Charles Sturt University
Graham Centre for Agricultural Innovation

Integrated weed management

Researchers

Project resources

Summary

Investigating weed management strategies for no-till and mixed farming systems.

Aim

This research is equipping southern Australian farmers with tools to optimise the use of both chemical and non-chemical weed control tactics.

This is important given the development of herbicide resistance.

What's involved

Weed management strategies in mixed farming systems

A comprehensive survey at the beginning of the project identified key herbicide resistant weed species.

Weed control and management approaches were tested over five growing seasons at sites across southern New South Wales, southern Victoria, the Victorian Mallee, and South Australia’s Eyre Peninsula and Mid North.

The trials focused on:

  • assessing the weed suppression mechanisms of competitive wheat, barley and canola,
  • targeted weed control strategies combining chemical and cultural tactics;
  • the impact of long-term rotational strategies on in-crop seasonal weed management and seedbank dynamics.

The research found:

  • rotations with diverse and competitive crop types correlated strongly with effective weed suppression
  • early crop vigour, leaf area index, canopy closure preventing light interception and high total biomass production in canola, barley and
  • wheat varieties were also effective in suppressing weeds
  • post-harvest weed management in fallow was significantly influenced by the type and amount of crop residue and its decomposition
  • different crops, including cereals and annual pasture legumes, release significant quantities of metabolites (allelochemicals) into the soil during breakdown that appear to influence weed suppression

The project, 'Weed Management in Mixed Farming Systems: Strategies to Combat Herbicide Resistance', was a collaborative partnership involving the Grains Research and Development Corporation (GRDC), Charles Sturt University and the University of Adelaide.

photo of people looking at a crop

Pasture focus

A separate, but concurrent project supported by Meat & Livestock Australia ensured the research addressed weed management across the entire farming system.

This involved studying weed seed impacts on carcass quality, the use of integrated weed management techniques including competitive pasture crops, establishment of summer cover crops, and timing of cutting hay or silage for weed suppression.

The research found:

  • Barley grass is a key weed species responsible for carcase damage in central and southern NSW.
  • Carcase quality can be improved by early detection and management of weed seed prevalence.
  • In annual sub clover pastures when barley grass incidence is low, a silage harvest should be considered as a strong option to reduce reliance on herbicides that are required when barley grass levels are high.
  • Annual pasture legumes, particularly arrowleaf clover and biserrula, can be highly weed suppressive depending on the year, location and seeding time.
  • Growing and harvesting forage crops for hay and silage can be an effective weed control option but its success depends on seasonal differences, harvest timing and subsequent management of weed regrowth.
  • Making silage reduces weed seed viability but efficacy declines as dry matter content increases. This has significant implications for the use of baled silage with high dry matter content.