Fleabane (Conyza spp.)
Mature flaxleaf fleabane
(Photo A. Storrie)
There are three main species of fleabane in Australia: flaxleaf fleabane (Conyza bonariensis), tall fleabane (C. sumatrensis) and Canadian fleabane which comprises two varieties (C. canadensis var. canadensis and C. canadensis var. pusilla). Of the three species, flaxleaf fleabane is the most common across Australia particularly in cropping and fallow paddocks. It is not uncommon for multiple species to be in the same paddock.
Flaxleaf fleabane can grow up to 1 m tall and has deeply indented leaves. It has the narrowest leaves at rosette stage when compared with other Conyza species. Its branches often grow taller than the main plant axis.
Tall fleabane can grow up to 2 m tall. Its leaves are less indented than flaxleaf fleabane and its branches do not grow taller than the main plant axis.
Both flaxleaf and tall fleabane have flower-heads of approximately 10 mm when pressed. By comparison, Canadian fleabane has smaller flower-heads of 5 mm when pressed.
The two varieties of Canadian fleabane also differ, with var. canadensis possessing very hairy leaves and var. pusilla having virtually hairless leaves.
Flaxleaf fleabane has a smoothly pitted receptacle while tall fleabane has a roughly pitted receptacle.
Each of the fleabane species is characterised by the production of fluffy cream seed-heads that possess a pappus. They also produce a very long taproot that can grow up to 350 mm in length.
Factors that make fleabane a major weed:
- A prolific seed producer, each plant producing up to 110 000 seeds
- A major weed of fallows, summer and winter crops and pastures
- Very difficult to control with herbicides
- Capable of developing herbicide resistance (multiple populations of Conyza bonariensis are glyphosate resistant)
- Emerges throughout most of the year
Further detail about this weed including integrated weed management tactics that could be considered when developing a management plan can be found in the section on problem weeds in the Integrated Weed Management Manual.
Ecology and biology of common weeds are outlined in section 6 of the Integrated Weed Management Manual.
GRDC fact sheets and other publications
Flaxleaf fleabane (2013)
Status of key summer fallow weeds in the Riverina an update (2016)
Farming systems strategies to manage fleabane and feathertop Rhodes grass (2015)
Biology and management of summer weeds (2015)
Weeds and resistance considerations for awnless barnyard grass chloris and fleabane (2014)
Fleabane ecology and control in cropping systems of southern Australia (2013)
Weeds and resistance considerations for awnless barnyard grass, Chlorosis spp and fleabane management (2013)
Problem weeds - latest research and control strategies for feathertop Rhodes grass, fleabane and herbicide resistance (2011)
Common sowthistle and flaxleaf fleabane. Understanding the weeds lifecycles for management strategies that work (2009)
GRDC Video links
Double knock applications - target weed species & application strategy - Michael Widderick, DAFFQ weed specialist on the principle behind the 'double knock' for controlling summer weeds such as feathertop Rhodes grass, barnyard grass and flaxleaf fleabane.
GRDC webinar on Advances in Weed management: Managing fleabane in zero till farming systems (2013)
Groundcover TV episode on Flaxleaf fleabane (2011)
Flaxleaf fleabane - A weed best management guide (QAAFI)
Double knock for controlling flaxleaf fleabane (QAAFI)
Managing flaxleaf fleabane, a difficult-to-control weed in dryland cropping systems associated with zero-tillage (DAFF Qld)
Management of flaxleaf fleabane (DAFF Qld)
Seedling fleabane control Narromine & Coonamble 2012 (GOA)