Researchers from the University of Missouri recently conducted two field studies to explore the effectiveness of electricity in weed control. They used a tractor attachment called The Weed Zapper™ to electrocute eight types of weeds common in soybean crops, including herbicide-resistant waterhemp.
The first study showed that control was more effective in the later stages of weed growth and was most closely related to plant height and the moisture in the plant at the time of electrocution. Once the weeds had set seed, the treatments reduced viability by 54 to 80 percent across the weed species evaluated. A second study showed electrocution reduced late-season, herbicide-resistant waterhemp plants by 51 to 97 percent.
At some stages of growth, the soybean crops exhibited yield losses of 11 to 26 percent following electrocution treatments – though researchers say those results likely represent a worse-case scenario. In late-season treatments, for example, the clear height differential between waterhemp and the soybean canopy means the electrocution device can treat the weed without sustained contact with the crop.
The net takeaway: When used as part of an integrated control program, electrocution can eliminate many late-season, herbicide-resistant weed escapes in soybean crops and reduce the number and viability of weed seeds that return to the soil seedbank.
From the Weeders of the West (WoW) blog ∴ March 11, 2021
Marcelo Moretti is a Professor in the Dept. of Horticulture at Oregon State University and an alumnus of UC Davis and California State University, Fresno.
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Managing Herbicide Resistance with Electric Weed Control
Herbicide resistance has also been a problem in tree nut crops for quite some time. In hazelnuts in Oregon, the most problematic herbicide-resistant weed is Italian ryegrass. Resistance is now confirmed to herbicides in groups 1, 2, 9, 10, 15, and 22. Resistance to more than one mode-of-action is often found in the populations. Non-chemical alternatives are needed. We recently started a project to evaluate electric weed control (EWC) funded by USDA – Crop Protection and Pest Management program.
Electric weed control (EWC) has been investigated for almost 40 years. However, it remains an emerging technology in the USA and elsewhere in the world. A few companies, mostly in Europe and Latin America, offer commercial EWC units. In Oregon, we initiated our work on EWC only this morning! Assembly details and small changes required a couple of weeks to resolve, but now we are ready to start EWC trials in Oregon for 2021. We are collaborating with Zasso (Indaiatuba, Brazil), working with an EH30 Thor unit (Figure 1).
The system generates a high voltage current that is applied directly to the plant via foliage contact with a metal bar. The voltage is conducted through the plant towards the roots. As high voltage passes through the plant, electrical resistance generates heat, leading to cell membrane rupture and plant death. Watch a short YouTube video of the process.
Power requirement
A PTO-driven generator produces electricity. A transformer increases the generator's voltage to 5,000-12,000 V. Tractor horsepower, and EWC unit configuration controls the voltage. The unit requires at least 75 hp power at the PTO, but I am inclined to say that you may want a bit more in wet soils with high clay content soil.
The USDA Crop Protection and Pest Management Program funds this work (award no. 2020-70006-32982). I would also like to acknowledge the Oregon Hazelnut Commission's support and the local growers who will participate in this project.
Original source: Weeders of the West (WoW) blog ∴ March 11, 2021
Start with a heaping helping of weeds in an orchard owned by an electrical engineer, then add in a weed scientist and a dash of Western IPM Center funding.
What you get is a promising (dare we say shocking?) new way to control weeds in certain landscapes.
It's electric weed control, and New Mexico State University's Paul Neher, the engineer, and Erik Lehnhoff, the weed scientist, are pioneering the technology.
“It uses a low dose of electricity over an extended period of time to kill weeds and unwanted small trees,” Lehnhoff explained. “It works extremely well.”
Test plots using the system are 100 percent weed free, and the pair have also shown it can prevent bindweed from climbing power poles.
Solar panels at UC Merced's Science and Engineering building. Credit: Elena Zhukova
The University of California has doubled its use of clean, renewable electricity over the past two years, and now uses more “green power” than any other university in the country, according to the Environmental Protection Agency. UC also leads other U.S. universities in the amount of renewable electricity it generates on its campuses.
Voluntary renewable energy sources account for roughly one-quarter of UC's electricity purchases, according to the EPA. Since 2017, UC's use of renewable sources of electricity has grown from 128M kilowatt hours per year to 273M kilowatt hours — the rough equivalent of taking more than 40,000 cars off the road.
“Over the next six years, UC will transition to 100 percent clean or renewable sources of electricity,” said David Phillips, UC's associate vice president of Energy and Sustainability. “UC's power company, which supplies electricity to its eligible campuses and medical centers, will hit that milestone even sooner, with all of its electricity coming from zero-carbon sources by the end of this year.”
In response to the urgent threat posed by the climate crisis, university leaders have pledged that UC will achieve carbon neutrality by 2025. Across the UC system, a wide range of operational efforts are underway to help meet that goal, from policies that mandate green building standards to more climate-friendly foods in the dining halls and medical centers.
One touch from old sparky and the current brings down the curtain—death by electricity. Could electricides serve farmers as a weed killer?
“Electricity is the most viable source of weed-control energy,” says grower Kevin Olson. “I don't believe there are other real long-term options.”
Against a backdrop of agriculture's ongoing herbicide resistance issues and pesticide litigation, the use of electricity as a viable means of weed management in general row crops is gaining traction as both old and new technologies capable of sizzling weeds attract attention. RootWave combines a phalanx of cutting-edge electricide technology and aims for market entry in 2020. Lasco Lightning Weeder, an electrical discharge implement, is a late-1970s machine catching renewed interest from producers.
See & Zap
The attempt to harness electrical energy as a means to manage vegetation dates back to the 1800s. Railroads attempted to clear brush growth with charged wires, and agriculture researchers experimented with various rudimentary devices into the 1940s. The concept and theory of electric control was present, but successful mechanical transference to farmland was absent.
However, the digital age has enabled technology to catch and pass supposition, according to Andrew Diprose, CEO of UK-based RootWave, who says electricides soon will be a common practice in weed management: “Beyond chemicals, people are desperate for another way to fight weeds and electricity is back on the agenda.”
Compared with other alternatives such as thermal and steam, electricity has major advantages, Diprose says. “No waste and no energy lost to ambient air or soil. The energy throughout the circuit treats the weed under the ground and boils it from the inside out.”
RootWave is partnering with Steketee on a pull-behind unit covering 8-12 rows using camera imagery to spot and zap weeds on the go, rolling at roughly 3 mph, with power sourced from the PTO. Essentially, visual recognition identifies weeds in real-time and RootWave makes contact with individual weeds to deliver a 5 kilovolt jolt (5,000 volts) with no soil disturbance.
The scalable unit serves all crop types and the voltage is flexible, Diprose explains. Initially, RootWave is targeting weeds up to 2”. “The fundamental technology in now in place so our next step is to scale and adopt the technology to treat mature weeds as well,” he explains.
Differences in silt loam, buckshot, heavy sand and general variations in soil types (and moisture content) sometimes require changes in voltage. There are also nuances with root type. “Fibrous or taproots aren't an issue, but a rhizome may require multiple passes,” Diprose describes.
What about microbial activity subjected to electricity? RootWave has undergone a series of agricultural environmental tests and Diprose says the results are promising: “The research is very positive, but we will get a definitive and scientific answer. We don't see it as a problem at all.”
And cost? “This will start as cost-comparable with herbicides, but in time, the potential is strong for a lower than chemical cost,” he adds. “There are basically no inputs other than capital depreciation.”
Brian Clevinger, co-founder of The Yield Lab Europe and managing director at Prolog Ventures, says electrical energy is a major draw for the farming industry. “There is an increasing swirl around resistance, costs and chemical litigation, and people are looking for innovation. A lot of people are looking into this technology and it could be a very, very big field. The need is huge.”
“Certainly there are general uses for RootWave technology in multiple spheres, but I think the average farmer could be using this product in a short time span,” Clevinger continues. “We're trying to help form partnerships to get this in the market. The technology is here and it's now an issue of getting people comfortable. Farmers want to be sure it works before they lay down money.”
Last Lasco Standing
In 1979, Kevin Olson was splitting time between his North Dakota corn fields in Grand Forks County and work as an electrical contractor when the Lasco Lightning Weeder was introduced in the region. Several potato and sugarbeet producers using Lightning Weeder units ran into mechanical issues and called on Olson's expertise. After successful repairs, Lasco's president caught wind of Olson's know-how, and within a few months, the Grand Forks grower was a Lasco dealer-distributor.
According to Olson, as of 2018, he is the last Lightning Weeder man standing and holds the rights to Lasco. Each year, he rents four units to soybean and edible bean growers spread across the Midwest (Illinois, Michigan, Missouri and Ohio) and has several units for sale.
“This technology is often unknown, but is amazing,” Olson describes. “It doesn't hurt the soil; we've tested a lot and never found any negative results. There's no damage to crops, and there are no safety issues for drivers.”
A metal applicator bar is charged with up to 14,500 volts of electricity, powered by a PTO generator. According to canopy height, the bar can be dropped to the ground or raised just shy of 4' high. Any vegetation contacted by the bar receives a full dose of voltage. However, Olson recommends reduced voltage (often a 30% drop) for early-season weeds, depending on moisture and dew (conductivity factors). “If you're running the bar over 5-6” weeds or less, you don't need full energy. Put 14,500 volts in small weeds and the power is so great you will carry a continuous arc that will destroy the crop. Later in the season, mature weeds get the maximum dose.”
Lightning Weeder has two models: 24' and 30'. The units can be front-mounted or utilized as a pull-behind. Olson suggests a tractor speed of 4 mph with low weed pressure; 2.5 mph with heavy weed pressure. “All this time and the Lasco is still very state of the art. There have been similar machines built, but they can't control amperage or voltage. To this day, Lasco technology holds so strong,” Olson says.
Spurred by renewed interest in electricides, Olson intends to restart the manufacture of Lightning Weeders. “I own the rights and I've been doing this since 1980. With a touch of the bar, the weed dies right down to the bottom of the root. Contact is death.”
Electric Avenue
Problems surrounding weed management have flipped the script on the potential of electricides, Olson says: “Herbicide issues are unrecognizable from what we dealt with as farmers 40 years ago. There are no two ways about it—the Lasco kills weeds and leaves behind no resistance issues. Electricity works and people are taking notice.”
Will weed-fighting machines wielding voltage be a common feature beneath equipment shops and sheds? Diprose believes row crop agriculture is on the cusp of weed-zapping options. “Mass acre farms will be able to control weeds with electricity,” he contends. “RootWave is going to be a common product across the farm world.”