Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract Full Text

Colonisation of agricultural regions in Western Australia by Conyza bonariensis.


Conyza bonariensis is common throughout the wheat-belt of Western Australia (WA), as a weed of wastelands, but has the capacity to invade cropping systems. The feasibility of slowing the rate of invasion depends on the rate of short distance seed dispersal and colonisation (establishment of seedlings). This was investigated in 2008/2009, at the Department of Agriculture and Food WA Merredin Research Station. The Station, and all farms and road verges within a 2 km radius of the Station, were checked for C. bonariensis plants from winter to summer 2007, but no plants were discovered. Conyza bonariensis seed were subsequently planted in a 4 m2 plot, on the Station, in December 2007. Of the emerging cohort, a single plant survived to produce an estimated 5965 seeds in April and May 2008, which were allowed to naturally disperse. Monitoring of the Station and surrounding area continued until March 2009, to find and destroy the resulting fleabane rosettes (359 in total). Rosettes were found a maximum of 1842 m from the Parent Plant. Close monitoring of spring, summer and autumn weed growth to prevent seed set of C. bonariensis would be required to delay the spread of this weed on individual farms.