Research priorities for weed suppression by crops in Australia.

Crop competition is an important tactic for suppressing weed growth and maintaining crop yield, especially with the increasing levels of herbicide resistance in Australia. In 2015, a team of weed scientists from the western, southern and northern grain production regions conducted a comprehensive review of research on crop competition in Australia, funded by the Grains Research and Development Corporation (GRDC). The aim of the study was to enable a 20% increase in grower adoption of this tactic for weed suppression by 2020. The project team: identified priority weed species; conducted a meta-analysis of pooled data to identify common trends; conducted a knowledge gap analysis based on the literature review and the meta-analysis; defined an approach for improved future crop competition experimentation; and identified and provided recommendations for future Research, Development and Extension (RD&E). An updated assessment of priority and key weed species was provided. The need for more studies on agronomic means of enhancing weed competition were identified, especially for weakly competitive crops such as pulses. These included crop rotation, fertiliser manipulations and determination of traits conferring competitiveness that can be used in varietal selection and breeding programs. Further, it is necessary to guide farmers on understanding the benefits of growing a competitive crop as a viable alternative to chemical weed control. Plant breeding for crop traits associated with strong competitive ability will provide an alternative and longer-term solution to weed management.