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Phorate can reverse P450 metabolism‐based herbicide resistance in Lolium rigidum
Author(s) -
Busi Roberto,
Gaines Todd Adam,
Powles Stephen
Publication year - 2017
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.4441
Subject(s) - lolium rigidum , phorate , trifluralin , biology , avermectin , weed , organophosphate , toxicology , pesticide , agronomy , herbicide resistance , anatomy
BACKGROUND Organophosphate insecticides can inhibit specific cytochrome P450 enzymes involved in metabolic herbicide resistance mechanisms, leading to synergistic interactions between the insecticide and the herbicide. In this study we report synergistic versus antagonistic interactions between the organophosphate insecticide phorate and five different herbicides observed in a population of multiple herbicide‐resistant Lolium rigidum . RESULTS Phorate synergised with three different herbicide modes of action, enhancing the activity of the ALS inhibitor chlorsulfuron (60% LD 50 reduction), the VLCFAE inhibitor pyroxasulfone (45% LD 50 reduction) and the mitosis inhibitor trifluralin (70% LD 50 reduction). Conversely, phorate antagonised the two thiocarbamate herbicides prosulfocarb and triallate with a 12‐fold LD 50 increase. CONCLUSION We report the selective reversal of P450 ‐mediated metabolic multiple resistance to chlorsulfuron and trifluralin in the grass weed L. rigidum by synergistic interaction with the insecticide phorate, and discuss the putative mechanistic basis. This research should encourage diversity in herbicide use patterns for weed control as part of a long‐term integrated management effort to reduce the risk of selection of metabolism‐based multiple herbicide resistance in L. rigidum . © 2016 Society of Chemical Industry