A NEW tool is available that can help test a range of weed management options for barley grass (Hordeum spp) – a weed which is requiring increasingly strategic and integrated management by grain growers.
The Barley Grass RIM tool is hands-on, user-friendly decision-support software for growers and advisers that has been adapted from the well-known RIM (Ryegrass Integrated Model) for annual ryegrass (Lolium rigidum).
Its development follows the release of a Brome RIM tool for brome grass (Bromus diandrus and B. rigidus) earlier this year.
The original RIM model, that was developed by the Australian Herbicide Resistance Initiative (AHRI), was used by CSIRO to develop the new barley grass and brome grass versions.
Investment came from the Grains Research and Development Corporation (GRDC) as part of the GRDC Stubble Initiative, as well as from CSIRO.
AHRI, the University of Adelaide and grower groups including Mallee Sustainable Farming and the Eyre Peninsula Agricultural Research Foundation (EPARF) helped to develop and test the new tools.
CSIRO farming systems scientist Rick Llewellyn, who with colleague Marta Monjardino led the development of the Barley Grass and Brome RIM tools, said barley grass was an important weed in the no-till farming systems of several major cropping areas of southern Australia, often in low-rainfall, low-cost cropping environments.
“Managing this weed is an increasingly challenging task requiring integration of several practices, as herbicide options can be relatively limited and harvest weed seed control practices that are used for other weeds such as ryegrass are much less effective on barley grass,” Mr Llewellyn said.
“Barley grass has a very short growing season which allows it to set seed even in the driest of seasons.
“Evolving barley grass populations with delayed germination and early seed set mean a strategic integrated weed management approach needs to be applied to manage this weed.”
Dr Llewellyn said the Barley Grass RIM tool allowed users to look at long-term management scenarios, weed number outcomes and the profitability of a range of combinations of control strategies.
“This tool models the population dynamics of barley grass over a period of up to 10 years,” he said.
“The enterprise choices within the models include crops like cereals, canola and grain legumes, as well as three types of pastures/fodder for livestock.
“Weed control includes sowing-related options, selective and non-selective herbicides, grazing, spring and harvest options, as well as other user-defined practices.
“The user specifies the crop/pasture and management sequences for up to 10 years and the model calculates the consequences with respect to crop yields, weed populations and profitability.”
Mr Llewellyn said analysis using the Barley Grass RIM tool found a ‘high crop competition’ scenario – involving a high seeding rate of 90 kilograms per hectare for barley and wheat and 120kg/ha for legumes – returned an average annual net benefit of $16 per hectare when compared with the use of standard crop seeding rates.
“These results indicate the potential for greater crop competition to be used as a tool to reduce weed seedbanks and improve profits,” he said.