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Coltsfoot

Tussilago farfara

Summary 6

Tussilago farfara, commonly known as coltsfoot, is a plant in the family Asteraceae that has traditionally had medicinal uses. However, the discovery of toxic pyrrolizidine alkaloids in the plant has resulted in liver health concerns. T. farfara is the only species in the genus Tussilago; the name "tussilago" itself means "cough suppressant".

Impacts and control 7

More info for the terms: cover, density, fire management, invasive species, natural, prescribed fire, rhizome

Impacts: Coltsfoot often forms dense stands, particularly along roadsides (e.g., [21,22,59]), and occasionally dominates disturbed native plant communities (e.g., [2,80]). Coltsfoot's ability to dominate disturbed areas is attributed to its high seed production, fast vegetative spread, and ability to tolerate a wide range of environmental conditions [66,77]. According to management guidelines from 2005, however, evidence was lacking that coltsfoot out-competes other vegetation in relatively undisturbed native habitats [58]. In 2004, a compilation of invasive species lists and expert opinion from throughout the northeastern and north-central United States indicated that coltsfoot was “not currently known to be especially invasive” [101]. Although coltsfoot was introduced in Canada in the 1920s, Wright [109] stated that by 1997 it had not spread extensively. Most fact sheets, government publications, and weed management guides indicated that coltsfoot had no more than a moderate impact on native vegetation [20,26,95,101]. In the Upper Midwest, coltsfoot appears most invasive in grasslands and wetlands [26]. In Massachusetts, coltsfoot appears most invasive in lime seeps and disturbed sites [58]. Photo courtesy of Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Control: Coltsfoot control is complicated by its abundant seed production and ability to sprout from rhizomes following disturbance [77,109]. Because coltsfoot often becomes established after disturbance, control efforts should focus on management of existing infestations and minimization of disturbance to forests, wetlands, and other natural communities. Control effectiveness may depend on a program that integrates multiple management procedures such as herbicides, seeding of desired species, and other techniques that decrease coltsfoot spread and favor desired species.

In all cases where invasive species are targeted for control, no matter what method is employed, the potential for other invasive species to fill their void must be considered [17]. Control of biotic invasions is most effective when it employs a long-term, ecosystem-wide strategy rather than a tactical approach focused on battling individual invaders [55].

Prevention: Coltsfoot's preference for disturbed sites (see Successional Status) suggests that its establishment may be prevented by minimizing soil disturbance. It is commonly argued that the most cost-efficient and effective method of managing invasive species is to prevent their establishment and spread by maintaining "healthy" natural communities 55,87 and by monitoring several times each year [49]. Managing to maintain the integrity of the native plant community and mitigate the factors enhancing ecosystem invasibility is likely to be more effective than managing solely to control the invader [44].

Weed prevention and control can be incorporated into many types of management plans, including those for logging and site preparation, grazing allotments, recreation management, research projects, road building and maintenance, and fire management [102]. See the Guide to noxious weed prevention practices [102] for specific guidelines in preventing the spread of weed seeds and propagules under different management conditions.

Fire: For information on the use of prescribed fire to control this species, see Fire Management Considerations.

Cultural control: Because increased vegetation density and cover may result in decreased coltsfoot cover (see Successional Status), it may be possible to control coltsfoot by establishing native vegetation. In a greenhouse in Poland, coltsfoot seedling survival decreased with increased seedling density, and increased seedling density also delayed coltsfoot seedling development [66]. In field experiments in the Netherlands, coltsfoot did not grow well from germination to the reproductive stage when grown among dense agricultural crops, due in part to low light intensities under these crops [4]. Other researchers reported that because coltsfoot was low-growing, vegetative reproduction was reduced by the abundance of other low-growing herbs such as clover (Fabaceae) and ryegrass (Lolium spp.) (review by [4]). In combination, these studies suggest that establishing native vegetation may slow coltsfoot establishment and spread. For more information on this topic, see Seedling establishment and plant growth.

Physical or mechanical control: Coltsfoot has deep, brittle rhizomes, making it difficult to control by hand-pulling. Small coltsfoot infestations may be eradicated by carefully digging out plants [26,95]. It is critical that all underground portions of the plant are removed because even small fragments of rhizomes left in the soil are likely to give rise to new plants [66]. According to a fact sheet, coltsfoot roots can remain dormant underground for long periods [95] and presumably retain the potential to generate new plants. Coltsfoot seedlings hand-pulled after germination but prior to rhizome development are usually killed and not capable of vegetative reproduction (see Vegetative regeneration) [4]. Hand-pulling before the plant has set seed may reduce spread [95].

Biological control: No biological controls of coltsfoot are known as of this writing (2011). Biological control of invasive species has a long history that indicates many factors must be considered before using biological controls. Refer to these sources: [104,108] and the Weed control methods handbook [98] for background information and important considerations for developing and implementing biological control programs.

Chemical control: Herbicides may control coltsfoot. Fact sheets provide information on specific chemicals that may be used to control coltsfoot: [95,109]. However, little detailed information regarding the effectiveness of herbicides on coltsfoot was available as of this writing (2011). Herbicides are effective in gaining initial control of a new invasion or a severe infestation, but they are rarely a complete or long-term solution to weed management [18]. See the Weed control methods handbook [98] for considerations on the use of herbicides in natural areas and detailed information on specific chemicals. Integrated management: Integrated management includes considerations of not only killing the target plant but also of establishing desirable species and maintaining weed-free systems over the long term. Integrated management techniques may be more effective than individual methods at controlling coltsfoot, but as of this writing (2011) no information was available.

Sources and Credits

  1. (c) Peter O'Connor aka anemoneprojectors, some rights reserved (CC BY-SA), https://www.flickr.com/photos/anemoneprojectors/5602737284/
  2. (c) M.M. R, some rights reserved (CC BY-NC), http://www.flickr.com/photos/46774986@N02/5540458145/
  3. (c) Monteregina (Nicole), some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/monteregina/5693266740/
  4. (c) Rl, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/thumb/2/2d/2007_tussilago_farfara.jpg/460px-2007_tussilago_farfara.jpg
  5. (c) Andreas Trepte, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Coltsfoot.jpg/460px-Coltsfoot.jpg
  6. Adapted by Kate Wagner from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Tussilago_farfara
  7. Public Domain, http://eol.org/data_objects/24630449

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