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Farm Robots Need to Be Trusted to Tell Crops From Weeds

June 13, 2018, 12:27 PM

Robots will move along fields either spraying herbicides through a pen-like nozzle or pulling weeds as soon as 2019 after their makers perfect programming them to distinguish weeds from crops like tomatoes.

Farmers appear to be warming to the idea, as challenges recruiting field workers are leading them to seek alternatives.

Still, robot manufacturers acknowledge that they have to ensure their creations are discerning and won’t overspray or accidentally destroy crops with herbicides. They also must promote trust among potential customers who may be wary about artificial intelligence after accidents with Tesla’s and Uber’s autonomous self-driving vehicles, according to robot makers.

Robot developers are promoting the machines as better for the environment. Precision sprayers are projected to reduce herbicide usage on fields by 20 percent to 90 percent, with computer sensors telling the robot how much of the chemical is actually needed. But first the developers must ensure the robots can distinguish fruits and vegetables from the weeds around them.

Autonomous Weeders?

David Slaughter, an agricultural engineer and leader of the Smart Farm Initiative at University of California, Davis, said his research group is advancing mechanized robotic agricultural technology.

The UC Davis team is testing an automated cultivator, which is a mechanized tractor programmed to seek weeds around row crops and remove them. The cultivator has faced challenges in distinguishing between weeds and crops though, Slaughter said.

“In crops where the weeds are closely related like tomatoes, getting a smart machine to distinguish between the crop and the weed that are in the same family is difficult,” he said.

“Some weeds are much easier to recognize than others. The other challenge is when one plant hides another—if you get one growing over the other, it’s also hard to find, especially since 3D vision is still in its infancy.”

Slaughter told Bloomberg Environment that his team has applied for patents for their robotic creations. They don’t plan to sell them soon but want to put them in the hands of farmers, he said.

2019 Launch

Blue River Technology, a California-based tech startup that was acquired by John Deere in 2017, introduced its precision spraying weeder, called the See and Spray, in May 2018. It’s been tested in cotton fields and is slated to hit the broader market in 2019.

The robotic sprayer is hauled by a tractor that’s operated by one person. It has computer sensors that look at each plant and decide which treatment is needed.

The tractor goes 6 to 8 miles per hour, and the See and Spray can make “5,000 decisions per minute” on how much herbicide should be used, according to a video put out by Blue River.

The sprayer, while patrolling the field and covering 8 to 12 rows in one pass, compares plants to distinguish fruits and vegetables from weeds. It doesn’t depend on spacing between crops or color to identify weeds, according to the company’s website.

The robot then releases specified amounts of herbicide through a nozzle—instead of spraying the entire field, covering crops as well as weeds. It also adjusts its herbicide measurements as it moves along the field.

Self-Driving Setbacks

A Tesla Inc. self-driving car’s fatal crash in March 2018 prompted concern about robotic vehicles, but tech companies and farmers continue to be interested in machine learning and artificial intelligence to assist in managing crops.

“The only thing that will help the mindsets for autonomous machinery is if re-testing goes well,” Henrik Lynge Jacobsen, the chief compliance officer of Denmark-based robotic maker AgroIntelli, told Bloomberg Environment. “The accidents with Tesla and Uber has made it a bit harder to get acceptance for this.”

Curt Blades, senior vice president of agriculture services for the Association of Equipment Manufacturers, is optimistic that creators will restore trust, especially among consumers, once the technology matches expectations.

“The cons to the machine really have more to do with the technology, which is evolving at a rapid pace to remove concerns,” Blades told Bloomberg Environment.

Help Wanted

Slaughter said that the technology will give farmworkers the opportunity to operate the machinery.

“If you have a child would you want to envision your child having a career in pulling weeds or would you rather envision your child working on robots for weeding?” he said. “With agricultural robots there can be short-term job loss. Anytime that anybody loses a job it’s awful, but we hope that through this initiative we’re providing new careers and new opportunities in agriculture.”

Some farmers also see these robots as being one solution for a tight labor market, creating high-tech, high-wage jobs instead of multiple manual labor positions in a shrinking labor pool. In California, for example, farmers say they are bidding against one another for farmworker crews, said Bryan Little, the director of employment policy at the California Farm Bureau Federation.

Labor Markets

The labor markets are going to make mechanization more attractive. If you have mechanical invention that really works, it could increase the wages of farmworkers. History has shown that when we went from labor intensive to capital intensive, wages increased,” Little told Bloomberg Environment.

Virginia Ruiz, director of occupational and environmental health at Farmworker Justice, told Bloomberg Environment that farmworkers may get more money for being able to operate the robots, but it’s hard to say how they’ll actually be affected.

“They’re still going to need people to operate them and load the pesticide and people will presumably need to go in afterward and harvest,” she said. “So, there will still be work. Maybe, if some of workers can learn to use the products or maintain them, then maybe that’s a better-paying job for them.”

Seasonal California farmworkers earned roughly $10 an hour in 2015, according to an Economic Policy Institute study.

Agricultural robots will change how weeding and weed killing is done, once farmworkers are trained to operate them, according to Blades.

“There’s not anything that’s fully autonomous and I think we’re a ways away from that being the case,” Blades said. “Anything we can do that’s going to create efficiency in farm production is good. Are there going to be workers displaced? Maybe. But instead of saying we’re taking jobs, the description of the job will change.”

To contact the reporter on this story: Ayanna Alexander in Washington at

To contact the editor responsible for this story: Rachael Daigle at