Although small in scale, one research project at New Mexico State University's Fabián García Science Center has the potential to revolutionize weed control without using chemicals.

Erik Lehnhoff, an associate professor of weed ecology, Leslie Beck, an Extension weed specialist, and Andres Indacochea, an electrical engineering master's student at NMSU, have teamed up to explore the use of electric mulch connected to solar panels to suppress weeds under crop canopies. The project – currently in use along a cluster of grapevine rows at the science center – has seen about 100% effectiveness.

In xeriscaping, electric mulch consists of metal mesh placed beneath layers of gravel that is connected to solar panels, with the bottom layer of gravel preventing water from reaching the mesh. This also hides the screen from view.

However, the project at the Fabián García Science Center doesn't use any gravel. The screen is loaded with a low dose of electrical power that's able to kill weeds and small invasive trees but not enough to be lethal to animals or humans.

"As the weed touches the screen, it gets a jolt of electricity, which keeps the plant from growing," Lehnhoff said. "The electricity acts essentially the same as a pre-emergent herbicide, killing weeds before they have an opportunity to interfere with crop growth. So far, we don't know the mechanism that kills the weed."

Lehnhoff said this is comparable to the development of herbicides. Initially, he explained, scientists didn't understand why some herbicides were effective. At NMSU, he said researchers analyzed leaf-and-tissue samples from plants killed by electricity and found elevated stress responses compared to control samples.

"Collaborating with Dr. Donovan Bailey from the NMSU Department of Biology, we grew plants and applied sub-lethal doses of electricity," Lehnhoff said. "We collected leaves from the plants and used transcriptomics to elevate stress responses."

Indacochea said the heat produced by the electricity is strong enough to kill weeds, adding that grass has a higher thermal tolerance.

"Thermal is a big part, but other factors might play a bigger part," he said.

The idea for the research project started with Paul Neher, an electrical engineer at White Sands Missile Range who successfully experimented with using electricity to kill weeds and small trees at his home. Neher approached Lehnhoff about further research.

Lehnhoff said the electric mulch works when a weed touches the screen to complete the electrical circuit. The solar panels generate electricity, which flows through a wire to the screens.
"There is no electricity flowing until a weed comes up and touches the screen, and that completes the circuit," Lehnhoff said.

As far as costs, Indacochea said, the technology is relatively inexpensive. For its project, the NMSU team purchased solar panels – by far the biggest cost – at a home improvement store in Las Cruces. The wire mesh and system operation would generally cost less than a dollar or two a month. So far, the NMSU project has received funding from the Agricultural Experiment Station, the Western Integrated Pest Management Center and the Weed Science Society of America.

A similar project in Oregon has shown effectiveness in a blueberry field, Lehnhoff said. He hopes the technology will one day become available for commercial landscaping and residential uses. However, the method warrants additional research, particularly in large-scale farming, where introducing electricity as a weed control could present hazards with irrigation.

With solar panels providing electricity, Lehnhoff said a consumer could have effective weed control without relying on herbicides – a potential boon for organic crop production where herbicide use is strictly prohibited.

A version of this story was originally published in the fall 2024 issue of ACES Magazine. For more stories, visit https://nmsu.news/aces-magazine-fall-2024.

The full article can be seen at https://newsroom.nmsu.edu/news/nmsu-researchers-turn-to-electric-mulch-to-keep-weeds--invasive-trees-at-bay/s/16b7972c-1120-49b9-b5f4-29a96da18dac