Drone technology offers new approach to combat weeds

As farmers wrestle with increased weed resistance to herbicides, new management techniques offer modernized ways to combat weeds. Rapid improvements in drone technology have allowed farmers to attack hardy herbicide-resistant weeds from the sky.

Scouting sidekick

Scouting from above can help farmers better understand their fields by obtaining aerial views of the topography. This helps them identify weed patch locations and escapes, says Jared Roskamp, a BASF technical service representative.

“We’ve seen more growers trying to get better images and understanding of where weed spectrums are in their field as well as other pests,” he adds.

Farms of all sizes and locations could benefit from the autonomous scouting opportunities drones may offer soon.

“Instead of being able to only physically check a few areas in the field at infrequent levels, with something like a drone it’s possible to check potentially larger areas more frequently,” says Steve Bowe, group leader for biology R&D/technology integration and knowledge systems at BASF. “As that becomes more autonomous, then you almost have real-time monitoring. That’s a little bit down the road, but probably not as far off as we think.”

Spray from the skies

Companies such as Rantizo use drone technology for more than just scouting. Recent improvements have allowed the drones to hold more weight and operate for longer periods.

“Naturally, we put a tank on them, and now we can make applications with them,” says Ben Johnson, a territory sales manager for Rantizo, based in Iowa City, Iowa.

Drones eliminate the need for heavy ground rigs to pass over the field and offer a more precise application than traditional aerial application methods such as helicopters and airplanes.

“Some fields are less than 20 acres, so a lot of times a helicopter won’t spray there because of the hazards to the pilot and equipment,” Johnson says, but drones are able to effectively fly into smaller areas and make applications that would be difficult for larger equipment.

A drone’s design also boosts application efficiency compared to larger counterparts. The propellers naturally drive products deeper into the plant canopy, allowing herbicides and fungicides to work more effectively.

While drone applications won’t work for every operation, farmers with certain conditions may want to consider adding them to their management plans.

“The first one would be what we call the awkward acre, those smaller fields that have obstacles that make ground rigs inefficient,” Johnson says. “The other would be those places where there’s a lot of risk to aerial applications like tree lines or small acres.”

Drones typically fly 7 to 10 feet above the canopy, providing around 20 feet of spray coverage at a time. The DJI Agras T30 drone has a 30-liter tank.

“We typically look at acres per hour,” Johnson says. “A number we’re confident in is about 18 to 20 acres per hour with the T30 model drone.”

Limitations linger

Drones can be a useful addition to weed management programs, but the technology isn’t perfect.

“Make sure you’re using them as a resource and not missing the timing with a ground rig or an aerial applicator,” Roskamp says. “Walking out and looking at weeds is still an option, so just make sure drones are integrated in your plan and you don’t whole-heartedly jump in too fast.”

Short battery life and weather concerns are other limitations.

“A typical drone, especially on the application side, can only fly for maybe 10 to 30 minutes before you have to come down and charge or change batteries,” Bowe says. “Similarly, how much payload or spray solution it can carry is limited, because it’s all related to weight and that power it takes to lift it and carry it.”

Like many things in agriculture, weather will dictate when drones can make applications.

“Wind is going to blow you out of spraying long before the drone would be unsafe to fly, so everyone is on an equal playing field there,” Johnson says.

In some cases, drone applications could allow for more timely applications in the right conditions.

“Let's say it rained last night, but it’s clear now and the dew has dried off,” Johnson says. “That’s a great time to spray, but you couldn’t go out and do that with a ground rig because you’d get stuck.”

Regulations rule

Though drones are commercially available, not everyone can legally operate them. Drones are under the jurisdiction of the Federal Aviation Administration and require a specific pilot’s license. To spray chemicals, the operator will also need a crop duster license.

“A lot of times the misconception is if you have a pesticide applicator’s license, you can buy a drone and go out and use it,” says Emily Carlson, director of marketing and customer operations for Rantizo. “It is a different conversation because there is the FAA component and the state licensing aspect. Whether they’re doing custom application work or doing work in their own fields, the regulations are the same.”

Pioneering pilots

While the technology is still in the early stages, price reductions make drones more accessible to farmers.

Bowe says low-cost options exist particularly on the image-sensing side, and he suggests farmers get familiar with the technology now. “I know how it’s impacting us on the R&D side in helping us develop our crop protection pipeline,” he says. “There’s a lot of potential there, but it’s early technology. Fasten your seat belts because it’s going to take off.”