Control


Despite the scale of the problem, wilding conifers are relatively easy to control - their spread is visible and predictable, and seeds rot quickly in the ground. Choosing the control technique(s) is best suited to an area, depends on the density and spread of infestation, its surrounding environment, and accessibility to the site.

Each of these control techniques have been researched and refined throughout the life of the wilding conifer programme. These techniques capture the collective national knowledge of stakeholders and operators involved in conifer control, and are now accessible as good practice guidelines.

The good practice guidelines (where available) are linked below. Note, these guidelines will be refined as new management techniques and research emerge. To enable updated guidelines, any feedback is welcomed through  wilding.conifer@mpi.govt.nz 

Good Practice Guidelines

Aerial Foliar Spray Application (AFSA)

  • Boom spraying - spraying herbicide onto foliage in a large swath from the air. A cost-effective way of treating large, dense infestations (over 80% canopy cover), and where damage to surrounding, woody vegetation is not an issue. 
  • Spot spraying - spraying herbicide onto foliage to a specific area from the air. Best where canopy cover is less than 80% but basal area of conifers not fully accessible to allow use of ABBA (i.e. trees densely grouped)or if there is a potential to effect surrounding valued vegetation. 
Aerial Foliar Spray Application (AFSA) Good Practice Guide

Ground Basal Bark Application (GBBA)

Oil-based herbicide which chemically ring-barks conifers with trunk diameters of up to 20 cm. This is less labour intensive than drill-and-fill, but can take a couple of years for herbicide to take full effect.

Ground Basl Bark Application (GBBA) Good Practice Guide

Drill-and-Fill

Involves drilling holes into the tree trunk, at regular spacing’s around its diameter, and filling them with herbicide. It is most useful for large trees as an alternative to felling in difficult terrain where felling can be unsafe, or where felling can encourage pest establishment or reduce grazing. 

Hand-held tools/manual removal 

Removing conifers through, hand-pulling, hand-tools, and felling with chainsaws. Best method in easily accessible areas, on seedlings and small trees (up to 20 cm diameter at breast height).