An invasive weed in Lake Benmore could be targeted by a new spray that has the potential to kill it, not just control it.
Land Information NZ is planning to trial the spray, Aquathol, on lagarosiphon, which has established itself in the Ahuriri arm of Lake Benmore.
A Southland trial had shown significant success in killing the lake weed.
However, before it could be used in Lake Benmore, Linz would need consents from Environment Canterbury and the Environmental Risk Management Authority, Linz strategic communications team leader Dionne Barton said.
Past control in Benmore has used the weed spray Diquat which suppresses and controls the weed, but does not kill it outright.
The new spray, recently approved for use in New Zealand but already used successfully on another invasive weed in the United States, can kill lagarosiphon.
Control methods, including Diquat spraying, hand weeding and suction dredging, would still be used in Lakes Dunstan and Wanaka, she said.
The Southland trials were carried out by the National Institute of Water and Atmospheric Research (Niwa) and Environment Southland.
The herbicide removed all fragments of the weed from a pond and left many desirable aquatic plant species intact.
Environment Southland senior biosecurity officer Keith Crothers said.
Indications were that, in certain situations, it could be possible to eradicate lagarosiphon at a reasonable cost with little environmental impact.
"This is highly significant, because the negative impacts of aquatic weeds are immense," he said.
They restricted water flow, raising water levels and impeding drainage, and blocked irrigation and hydro-electricity intakes.
Recreational activities were also affected and native aquatic ecosystems seriously damaged.
