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Shocking weeds into submission

The Weed Zapper uses electricity to mortally injure weeds

The Weed Zapper has a front applicator bar that disperses electricity to the plants, and is powered by a generator on the back.

Controlling weeds can be a tough challenge for organic growers with few chemical options, and also for conventional growers battling herbicide-resistant weeds. 

For this reason, mechanical weed control has been making a comeback and innovators are now offering more options. 

One such option is the Weed Zapper, which uses electricity to kill weeds and does not require any tilling of the soil. It was featured as part of the July 13 Research and Tire-Kicking digital event hosted by Canada’s Outdoor Farm Show. 

Farmtario talked with Ben Kroeger, who owns Old School Manufacturing LLC in Missouri along with his brother and father. 

Designing a tractor attachment that uses electricity to control weeds seemed like a natural fit for the Kroegers, who are commercial electricians by trade and also farm organically. It was heavy weed pressure and lack of effective options that led the Kroegers to begin development of the Weed Zapper six years ago. 

Kroeger admits they didn’t come up with the concept — in fact a machine using electricity to kill weeds was developed in 1979 but the company went out of business three years later. 

“I tell everyone we found an old rusty nail, polished the corners and made it roll a little more smoothly.”

How it works

The Weed Zapper doesn’t actually kill weeds, said Kroeger, “it mortally injures them.” It does this by conducting a positive charge of electricity into the top of the weed, and a negative charge of electricity is conducted at the earth through the attachment’s grounding system. 

This results in “hyper-heating” of the moisture in the stem of the weed touched. Kroeger said whenever moisture is hyper-heated, it expands quickly and ruptures and the plant cells can no longer hold or retain moisture. This gravely injures the plant and “the sun is what kills the plant itself,” he said. 

The Weed Zapper is basically a copper bar that has voltage on it. As soon as a plant touches the bar, current starts flowing down the plant stem. photo: Supplied

The front applicator bar of the Weed Zapper is made of copper and voltage is driven to it by a generator which sits on the back of a tractor. Kroeger said his company didn’t design the generator portion of the Zapper, but modified it so that it can vary both the frequency and voltage output. The maximum voltage output of the Weed Zapper is 15,000 volts. 

As for effectiveness, Kroeger said preliminary results of a study conducted by the University of Missouri show a 98.6 per cent kill rate on what the Zapper touches. This is primarily for large plants that have a large stem such as giant ragweed and Canada thistle. Grass-type weeds can be more challenging, he said, as they don’t have as much moisture to conduct as deeply into the roots. 

The Weed Zapper works above the crop canopy, but Kroeger said Old School Manufacturing offers between the row combs that will allow operators to reach down below the canopy for weeds that emerge between rows. 

“The Weed Zapper is more of a maintenance tool after a pre-emergent herbicide or first herbicide application, or after cultivation and mechanical weed control.” 

Safety

Kroeger said the Weed Zapper has a standalone safety system that is integrated into the machine itself. The system comes with a seat pad that the operator puts on the seat of the tractor and sits on. The attachment also has speed and wing sensors that shut the machine down if forward motion is no longer maintained. He said if a forward motion of five miles per hour is not maintained, the system will automatically shut off. 

It also has a grounding system on it and when the operator shuts off the PTO the electricity is grounded and no residual charge remains. 

The fact that the applicator boom is in the front of the tractor is also one of the greatest safety features of the machine, said Kroeger, as it allows forward peripheral vision. 

Since the first prototype was developed in 2015, the Weed Zapper now offers an operating system that has a horsepower range of 65 to 350 and applicator bars are available from 10 feet (four row 30-inch crop configuration) all the way up to 44 feet. 

Kroeger said they are currently prototyping a 60-foot applicator and are also working on an automatic height control system.

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