GRDC-funded project puts green on green on horizon

Liz Wells, May 29, 2024

David Keetch. Photo: Nufarm

A PROJECT to develop green-on-green camera spraying is under way to give Australian growers an automated means of controlling weeds in direct-drilled winter crops.

Its cornerstone will be the systematic collection of crop and weed images from paddocks across Australia, supplemented by images of crops and weeds photographed in the controlled environment of the Australian Plant Phenomics Facility at the University of Adelaide’s Waite Campus.

The project is part of a four-year package funded by the Grains Research and Development Corporation, and led by David Keetch, who last month took up the new role of Nufarm’s green-on-green program director.

As is the common theme across the southern Australian grainbelt this month, Mr Keetch is waiting for rain to get the project moving.

“I’m ready to start building this image data base; just add water,” Mr Keetch said from his base on the Adelaide Plains.

“I’ll be spending the season collecting images en masse for annotation.”

Croplands has engaged third parties to provide their technology stacks to the project, which will enable them to accelerate their algorithm development for Australian crops and conditions.

It will also be the initial interface between green-on-green herbicide specific registrations  and the Australian Pesticides and Veterinary Medicines Association.

The GRDC projects have funding of more than $5 million in total, and are both led by Nufarm.

The Enabling site-specific herbicide application in-crop via boom-sprays project runs until March 2028, and Framework for site-specific chemical application runs until January 2029.

Breaking new ground

Globally, green on green is already used in broadacre, primarily in the US and Europe in row cropping, where weeds growing between furrows can be easily targeted.

In Australia, the GRDC-funded project aims to augment commercially available offerings in the camera-spraying space by expediting their ability to tackle Australian weeds in Australian crops.

“In other regions of the world, green on green is being used on wide-spaced row crops with low plant densities, like cotton, corn and soybeans.

“Australia’s direct-drilled crops with narrow row spacings provide a greater challenge for current green-on-green technology.

“I think where we’re going to go initially is wheat and barley…for spraying out broadleaf weeds.”

Among the preliminary targets is sow thistle, which Mr Keetch said has become a problem in southern and northern growing regions, and wild radish, which has a particularly big impact in Western Australia.

Indian hedge mustard and spiny emex are among the broadleaf weeds with a more prostrate habit that green on green may be useful in tackling in other crops prior to canopy closure.

Starting from his base in South Australia, Mr Keetch will oversee the collection of images taken in wheat, barley and canola, with the project extending into the northern region and Western Australia in following seasons.

“We’re hooking those cameras up to booms, going into the field, and collecting an enormous amount of images.”

At the Waite’s phenomics facility, potted weeds on a conveyor belt will also be photographed for the project.

“We’ll use that as a second means of image collection.”

Interface with APVMA

The second GRDC-funded project aims to develop herbicide crop safety and residue trials fit for green-on-green applications that also meet the APVMA’s standards for registering herbicide-use patterns.

This may include testing higher herbicide rates, extended crop growth stage timings, or even alternative mode of action herbicides previously considered too damaging to crops when applied to an entire field.

“We do need to have discussions with the APVMA, and we’re in the process of lining up stakeholders to discuss what might be capable with this type of application technology.

“The exciting part might be the ability to use modes of action we don’t currently use in crop because we only apply it to a small percentage of the crop area.

“There are also some herbicide registrations that cut off once the plant gets to a certain growth stage; can we extend that and put a restriction on the area of crop we spray to meet maximum residue limit requirements?

“For example, if we spray less than 50pc of paddock, we may not run into residue issues.

“That’ll be one of the end goals, to come up with unique registrations.”

Mr Keetch said increasing herbicide resistance, as being seen in some weed species, was a key driver of the push to develop green on green for Australian conditions.

“Any of this technology is a wonderful opportunity to tackle resistance head on.”

Further out, Mr Keetch said the battle against grassweeds in cereals could well do with some help from green on green.

“Annual ryegrass is the number one weed pest in Australia, and wild oats, particularly in the northern region, are of concern too.”

Finding a fit for farmers

Mr Keetch said green on green needs to be versatile across the season to make economic sense for growers, and units should also be able to be used for green-on-brown applications, and eventually for spraying herbicides in pulse crops.

“A lot of these weeds we’re targeting in cereals are problematic across pulse crops too.

“Once you’ve got resistant sow thistle or mustard up in a lentil crop, there’s nothing we can do about it at this stage.”

Mr Keetch said he envisaged the same units, once fitted with new hardware and software, could be used to spray weeds in fallow and in crop.

“I think what a grower wants to be doing is using green on brown in summer fallow, and then turn around and use the same machine for green on green to get broadleaf weeds out of their wheat and barley for starters.”

With its more complex algorithms and cameras, spray units that can spray green on green are expected to be more expensive than the green-on-brown units already widely used.

“From a grower perspective, they need to get a return on investment.

“How they get that is not only through a cost saving on herbicides, as we’ve seen with green on brown, but also being able to use new herbicide use patterns to tackle key weeds.  Nufarm led the way with unique green-on-brown herbicide use patterns and aims to do the same with this emerging technology.

Beyond the GRDC-funded initiatives, work is already being done overseas to develop green-on-green technology to spray speeds within, instead of just between, rows in crops like soybean and corn.

Mr Keetch said he has a question to put to himself to help keep the project on track, and make the most of work to be done from the current season through until 2027: “How can I speed up the algorithm development for Australian crops in Australian conditions?”

As has been seen with the development of green-on-brown spraying globally, several companies are developing green-on-green technology.

Mr Keetch said GRDC’s funding of a project to develop both algorithms and the basis for a regulatory framework when it comes to APVMA permits were likely to deliver benefits to Australian growers faster than if market participants worked on their own projects.

“Green on green would be slower to develop for the Australian market without it.”


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