Using electricity to kill weeds is proving effective, a trial at Oxford Botanic Garden (OBG) has found.
According to senior curator Alison Foster, the apparatus built by engineering consultant Roger Balls and electrical engineer Dr Mike Diprose had shown success in initial trials on rampant onion weed, Nothoscordum (approx equal to) borbonicum.
Diprose, who runs Spectrum-tec, said electrical weed-control involves the application of very high-voltage, short duration pulses or a high-voltage AC or DC current of 750V-3kV.
He added that the method is environmentally friendly, leaving no harmful residues. Although it has been practised for more than 100 years, it has not become a widely established means of weed control possibly due to lack of suitable equipment and unfamiliarity, he said.
"But as more chemicals are removed from regulated use, alternative herbicide control methods are needed. Electrical weed-control is another option," said Foster.
She added: "It is therefore extremely important for us to find alternatives to pesticides because legislation is restricting the choices we have to kill weeds.
"Any workable alternatives that are sustainable as well as safe are definitely worth investigating."
How the weed-control equipment works
"We used a portable transformer pack running off 240V mains power, in the 1kV and 3.5kV ranges. The plants were touched with a handheld, insulated lance for one-to-two seconds until they drooped or collapsed in a cloud of steam. We returned about two weeks later and retreated new plants.
"We would like to establish whether the electricity breaks down the plant's apical dominance by which it sends up only one new stem if the main bulb is killed.
"We envisage that operators would be licensed in the same way as sprayer operators. We are also building a tractor-mounted, field-sized electrocutor for the vegetable sector and are involved in trials on weed control in blackcurrants and raspberry beds."
Roger Balls, Engineering consultant