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Cinmethylin controls multiple herbicide‐resistant Lolium rigidum and its wheat selectivity is P450‐based
Author(s) -
Busi Roberto,
Dayan Franck E,
Francis Ian,
Goggin Danica,
Lerchl Jens,
Porri Aimone,
Powles Stephen B,
Sun Ci,
Beckie Hugh J
Publication year - 2020
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.5798
Subject(s) - lolium rigidum , phorate , agronomy , biology , weed , lolium , trifluralin , weed control , resistance (ecology) , poaceae , herbicide resistance , pesticide
Abstract BACKGROUND Multiple‐herbicide resistance in Lolium rigidum and other weed species is increasingly exerting pressure on herbicide discovery research for solutions against resistance‐prone weeds. In this study we investigate: (i) the responses of L. rigidum populations and wheat to the new herbicide cinmethylin in comparison with other pre‐emergence herbicides, (ii) the effect of seed burial depths on cinmethylin efficacy and crop selectivity, and (iii) the basis of cinmethylin selectivity in wheat. RESULTS Cinmethylin at 400 g ha −1 controls herbicide‐susceptible and multiple‐resistant L. rigidum , with a reduction of >85% in plant emergence and 90% in aboveground biomass. Cinmethylin provides effective control of a large number of field populations of L. rigidum with evident resistance to trifluralin. When the wheat seed is buried ≥1 cm below the cinmethylin‐treated soil surface, the emergence of crop seedlings is not different from the untreated control. The organophosphate insecticide phorate synergizes cinmethylin toxicity in wheat, with an LD 50 of 682 g ha −1 in the absence of phorate versus 109 g ha −1 in the presence of phorate (84% reduction). The synergistic effect of phorate with cinmethylin on herbicide‐susceptible L. rigidum appears smaller (a 44% reduction in the LD 50 of cinmethylin). CONCLUSIONS Cinmethylin is effective in controlling multiple‐resistant L. rigidum and appears safe for wheat when the seed is separated at depth from the herbicide applied to the soil surface. The basis of this metabolism‐based selectivity is likely regulated by cytochrome P450 monooxygenases. © 2020 Society of Chemical Industry