September 10, 2003

Growers in Western Australia’s northern agricultural region (NAR) are uncovering disturbing trends in herbicide resistance that require further farming systems reform and judicious herbicide use.

Supported by the Grains Research and Development Corporation (GRDC), growers are adopting a united and systematic approach to the weed and herbicide resistance threats curbing production across the 7.5 million hectare NAR.

The group is led and advised by the Department of Agriculture’s Peter Newman, who last year co-ordinated 12 trials (11 on participating farms) to investigate integrated weed management (IWM) strategies.

The group is making significant progress, showing that, under suited conditions, crop topping lupins could control 98 per cent of annual ryegrass seed set.

Meanwhile, extensive research is underway to develop new IWM techniques for wild radish, which could soon surpass ryegrass as the largest weed threat.

Mr Newman expects the group’s focus to move from chemical treatments to farming systems alternatives, such as burning header windrows, which destroyed 99 per cent of ryegrass seeds in trials last year.

The need for good alternatives to chemical treatments was reinforced when the group recently found nine wild radish populations with resistances to phenoxy herbicides, including 2,4-D Amine (Group I).

Many of the IWM systems are being trialed across 51 focus paddocks. The GRDC supported WA Herbicide Resistance Initiative is identifying the latest IWM packages and sharing resistance testing information with the group.

The GRDC places high priority on support of on-farm, grower research. The direct participation of more than 250 NAR growers shows the model is an equally high priority with growers.

The project aims to increase NAR yields by 100 kg/ha.