Kulin growers Derek and Rhonda Young have reduced their summer herbicide costs by more than 90 per cent simply by adopting optical spraying technology.

The green-on-brown technology provides targeted weed control through a series of sensors that identify green plants against a brown paddock background.

The Youngs' system is mounted to a dedicated boom, which is fitted on to the main sprayer at the end of the growing season.

Since adopting this technology, the Youngs no longer have to blanket spray paddocks throughout the summer period.

This not only means huge savings on their annual chemical bill, but also allows for a more efficient and effective weed management system.

"We now have the capacity to eliminate difficult weeds such as fleabane and sow thistle with herbicide rates that are not economical in a blanket spray situation," Derek says.

The Youngs were first adopters of the technology, buying the third machine that was imported into the country in 2009.

Over the past decade, Derek estimates he has saved more than $500,000 in herbicide costs by ending the blanket spray approach.

"Even by spraying up to 60 per cent of the paddock, we are still making massive savings and the technology paid for itself in only two years," he says.

Derek and Rhonda have now turned their attention to tackling in-season weeds, with a particular focus on ryegrass.

The Youngs participated in a recent Australian Herbicide Resistance Initiative (AHRI) focus paddock survey that investigated ryegrass resistance levels across Western Australia's grain growing regions.

The survey highlighted some resistance issues on their property, to both pre and post-emergent herbicides.

To solve this problem, the Youngs have re-introduced tillage back into some of their cereal cropping system, allowing them to incorporate trifluralin into the pre-emergent weed management program.

After 16 years of no-till seeding, this was a big change for the business, but one Derek says is now paying dividends in crop establishment and weed control.

While resistance levels to Group A and B herbicides are now widely accepted across the industry, developing resistance levels have been identified in some pre-emergent chemicals.

Despite this, AHRI research fellow r Roberto Busi says, pre-emergent herbicides remain an important strategy to tackle ryegrass.

"Importantly, the survey did not identify any resistance to mixtures of pre-emergent herbicides," he says.

He says statewide monitoring of resistance levels to pre-emergent chemicals, particularly prosulfocarb, pyroxasulfone and new herbicides coming to the Australian market, will be critical in coming years.

More information: Dr Robert Busi, AHRI, roberto.busi@uwa.edu.au

Read more about the Young’s optical spray technology money-saver.