The University of Arizona

College of Agriculture and Life Sciences

Improving Lives, Communities and the Economy

'Extension Experts' Help Farmers Eliminate Weeds Using Technology

As traditional and organic farmers face labor shortages and higher production costs, they say the work of a University of Arizona Cooperative Extension Expert in Yuma is helping to “weed out” some of those issues using technology.

“I cannot use chemicals as an organic farmer, so my option is labor.  Weeding by hand, and with minimum wage laws, and rising labor costs, I’m forced to look for other options, so I can stay in business,” says Sutton Morgan, who owns Oasis Organics, roughly 2500 acres in the Imperial Valley, in Southeastern California.

That’s where Cooperative Extension’s Mark Siemens steps in, to introduce some of those options.

Siemens is an agricultural engineer in Yuma – who works to integrate technology with farming. His research and extension program focuses on developing and evaluating new machine systems to improve the profitability, sustainability and environmental soundness of vegetable and fruit production systems.

He’s been working to evaluate machines that actually weed between individual crop plants within the crop row.

Many of the machines were developed in Europe – and the goal was to see if they’d work in U.S. vegetable farms, says Siemens, who is an Associate Specialist and Professor in Agricultural and Biosystems Engineering.

“Supported by a USDA-NIFA Crop Protection and Pest Management grant, we conducted field trials to determine their efficacy and the amount that hand weeding labor requirements were reduced.  We also provided the opportunity to have growers evaluate the technology on their farm so they could make their own decisions about how the technology would fit into their farming operation,” Siemens says.

That opportunity is something Yuma Farmers appreciate.

“As farmers, we’re lay people – we don’t really understand all of the technology, and what it takes to make it work,” says Steve Alameda, a partner with TopFlavor Farms in Yuma, and President of the Yuma Fresh Vegetable Association.

Alameda, and others like he and Morgan, work side-by-side with Siemens to evaluate and test this new machinery.

“We do what we need to do to give indication of where we need help, and then their expertise kicks in, to really solve the big problems, and get into the details,” Alameda says about Siemens, and other Extension specialists in Yuma he’s worked with.

“They come up with practical things that work for us, and it’s all about trying to make money – not even make money – to stay in business.  Nowadays, it’s all about staying in business,” Alameda says.

In addition to evaluating new systems, Siemens is also part of a team developing a precision weeding machine for removing weeds close to crop plants. 
The team is made up of Siemens, and colleagues from U.C. Davis and Washington State University.  The project is supported by a $2.7 million USDA-NIFA Specialty Crop Research Initiative grant. 

The prototype uses a camera-based vision system to differentiate between crop plants and weeds. Based on data from the camera, a sprayer nozzle is then activated to spray weed-killer on individual weeds.

 Mark Siemens

The team is currently integrating the machine vision and sprayer assembly components and plans to test the machine this summer.

 Humberto Hernandez

“I’ve seen it, and worked with him on these machines - they’re good.  He’s working on his aspect and people in the private sector pick up on what he’s discovered. His job is to make the prototype, and work on the details so someone will take it and make it available to the farmer.  I like Extension – everyone is very accessible.  They’re seeking out what we’re doing, and they try to find out what problems we have, and what they can do to help,” Alameda says.

That’s the part of his job that Siemens especially enjoys.
“I enjoy solving engineering type problems and helping people with technology.  It’s a good feeling when you share what you’ve learned and people benefit from that information” Siemens says.

To learn more, click here to reach out to Mark Siemens, or click here to head to the Specialty Crops Mechanization page,