Mr Hensman told more than 60 people at the group’s annual meeting in Queenstown on Wednesday funding would have to come from the "public purse" to be sustainable.
In the Wakatipu, the good work being done by the group and others — such as the Wakatipu Reforestation Trust and the Routeburn Dart Wildlife Trust — would be undone if wilding trees were left to spread unchecked, Mr Hensman said.
"Unless we make noise and get the national funding required, all I have outlined above will come to pass sooner than we imagine."New Zealand had a habit of procrastinating about pest issues until the "horse has bolted".
"All of us have a role to play by influencing our neighbours and friends to recognise the urgency of the issue, and be willing to pay to fix it at a national level."
The group is budgeting to spend $1.9 million on wilding control in the 2018-19 year.Its annual report for last year shows its operating income was just under $2 million.
It had total grants of about $1.75 million, including $945,000 from the Ministry for Primary Industries and $500,000 from the Queenstown Lakes District Council.
Landowners made contributions of about $200,000.
Wilding pines
Control in the Wakatipu 2017-18
• Aerial lancing 22,100ha
• Ground clearance 2176ha
• Helicopter boom spraying 359ha
• 12,000 wildings removed from The Remarkables
• 12,492 wildings removed or sprayed on Cecil Peak
• 9400 volunteer hours
• $1,945,568 spent
