Paraquat Resistance of Sumatran Fleabane (Conyza sumatrensis)

L.H.S Zobiole,V.G.C Pereira,F.S Adegas,L.P Albrecht,A.J.P Albrecht,R.S Rubin

doi:10.1590/s0100-83582019370100018

L.H.S Zobiole, V.G.C Pereira + Show 4 more

Open Access

https://doi.org/10.1590/s0100-83582019370100018

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Abstract

ABSTRACT: In Brazil, some populations of Conyza bonariensis and C. canadensis are glyphosate resistant and there are populations of C. sumatrensis (Sumatran fleabane) presenting multiple resistance to both glyphosate and chlorimuron. During the 2014/2015 and 2015/2016 seasons, growers reported failures to control Sumatran fleabane with paraquat. This study investigated the potential of paraquat resistant Sumatran fleabane populations in Paraná state, Brazil. Populations with suspected paraquat resistance were tested in the field in 2016 season. In 2017, seeds from these populations were collected, sown and grown in a greenhouse. Paraquat dose-response curve experiments were performed in Mogi Mirim, SP; Londrina, PR and Palotina, PR using doses of 0, 50, 100, 200, 400, 800, 1,600 and 3,200 g ha-1, following all standard criteria for confirmation of weed resistance cases. Percentage control was assessed at 3, 7, 14, 21 and 28 days after application and data were fitted to a nonlinear, log-logistic model, and dose response curves were generated. The results of this study confirmed significant levels of resistance of Sumatran fleabane biotypes to paraquat with resistance factors between 3,57 to 34,29. Therefore, the first case of C. sumatrensis resistance to paraquat was confirmed in biotypes from the western area of Paraná state, Brazil.

Highlights

Conyza sp. is an annual dicot weed that often emerges in the autumn and winter (Tozzi and van Acker, 2014)
In Brazil, the winter fallow period (May to September) corresponds to the emergence peak of Sumatran fleabane; this period allows the plant to grow undisturbed in fallow and reach sizes where control with herbicides becomes very difficult (Oliveira Neto et al, 2010)
In Brazil, populations of C. bonariensis, C. canadensis have been selected for glyphosate resistant and populations of C. sumatrensis can exhibit multiple resistance to both glyphosate and chlorimuron (Santos et al, 2014; Heap, 2017)

Summary

Introduction

Conyza sp. is an annual dicot weed that often emerges in the autumn and winter (Tozzi and van Acker, 2014). In Brazil, the winter fallow period (May to September) corresponds to the emergence peak of Sumatran fleabane; this period allows the plant to grow undisturbed in fallow and reach sizes where control with herbicides becomes very difficult (Oliveira Neto et al, 2010). Such biological characteristics, agronomic practices, and the selection for herbicideresistant biotypes contribute to the wide expanding areas of Conyza populations (Dauer et al, 2009). There are many countries where Conyza sp. has been reported to be resistant to paraquat since 1980, e.g., Hungary (Pölös et al, 1987), Taiwan, Japan, Egypt, Malaysia, Canada, Unites States, Belgium, Sri Lanka, South Africa; the last report in 2016 was in Australia (Chiang and Chiang, 2006; Heap, 2017; Preston, 2017)

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