The 'Laser Weeder' from Carbon Robotics eliminates weeds by first identifying them and then burning them with a high-energy laser.
Advances in weeding technology that reduce the use of chemical sprays now make it possible for farmers to further fine tune mechanical and laser capability to within a centimetre of a crop plant.
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Agriculture Victoria showcased three such advances in weeding technology in a webinar held on Thursday, June 20 from the Tatura Smart Farm.
Nick Raleigh, from Sandmount Farms near Katunga, said his wish in farm management was to eliminate the use of the soil fumigant metham sodium.
“It is an unpleasant product, it’s a bit old school and has a high cost,” Mr Raleigh said.
Sandmount Farms harvests about 120 tons per hectare of tomatoes each season and was trialling the use of the Austrian-made Einböck Chopstar soil cultivator which utilises mechanical fingers’ that can, in some crops, reach between seedlings.
Mr Raleigh said weed control had limited opportunities of application in the growing season with the time just after weeds emerge crucial for management.
“This is really our narrowest application window of control, and we can only target very small weeds,” he said.
“There are very few effective post-emergent control options and once (the weeds) get away, then they are very invasive.”
Finger weeders have been developed to hoe soil to within a centimetre of most crop plants.
The cultivator can be further enhanced with an automatic camera-steered side-shift frame with two high-definition lenses.
This technology allows for a range of different colour detections between weeds and soil and crop plants, resulting in 95 per cent of weeds being removed.
Farmer Justin Colby said the camera could look for darker or lighter green colours against the weed colour.
“The camera will find those colours predominantly and adjust itself to recognise the row,” Mr Colby said.
“And can even be used with red cabbages.”
Another function is for the cultivator is to recognise a three-dimensional view of a row to help further identify crop plants against their backgrounds, allowing the finger weeders to hoe within one centimetre of a crop plant.
Mr Colby has used the cultivator with cabbages and corn and has trialled it for broccoli.
The highlight of the webinar was the introduction to the ‘Laser Weeder’ made by US company Carbon Robotics.
VegNET regional development officer Danielle Park and Farmer Frankie Ruffo have been trialling the laser weeder at the Ruffo family farm — Tripod Farmers — at Bacchus Marsh.
Mr Ruffo said the weeder was crucial for managing baby leaf salads.
“Consumers do not want any weeds at all in their salads, which is challenging in our high-density crops,” Mr Ruffo said.
“It’s a really good tool — an extra tool — in our plan, it’s great to have that other option to throw at the weeds.”
Although Mr Ruffo was confident that the weeder had improved productivity, he said there was an ‘awful lot’ of data still being collected after a four month trial.
“That’s going to be how much crop per hectare and the weed population and the weed types as well,” he said.
“It’s giving us some really accurate numbers.”
The weeder burns weeds in their centre, and worked better on smaller weeds.
“You can’t even see that weed any more,” Mr Ruffo said.
“They are a lot harder to kill when they get a bit bigger, maybe we kill only about 95 per cent.”
The Laser Weeder operates at a very slow pace — often down to 100m per hour — and although it requires very high revolutions from a tractor motor to drive the laser generator, it consumes about 30 litres of diesel per hour.
The weeder uses high resolution AI-guided cameras to firstly identify target weeds and then direct a high-energy laser at them.
The CO2 laser with ‘sub-millimetre’ accuracy then burns each weed individually.
Ms Park said for leafy vegetables, the weeder would need recalibration as the crop plants grew bigger.
“There is a level of skill with operating it to identify the kill rate, depending on the crop and the object you are trying to achieve,” she said.
“Because the weeds are being burnt you do get a distinctive smell of the weeds burning and yes it’s a very satisfying sight to see the burnt weed bent over.”
