What do you do with stubborn weeds? Zap ‘em.
High voltage is one method of dealing with troublesome interlopers, especially those that have developed herbicide resistance. But many hurdles remain.
“Certainly, electrocution enters into the conversation,” said Kevin Bradley of the University of Missouri.
Bradley is the coordinator of a research project that includes scientists from several universities. They have spent the past few years trying out varying modes of electric weed control in field trials. So far, efficacy has been limited.
“That market has primarily been in organics and specialty crop markets,” he said. “We started looking at whether the Weed Zapper can be used in conventional soybeans in the future.”
The machines include PTO-connected generators and hydraulic booms that electrocute the weeds as they touch them on a pass through a field. The booms are adjustable.
Weed Zapper, a brand of Old School Manufacturing, offers models with varying boom sizes. They range in cost from $69,000 for one with a 15-foot boom to $270,000 for a self-propelled model with a 60-foot boom.
While organic growers are the biggest users, the practice may be expanding to other types of farming.
“I would say that our current customer base is 70/30 organic to conventional. With that being said the tide is changing,” said Nicole Kroeger of Old School Manufacturing. “We are selling to more conventional farmers now than we ever had before. This is due to chemical price as well as some weeds resistance to chemicals.”
The company has set its sights high.
“We are currently developing a model that will enable The Weed Zapper to be used as the only weed control necessary for an operation,” Kroeger said. “This will enable a complete burn down before planting as well as eliminate the need for mechanical cultivation.”
The company Lasco also offers a product named the Lightning Weeder.
While efficacy is limited, the method can be successful in some conventional row-crop farming. It holds promise as a tool in the continuing battle against weeds resistant to herbicides such as glyphosate.
“It’s gaining popularity for use on herbicide-resistant weed escapes in row crops, but it’s not applicable to tall-stature crops such as corn,” said Bryan Young, a weed scientist at Purdue University. “Some say it’s more effective on broadleaf species than grass species, which is good from my perspective since we have more broadleaf problems currently.”
Bradley, Young and other scientists are seeking efficient methods of using electric weed control beyond its current applications.
“There are people in the Dakotas using them on sugar beets and those in the East Coast on vegetables,” Bradley said. “There isn’t a whole lot of research into soybeans and other crops like those we’ve been looking at.”
Researchers have been encouraged by the killing power of the machines, though it is limited to plants that are tall enough to be engaged by the boom.
“It may have some activity on perennial weeds since the current runs down the plant into the ground,” Young said. “It also may reduce the viability of the weed seeds on the plants being controlled.”
Safety is an obvious consideration. Manufacturers stress that safeguards are in place, but still caution operators to be aware of the potential danger of the machines. Lasco’s EDS Lightning Weeder has a safety interlock system for will break the circuit of the generator power output when the operator is not on the tractor, the boom gets too close to the ground or other actions present the possibility of improper electricity output.
The company warns that, “It must never be assumed that shields will adequately protect any person or animal from lethal shock.”
Bradley acknowledges the risk, though minor.
“It’s hazardous by its very nature,” he said. “It’s not like going out there and spraying. If something bad would happen — and I don’t know how, since there are a lot of safety precautions — if somebody touched it or something, it would be a bad day.”
Young pointed to other drawbacks. The equipment must run slowly and requires significant horsepower to operate anything with a toolbar longer than 15 feet. The height limitation is certainly a negative.
“Right now, it doesn’t help in row crops unless the weeds are taller than the crop,” he said. “Also, how can you use these late in the season if you have narrow-row soybeans? you would be driving over a lot of soybeans even if you had a 40-foot toolbar for each pass.”
Bradley acknowledges the limitations of the system, but believes it has a role to play in certain situations.
“We’ve never looked at this from the standpoint of weed management; it’s not good weed management,” he said. “But can work for control of weed escapes, if maybe we get to July and something has gone wrong, whether we’ve just discovered resistance for the first time or the fields wasn’t sprayed right.”
He doesn’t have high expectations for electronic weed control, but doesn’t dismiss the possibilities either.
“It’s research; that’s why we do it,” Bradley said. “It’s not the be-all, end-all answer, but we have found we can kill escaped weeds and seed viability of these weeds, so it might have fit in future.”
