Keywords activated carbon allelopathy centaurea maculosa. In this paper, fundamental components of analytical techniques, including method development, validation, and appropriate. The flora of north america reports that diffuse knapweed readily hybridizes with spotted knapweed c. The case against catechin involvement in allelopathy of centaurea stoebe spotted knapweed. The efficacy of americorps weed treatments in montana. Genomics resources and approaches for studying spotted. A study of invasive spotted knapweed pierce cedar creek institute.
In the spotted knapweed centaurea maculosa, catechins. Spotted knapweed, centaurea stoebe, early detection and rapid. Its name is derived from the spots formed by black margins on the flower bract tips. Spotted knapweed national invasive species information center. The deep taproot of spotted knapweed can access moisture deep in the soil. This is called allelopathy and further increases spotted knapweed s competitive advantage over native species. Spotted knapweed, as the plant is more formally known, is a national menace, a weed of mass destruction. Spotted knapweed centaurea biebersteini is the dominant invasive species. Spotted knapweed was first documented in north america in victoria, british columbia in 1893, and diffuse knapweed was first recorded in washington in 1907. This phenomenon, called allelopathy, has been welldocumented in chaparral shrubs that secrete terpenes which inhibit the germination of wildflower seeds. The strategy spotted knapweed centaurea stoebe maculosa ssp. However, hybridization only occurs between diploid diffuse knapweed and. Reports of catechin to be the novel weapon used by centaurea stoebe spotted knapweed to invade new territories are not supported by the paper featured. Ultimately, spotted knapweed crowds out native plants.
It is highly competitive and aggressive, and forms dense colonies. Spotted knapweed flower heads showing the blacktipped involucre bracts and the light purple flowers. Spotted knapweed is currently found throughout the sea to sky corridor, so the best approach to controlling its spread is by containment. Allelopathy one species use of chemicals to harm other species may be a key ingredient in successful invasions of alien plants into established communities. Spotted knapweed, centaurea stoebe, early detection and. Spotted knapweed also was thought to have been introduced in soil discarded in ship ballast. Allelopathic weed suppression through the use of cover crops. Zn allelopathy aides in the successful spread of rk in the west. Spotted knapweed infests a variety of natural and seminatural habitats including barrens, fields, forests, prairies, meadows, pastures, and rangelands. Russian knapweed has been documented to survive from the root for over 75 years. Dead spotted knapweed stems generally remain erect during the winter unless crushed by heavy snowpack.
It outcompetes native plant species, reduces native plant and animal biodiversity, and decreases forage production for livestock and wildlife. Finally, proof of weapons of mass destruction science. Invasive plant fact sheets for plant species trees, shrubs, vines, herbs and aquatic plants that have impacted the states natural lands. Ask students if they recognize the plant and if they have ever seen knapweed. Spotted knapweed was located in 19 counties in washington in 1987 roche and roche 1988. Spotted knapweed grows 12 to 60 inches tall, is more erect and has more limited branching than diffuse knapweed. Allelopathic potential of diffuse knapweed canadian. No significant effect of activated carbon in 2006 or 2007. Centaurea diffusa, also known as diffuse knapweed, white knapweed or tumble knapweed, is a member of the genus centaurea in the family asteraceae. When mowed repetitively this plant can adjust and grow flowers and seeds close to the ground, so spotted knapweed can range from 2 tall to 4 tall depending on management. Wicked weed of the west science smithsonian magazine.
Stem leaves alternate, with lower stem leaves resembling rosette leaves, becoming small long, entire and linear higher up the stem. The bracts have black tips, giving the plant its spotted appearance. Therefore, we undertook this study to provide pcci with baseline data that could be useful to their prairie reconstruction and management efforts. Knapweeds are allelopathic, inhibiting the growth of surrounding plants lym and zollinger 1992, royer and dickinson 1999, whitson et al. Holben1,3 1 microbial ecology program, division of biological sciences. Both knapweeds spread in alfalfa seed and hay before they were considered problem weeds. Centaurea stoebe, the spotted knapweed or panicled knapweed, is a species of centaurea native to eastern europe. Apr 04, 2021 cnicin is an allelopathic compound that has been isolated from spotted knapweed leaves and shoots fletcher and renny 1963. Expansion of knapweed colonies occurs through germination of seed along the peiipheiy of stands, which may be aided by allelopathic compounds bais et al.
It grows from 2 to 5 feet in height, producing from 1 to 15 stems from a stout tap root. Phytotoxins identified include sorgoleone in sorghum species,57 mtyrosine in festuca rubra,8,9 momilactone b in rice,10,11 and catechin in centaurea stoebe spotted knapweed. Invasive species, such as spotted knapweed, often threaten the establishment of desirable plants in vegetation restoration projects emery and gross 2005. Differing effects on dicots and monocots by centaurea. Spread spotted knapweed spreads by seed, however, entire plants can be transported in soil and on the root balls of horticultural trees and shrubs. Population structure, ploidy levels and allelopathy of. A fertile hybrid between diffuse knapweed and spotted knapweed c. Pdf role of allelopathy in plant invasion and control of. At high catechin concentration, seedling establishment of spotted.
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