The biology of Canadian weeds. 115. Conyza canadensis

Conyza canadensis (L.) Cronq. (Canada fleabane, horseweed, mare’s-tail) is a winter or summer annual, native to North America, and found in all provinces of Canada except Newfoundland. It is a weed of orchards, vineyards, roadsides, and arable fields where tillage has been reduced or eliminated. Mos...

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Bibliographic Details
Published in:Canadian Journal of Plant Science
Main Author: Weaver, Susan E.
Format: Article in Journal/Newspaper
Language:English
Published: Canadian Science Publishing 2001
Subjects:
Online Access:http://dx.doi.org/10.4141/p00-196
http://www.nrcresearchpress.com/doi/pdf/10.4141/P00-196
Description
Summary:Conyza canadensis (L.) Cronq. (Canada fleabane, horseweed, mare’s-tail) is a winter or summer annual, native to North America, and found in all provinces of Canada except Newfoundland. It is a weed of orchards, vineyards, roadsides, and arable fields where tillage has been reduced or eliminated. Most seedlings emerge from late August through October and form rosettes which overwinter. Large numbers of small, wind-dispersed seeds, ranging to over 200 000 seeds per plant, are produced in late summer. Populations of C. canadensis in more than ten countries have evolved resistance to herbicides such as paraquat, atrazine, chlorsulfuron or glyphosate. Several paraquat resistant populations were found in orchards in Essex Country, Ontario. It serves as a wild host of the tarni shed plant bug, and of aster yellows, a mycoplasma disease transmitted by the aster leaf hopper. Key words: Canada fleabane, ERICA, Conyza canadensis, Erigeron canadensis, horseweed