Annual Ryegrass (ARG) is one of the most challenging weeds for grain growers in South-West Victoria’s high rainfall zone. A new five-year Grains Research and Development Corporation (GRDC) initiative designed to support grain growers with persistent weed issues is now underway in Australia. The Weed Management Initiative is a $47 million dollar investment with four nodes set up nationally.

Dr Chris Preston of the University of Adelaide is lead researcher for the southern node with a long-term trial collaborating with Southern Farming Systems (SFS) aimed at managing annual ryegrass (ARG).

“Widespread herbicide resistance to ARG poses significant challenges both economically and agronomically to farmers in the region” said Ashley Amourgis, SFS General Manager.

“Control of ARG often requires a multifaceted approach with chemical, mechanical and cultural control methods” said Ms Amourgis. The five-year trial is established in a paddock near Inverleigh with known ARG resistance to common herbicides such as glyphosate and paraquat.

The main aim of the trial is to identify practices that can manage complex, multiple resistant annual ryegrass problems.

The trial includes four key strategies:

1. Grower standard practice – glyphosate knockdown, average pre-emergent herbicide options, standard crop rotation
2. Alternative knockdown, higher pre-emergent herbicide options, standard crop rotation
3. Reduced herbicide application, increased cultural control methods
4. A combination of strategies 2 and 3

These strategies will remain the same for the duration of the five-year trial, however the specific treatments that are applied will be adjusted based on crop type and learnings as the trial progresses.

The current crop type is wheat, and trial plots are large-scale to allow the use of farmer machinery for cultural control methods, as required. Some of the cultural control methods may include crop type, crop competition (sowing rates), time of sowing and harvest weed seed control such as the use of a Seed Terminator or similar.

Crop walks and learning opportunities will be planned for key times during the season with the SFS team, Dr Chris Preston and other industry experts in the herbicide and weed management area. Keep an eye out for these events. This long-term trial will deliver practical outcomes, driven by collaboration and innovation for farmers who continually face increasingly complex weed challenges.

Image: SFS Inverleigh Trial Paddock sown to Wheat, showing the ARG resistant weeds taken 27-6-24.