Erigeron canadensis explained

Erigeron canadensis (synonym Conyza canadensis) is an annual plant native throughout most of North America and Central America. It is also widely naturalized in Eurasia and Australia. Common names include horseweed, Canadian horseweed, Canadian fleabane, coltstail, marestail, and butterweed. It was the first weed to have developed glyphosate resistance, reported in 2001 from Delaware.

Description

Erigeron canadensis is an annual, herbaceous plant growing to 1.50NaN0 tall, with sparsely hairy stems. The leaves are unstalked, slender, NaN1NaN1 long, and up to 11NaN1 wide, with a coarsely toothed margin. They grow in an alternate spiral up the stem, and the lower ones wither early. The flower heads are produced in dense inflorescences and are 11NaN1 in diameter. Each individual flower has a ring of white or pale purple ray florets and a centre of yellow disc florets. The fruit is a cypsela tipped with dirty white down.[1]

Erigeron canadensis can easily be confused with Erigeron sumatrensis, which may grow to a height of 21NaN1, and the more hairy Erigeron bonariensis, which does not exceed 11NaN1. E. canadensis is distinguished by bracts that have a brownish inner surface with no red dot at the tip, and are free (or nearly free) of the hairs found on the bracts of the other species.[2] [3] [4]

Distribution and habitat

Horseweed originated in North America and Central America and is widespread in its native range.[5] It has spread to inhabited areas of most of the temperate zone of Asia,[6] Europe,[1] [7] and Australia.[8] It is found in Britain from northern Scotland to Cornwall, growing as a weed of arable land and man-made environments. It is considered invasive in China.[9]

Weed status

Horseweed is commonly considered a weed, and in Ohio, Oregon, and some other locations,[10] it has been declared a noxious weed.[11] It was the first weed to have developed glyphosate resistance, reported in 2001 from Delaware.[12]

It can be found in fields, meadows, and gardens throughout its native range. Horseweed infestations (specifically of 105 plants per 10 ft2) have reduced soybean yields by as much as 83%,[13] with one estimate claiming it can reduce yields by up to 90%.[14] Severe infestations have reduced sugar beet yields by 64%.

It is an especially problematic weed in no-till agriculture, as it is often resistant to glyphosate and other herbicides.[15] Farmers are advised to include 2,4-D or dicamba in a burndown application prior to planting to control horseweed.[16] [17]

Uses

The Zuni people insert the crushed flowers of E. canadensis var. canadensis into the nostrils to cause sneezing, relieving rhinitis.[18] Other Native Americans have used a preparation of the plant's leaves to treat sore throat and dysentery.[19] A tincture can be made from the dried flowering tops of the plants.

Horseweed is a preferable material for use in the hand drill-method of making friction fire.[1]

Gallery

Other forms

Notes and References

  1. Web site: Canadian Fleabane: Conyza canadensis . NatureGate . 2013-12-31.
  2. http://www.iewf.org/weedid/Conyza_sumatrensis.htm Conyza sumatrensis
  3. Web site: Horseweed, Marestail . Deane . Green . 31 August 2011 . 2014-08-09.
  4. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200023708 Flora of North America, Conyza canadensis (Linnaeus) Cronquist, Bull. Torrey Bot. Club. 70: 632. 1943. Vergerette du Canada
  5. http://bonap.net/MapGallery/County/Erigeron%20canadensis.png Biota of North America Program, 2014 county distribution map, Erigeron canadensis
  6. http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=242422265 Flora of China, Erigeron canadensis Linnaeus, Sp. Pl. 2: 863. 1753. 小蓬草 xiao peng cao
  7. http://luirig.altervista.org/flora/taxa/index1.php?scientific-name=erigeron+canadensis Altervista Flora Italiana, Cespica canadese, avoadinha, Berufkraut, Erigeron canadensis L.
  8. http://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:apni.taxon:683151 Atlas of Living Australia, Conyza canadensis (L.) Cronquist Canadian Fleabane
  9. 10.1111/1440-1703.12024 . Erigeron canadensis affects the taxonomic and functional diversity of plant communities in two climate zones in the North of China . 2019 . Wu . Bingde . Zhang . Huanshi . Jiang . Kun . Zhou . Jiawei . Wang . Congyan . Ecological Research . 34 . 4 . 535–547 . 2019EcoR...34..535W . 198244222 .
  10. Web site: Appendix H.Noxious and Invasive WeedControlPlan .
  11. Web site: Noxious Weed Program Deschutes County Oregon . 2023-06-13 . www.deschutes.org.
  12. VanGessel . Mark J. . 2001 . Glyphosate-resistant horseweed from Delaware . Weed Science . 49 . 6 . 703–705 . 10.1614/0043-1745(2001)049[0703:RPRHFD]2.0.CO;2 . 4046416 . 86256252 .
  13. Web site: Marestail (Horseweed) . 2023-06-13 . Weeds . en-us.
  14. Web site: Froemke . A. M. . April 24, 2020 . HORSEWEED (ERIGERON CANADENSIS) CONTROL IN NO-TILL SOYBEAN SYSTEMS ON A COARSE TEXTURED SOIL . June 13, 2023 . North Dakota State University.
  15. Kruger . Greg R. . Davis . Vince M. . Weller . Stephen C. . Johnson . William G. . 2010 . Growth and Seed Production of Horseweed (Conyza canadensis) Populations after Exposure to Postemergence 2,4-D. . Weed Science . 58 . 4 . 413–419 . 10.1614/WS-D-10-00022.1. 55366555 .
  16. Dilliott . Meghan . Soltani . Nader . Hooker . David C. . Robinson . Darren E. . Sikkema . Peter H. . March 15, 2022 . When using glyphosate plus dicamba, 2,4-D, halauxifen or pyraflufen/2,4-D for glyphosate-resistant horseweed (Erigeron canadensis) control in soybean, which third mix partner is better, saflufenacil or metribuzin? . Weed Technology . en . 36 . 2 . 295–302 . 10.1017/wet.2022.18 . 0890-037X. free .
  17. Web site: Horseweed/Marestail . 2023-06-13 . Take Action . en.
  18. Stevenson, Matilda Coxe 1915 Ethnobotany of the Zuni Indians. SI-BAE Annual Report #30 (p.55).
  19. Book: Niering . William A. . William Niering. Olmstead . Nancy C. . The Audubon Society Field Guide to North American Wildflowers, Eastern Region . 1985 . 1979 . Knopf . 0-394-50432-1 . 377.

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