Development of local strategies to enable the integrated & profitable management of Annual ryegrass seed banks in HRZ

The Grains Research and Development Corporation (GRDC) is a statutory corporation established under the Primary Industries Research and Development Act 1989. It is subject to accountability and reporting obligations set out in the Public Governance, Performance and Accountability Act 2013. It is responsible for planning, investing in and overseeing research and development, and delivering improvements in production, sustainability and profitability across the Australian grains industry.

The management of herbicide resistance is one of the highest priority issues limiting the productivity and profitability of farming systems across the high rainfall zone (HRZ). The population dynamics and ecology of important weeds; extent, type and mechanisms of herbicide resistance; climatic conditions and farming systems in the HRZ are all factors limiting the effectiveness of current control tactics and exacerbating the challenge and cost of management. The practicality of achieving effective seed set control in cereal crops in the HRZ is a challenge and the strategies employed in low and medium rainfall environments are frequently less effective. For example, the staggered and late germination of Annual Ryegrass (ARG) and practicality of narrow windrow-burning are key challenges. Therefore, it is frequently unfeasible to economically achieve complete prevention of seed set in all crops in all years.

A shift in the attitudes of growers and advisors is required to motivate change and increase the adoption of a disciplined and integrated approach to the management of ARG in HRZ farming systems. Evidence which quantifies the local relevance, impact and economic benefit of IWM strategies that incorporate a range of chemical and non-chemical control tactics is also considered essential to shift attitudes and drive adoption. The development and extension of best management guidelines for ARG control, tailored to local environment, farming systems and situation would provide growers and advisors with the knowledge and confidence required to support the adoption of improved practices. This investment will involve a number of large scale replicated demonstration trials to validate the economic benefit of different weed control tactics when integrated into various locally relevant best management programs. The investment will utilise a series of extension and communication activities to leverage and compliment the extensive historic and current R,D&E undertaken in the area of weed management.

The management of herbicide resistance is consistently identified as one of the highest priority issues limiting the productivity and profitability of farming systems across the high rainfall zone (HRZ). When left untreated yield losses of 50-60% may occur. The population dynamics and ecology of important weeds; extent, type and mechanisms of herbicide resistance; climatic conditions and farming systems in the HRZ are all factors which limit the effectiveness of current control tactics and exacerbate the challenge and cost of management. These factors, combined with the practicality of achieving effective seed set control in cereal crops in the HRZ mean that the strategies employed in low and medium rainfall environments are frequently less effective. For example, the staggered and late germination of Annual ryegrass (ARG) cohorts in these high rainfall environments makes it difficult to achieve high levels of control with relatively short-residual pre-emergent herbicides, whilst narrow windrow-burning is often impractical due to issues associated with containment of fire to header rows under high residue load. Therefore, it is frequently unfeasible to economically achieve complete prevention of seed set in all crops in all years.

The rapid development and increase in the levels and extent of resistance to key herbicide mode of action (MOA) groups – Group A, B, C, K and M in a range of important weed species, including ARG means that growers can no longer rely upon inexpensive chemical options only for control. The presence of resistance to multiple in-crop selective herbicide options frequently limits the ability to control later germinations of ARG in cereals. Herbicidal control is typically heavily reliant upon the use of pre-emergent chemistry and limited remaining effective early post emergent control options in canola and/or pulses, for example use of clethodim or butroxydim. Continuous cropping and a reliance on pre-sowing weed control strategies cannot provide effective long term management of ARG. Whilst ARG weed numbers may be significantly reduced over time by using an intensive and often high cost herbicide strategy, reliance upon herbicides alone is high risk and not sustainable long-term in driving down the weed seedbank. Growers and advisors recognise the principle need to adopt a resolute and relentless approach to reduce ARG numbers and prevent weed seed set using a range of integrated strategies, however the management practicality and financial profitability of achieving this in the HRZ is often perceived as difficult.

It is expected that this investment will involve a number of large scale replicated demonstration trials to validate the economic benefit of different weed control tactics when integrated into various locally relevant best management programs. This may include a comparison of grower standard practice with a ‘take-no-prisoners’ approach; a tactical strategy responsive to seasonal conditions; and a ‘best-bet’ strategy. The investment will utilise a series of demonstration trials, extension and communication activities to build upon the extensive historic and current R,D&E undertaken in the area of weed management. The project will utilise existing information generated from GRDC investments including Weed management in the southern region mixed farming systems - strategies to combat herbicide resistance, Harvest Weed Seed Control (HWSC), Stubble Initiative, Pastures in crop sequencing and others. It is also expected that the delivery of this investment will complement and value-add to the GRDC Cultural Weed Management investment.

By May 29, 2020, it is expected that this investment will motivate and enable at least 300 growers from across the high rainfall districts of South East of SA and southern Victoria to confidently adopt effective, diverse and locally tailored integrated strategies to profitably manage herbicide resistant Annual Ryegrass weed seed banks.

A total indicative budget of up to $600,000 is proposed for this GRDC investment, dependent on the quality of the proposal and the details of the services to be provided, taking into consideration any in-kind or financial contribution of the applicant. The GRDC is focused on delivering value to Australian grain growers; therefore, your application must demonstrate fair market value.