The GRDC ‘Maintaining profitable farming systems with retained stubble - upper Eyre Peninsula’ project aims to improve farm profitability while retaining stubble in farming systems on upper Eyre Peninsula (EP). Weed control in stubble retained systems can be compromised where herbicide efficacy is limited due to higher stubble loads, especially for preemergent herbicides. Current farming practices have also changed weed  behavior with later germinating barley grass genotypes now present in many paddocks on the Minnipa Agricultural Centre (MAC) (B Fleet, EPFS Summary 2011). Several MAC farm demonstrations  were undertaken in 2014 to address barley grass weed issues including later germinating types and barley grass resistance to Group A herbicides. An integrated approach to weed management aimed at lowering the weed seed bank can make use of diverse techniques such as cultivation, stubble burning, in-crop competition using higher sowing rates and possibly row orientation. The weed seed bank can be reduced within the break phase by hay making, or green or brown manuring. Other techniques used effectively in WA on ryegrass and wild  radish have been narrow windrows and chaff carts. However there is limited information on the effectiveness of these tactics on barley grass in part because it is believed that most seed is shed well before harvest, limiting control. In 2015 the monitoring of farm paddock demonstrations in low rainfall farming systems to  assess control methods for grass weeds, mainly targeting barley grass, were undertaken by;
• Monitoring of narrow windrows in MAC paddocks N1 and N6W, and Bruce Heddle’s paddock CE42 (windrows and chaff dumps).
• Spray topping after oat and vetch hay (MAC paddock S4) using both crop competition (high seeding rate) followed by spray topping after the hay cut.

• Weed seeds were found in narrow windrows and chaff dumps, ryegrass was more prevalent than barley grass which is more prone to shedding seed early.
• Burning reduced the viable ryegrass and self-sown cereal seed density by 85%, reducing the overall weed seed bank, but results for barley grass were lower at 38%.
• Conditions (i.e. temperature and humidity) and timing of burn were shown to strongly influence the effectivenessof this cultural management tactic.
• Burning windrows resulted in fewer weed seeds returning to the weed seed bank.
• There is a cost associated with windrow harvesting due to lower harvesting height requiring reducing the harvest speed with larger throughput of straw.
• A better understanding of burning and the weather conditions needed to sterilise barley grass seed is needed.