Trees greater than 20cm trunk diameter or over 1.4m in height can be controlled by:
• felling - with a chainsaw
• ‘drill and fill’ - applying herbicide
• heavy machinery – tractors, diggers and bulldozers
Stay safe when controlling conifers:
Large wilding conifers may be felled with a chainsaw.
Benefits of felling:
Where standing dead trees could fall and create risks to high public use areas, such as tracks, campsites, roads or buildings, they are best controlled by directional felling. Felling, rather than ring barking or ‘drill and fill’, is sometimes preferred for aesthetic and safety reasons, as with the latter methods trees turn brown and can drop limbs or fall over a period of several years.
Issues with felling:
Felling by chainsaw is the most common way of removing medium-sized and large trees, but it is dangerous and requires training. It can also mean carrying considerable weight to the site (chainsaw, safety gear, fuel etc. Contractors must hold appropriate levels of chainsaw certification.
Standing dead wilding conifers provide shade and shelter for native plants, promoting recovery. Felling disturbs the plants growing around the conifer, and can encourage more conifer seeds to germinate in the disturbed ground. In a pasture situation, felling may reduce grazing and allow pests to establish. In such cases, ‘drill-and-fill’ herbicide application is better.
Also, where a dense infestation of large trees is felled, it can be hard to get around the site later for follow-up control work.
Only experienced and certified chainsaw users should fell conifers. Please use all recommended safety equipment.
Manual ringbarking of trees is not a preferred option for control of wilding conifers, as it takes a very long time for a tree to die and there is a risk of regrowth.
A traditional clearance method for medium-sized and larger wilding conifers involves using a digger, bulldozer, or mulcher to remove trees and place them in windrows for later removal or burning. It’s most effective on dense areas of medium-sized and large wildings. However, windrow removal can be costly and they don’t burn well.
This method can also have a major impact on non-target species (often natives) and creates the ideal soil surface for new seedling invasion. Monitoring the site for 5 years and removing re-sprouting wilding seedlings is essential, as is sowing or planting other desired species with low spread risk.
Digger and dozer conifer removal also requires skilled operators.
Herbicides control methods include drill-and-fill and cut stump procedures. Whenever you use herbicides, it’s essential to follow the safety and use instructions on the label. This includes wearing the proper protective clothing.
Drill-and-fill stem poisoning is simple and can give impressively quick results. It involves drilling holes into the tree trunk, at regular spacings around its diameter, and filling them with herbicide.
It is most useful for large trees in difficult terrain, in bush and shrublands where felling can create light-wells and promote new wilding establishment, and in pasture where felling can reduce grazing and allow pest establishment.
The drill and fill method is more reliable than ring-barking. However, like ring-barking, it’s best for areas where aesthetics and safety are not issues, as the trees turn brown and take several years to fall, dropping limbs and leaving a spar for some time.
Where dead standing trees are not wanted, the trees can be felled with a chainsaw and herbicide applied to the stump. The herbicide kills the root system and prevents regrowth. This is a good method on screes 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 Vigilant Gel or metsulfuron methyl), to the top of the cut stump – particularly its edges (the ‘cambium’ layer).
For information on aerial control using herbicide, please follow the link below Aerial Control of scattered trees and dense stands
For controlling trees with trunk diameter less than 20-30cm at breast height, please follow the link below Ground Control of scattered seedlings and small trees.
Besides removing trees, controlled areas need to be monitored regularly. Conifer seeds are viable for about 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, but occasional checks should still be made. 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.