The wilding pines issue is being taken seriously by the Department of Conservation, as about 50,000ha of land in the South Island is affected by the problem annually.
Doc director-general Lou Sanson was in Queenstown on Monday to speak at a public meeting about planned wilding control work in the resort this summer, which would focus on creating a containment line in the wilding forest above the Fernhill subdivision.
The area comprises about 30ha of the 200ha wilding forest.
Mr Sanson said Doc was working with local government, the Ministry for Primary Industries and others to try to halt the spread.
''Without it [control] we will lose large areas of New Zealand's natural tourism landscape, particularly as the alpine freezing line gets higher.''
While it was becoming more difficult to control the spread of wilding trees, the cost of doing so had halved since 2007.
In Queenstown the Douglas fir would be controlled by aerial boom spraying, using Answer herbicide, with a 250m buffer from any dwellings.
The $1.4 million project would be carried out before the end of February.
Mr Sanson said every seven years wildings gave off seed and it was ''critical'' to stop the trees before the next seeding cycle.
The Wilding Control Group said it would take up to two years for the trees to die after spraying.
How long trees would stay standing dead was unknown.
''Trees tend to melt rather than fall over. The limbs come off first, then the top section and so on.''
The programme was being funded by a range of partners including the Queenstown Lakes District Council, Doc, Skyline Enterprises, Central Lakes Trust, the Lotteries Commission, Land Information New Zealand and concerned landowners and managers.
