The future of spraying is green. Green-on-green.
That is the opinion of crop science and herbicide resistance expert Stephen Powles, who believes autonomous spot spraying for both summer and in-season spraying is the most suitable form of application that will cater to cost, chemical retention and environmental considerations.
An Emeritus Professor at the University of Western Australia, Professor Powles presented at Grain Producers SA's spray forum at Freeling last week.
He agreed with the majority of speakers that the grains sector needed to improve when it came to herbicide application and said spot spraying and associated technologies were a "mini-revolution" that would help achieve that.
Prof Powles was of the the opinion that for large-scale broadacre farms across the globe, herbicides would remain the dominant weed control technology largely due to economics.
"It is very hard to control weeds in big paddocks at low cost and herbicides do the job. They may not be perfect, but they do the job," he said.
"New herbicides will be discovered, but it will be rare. If new discoveries are made, we should treat them as a precious resource and not spray them like they're going to be here forever.
"The way to do that is through (herbicide) diversity, good agronomy and good farming.
"In my view, precision spot spraying will become widely adopted for knockdown and fallow, and in-crop post-emergent herbicides in grain crops.
"If that's true, we'll have greater herbicide options, diversity of greater options, we'll save dollars and we'll have environmental benefits."
Alternative technologies for weed control already being used, such as herbicide application by drone in small Asian rice enterprises or laser and fire weed removal, were unlikely to be cost effective or practical for large Australian grain farms in the near future.
With 'green-on-brown' spraying technology already in use, and early 'green-on-green' technology commercially available, Prof Powles expects widespread adoption over the coming decade.
"We have been doing so-called green-on-brown (spraying) for some time - the use of fluorescent camera sprayers on booms for weed control during the summer," he said.
"They detect the fluorescence of green leaves. Green-on-brown is precision spraying and in its best use gives a 90 per cent reduction in herbicide use.
"For all those that are worried about spray drift, surely this is a great development, in that the potential for drift is much less if you're only spraying where the weeds are than when you blanket spray the entire paddock.
"Doing so called green-on-green or in-crop is a much bigger technical challenge as you'd expect."
Prof Powles said green-on-green technology - like John Deere See and Spray Select and Bilberry Trimble - was currently expensive (about $200,000 to fit the Trimble technology on a sprayer), but commercially available.
"I expect this sort of technology will become widespread and adopted in broadacre Australian agriculture," he said.
"In my view it is without doubt a good thing.
"We'd be using much less chemical, the drift potential is much lower when you're only spot spraying, the commercial outlay on herbicides is much lower."
Prof Powles also thinks robotics will have a part to play in Australia's future herbicide application best practice, pointing to Qld company SwarmFarm Robotics as an example of what's in store.
"They have over the last ten years or more been developing the SwarmFarm robots which are small, lightweight, autonomous robots with sensors mounted on the sprayboom behind the unit delivering precision spot spraying," he said.
