Scattered seedlings & small trees

A wilding conifer is easiest to kill while it is still small. Seedlings and small trees (up to 20 cm diameter at breast height) can be dealt with using hand and machine tools, or basal bark herbicide application.

As conifers increase in age, size and abundance, they become more difficult to remove, and costs rise exponentially. They also start producing seeds – which spread and compound the infestation. Removing sparse young seedlings can cost as little as $1/ha, but treating dense infestations may cost over $10,000/ha. Wilding control: Guidelines for the control of wilding conifers

Stay safe:

  • Wilding conifer control methods can involve heavy work, sharp tools, dangerous machinery and chemicals, so take care and follow all health and safety precautions.
  • Contractors must be appropriately certified to use the machines and herbicides.

Removing seedlings and small conifers

There are two main ways to control wildings: physical (by hand or machine) and chemical. Seedlings and small trees can be controlled in the following ways:

  • Pulling small seedlings by hand

  • Cutting down small trees with loppers, axe or a handsaw

  • Using a chainsaw or scrub bar (a weedeater with a tungsten circular blade)

  • Ground Basal (base-of-tree) Bark herbicide Application (GABBA)

  • Mob-stocking to eat seedlings

  • Fertilising to encourage competition from grasses (best coupled with mob-stocking)

  • Using a mechanical mulcher.

See below for descriptions of each control type, and its good practices.

Hand pulling

Hand-pull seedlings up to 30 cm tall, or ease them out of the ground with a tool such as a grubber or mattock. The smaller the seedling, the easier it is to remove. Finding the seedlings (for identification, please follow the quick link below)  is the main challenge, but once they’re found, the job is straightforward. Volunteers are very helpful for this work.

Useful equipment:

  • gloves to protect your hands

Method:

  • pull the plant out of the ground
  • Shake the soil from the roots and lay plant on the ground
  • Don't leave bare soil, as it encourages other conifer seeds to germinate there

Health and safety:

  • Give appropriate instructions to workers and ensure they have the training and safety equipment needed.
  • Use a good pulling technique by bending your knees to protect your back
  • Know your limits – don’t try to pull up large seedlings, as this could result in injury

Cutting down with hand tools

Cutting down small and medium-sized conifers with hand tools is relatively simple, but labour intensive. It’s important to remove all branches and green foliage below the cut or apply herbicide to the stump or the tree may resprout (see Cut stump herbicide application below).

Loppers in use

web hand tools 2

Useful equipment:

  • Gloves to protect your hands

  • Mattock, lopper, handsaw or secateurs

Method:

  • Cut the tree as close to the ground as possible

  • Remove all branches and green needles from remaining stem

Health and safety: 

  • Give appropriate instructions to workers and ensure they have the appropriate tools, training and safety equipment needed.

Using a chainsaw or scrub bar

Chainsaws are useful for quickly cutting down dense stands of wildings, from small seedlings to saplings up to 15 cm in diameter at the trunk base; scrub bars (weedeaters with a tungsten circular blade) are used less often. Young trees may resprout from any green needles left at their base. So remove these, or else treat the stump with herbicide (see Cut stump herbicide application below).

Remove any green needles from the base

remove green needles

Tools:

  • Chainsaw or scrub-bar,
  • special sharpening gear,

  • associated safety equipment (ear protection, helmet, visor, chainsaw chaps, steel toe-capped boots)
  • optional spray attachment  for applying herbicide to cut stumps

Operators need to be skilled and hold appropriate certifications.

Herbicide control for seedlings and small wilding conifers

Herbicides are used for chemical ring barking, or to reduce the risk of regrowth from a cut stump.  Whenever you use herbicides, it’s essential to follow the safety and use instructions on the label. This includes wearing the proper protective clothing.

Also, when using herbicides, be careful of non-target species. Use low spray pressure at the right concentrations, spray directly on the tree, and avoid spraying or runoff into waterways.

Ground Basal Bark Application (GBBA)

Oil-based herbicide pre-mixtures chemically ring-bark unwanted conifers with trunk diameters of up to 20 cm.  Apply the herbicide using a knapsack sprayer, with the nozzle set at low pressure to reduce spatter, and apply a wide collar around the basal bark (bark at the base of the trunk). This is less labour intensive than delivering herbicide internally to the trunk, such as ‘drill-and-fill’, which is outlined in control methods for larger wildings.  It can take a year or two for a tree to die – so don’t worry if this doesn’t happen immediately.

Ground Basal Bark Application
Ground Basal Bark Application2 

Operators need initial training in good practices to effectively use this technique. Click this link and see more about Basal Bark Application methods.

Cut stump herbicide application

Where dead standing trees are not wanted, the trees can be felled with a chainsaw, scrub bar or handsaw and herbicide applied to the stump. The herbicide kills the root system and prevents regrowth. This is a good method on screes or where a thick grass sward surrounds the tree's base - ie. where it is very hard to get all the green needles around the base of the tree. Double-handling (cut stem and apply) is labour intensive, and herbicide needs to be applied to the stump at the time of felling.

If using X-tree Wet and Dry apply the herbicide to the bark on the remaining stump. Apply all other herbicides (eg a stump gel or metsulfuron methyl), to the top of the cut stump – particularly its edges (the ‘cambium’ layer).

Land management to reduce wilding seedlings

Burning
Burn-offs can be a relatively inexpensive solution for small wildings.  However burning carries significant risks and can be time consuming. Burning will require a resource consent and a fire permit.

Grazing 

Annual mob-stocking for long term control of small seedlings is a simple way of reducing wilding conifers in a farm setting. It’s only effective on very young seedlings (1-2 years old), and works best when combined with applying fertilisers to encourage other vegetation like grasses.

Fertilising controlled areas helps vegetation like grasses compete with wildings, but it may reduce native plant numbers. It’s a simple and effective option for professional farmers and best used in pasture and grasslands, especially when combined with grazing. However check your local nutrient management requirement sunder the RMA.

Mulching seedlings 

Depending on the machine size, mulchers can tackle seedlings through to trees with trunks up to 20 cm diameter.  Mulching is a very cost-effective tool for dense stands of small- to medium-sized wilding conifers on smooth sites that aren’t too steep. However, tractor mulchers may fail to remove low green foliage, especially on uneven sites. They also create an ideal soil surface for new seedling invasion, so it’s important to monitor the site after mulching, and follow up.  The choice of machine size important, as-is a skilled and experienced driver.

Further information on control methods Wilding control: Guidelines for the control of wilding conifers summarises the benefits of the various control methods and helps you choose an appropriate method.

For controlling trees with diameters at breast height over 20-30 cm, please follow the quick link below to Ground Control of larger trees and dense stands.

For aerial methods, please follow the quick link below to Aerial Control of scattered trees and dense stands.

Monitor your site

Besides removing trees, controlled areas need to be monitored regularly. Conifer seeds are viable for up to 6 years. Check controlled sites after 2-3 years and hand-pull any seedlings that have sprouted. Repeat this 2-3 years later.
Generally, if the site is clear of wildings after 6 years from the original control, the operation will be complete. Although if there is a seed source that cannot be removed, then control will be ongoing.  We recognise however the need for a standard good-practice method of post-control monitoring. This will be developed in future.


 

Ground control

For larger trees and dense stands

Aerial Control

For scattered trees and dense stands

Conifer identification

Identification guide for wilding conifers

Site restoration

Replant or restore the area you have controlled

Post-control monitoring

Monitor regularly to prevent re-infestation