Western Australia - Researchers target new weed control systems in barley

Grains researchers have found new combinations of herbicide control that can be highly effective in managing barley grass and brome grass weeds in barley crops.

Department of Primary Industries and Regional Development (DPIRD) senior research scientist Harmohinder Dhammu said brome and barley grass are problematic weeds, with staggered emergence patterns posing a challenge for management using pre-emergent herbicides in cereal crops.

DPIRD Senior Research Scientist Dr Harmohinder Dhammu presenting the barley grass trial at a field day at East Pingelly in spring 2023.

″Field trials found new barley herbicide tolerance technologies, such as CoAXium^® and Clearfield^®, either used with only the appropriate Group 1 or 2 herbicide registered for that system, or including other pre-emergent herbicides, could offer effective control of these species,″ Dr Dhammu said.

The research, which has co-investment from the Grains Research and Development Corporation (GRDC), was presented at the recent 2025 GRDC Grains Research Update in Perth.

Western Australian field trials compared the efficacy of five treatments against barley grass in 2023 and brome grass in 2024.

″CoAXium^® and Clearfield^® barley systems were more effective in managing barley and brome grass than a standard herbicide combination used in conventional wheat,″ Dr Dhammu said.

″CoAXium^® barley system using quizalofop (e.g. Aggressor^® AX) on Titan AXPBR symbol barley at the 3–4 leaf stage provided 100 per cent barley grass and 94 per cent brome grass control.

″Clearfield^® barley system using imazamox + imazapyr on Maximus CLPBR symbol barley at the 5-leaf stage achieved 92 per cent control of barley grass and 65 per cent control of brome grass. Although control was not as high as with quizalofop, the surviving weeds were severely stunted with root pruning.

″In paddocks with mixed populations of brome grass or barley grass that also include annual ryegrass, effective herbicides for each species are essential. Growers should consider including other herbicide options if the ryegrass is resistant to Group 1 and 2 herbicides used in these barley systems.″

The 2025 GRDC Grains Research Update was held in Perth on 24 and 25 February.