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Recurrent selection with reduced 2,4‐D amine doses results in the rapid evolution of 2,4‐D herbicide resistance in wild radish ( Raphanus raphanistrum L.)
Author(s) -
Ashworth Michael B,
Walsh Michael J,
Flower Ken C,
Powles Stephen B
Publication year - 2016
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.4364
Subject(s) - acetolactate synthase , herbicide resistance , biology , cross resistance , population , mcpa , pesticide resistance , weed , crucifer , trifluralin , botany , pesticide , agronomy , genetics , gene , demography , sociology
BACKGROUND When used at effective doses, weed resistance to auxinic herbicides has been slow to evolve when compared with other modes of action. Here we report the evolutionary response of a herbicide‐susceptible population of wild radish ( Raphanus raphanistrum L.) and confirm that sublethal doses of 2,4‐dichlorophenoxyacetic acid (2,4‐D) amine can lead to the rapid evolution of 2,4‐D resistance and cross‐resistance to acetolactate synthase ( ALS )‐inhibiting herbicides. RESULTS Following four generations of 2,4‐D selection, the progeny of a herbicide‐susceptible wild radish population evolved 2,4‐D resistance, increasing the LD 50 from 16 to 138 g ha −1 . Along with 2,4‐D resistance, cross‐resistance to the ALS ‐inhibiting herbicides metosulam (4.0‐fold) and chlorsulfuron (4.5‐fold) was evident. Pretreatment of the 2,4‐D‐selected population with the cytochrome P450 inhibitor malathion restored chlorsulfuron to full efficacy, indicating that cross‐resistance to chlorsulfuron was likely due to P450 ‐catalysed enhanced rates of herbicide metabolism. CONCLUSION This study is the first to confirm the rapid evolution of auxinic herbicide resistance through the use of low doses of 2,4‐D and serves as a reminder that 2,4‐D must always be used at highly effective doses. With the introduction of transgenic auxinic‐herbicide‐resistant crops in the Americas, there will be a marked increase in auxinic herbicide use and therefore the risk of resistance evolution. Auxinic herbicides should be used only at effective doses and with diversity if resistance is to remain a minimal issue. © 2016 Society of Chemical Industry