Canada Fleabane

Identify and control glyphosate resistant Canada fleabane in Eastern Canada.

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Canada Fleabane Biology

  • Canada fleabane (Conyza canadensis) is a winter or summer annual with one or more erect, flowering stems and can grow up to 180 cm in height
  • It can be found on all soil types, including organic soils but is most common on coarse textured soils
  • Canada fleabane seeds are 1-2 mm long, almost transparent, and have an attached pappus, or parachute, which carries the seed for long distances
  • The weed has a short taproot, sparsely hairy leaves with smooth or slightly toothed margins
  • Canada fleabane seeds have a short-term seed bank. They can survive for more than a year, but probably not more than 3 years under most conditions
  • The number of seeds produced per plant is proportional to plant height. A plant 0.4 meter tall produces about 2,000 seeds while a plant 1.5 meter tall produces about 230,000 seeds2

Weed Interference and Resistance

  • Canada fleabane interference in crops is influenced by time of emergence and density3
  • Canada fleabane at densities of 100-200 plants per square meter can reduce crop yield by 90% and still produce 100,000 seeds per plant1
  • At a density of 100 plants per square meter, Canada fleabane reduced soybean yields by 97%3
  • Glyphosate-resistant Canada fleabane populations have been confirmed in the U.S., Czech Republic, Brazil, China, Spain and in Southwest Ontario
  • Canada fleabane resistance to ALS herbicides (Group 2) is widespread in the U.S.


  • Start clean and control weeds early
  • Use Roundup Ready® technology as your foundation
  • Add other herbicides and cultural practices where appropriate as part of the Roundup Ready cropping system
  • Use the right rate at the right time
  • Control weeds throughout the season and reduce the weed seed bank


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  • Answer 10 field-related questions
  • Get your risk rating score
  • Discover how to lower your risk
  • Learn best management practices for reducing your risk of developing glyphosate resistance

Recommendations for Control of Glyphosate Resistant Canada Fleabane

Genuity® Roundup Ready 2 Yield® Soybeans

  • Pre-plant: Tank-mix Roundup Transorb® HC with Eragon®, Integrity®, Optill® or Sencor®.

Winter Wheat

  • POST: 2,4-D ester, Estraprop® or Infinity®.

Corn hybrids with Roundup Ready® 2 Technology

  • Pre-emergence: Tank-mix Roundup Transorb HC with Banvel® II, Integrity and Marksman®.
  • Post-emergence: Apply Distinct®, or tank-mix Roundup WeatherMAX® with Banvel II or Marksman.
  • Tillage is also an effective option to control Canada fleabane
  • Scout fields and control weeds throughout the season
  • Proper application timing protects yield, ensures correct use rate for weed size and considers the impact of environmental conditions on performance

The effective use of Roundup® agricultural herbicides and Roundup Ready® crops has continued in areas where glyphosate resistance has occurred. Glyphosate resistant weeds have been effectively managed by including tank mixes, tillage and other cultural methods of weed control.



1Bruce, J.A., and Kells, J.J. 1990. Horseweed (Conyza Canadensis) Control in No-Tillage soybeans (glycine max) with preplant and preemergence herbicides. Weed Technology. 4:642-647

2 Canada Fleabane Factsheet. Ontario Ministry of Agriculture, Food and Rural Affairs. crops/facts/02-067.htm

3 Dauer, J.T., Mortensen, D.A., and Vangessel, M.J. 2007. Temporal and special dynamics of long-distance Conyza Canadensis seed dispersal. Journal of Applied Ecology. 44:105-114.