The unchecked spread of wilding pines can pose a real risk to biodiversity, landscape and recreational values.
They compete for space with native trees and plants but do not have the berries and nectar that encourage native birdlife and insects. A carpet of pine needles discourages regeneration of native forest floor species.
Wilding pines pose a threat to the landscape values of covenants as they can eventually dominate regenerating native forest.
They may reach many metres above the canopy of the bush and are especially noticeable on bush margins.
Once a covenant is fenced and protected, the lack of grazing by stock can hasten this spread and establishment.
Right: A typical wilding pine on a steep sidling in Alec Olsen’s 54ha covenant beside the Mangaone River in Hawke’s Bay.
With contributions from the Biodiversity Condition Fund, QEII, Hawke’s Bay Regional Council and the landowner, wilding pines in this covenant have now been controlled.
Wilding pine spread is very predictable. Guidelines are available from your Regional Council or the Department of Conservation on safe and efficient control.
See Wilding conifers: Prediction and Prevention, Open SpaceTM Issue 60, March 2003 or download here (PDF, 824KB).
The most appropriate method for controlling wilding pines depends upon factors such as the extent of the infestation, density of trees, size and age of trees, native species present, access to the site, and the skills and resources available.
Where immediate complete control is not possible, give priority to controlling isolated trees and mature trees on ‘take off’ sites such as ridges and hilltops from where seeds are likely to be blown long distances.
Large infestations should initially be contained by controlling trees on the perimeter before they seed. Follow-up control is important at intervals of 5 to 10 years.
Hand pulling is the most effective option for small seedlings less than 0.5m tall. Repeat every 3 to 5 years.
Felling is an effective method of control provided all live foliage is removed from the stump.
If this is not possible because of the terrain, apply herbicide to the stump. Use glyphosate (e.g. Roundup®) 200ml /1 litre water, plus 20ml penetrant (e.g. Pulse®).
Where felling is difficult, pines can be poisoned by drilling holes at a downward angle about 50mm into the trunk.
Fill with about 25ml of neat glyphosate. Space holes about 200mm apart around the trunk.
A modified method using metsulfuron has been trialled and found to be as effective as glyphosate and significantly faster.
For full details of herbicide use, see Environment Bay of Plenty Pest Plant Control Factsheet 21 – Wilding Pines or download here (PDF, 106KB) www.envbop.govt.nz and Marlborough District Council/ Department of Conservation Wilding Radiata Pine – Poisoning Factsheet 174 or download here (PDF, 195KB) www.marlborough.govt.nz
One of the most important management issues is the restoration of infestation sites once wilding pines have been removed.
Options include sowing seed of native shrub species or interplanting infestations with native tree species and then removing the pines once the natives are well established.
Wilding pine control in covenants can be difficult as protected areas are often in steep terrain that is difficult to access.
Damage to native vegetation and covenant fences is a risk. Felling with the assistance of an excavator may be required to avoid damage.
Above: A pine in a covenant on the Te Maire property in Hawke’s Bay eight months after being poisoned.
With contributions from the Biodiversity Condition Fund, the landowners, Hawke’s Bay Regional Council and QEII, scattered wilding pines were controlled in three adjacent covenants on the Te Maire property owned by the Williams family at Tikokino in Central Hawke’s Bay.
This series of covenants is one of the oldest in Hawke’s Bay, with the first covenant registered in 1984.
The totara forest covenants have high landscape values. Felling of the pines was the most appropriate method of control, some with the assistance of an excavator to avoid damaging covenant fences. Some poisoning was also undertaken in steep areas.
Above: Before control: Despite a very good canopy cover, wilding pines in the Te Maire covenants were increasing in number from the seeds of mature trees.
Above: After control: Pines in the protected forest dying following poisoning.
Above: Large old pines were poisoned by making multiple chainsaw plunge cuts into the base of the trees and injecting poison with a drench pack.
On SH5 between Napier and Taupo, a kanuka covered gorge was protected by Ross Bramwell with an 87ha covenant in 2004.
Wilding pines were spreading through the particularly steep gullies. Ross had already successfully poisoned pines in the upper part of the covenant so with contributions from the Biodiversity Condition Fund, Hawke’s Bay Regional Council, QEII and the landowner, further poisoning work was carried out.
Above: Dying pines in the steep gorge in Ross Bramwell’s covenant following poisoning by the contractor Pan Pac Forest Products Limited.
Above: Drill hole and poison.
‘These projects brought together a range of agencies to support landowners wanting to solve the problem of wilding pines in their covenants,’ says Troy Duncan, QEII Hawke’s Bay Regional Representative.
‘We are still experimenting with poisoning recipes as we don’t yet know how little we can use and still kill the tree.
'There are different factors like the time of year and season and which way the sap is flowing to take into account.
'The underlying message I have learnt so far is that when it comes to poisoning pines, don’t be shy on the chemical.
‘Getting to the tree and the labour are the most costly and time consuming parts of the job.
'The chemical is the relatively inexpensive component, so use enough the first time round.’
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Open SpaceTM Magazine No. 78 March 2010 © QEII National Trust