Weed age affects chemical control of Conyza bonariensis in fallows

Walker, Steven, Boucher, Luke, Cook, Tony, Davidson, Bill, McLean, Andrew and Widderick, Michael (2012) Weed age affects chemical control of Conyza bonariensis in fallows. Crop Protection, 38 15-20. doi:10.1016/j.cropro.2012.03.008

Author Walker, Steven
Boucher, Luke
Cook, Tony
Davidson, Bill
McLean, Andrew
Widderick, Michael
Title Weed age affects chemical control of Conyza bonariensis in fallows
Journal name Crop Protection   Check publisher's open access policy
ISSN 0261-2194
Publication date 2012-08
Sub-type Article (original research)
DOI 10.1016/j.cropro.2012.03.008
Volume 38
Start page 15
End page 20
Total pages 6
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2013
Language eng
Formatted abstract
In the last decade, Conyza bonariensis has become a widespread and difficult-to-control weed in Australian broad-acre cropping, particularly in glyphosate-based zero-tilled fallows of the subtropical grain region. The first Australian populations of C. bonariensis, where it is known as flaxleaf fleabane, were confirmed resistant to glyphosate in 2010. Control with alternative herbicides in fallows has been inconsistent, with earlier research indicating that weed age could be a potential contributing factor. In two field experiments, the impact of weed age (one, two and three months) was measured on the efficacy of six non-selective herbicide mixtures and sequential applications for control in fallows. In another two experiments we evaluated 11 non-selective herbicides, mixtures and sequential applications applied to one and three month old weeds using higher rates on older weeds. When herbicide rates were consistent for different weed ages, efficacy was reduced only by an average of 1% when two month old weeds were treated compared to one month old weeds. However when applied to three month old weeds, efficacy of treatments was significantly (P < 0.001) reduced by 3–30%. When herbicide rates were increased, weed age had no adverse effect on efficacy, which ranged from 90 to 100%, for amitrole, glyphosate mixed with 2,4-d amine plus picloram, and three sequential application treatments of glyphosate mixtures followed with bipyridyl products. Thus, this problem weed can be controlled effectively and consistently at the rosette stage of one to two months old, or three month old weeds with several different treatments at robust rates. These effective glyphosate alternatives and sequential-application tactics will minimise replenishment of the soil seed-bank and further reduce the risk for further evolution of glyphosate resistance.
Keyword Glyphosate
Herbicide resistance
Sequential application
Double knock
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Queensland Alliance for Agriculture and Food Innovation
Official 2013 Collection
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Citation counts: TR Web of Science Citation Count  Cited 7 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 7 times in Scopus Article | Citations
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Created: Thu, 15 Nov 2012, 14:50:30 EST by System User on behalf of Qld Alliance for Agriculture and Food Innovation