Illuminate weed, isolate it, then kill

Targeting a weed with lethal dose eliminates it from the enemy gene-bank while conserving herbicides, lowering costs

As farmers continue dealing with the problem of herbicide-resistant weeds, the global crop protection industry has stepped up with new strategies, equipment and digital technology to help fight weeds.

Croplands Equipment of Australia is one of those global companies whose weed killing initiatives arrived in Canada through a relationship with Nufarm. Croplands has spent the past several years developing a nozzle control system they call WEED-IT.

WEED-IT uses sensors to detect chlorophyll in weed leaves in fallow fields, triggering a targeted herbicide application. The precision spraying technology saves growers time and money with spraying and reduces overall herbicide use.

The concept is not new to Western Canada. Ironically, it’s Australian. Some people may remember a similar but more primitive system demonstrated in southern Saskatchewan in the 1990s. The sensors only functioned correctly in black summerfallow fields, and the introduction came at a time when black summerfallow fields were becoming history.

Croplands Equipment’s Steve Ross was in Saskatchewan this summer to help with the Canadian introduction of WEED-IT.

Ross said, “Although we have different climates, Australia and Canada face similar issues when it comes to crop protection, including herbicide resistance, increased environmental awareness and rising input costs.”

The new Croplands WEED-IT specialist in Western Canada is Jesper Voois. Before joining Croplands, he worked with Rometron, the manufacturers of WEED-IT. He provides some detail in how the system works.

“Our sensors put out an illumination of a well-known wavelength toward the ground. Leaves containing chlorophyll will convert that illumination into a different wavelength. That conversion is picked up by our sensors,” says Voois.

“We can detect leaves smaller than your thumbnail at working speeds of 16 mph. With this information, we trigger the nozzles so you just spray when you need it. As a farmer, you’d like to see performance close to 100 percent detection.

Advanced sensors detect the chlorophyll in weed leaves in fallow fields, triggering targeted applications. | WEED-IT photo

“In the spring burn-off, you’d like to spray those seedlings, which are way smaller than a thumbnail. Then we apply a background spray of 30 percent over your whole field to get those seedlings. When the sensors pick up a bigger plant, it gets a bigger burst. That way you don’t leave any plants that will build up a resistance. Your saving in spray costs will range from 50 to 95 percent.”

Voois points out that if you can target the weeds and volunteer crops, and reduce total spray volume, then it becomes feasible to program in a high dose of herbicide or put together a more expensive mix.

He says the conventional method of giving the whole field just enough active ingredient to barely kill everything is dangerous because it brings the weed population right to the edge of resistance. It’s too easy for a few problem plants to survive.

Each sensor takes in a swath of about three feet, or four nozzles. Voois says WEED-IT is a standalone system, meaning that all the action happens out at the sensor and not in the controller. To make the system fast, the sensor handles all detection, calculations and nozzle control. The operator changes settings as needed from the cab.

“We’ve collected data from customers with 10,000 acre farms. They are saving on average over $7 per (acre per) year on their chemical bill.”

A full system with 36 sensors on a 120-foot boom carries a list price of $190,000.

Voois says since WEED-IT was introduced to Western Canada last summer, Croplands has sold a half dozen full size units.

Croplands Equipment been the leader in bringing WEED-IT to market, with more than 10,000 sensors sold worldwide in five years. Croplands recently announced it is working on a new sensor capable of discerning between weeds and crops for in-crop spraying.

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