Investment

Weeds and their associated control are a major limitation and cost to the Australian grains industry. A recent industry survey suggest that both these factors have increased significantly over the past fifteen years, particularly in high intensity continuous cropping systems based on no-till and stubble retention. In the past these systems have relied heavily on in-crop herbicide control options, however due to the limited availability of new herbicides combined with the rapid development of herbicide resistance weeds, new whole of system integrated approaches to weed management are now required for effective sustainable control. The farming systems of southern Australia are somewhat unique in Australia due to the range and intensity of break crops grown providing both new weed control problems but also different tactical weed control opportunities. While herbicide resistant rye grass and to a lesser extent brome grass and wild radish still present major problems, a number of broadleaved weeds limit production of some or all break crop options available to growers. The rapid availability of multiple crops with group B 'IMI' herbicide tolerance has offered new weed control options in these farming systems. However the long term strategic use of this technology along with the judicious use of effective integrated weed management (IWM) practices will be required to not only control weeds but sustain the long term viability of high break crop intensity farming systems in southern Australia. Expected Outcome The project has two aims: 1) provide SA farming system groups, growers and their advisors with successful and sustainable integrated weed management strategies that allow effective weed control of the major weeds in high break crop intensity rotations which incorporate new herbicide tolerant break crop options, no-till and high stubble retention, 2) to build regional agronomic research capacity in South Australia (SA) through the training and retention of a skilled agronomist based at Clare in the Mid North/Yorke (MN/YP) Peninsula region of SA and which supports other regional agronomists to deliver R,D & E project outcomes to all cropping regions of the state. Nature and scope of work The project will have five components: The development of effective weed management strategies for rapidly reducing and maintaining low seed bank numbers of key broad leaved and Group A 'dim' resistant rye grass weeds in tight cereal/break crop rotations of southern Australia. This will occur by: 1) measuring weed populations in strategically targeted commercial 'focus paddocks', concentrating on those with high break crop intensity and known major resistant and broadleaved weed backgrounds, following the implementation or not of a few selected key targeted weed control strategies, 2) targeted trial plot research in high break crop intensity systems that incorporate no-till and stubble retention. The development of herbicide recommendations required for maximising weed control in 'IMI crop' and part 'IMI crop' rotations in line with current stewardship guidelines, including quantifying the impact of Group B residues on yield, biomass production and nodulation/N fixation of subsequent 'non-IMI crops'. Targeted rotational residue trial plot research will occur in high break crop intensity systems that incorporate no-till and stubble retention. An improved understanding of the effectiveness and impact of agronomic IWM tactics such as crop competition, plant population, east to west planting direction, sowing date, row spacing, inter row sowing and incorporation of new herbicide tolerant pulses on weed control and crop performance in southern region pulses, and where gaps exist in cereals and canola. Targeted trial plot research addressing some or all of these tactics in high break crop intensity systems that incorporate no-till and stubble retention will occur. Collaboration and Communication with industry stakeholders. This project forms