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Flaxleaf fleabane (Conyza bonariensis) populations have developed glyphosate resistance in north-east Australian cropping fields

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Walker, S., Bell, K. L., Robinson, G. and Widderick, M. J. (2011) Flaxleaf fleabane (Conyza bonariensis) populations have developed glyphosate resistance in north-east Australian cropping fields. Crop Protection, 30 (3). pp. 311-317. ISSN 0261-2194

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Article Link: http://dx.doi.org/10.1016/j.cropro.2010.11.010

Publisher URL: http://www.sciencedirect.com/science/article/pii/S0261219410003327


In recent years flaxleaf fleabane has become a widespread and difficult-to-control weed in no-tilled fallowed fields, where weeds are controlled by applications of glyphosate, in annual cropping systems of north-east Australia. Fifty-two populations, collected in a national survey from agricultural and non-agricultural areas, were tested in two glyphosate dose-response pot experiments. In two subsequent pot experiments, a sub-set of these populations was tested with a field rate of glyphosate when weeds of two ages were grown at different soil moistures. In the first and second experiments, most populations collected from chemical fallowed or cropped fields in north-east Australia had GR50 (estimated dose for 50% biomass reduction) values three to six times greater than the susceptible populations, indicating low levels of glyphosate resistance. Several populations from roadsides adjacent to chemical fallowed or cropped fields also had higher GR50 values, indicating movement of seeds from resistant plants. In the third experiment, weed biomass of all populations from chemical fallowed or cropped fields was 70–98% of unsprayed compared to 2–3% for the susceptible populations, irrespective of weed age or soil moisture. In the fourth experiment which treated older weeds, the response of several resistant populations to glyphosate was unaffected by differences in weed age and soil moisture, whereas the biomass of the other resistant populations was greater following spraying of older and/or moisture stressed plants compared with smaller non-stressed plants. Thus, exclusive reliance on glyphosate for fallow weed control in this region has resulted in the evolution of resistance in flaxleaf fleabane populations in a cropping system with annual non-transgenic crops. Prolific production of windborne seeds, combined with poor control associated with spraying large moisture-stressed weeds, is likely to have contributed also to flaxleaf fleabane becoming such a problem weed.

Item Type:Article
Business groups:Crop and Food Science
Keywords:Herbicide resistance Soil moisture Weed age Glyphosate Flaxleaf fleabane Conyza bonariensis (L.) Cronquist
Subjects:Plant pests and diseases > Weeds, parasitic plants etc
Plant pests and diseases > Pest control and treatment of diseases. Plant protection > Pesticides
Live Archive:05 Apr 2019 00:36
Last Modified:03 Sep 2021 16:45

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