Wilding-Pines

How to Control Wilding Pines in New Zealand

Botanical name: Pinus, Pseudotsuga & Larix spp.  |  Also known as: wilding conifers, wilding trees

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Quick answer:

Wilding pines are self-seeded exotic conifers spreading well beyond the forests they were planted in, now covering more than 2 million hectares of New Zealand. Small seedlings can be hand-pulled, but established trees need drilling and herbicide injection, cutting and pasting the stump, or (for scattered seedlings over a wide area) contractor spraying. The herbicide you need depends on the species: lodgepole pine (Pinus contorta) and Pinus pinaster need a different mix to every other wilding conifer.

• Look for pine, fir or larch trees growing outside forestry blocks, on hill country, high country, roadsides or conservation land
• Spreads on the wind from cones, sometimes for kilometres, which is why isolated "outrider" trees matter as much as dense stands
• Best control for established trees is drill and fill (metsulfuron-methyl for most species) or cut stump with a herbicide gel
• Lodgepole pine (Pinus contorta) does not respond to metsulfuron-methyl - it needs a different herbicide, and it's the species most likely to be growing near you

Wilding pines are one of New Zealand's biggest weed problems by area, not just a backyard nuisance. If you've got scattered pines, firs or larches coming up on hill country, roadside margins or land bordering forestry, here's what they are, why they're worth dealing with early, and how to control them properly.

What Are Wilding Pines?

Wilding pines (also called wilding conifers) are self-seeded exotic conifer trees growing outside the managed forestry blocks or shelterbelts they were originally planted in. They're the wind-blown offspring of pines, firs and larches planted from the 1800s through the mid-1900s for forestry, erosion control and shelter, and they now cover more than 2 million hectares of New Zealand.

Several species are involved, but lodgepole pine (Pinus contorta) is by far the most aggressive: it cones earliest, spreads furthest on the wind and has been a declared unwanted organism under the Biosecurity Act since 2010. Douglas fir (Pseudotsuga menziesii) is the next most invasive. Other species that go wilding include radiata pine, Corsican pine, Scots pine, ponderosa pine, maritime pine (Pinus pinaster), bishop pine, dwarf mountain pine and European larch. A single stand of wildings can throw seed for kilometres, so isolated outrider trees on your own land are often the leading edge of a much bigger infestation nearby, worth dealing with while they're small.

There's no approved biological control for wilding conifers in New Zealand, so control comes down to manual removal, herbicide, or a combination of both.

Where Do Wilding Pines Grow in NZ?

Wilding pines turn up almost anywhere seed can blow in from an existing forestry block, shelterbelt or established wilding stand, and they're now found from Northland to Southland.

• High country and hill country stations, particularly land adjoining or downwind of forestry blocks
• Conservation and public land, including iconic landscapes like Mt Tongariro, the Mackenzie Basin, the Coromandel coastline and land above hydro catchments
• Roadsides, farm tracks and unmanaged margins where seedlings go unnoticed until they're large
• Low-growing alpine, geothermal and tussock ecosystems, where dense wilding stands out-compete and eliminate native plant communities
• Nine regional councils (Northland, Waikato, Bay of Plenty, Horizons, Marlborough, Tasman, Canterbury, Otago and Southland) currently run coordinated control operations under the National Wilding Conifer Control Programme, so check with your regional council if you're in one of these areas - there may be funding or coordinated support available for larger infestations

Left unmanaged, wilding conifers are projected to spread across up to 7.5 million hectares within three decades, so early control on your own land, before trees reach coning age, is worth far more than waiting.

How Do I Remove Wilding Pines Manually?

Manual removal works well for small trees, and gets progressively less practical as trees get bigger. Hand-pull seedlings up to about 500mm tall, roots and all, and expect to go back over the same ground every couple of years as new seed keeps arriving on the wind.

For larger trees, felling is an option, but felling alone doesn't stop regrowth: strip all live growth off the stump and swab the fresh-cut surface with herbicide straight away, or the stump will resprout. Ring barking (two parallel axe cuts through the bark, about 5cm apart, right around the trunk) can kill a standing tree on its own over time, but success rates go up a lot when it's combined with herbicide applied into the cut. For most established trees, drill and fill or cut stump treatment (below) is now the more reliable and better-documented method.

What Products Control Wilding Pines?

For most wilding conifer species, a metsulfuron-methyl herbicide (MSF600) injected into drilled holes is the standard, well-documented method for trees over about 10cm trunk diameter. Smaller stems are better handled by cutting and pasting with a herbicide gel. Read on for the one important exception on species.

Drill and fill (trees over 10cm trunk diameter)

This follows the National Wilding Conifer Control Programme's Drill and Fill Good Practice Guide (V3.1, March 2025):

• Drill holes 13-20mm in diameter, 4-8cm deep (enough to hold about 10ml of mix), angled about 45° downward and 30° out from the trunk
• Drill into the base of the tree, as close to the ground as possible, near the main feeder roots
• Space holes evenly around the trunk. The bigger the tree, the more holes it needs - roughly 1 hole per 10cm of trunk diameter (measured at breast height), up to around 13 holes on a very large tree
• Fill each hole with 10ml of herbicide mix immediately after drilling, so it reaches the cambium layer at the outer edge of the sapwood
• Best done during active growing conditions, September to February

Test the mix pH before use and keep it above 7. If it tests below 7, raise it with sodium bicarbonate or soda ash (sodium carbonate) - hydrated lime also works but is more caustic and harder to dose accurately. Add FoamCrusher to the mix as well, to stop foaming issues when filling the drilled holes.

Cut stem / stump treatment

The National Programme's Cut Stump guide lists a metsulfuron gel option as suitable for "all species", but it never specifically names lodgepole pine the way the Drill and Fill guide does when it excludes it - so treat that as a general option for the species where drill and fill already works, rather than a confirmed fix for lodgepole. Cut the tree down and apply herbicide to the stump within a couple of minutes of cutting, before the cut surface dries out.

Use MetGel with caution: it's ground-residual and can travel through the soil to affect the roots of neighbouring trees or shrubs you want to keep, so avoid treating stumps close to desirable plantings.

Cut'n'Paste MetGel is not ACVM-registered - it's HSNO-approved for home garden use only, so it must not come into contact with food or feed crops, grazed pasture, or any other feed-producing area. Keep it to non-pastoral, non-cropping situations.

Large-scale or inaccessible infestations

For scattered seedlings over a wide area, steep or inaccessible country, or heavy infestations beyond what ground crews can reasonably drill or cut, aerial spraying is the usual approach - but it uses specialist tank-mix formulations (not a straight MSF600 mix) and is typically arranged through a contractor or the National Wilding Conifer Control Programme rather than done DIY. Talk to your regional council or a control contractor if this is the scale you're dealing with.

Common Mistakes

Quick Checklist

• Identify the species before choosing a herbicide - lodgepole pine (Pinus contorta) and Pinus pinaster need different products to every other wilding conifer
• Pull seedlings under 500mm by hand, roots and all, and recheck every couple of years
• For trees over 10cm trunk diameter: drill and fill with MSF600 50g per litre of water (pH above 7, plus FoamCrusher), except on lodgepole pine or Pinus pinaster
• Unsure of species, or drilling isn't practical? Cut stump and paste with Cut'n'Paste MetGel instead - for confirmed lodgepole pine, use a certified contractor with the triclopyr/aminopyralid product, not MetGel
• Fill drilled holes with herbicide within seconds of drilling, and paste cut stumps within a couple of minutes of cutting - both lose effectiveness once the cut surface dries
• Large or hard-to-access infestations: talk to your regional council or a control contractor about coordinated/aerial options

Next step: Confirm the species, then order MSF600 and FoamCrusher for drill and fill, or Cut'n'Paste MetGel for cut stump treatment - contact us if you're not sure which species you've got or which method suits your situation.

Frequently Asked Questions

Does MSF600 kill all wilding pines?

No. MSF600 (metsulfuron-methyl) controls most wilding conifer species when drilled and filled at 50g per litre of water, but it does not work on lodgepole pine (Pinus contorta) or Pinus pinaster. Lodgepole is the most common wilding conifer in NZ, so check the species before you start. Lodgepole needs a triclopyr amine + aminopyralid product applied by a certified contractor - we can't confirm metsulfuron (including the MetGel cut stump gel) as an effective alternative on this species.

What's the mixing rate for drill and fill on wilding pines?

50g of MSF600 (600g/kg metsulfuron-methyl) per 1 litre of clean water, with the mix pH kept above 7. Inject 10ml into each drilled hole immediately after drilling. This matches the National Wilding Conifer Control Programme's Drill and Fill Good Practice Guide (V3.1, March 2025).

How many holes do I need to drill?

It scales with trunk diameter, measured at breast height: roughly one hole per 10cm of trunk diameter, spaced evenly around the tree, up to around 13 holes on a very large tree. This method is for trees over about 10cm trunk diameter that are accessible to ground crews.

Can I use drill and fill on a small pine seedling?

Drill and fill is for established trees over about 10cm trunk diameter. Seedlings up to 500mm tall are better hand-pulled, roots and all.

How long does it take a drilled tree to die?

Expect the crown to start browning within a few weeks, with the tree fully dead over the following months. Timing varies with tree size, species and season, so don't expect an overnight result.

Do I need any special certification to treat wilding pines myself?

Standard drill and fill with MSF600, and cut stump treatment with Cut'n'Paste MetGel, don't require special certification beyond following the label directions and wearing the recommended protective equipment. The neat triclopyr amine + aminopyralid option needed for lodgepole pine does require GROWSAFE certification and an eye wash station on site, which is why we'd suggest a certified contractor for that species.

Further Reading

• Gorse - another tough scrub weed MSF600 controls, often found alongside wilding pines on hill country
• Blackberry - a common companion weed on the same marginal land wilding pines invade
• National Wilding Conifer Control Programme - Good Practice Guides - the source technical guides for drill and fill, cut stump and aerial methods