The GRDC ‘Maintaining profitable farming systems with retained stubble’ projects on upper and lower Eyre Peninsula (EP) aim to improve farm profitability while retaining stubble in farming systems. Grass weed management is one of the key issues of current cropping systems with annual ryegrass and barley grass being of most importance on lower EP (LEP) and upper EP (UEP) respectively. Herbicides continue to be the main strategy for weed control, and on LEP the intensification of cropping rotations and the decrease in livestock from farming systems has resulted in even further pressure on herbicides, resulting in the accelerated development of herbicide resistance in ryegrass.

An integrated approach to weed management (IWM) is required to slow the development of herbicide resistance and improve the sustainability of our farming systems. IWM aims to lower the weed seed bank with the use of herbicides as well as non-chemical techniques such as cultivation, higher sowing rates, and harvest weed seed management such as burning stubble, narrow windrow and chaff cart dumps. Demonstration paddocks were monitored to assess grass weed management strategies in current farming systems. This information will be used to improve the Ryegrass Integrated Management (RIM) model for EP systems, and potentially produce other grass weed management models (barley grass).

• The ability to capture barley grass seeds at harvest is limited.
• If seed can be captured and placed in windrows, windrow burning can reduce grass weeds.
• Seed capture at harvest is higher with annual ryegrass than with barley grass.
• Burnt narrow windrows sustained temperatures above 400^oC for longer than 10 seconds, which is sufficient to sterilise annual ryegrass seed.
• Snail numbers were reduced with windrow burning.
• Barley grass germinates later in Minnipa Agricultural Centre cropped paddocks than in non-cropped areas.