A Trp574–Leu substitution confers resistance to three classes of acetolactate synthase inhibitors in A ustralian brome grass ( B romus diandrus )
Year: 2026
Type: article
Abstract: BACKGROUND: Brome grass (Bromus diandrus) is a prevalent weed in southern Australian cropping regions which causes significant economic damage in crops and pastures. Before harvest 2023, two populations (named 6-24 and 7-24) suspected of resistance to imidazolinone herbicides were collected from separate fields. Preliminary screening indicated that these populations were resistant to several different acetolactate synthase (ALS)-inhibiting herbicides. Therefore, further characterisation of the level and mechanism of resistance was carried out. RESULTS: , 2× the label rate for use in imidazolinone-tolerant crops). All examined individuals (15 from each population) carried the same point mutation causing a tryptophan-to-leucine substitution at position 574 in the ALS protein. Application of the cytochrome P450 inhibitor malathion prior to herbicide treatment did not affect survival rates. CONCLUSIONS: This is the first study reporting a Trp574-Leu mutation as the basis for cross-resistance to ALS-inhibiting herbicides (sulfonylureas, imidazolinones and triazolopyrimidines) in Australian populations of B. diandrus. Control of these populations will require strategic use of pre-emergence herbicides and herbicide-tolerant crops in combination with harvest weed seed control. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Source: Pest Management Science
DOI: 10.1002/ps.70979
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: hybrid
Estimated APC paid: $5,360
Awards: G2207888923, G4100456764
OpenAlex ID: W7162941730