What does it look like?
Wilding conifers or wilding pines can grow into tall, cylindrical trees up to approximately 70m tall and 2m in diameter. Their leaves are needle-like and have a resinous scent when crushed. They do not produce flowers but grow cones instead.
Wilding conifers can grow in a range of habitats, including grasslands, shrublands, scrub riparian ecosystems and coastal dunes, from high altitudes to the near sea level. Low stature native vegetation/ecosystems such as shrublands are particularly vulnerable to wilding conifers.
Spread by seeds, they can start reproducing at 8 years of age, or even younger in some cases. Known seed viability ranges from 4 years (P.contorta) to 15 years (Pseudotsuga menziesii).
Why is it a problem?
When conifer cones mature on the tree, they open to release masses of wind-blown seeds. These seeds travel kilometres downwind and need no special conditions to take root and grow.
Wilding conifers are a major problem in areas where there is no native forest, such as above the bush line, in mineral belts and tussock grasslands. In these areas, wilding conifers modify the natural ecosystems so much that the unique New Zealand landscape is lost and native plants and animals are evicted or die.
In native forests, wilding conifers compete for space with native trees and plants and don't provide the advantages that native trees do, such as food for native birds or insects. Their needles form an acidic carpet which discourages regeneration of native forest floor species. They can be visually intrusive in native forest areas.
- Drill holes at 100mm intervals around the trunk and put in undiluted glyphosate or 20mls of 20g metsulfuron-methyl (600g/kg e.g. Escort ®) per 1 litre water.
- Spray a collar around the trunk with one part triclopyr (300g/1 eg Grazon®) to three parts biodiesel (eg codacide).