More crop, fewer weeds:revamped RIM aids ryegrass decisions

Evaluating the long-term profitability of ryegrass management methods is now easier and more effective than ever following an upgrade of the Ryegrass Integrated Management (RIM) model.

The improved decision support tool for growers and agronomists will be launched at the Global Herbicide Resistance Challenge by Australian Herbicide Resistance Initiative (AHRI) researcher Myrtille Lacoste.

With funding from the Grains Research and Development Corporation (GRDC), Ms Lacoste, who is based at The University of Western Australia (UWA), led the upgrade of RIM a decade after it was first developed.

Integrating ryegrass biology, agronomy and economics in a dynamic and user-friendly framework, RIM is free software which simulates the effect of strategic and tactical control methods on ryegrass populations and paddock economic returns over a 10-year period.

Ms Lacoste said improvements to the model meant it would continue to be a key tool to help Australian growers control weeds sustainably, and it was an ideal way to test management practices before risking real dollars.

"RIM won’t replace your expert judgement, but it will give you one more piece of evidence so you can make important changes with increased confidence,” she said.

Ms Lacoste said the upgrade included entirely reviewing and updating management options including timing of crop seeding; soil preparation; herbicides; grazing; crop sacrifice; topping and harvest weed seed control.

"RIM now also has simpler, more flexible settings so the user can easily build strategies, observe the effects of the various options on ryegrass numbers and assess the financial implications of their choices,” she said.

New features include the ability to compare two different strategies or paddock profiles in terms of:

•    Seed bank dynamics;
•    Ryegrass burden on yields;
•    Weed control budget allocation and economic returns.

RIM was first developed by Professor David Pannell from UWA and AHRI, with support from researchers from various organisations including the Department of Agriculture and Food (DAFWA).

To be held at the Esplanade Hotel in Fremantle, Western Australia from February 18 to 22, the Global Herbicide Resistance Challenge is an international, multidisciplinary research conference addressing herbicide resistance – a major threat to global and Australian agriculture.

More than 250 delegates from more than 30 countries have registered for the event, which has attracted wide ranging keynote speakers from Australia and overseas.

Major issues to be discussed include the threat of herbicide resistance and its impact on global grain production, alternatives to chemical weed control and the latest gene modification advances.