HARRINGTON, P.E.I. - At a federal research farm in P.E.I. a machine called the Weed Zapper is using high-voltage electricity to kill unwanted plants as researchers test whether it can help farmers reduce herbicide use. The Weed Zapper will not replace chemical control — so farmers will still need traditional spraying or cultivation programs — but it can serve as a second pass for weeds that survive herbicides or are resistant to them. It also offers an organic option according to Nicolle MacDonald, a biologist with Agriculture and Agri-Food Canada. “It sparks joy,” MacDonald said with a laugh. “It’s just another tool in our toolbox when we’re trying to take an integrated approach to weed management.” How it works A height-adjustable copper pipe, which can span 3.5 to 4.5 metres, is mounted at the front of a conventional tractor and a wire connects the pipe to a large power generator attached to the tractor. As the tractor moves through a field, the tops of weeds brush against the pipe, or come close enough for electricity to surge through them. The plants begin to wilt within minutes and turn black as they begin to die hours after. There are limitations, said Dalhousie University weed scientist Scott White, who has also tested the tool. The weeds should be at least 15 to 20 centimetres taller than the crops to avoid killing both, since the Weed Zapper current can’t distinguish between them. “The machine is pretty lethal on vegetation in general,” White said. It’s most effective against annual weeds that grow from seed and die within a single growing season. Perennial weeds, like Canada thistle, can regrow from roots below the ground and might require repeated treatments. Fire risk Dry conditions bring another risk: fire. That’s a concern after a drought hit P.E.I. and much of the Maritimes last year. The machine works best on weeds that still contain moisture. As electricity surges through the plant, it essentially boils the water inside, damaging the weed’s tissue. That moisture also helps conduct the current and lowers the risk of fire. “I wouldn’t go over a field of wheat or barley that’s starting to dry down, even if the weeds are moist, because it has a chance to go to the barley and then set fire,” MacDonald said. To avoid potential fires, researchers say they avoid extremely dry fields and check local burn bans before operating the machine, which is equipped with sensors and a fire extinguisher. Costs Pesticides are creeping up in price White said, but herbicides remain one of the most affordable ways to control weeds. Some Weed Zapper units can cost more than $100,000, he added, making the machine a significant investment. But farm equipment is generally expensive, and the machine’s versatility and potential to reduce repeated chemical purchases could make it worthwhile. MacDonald said the machine could also be used in a cost-sharing arrangement, with a group of farmers or a co-operative splitting the expense. It can travel at roughly between three and 11 kilometres per hour, making it a relatively fast way to treat a field. Part of the research will include a cost-benefit analysis comparing electric weeding with conventional herbicide use. ‘Not a gimmick’ The concept of using electricity to destroy weeds dates back to the late 1800s, while the first electric weed-control equipment was developed in the 1970s, according to Agriculture and Agri-Food Canada. Electric weeding tools are more commonly used in South America and the United States, but interest has been picking up among Canadian producers over the past five to 10 years. “Many growers who are not familiar with it are going to be like, ‘Well, what the hell are you talking about?’” White said. “But when they see it in action and when they see what it can do, then I think they’ll realize that it’s not a gimmick, that it is legitimate technology for pest management.” MacDonald will test the Weed Zapper on potatoes, carrots, rutabagas, and beets in the coming weeks, with trials involving more vegetables planned for the next two years.
